94-26598. Guidelines for Preventing the Transmission of Mycobacterium Tuberculosis in Health-Care Facilities, 1994  

  • [Federal Register Volume 59, Number 208 (Friday, October 28, 1994)]
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    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 94-26598]
    
    
    [Federal Register: October 28, 1994]
    
    
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    Part II
    
    
    
    
    
    Department of Health and Human Services
    
    
    
    
    
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    Centers for Disease Control and Prevention
    
    
    
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    Guidelines for Preventing the Transmission of Mycobacterium 
    Tuberculosis in Health-Care Facilities, 1994; Notice
    DEPARTMENT OF HEALTH AND HUMAN SERVICES
    
    Centers for Disease Control and Prevention
    
    
    Guidelines for Preventing the Transmission of Mycobacterium 
    Tuberculosis in Health-Care Facilities, 1994
    
    AGENCY: Centers for Disease Control and Prevention (CDC), Public Health 
    Service, HHS.
    
    ACTION: Notice of Final Revisions to the ``Guidelines for Preventing 
    the Transmission of Mycobacterium tuberculosis in Health-Care 
    Facilities, 1994.''
    
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    SUMMARY: The purpose of this notice is to print the final ``Guidelines 
    for Preventing the Transmission of Mycobacterium tuberculosis in 
    Health-Care Facilities, 1994,'' and a summary of comments and responses 
    to those comments.
    
    EFFECTIVE DATE: October 28, 1994.
    
    ADDRESSES: This document is also being printed in its entirety as a 
    Morbidity and Mortality Weekly Report (MMWR), Recommendations and 
    Reports. For copies of the MMWR printing, call CDC's Voice Information 
    System (VIS) at (404) 639-1819 or write to the Centers for Disease 
    Control and Prevention (CDC), Information Services Office, Mailstop E-
    06, Atlanta, GA 30333. An electronic version of this document will be 
    available via Anonymous FTP from ftp.cdc.gov after November 18. Type 
    ``Anonymous'' for the user name and your e-mail address for the 
    password. Select the pub directory, then the tbdoc subdirectory. 
    Retrieve the README file for instructions on document viewing and 
    printing.
    
    FOR FURTHER INFORMATION CONTACT: CDC's Voice Information System at 
    (404) 639-1819.
    
    SUPPLEMENTARY INFORMATION:
    
    Background
    
        On October 12, 1993, CDC published ``Draft Guidelines for 
    Preventing the Transmission of Tuberculosis in Health-Care Facilities, 
    Second Edition,'' in the Federal Register at 58 FR 52810 with a 60-day 
    comment period (which was extended to January 13, 1994). More than 2500 
    comments were received and reviewed. The following represents a summary 
    of all major comments and a response to each. All comments were 
    reviewed and considered in developing the final guidelines. Changes 
    were also made to increase clarity and readability.
    
    Comments and Responses
    
    Section I. Introduction
    
    Section II. Recommendations
    
    A. Assignment of Responsibility
        No comments received on this section.
    B. Risk Assessment, Development of the TB Control Plan, and Periodic 
    Reassessment
        Comments: Provide more flexibility in levels of risk to accommodate 
    facilities that rarely or never provide services to patients with 
    tuberculosis.
        Response: Two new categories--``very low risk'' and ``minimal 
    risk''--were added to accommodate such facilities.
        Comments: Rationale for selecting six patients per year in a given 
    area as a criterion for risk level seems arbitrarily defined.
        Response: This criterion is based on surveys conducted by CDC in 
    conjunction with the American Hospital Association, the Society for 
    Health Care Epidemiology of America, and the Association for 
    Professionals in Infection Control and Epidemiology. These surveys 
    suggest an increased risk of tuberculin skin test conversion in 
    employees working in facilities admitting six or more TB patients per 
    year.
        Comments: Repeat skin testing at 3-month intervals in high-risk 
    settings is too frequent.
        Response: The high-risk setting is essentially an outbreak setting, 
    in which there is evidence of transmission of Mycobacterium 
    tuberculosis. In this situation, it is reasonable to conduct follow-up 
    skin testing 12 weeks (3 months) after the initial testing. If there is 
    no evidence of further transmission and any deficiencies in infection 
    control practices and facilities have been corrected, the area is no 
    longer considered high risk, and there is no need to continue testing 
    every 3 months.
        Comments: A cluster of skin test conversions is defined as two or 
    more conversions in one area within 3 months; however, because of the 
    limitations of skin testing, this may not represent true conversions 
    due to nosocomial transmission.
        Response: It is assumed that a cluster would be investigated to 
    determine the likelihood that it truly represents nosocomial 
    transmission. The situation would be classified as high risk only if 
    this evaluation supported a conclusion that nosocomial transmission had 
    occurred. The recommendation will be modified to clarify this point.
        Comments: Retesting all employees in a area when a single 
    conversion has occurred may not be warranted.
        Response: Clarified wording of this section.
    C. Detection of Patients Who Have Active TB
        Comments: Provide more information and place more emphasis on early 
    detection, specifically those categories of patients in whom TB should 
    be suspected.
        Response: Reemphasized the need for protocols for early detection 
    and the need to review and revise these protocols periodically. In 
    addition, explained that the index of suspicion varies from place to 
    place, depending on various factors, including the prevalence of 
    infection in the population served.
        Comments: Increase the recommended turnaround time for stat smears 
    for laboratories unable to use rapid methods and remove the term ``stat 
    smears'' from recommendations.
        Response: Reemphasized the importance of rapid laboratory results. 
    Discouraged batching of specimens and added the recommendation that 
    laboratories that perform mycobacterial tests infrequently refer 
    specimens to an experienced laboratory. Removed the term ``stat 
    smears''.
    D. Management of Patients in Ambulatory Care Settings and Emergency 
    Rooms
        Comments: Clarify the requirement that patients should wear 
    surgical masks but that health care workers (HCWs) must wear 
    particulate respirators.
        Response: Added a footnote to explain the rationale for each: one 
    to protect the worker from infection and the other to decrease the 
    amount of droplet nuclei in the air produced by the patient.
        Comments: Do not require isolation rooms in all ambulatory care 
    settings.
        Response: Restated and clarified that if TB patients are seen 
    infrequently or not at all in a facility, an isolation room is not 
    needed. However, there must be a protocol for referral and periodic 
    risk assessment.
    E. Management of Hospitalized Patients With TB
        Comments: Do not require isolation for most or all pediatric 
    patients.
        Response: Provided some examples of potentially infectious 
    pediatric TB patients and added a section explaining the need to 
    evaluate parents as possible source of infection.
        Comments: Radiology should not, and in many facilities, cannot have 
    a separate area for TB patients.
        Response: Clarified the section to refer only to facilities where 
    many TB patients are seen.
        Comments: Provide clearer recommendations for visitors and their 
    use of respiratory protection.
        Response: Expanded the recommendations to make clearer.
        Comments: Requiring three negative smears to release a patient from 
    isolation is excessive and unnecessary, especially for suspected TB 
    cases.
        Response: Clarified: if TB has been ruled out, there is no need to 
    retain the patient in isolation. Reiterated that if TB has been 
    confirmed the patient should have three consecutive negative sputum 
    smears collected on different days.
        Comments: The recommendation that TB patients not be discharged to 
    home if an HIV-infected person or young children are in the household 
    is potentially problematic.
        Response: Clarified that this is one of many factors that should be 
    taken into consideration when planning to discharge TB patients, not a 
    hard-and-fast rule.
        Comments: Labeling door TB Isolation would breach patient 
    confidentiality.
        Response: Recommended using the term Isolation rather than TB 
    Isolation giving hospitals the flexibility to label doors according to 
    individual policies or practices.
    F. Engineering Controls
    Ultraviolet Germicidal Irradiation
        Comments: Data are insufficient to recommend the use of UVGI. 
    Greater emphasis should be placed on the use of UVGI in health care 
    settings.
        Response: No change. No new information was provided and the 
    current guidelines were considered appropriate.
    Ventilation
        Comments: Provide specific recommendations on engineering controls 
    as they relate to risk level. Provide information on how to evaluate 
    air changes per hour (ACHs). There are no data to support requirement 
    for six or more ACHs.
        Response: Clarified: 6 ACHs are an absolute minimum, and a level of 
    12 or more ACHs are recommended, especially in new construction. 
    Referred to table S3-1, which provides the number of air changes per 
    hour and the minutes required for removal efficiencies of 90.0%, 99.0%, 
    and 99.9%. The 12 ACHs or more recommendation was arrived at by both 
    use of this table and NIOSH experimental data. Added discussion on the 
    benefits of higher ventilation and recommended ideal performance 
    criteria.
        Comments: Provide retrofit information and some examples of 
    alternative methods for achieving required ventilation.
        Response: In response to requests for information on alternative 
    methods, retrofit information, and interim guidelines, expanded the 
    introduction to this section and introduced a clearer hierarchy of 
    ventilation methods.
        Comments: Provide clearer directions on bronchoscopy location and 
    ventilation requirements.
        Response: The confusion about bronchoscopy location resulted from 
    inconsistency in the guidelines in relation to performing the procedure 
    in the operating room vs. an area of patient isolation. Clarified this 
    point.
    Room Units
        Comments: Provide information on room air ``cleaning'' units. Can 
    these units serve as a substitute for not having six or more ACHs?
        Response: Revised the document to present more clearly the 
    potential use of air cleaning units in areas where air changes are 
    limited and to set their place in a control hierarchy. In addition, 
    further clarified the importance of placement, performance, and 
    potential limitations. Added a statement that manufacturers of these 
    units should provide documentation of both the efficiency of the HEPA 
    filter and the efficiency of the device in lowering air contaminant 
    levels.
    Negative Pressure
        Comments: Because smoke can be an irritant, the use of smoke tubes 
    for continuous pressure monitoring should be replaced with flutter 
    strips. Daily monitoring of negative pressure is unnecessary and labor 
    intensive.
        Response: Made no change in the recommended monitoring schedule. 
    The concern over the use of smoke tubes is unfounded. Controlled tests 
    by NIOSH have shown that the quantity of smoke that is released is so 
    minute that it is not measurable in the air. The location of the 
    patient and the length of time the patient is exposed dilute the smoke 
    to several orders of magnitude below an 8-hour exposure limit. It is 
    not practical and often not effective to use flutter strips or 
    continuous monitoring devices as alternatives to indicate directional 
    air movement. The air flow (due usually to the small clearance area 
    under a door) is insufficient to move the flutter strip. Likewise, low 
    negative pressure, which will satisfactorily provide adequate 
    directional air flow into the isolation room, may not be readable on 
    continuous monitoring devices. Devices must be capable of reading 0.001 
    inch of water, the established minimum, to be effective. Clarified the 
    overall guidance in this area by indicating the use of smoke as the 
    optimum test procedure and clearly stating the potential results of 
    flutter strips and continuous instrumentation. Used illustrations to 
    clarify procedures for setting negative pressure.
    HEPA Filtration
        Comments: The recommendations on the use of HEPA filtration in a 
    ventilation system are not supported by the data. The purpose of its 
    use is unclear.
        Response: Addressed the general confusion on the use of HEPA 
    filtration by rewording the section.
        Comments: Provide information on the necessity of ``bag in--bag 
    out'' and ``red bag'' use when changing filters.
        Response: Eliminated the bag in--bag out requirement since there is 
    no evidence that it is needed. Retained the red bag recommendation 
    (treating filters as infectious waste).
    G. Respiratory Protection and Supplement 4. Respiratory Protection
        Comments: HEPA filtered masks are too expensive, and no data 
    support their use. Instituting a fit-testing program and, in general, a 
    respiratory protection program is too expensive. HCWs will not wear the 
    masks. The masks are uncomfortable, impede communication, and interfere 
    with general patient care.
        Response: Retained the original performance criteria on respiratory 
    protection; however, details on specific respirators such as dust-mist 
    and dust-fume-mist were removed. Removed the respiratory protection 
    table and accompanying performance characteristics in the supplement in 
    anticipation of the new certification process. Retained the 
    explanations about fit, fit testing and fit checking, and the elements 
    of a respiratory protection program. Added a statement about ongoing 
    research being conducted on various forms of respiratory protection.
        Comments: The performance criteria for respiratory protection for 
    HCWs exposed to tuberculosis fail to take into consideration the 
    potential higher level of risk for workers in selected settings (e.g., 
    bronchoscopy performed on patients suspected of having TB or autopsy 
    performed on deceased persons suspected of having TB at the time of 
    death).
        Response: Clarified that the facility's risk assessment may 
    identify those limited settings where the estimated risk for 
    transmission of M. tuberculosis may be such that a level of respiratory 
    protection exceeding the standard criteria is appropriate.
        Comments: NIOSH certification process should be changed to 
    accommodate the certification of a more appropriate mask for use in 
    health care settings.
        Response: On May 24, 1994, CDC published in the Federal Register 
    (59 FR 26850) a Notice of Proposed Rule Making on revised certification 
    requirements for respiratory protective devices. The certification of 
    air-purifying respirators under these proposed requirements would 
    enable respirator users to select from a broader range of certified 
    respirators that meet the current performance criteria in this 
    document.
        Comments: Provide information on the storage and reuse of 
    respirators.
        Response: Expanded the general guidelines on the reuse of 
    respirators classified as disposable and those with replaceable 
    filters. Retained the original suggestion to refer to manufacturers 
    recommendations concerning storage and reuse.
        Comment: It is unclear which facilities must have a respiratory 
    protection program.
        Response: Clarified that facilities that do not have isolation 
    rooms for TB, that do not perform cough-inducing procedures, and refer 
    all potential TB patients need not have a respirator program but must 
    perform a periodic risk assessment, have protocols for referral, and an 
    infection control plan that is periodically reviewed.
    H. Cough-Inducing Procedures
        No comments were received that differed substantively from those 
    covered in other sections of the document.
    I. Education and Training of Health-Care Workers
        Comments: In general, the comments supported the concept of 
    education for HCWs. Persons from a number of specialties noted that 
    educational programs should be flexible and should allow for the 
    selection of information to be included in these programs and that the 
    frequency of training should be based on the risk of TB transmission in 
    the facility or area. Some suggested emphasis on educating physicians 
    in the early recognition and proper treatment for persons with 
    tuberculosis. Because of difficulties with compliance with attendance 
    and the time needed away from the job in the busy health care 
    environment, concern was expressed about the increasing requirements 
    for mandatory annual educational training sessions on various subjects 
    (bloodborne pathogens, fire safety, hazardous exposure). A few persons 
    suggested that CDC provide standardized training materials. A few 
    commented on the expense of the training program, including the 
    respirator training program.
        Response: Modified section to allow more flexibility in selection 
    of topics to cover and frequency of education.
    J. Health Care Worker Counseling, Screening and Evaluation
    Counseling
        Comments: Most of the comments on this section were very favorable. 
    Some persons commented that the HIV-infected HCW may not report their 
    infection to the facility and asked about the facility's responsibility 
    to HCWs and to patients should this occur. Some expressed concern about 
    confidentiality and about the Americans with Disabilities Act.
        Response: No changes were considered necessary.
    Screening HCWs for Active Disease
        Comments: Evaluation of every HCW with a cough of 2 weeks or 
    greater duration is excessive.
        Response: Reemphasized the need to tailor each program to fit the 
    situation. The infection rate in a particular facility, the time of 
    year (e.g., flu season), the potential exposure of individual workers--
    all these need to be taken into consideration.
    Screening HCWs for Latent TB Infection
        Comments: Annual PPD testing in areas of low prevalence is 
    unnecessary. It is unclear which HCWs should be tested. Provide clearer 
    information on the number of conversions during a specified period to 
    trigger the testing of others from the same area or group.
        Response: Modified this section and coordinated it with 
    recommendations in the risk assessment and the skin testing supplement, 
    which give clearer guidance on who should be tested and how frequently.
        Comments: Two-step skin testing is not necessary for all HCWs, 
    especially those who are transferring from hospitals and whose PPD 
    results are negative and those from areas where the prevalence of 
    booster phenomenon is low or where boosting was assessed as no problem.
        Response: Clarified that 2-step testing is not necessary if an HCW 
    has had a documented negative PPD result in the past 12 months or if 
    the institution has determined that boosting is not common in their 
    population. Also added the potential consequences of misinterpreting a 
    boosted reaction as a new infection.
    Evaluation and Management of Health Care Workers With Positive PPD 
    Tests
    Evaluation
        Comments: M. tuberculosis antimicrobial susceptibilities should be 
    recorded in the HCW's medical record and given to the employee if he or 
    she leaves the facility. The HCW can then be put on appropriate therapy 
    if active disease develops. Persons who are PPD positive and have not 
    had adequate preventive therapy should be monitored at least annually.
        Response: Added these recommendations to this section.
    Routine and Follow-Up Chest Radiographs
        Comments: Consideration should be given to performing chest 
    radiographs on HCWs whose PPD tests are positive.
        Response: Reemphasized the need to monitor more frequently for 
    symptoms of TB in high-risk persons but retained the statement that 
    regular chest radiographs have not been shown to be effective in 
    detecting TB in these persons.
    Work Restrictions
        Comments: Requiring three consecutive negative smears before an HCW 
    who is receiving treatment for active TB can return to work is 
    excessive. A person who has improved does not cough and does not 
    produce sputum and may be kept off duty unnecessarily.
        Response: Confusion had been caused by an incorrect wording in the 
    guidelines, that ``negative smears on consecutive days'' were required. 
    This has been clarified. The recommendation for 3 consecutive negative 
    smears collected on separate days was deemed appropriate and retained.
        Comments: If an HCW who has a positive skin test result does not 
    take preventive therapy, the HCW should be required to be seen and 
    interviewed frequently.
        Response: The frequency of follow-up was not specified to allow for 
    flexibility.
    Supplement 2
        Comment: HCWs should be allowed to read their own skin test 
    results.
        Response: Retained the recommendation that they not read their own 
    test results and cited a reference as to why they should not.
        Comment: Clarification is needed on what constitutes a positive 
    skin test result for HCWs.
        Response: Added to the recommendation that a HCW may be considered 
    positive if the induration is 10 mm or more and referred to the 
    Diagnostic Standards (ATS/CDC statement).
    K. Problem Evaluation
        Comments and subsequent changes made in the risk assessment section 
    also apply here. Revised this section.
    L. Coordination With Public Health Department
        No substantive comments or questions received on this section.
    M. Additional Considerations for Selected Areas
        Comment: What controls are needed in special areas such as hospices 
    and nursing homes?
        Response: Added a statement on the need to conduct a risk 
    assessment and have an infection control plan, which should be reviewed 
    and revised regularly. For hospices and nursing homes, it was clarified 
    that TB isolation rooms are not needed if they do not provide care to 
    TB patients. Restated the need for a referral protocol with periodic 
    review.
    Supplement 5 Decontamination: Cleaning, Disinfecting, and Sterilizing 
    of Patient-Care Equipment
        Comments: Only one comment on this section concerned the cleaning 
    of ventilation ducts.
        Response: No changes were considered necessary.
    
    Revised Guidelines
    
        Following are the final guidelines based on analysis of the 
    comments described above.
    
        Dated: October 19, 1994.
    Arthur C. Jackson,
    Associate Director for Management and Operations, Centers for Disease 
    Control and Prevention (CDC).
    
    Guidelines for Preventing the Transmission of Mycobacterium 
    Tuberculosis in Health-Care Facilities, 1994
    
    Contents
    
    Executive Summary
    I. Introduction
        A. Purpose of Document
        B. Epidemiology, Transmission, and Pathogenesis of TB
        C. Risk for Nosocomial Transmission of M. tuberculosis
        D. Fundamentals of TB Infection Control
    II. Recommendations
        A. Assignment of Responsibility
        B. Risk Assessment, Development of the TB Infection-Control 
    Plan, and Periodic Reassessment
        1. Risk assessment
        a. General
        b. Community TB profile
        c. Case surveillance
        d. Analysis of HCW PPD test screening data
        e. Review of TB patient medical records
        f. Observation of TB infection-control practices
        g. Engineering evaluation
        2. Development of the TB Infection-Control Plan
        3. Periodic Reassessment
        4. Examples of Risk Assessment
        C. Identifying, Evaluating, and Initiating Treatment for 
    Patients Who May Have Active TB
        1. Identifying patients who may have active TB
        2. Diagnostic evaluation for active TB
        3. Initiation of treatment for suspected or confirmed TB
        D. Management of Patients Who May Have Active TB in Ambulatory-
    Care Settings and Emergency Departments
        E. Management of Hospitalized Patients Who Have Confirmed or 
    Suspected TB
        1. Initiation of isolation for TB
        2. TB isolation practices
        3. The TB isolation room
        4. Discontinuation of TB isolation
        5. Discharge planning
        F. Engineering Control Recommendations
        1. General ventilation
        2. Additional engineering control approaches
        a. HEPA filtration
        b. UVGI
        G. Respiratory Protection
        H. Cough-Inducing and Aerosol-Generating Procedures
        1. General guidelines
        2. Special considerations for bronchoscopy
        3. Special considerations for the administration of aerosolized 
    pentamidine
        I. Education and Training of HCWs
        J. HCW Counseling, Screening, and Evaluation
        1. Counseling HCWs regarding TB
        2. Screening HCWs for active TB
        3. Screening HCWs for latent TB infection
        4. Evaluation and management of HCWs who have positive PPD test 
    results or active TB
        a. Evaluation
        b. Routine and follow-up chest radiographs
        c. Workplace restrictions
        (1) Active TB
        (2) Latent TB infection
        K. Problem Evaluation
        1. Investigating PPD test conversions and active TB in HCWs
        a. Investigating PPD test conversions in HCWs
        b. Investigating cases of active TB in HCWs
        2. Investigating possible patient-to-patient transmission of M. 
    tuberculosis
        3. Investigating contacts of patients and HCWs who have 
    infectious TB
        L. Coordination with the Public Health Department
        M. Additional Considerations for Selected Areas in Health-Care 
    Facilities and Other Health-Care settings
        1. Selected areas in health-care facilities
        a. Operating rooms
        b. Autopsy rooms
        c. Laboratories
        2. Other health-care settings
        a. Emergency medical services
        b. Hospices
        c. Long-term care facilities
        d. Correctional facilities
        e. Dental settings
        f. Home-health-care settings
        g. Medical offices
    Supplement 1: Determining the Infectiousness of a TB Patient
    Supplement 2: Diagnosis and Treatment of Latent TB Infection and 
    Active TB
    I. Diagnostic Procedures for TB Infection and Disease
        A. PPD Skin Testing and Anergy Testing
        1. Application and reading of PPD skin tests
        2. Interpretation of PPD skin tests
        a. General
        b. HCWs
        3. Anergy testing
        4. Pregnancy and PPD skin testing
        5. BCG vaccination and PPD skin testing
        6. The booster phenomenon
        B. Chest Radiography
        C. Bacteriology
    II. Preventive Therapy for Latent TB Infection and Treatment of 
    Active TB
        A. Preventive Therapy for Latent TB Infection
        B. Treatment of Patients Who Have Active TB
    Supplement 3: Engineering Controls
    I. Introduction
    II. Ventilation
        A. Local Exhaust Ventilation
        1. Enclosing devices
        2. Exterior devices
        3. Discharge exhaust from booths, tents, and hoods
        B. General Ventilation
        1. Dilution and removal
        a. Types of general ventilation systems
        b. Ventilation rates
        2. Airflow patterns within rooms (air mixing)
        3. Airflow direction in the facility
        a. Directional airflow
        b. Negative pressure for achieving directional airflow
        4. Achieving negative pressure in a room
        a. Pressure differential
        b. Alternate methods for achieving negative pressure
        c. Monitoring negative pressure
        C. HEPA filtration
        1. Use of HEPA filtration when exhausting air to the outside
        2. Recirculation of HEPA-filtered air to other areas of a 
    facility
        3. Recirculation of HEPA-filtered air within a room
        a. Fixed room-air recirculation systems
        b. Portable room-air recirculation units
        c. Evaluation of room-air recirculation systems and units
        4. Installing, maintaining, and monitoring HEPA filters
        D. TB Isolation Rooms and Treatment Rooms
        1. Preventing the escape of droplet nuclei from the room
        2. Reducing the concentration of droplet nuclei in the room
        3. Exhaust from TB isolation rooms and treatment rooms
        4. Alternatives to TB isolation rooms
    III. UVGI
        A. Applications
        1. Duct irradiation
        2. Upper-room air irradiation
        B. Limitations
        C. Safety Issues
        D. Exposure Criteria for UV Radiation
        E. Maintenance and Monitoring
        1. Labelling and posting
        2. Maintenance
        3. Monitoring
    Supplement 4: Respiratory Protection
    I. Considerations for Selection of Respirators
        A. Performance Criteria for Personal Respirators for Protection 
    Against Transmission of M. tuberculosis
        B. Specific Respirators
        C. The Effectiveness of Respiratory Protective Devices
        1. Face-seal leakage
        2. Filter leakage
        3. Fit testing
        4. Fit checking
        5. Reuse of respirators
    II. Implementing a Personal Respiratory Protection Program
    Supplement 5: Decontamination--Cleaning, Disinfecting, and 
    Sterilizing of Patient-Care Equipment
    References
    Glossary
    Index
        List of Tables
        List of Figures
    
    Executive Summary
    
        This document updates and replaces all previously published 
    guidelines for the prevention of Mycobacterium tuberculosis 
    transmission in health-care facilities. The purpose of this revision is 
    to emphasize the importance of (a) the hierarchy of control measures, 
    including administrative and engineering controls and personal 
    respiratory protection; (b) the use of risk assessments for developing 
    a written tuberculosis (TB) control plan; (c) early identification and 
    management of persons who have TB; (d) TB screening programs for 
    health-care workers (HCWs); (e) HCW training and education; and (f) the 
    evaluation of TB infection-control programs.
        Transmission of M. tuberculosis is a recognized risk to patients 
    and HCWs in health-care facilities. Transmission is most likely to 
    occur from patients who have unrecognized pulmonary or laryngeal TB, 
    are not on effective anti-TB therapy, and have not been placed in TB 
    isolation. Several recent TB outbreaks in health-care facilities, 
    including outbreaks of multidrug-resistant TB, have heightened concern 
    about nosocomial transmission. Patients who have multidrug-resistant TB 
    can remain infectious for prolonged periods, which increases the risk 
    for nosocomial and/or occupational transmission of M. tuberculosis. 
    Increases in the incidence of TB have been observed in some geographic 
    areas; these increases are related partially to the high risk for TB 
    among immunosuppressed persons, particularly those infected with human 
    immunodeficiency virus (HIV). Transmission of M. tuberculosis to HIV-
    infected persons is of particular concern because these persons are at 
    high risk for developing active TB if they become infected with the 
    bacteria. Thus, health-care facilities should be particularly alert to 
    the need for preventing transmission of M. tuberculosis in settings in 
    which HIV-infected persons work or receive care.
        Supervisory responsibility for the TB infection-control program 
    should be assigned to a designated person or group of persons who 
    should be given the authority to implement and enforce TB infection-
    control policies. An effective TB infection-control program requires 
    early identification, isolation, and treatment of persons who have 
    active TB. The primary emphasis of TB infection-control plans in 
    health-care facilities should be achieving these three goals by the 
    application of a hierarchy of control measures, including (a) the use 
    of administrative measures to reduce the risk for exposure to persons 
    who have infectious TB, (b) the use of engineering controls to prevent 
    the spread and reduce the concentration of infectious droplet nuclei, 
    and (c) the use of personal respiratory protective equipment in areas 
    where there is still a risk for exposure to M. tuberculosis (e.g., TB 
    isolation rooms). Implementation of a TB infection-control program 
    requires risk assessment and development of a TB infection-control 
    plan; early identification, treatment, and isolation of infectious TB 
    patients; effective engineering controls; an appropriate respiratory 
    protection program; HCW TB training, education, counseling, and 
    screening; and evaluation of the program's effectiveness.
        Although completely eliminating the risk for transmission of M. 
    tuberculosis in all health-care facilities may not be possible at the 
    present time, adherence to these guidelines should reduce the risk to 
    persons in these settings. Recently, nosocomial TB outbreaks have 
    demonstrated the substantial morbidity and mortality among patients and 
    HCWs that have been associated with incomplete implementation of CDC's 
    Guidelines for Preventing the Transmission of Tuberculosis in Health-
    Care Facilities, with Special Focus on HIV-Related Issues published in 
    1990.* Follow-up investigations at some of these hospitals have 
    documented that complete implementation of measures similar or 
    identical to those in the 1990 TB Guidelines significantly reduced or 
    eliminated nosocomial transmission of M. tuberculosis to patients and/
    or HCWs.
    ---------------------------------------------------------------------------
    
        *CDC. Guidelines for Preventing the Transmission of Tuberculosis 
    in Health-Care Facilities, with Special Focus on HIV-Related Issues. 
    MMWR 1990; 39 (No. RR-17).
    ---------------------------------------------------------------------------
    
    I. Introduction
    
    A. Purpose of Document
        In April 1992, the National MDR-TB Task Force published the 
    National Action Plan to Combat Multidrug-Resistant Tuberculosis (1). 
    The publication was a response to reported nosocomial outbreaks of 
    tuberculosis (TB), including outbreaks of multidrug-resistant TB (MDR-
    TB), and the increasing incidence of TB in some geographic areas. The 
    plan called for the update and revision of the guidelines for 
    preventing nosocomial transmission of Mycobacterium tuberculosis 
    published December 7, 1990 (2).
        Public meetings were held in October 1992 and January 1993 to 
    discuss revision of the 1990 TB Guidelines (2). CDC received 
    considerable input on various aspects of infection control, including 
    health-care worker (HCW) education; administrative controls (e.g., 
    having protocols for the early identification and management of 
    patients who have TB); the need for more specific recommendations 
    regarding ventilation; and clarification on the use of respiratory 
    protection in health-care settings. On the basis of these events and 
    the input received, on October 12, 1993, CDC published in the Federal 
    Register the Draft Guidelines For Preventing the Transmission of 
    Tuberculosis in Health-Care Facilities, Second Edition (3). During and 
    after the 90-day comment period following publication of this draft, 
    CDC's TB Infection-Control Guidelines Work Group received and reviewed 
    more than 2,500 comments.
        The purpose of this document is to make recommendations for 
    reducing the risk for transmitting M. tuberculosis to HCWs, patients, 
    volunteers, visitors, and other persons in these settings. The 
    information also may serve as a useful resource for educating HCWs 
    about TB.
        These recommendations update and replace all previously published 
    CDC recommendations for TB infection control in health-care facilities 
    (2, 4). The recommendations in this document are applicable primarily 
    to inpatient facilities in which health care is provided (e.g., 
    hospitals, medical wards in correctional facilities, nursing homes, and 
    hospices). Recommendations applicable to ambulatory-care facilities, 
    emergency departments, home-health-care settings, emergency medical 
    services, medical offices, dental settings, and other facilities or 
    residential settings that provide medical care are provided in separate 
    sections, with cross-references to other sections of the guidelines if 
    appropriate.
        Designated personnel at health-care facilities should conduct a 
    risk assessment for the entire facility and for each area* and 
    occupational group, determine the risk for nosocomial or occupational 
    transmission of M. tuberculosis, and implement an appropriate TB 
    infection-control program. The extent of the TB infection-control 
    program may range from a simple program emphasizing administrative 
    controls in settings where there is minimal risk for exposure to M. 
    tuberculosis, to a comprehensive program that includes administrative 
    controls, engineering controls, and respiratory protection in settings 
    where the risk for exposure is high. In all settings, administrative 
    measures should be used to minimize the number of HCWs exposed to M. 
    tuberculosis while still providing optimal care for TB patients. HCWs 
    providing care to patients who have TB should be informed about the 
    level of risk for transmission of M. tuberculosis and the appropriate 
    control measures to minimize that risk.
    ---------------------------------------------------------------------------
    
        *Area: a structural unit (e.g., a hospital ward or laboratory) 
    or functional unit (e.g., an internal medicine service) in which 
    HCWs provide services to and share air with a specific patient 
    population or work with clinical specimens that may contain viable 
    M. tuberculosis organisms. The risk for exposure to M. tuberculosis 
    in a given area depends on the prevalence of TB in the population 
    served and the characteristics of the environment.
    ---------------------------------------------------------------------------
    
        In this document, the term ``HCWs'' refers to all the paid and 
    unpaid persons working in health-care settings who have the potential 
    for exposure to M. tuberculosis. This may include, but is not limited 
    to, physicians; nurses; aides; dental workers; technicians; workers in 
    laboratories and morgues; emergency medical service (EMS) personnel; 
    students; part-time personnel; temporary staff not employed by the 
    health-care facility; and persons not involved directly in patient care 
    but who are potentially at risk for occupational exposure to M. 
    tuberculosis (e.g., volunteer workers and dietary, housekeeping, 
    maintenance, clerical, and janitorial staff).
        Although the purpose of this document is to make recommendations 
    for reducing the risk for transmission of M. tuberculosis in health-
    care facilities, the process of implementing these recommendations must 
    safeguard, in accordance with applicable state and federal laws, the 
    confidentiality and civil rights of persons who have TB.
    B. Epidemiology, Transmission, and Pathogenesis of TB
        The prevalence of TB is not distributed evenly throughout all 
    segments of the U.S. population. Some subgroups or persons have a 
    higher risk for TB either because they are more likely than other 
    persons in the general population to have been exposed to and infected 
    with M. tuberculosis or because their infection is more likely to 
    progress to active TB after they have been infected (5). In some cases, 
    both of these factors may be present. Groups of persons known to have a 
    higher prevalence of TB infection include contacts of persons who have 
    active TB, foreign-born persons from areas of the world with a high 
    prevalence of TB (e.g., Asia, Africa, the Caribbean, and Latin 
    America), medically underserved populations (e.g., some African-
    Americans, Hispanics, Asians and Pacific Islanders, American Indians, 
    and Alaskan Natives), homeless persons, current or former correctional-
    facility inmates, alcoholics, injecting-drug users, and the elderly. 
    Groups with a higher risk for progression from latent TB infection to 
    active disease include persons who have been infected recently (i.e., 
    within the previous 2 years), children less than <4 years="" of="" age,="" persons="" with="" fibrotic="" lesions="" on="" chest="" radiographs,="" and="" persons="" with="" certain="" medical="" conditions="" (i.e.,="" human="" immunodeficiency="" virus="" [hiv]="" infection,="" silicosis,="" gastrectomy="" or="" jejuno-ileal="" bypass,="" being="">10% below ideal body weight, chronic renal failure with 
    renal dialysis, diabetes mellitus, immunosuppression resulting from 
    receipt of high-dose corticosteroid or other immunosuppressive therapy, 
    and some malignancies) (5).
        M. tuberculosis is carried in airborne particles, or droplet 
    nuclei, that can be generated when persons who have pulmonary or 
    laryngeal TB sneeze, cough, speak, or sing (6). The particles are an 
    estimated 1-5 m in size, and normal air currents can keep them 
    airborne for prolonged time periods and spread them throughout a room 
    or building (7). Infection occurs when a susceptible person inhales 
    droplet nuclei containing M. tuberculosis, and these droplet nuclei 
    traverse the mouth or nasal passages, upper respiratory tract, and 
    bronchi to reach the alveoli of the lungs. Once in the alveoli, the 
    organisms are taken up by alveolar macrophages and spread throughout 
    the body. Usually within 2-10 weeks after initial infection with M. 
    tuberculosis, the immune response limits further multiplication and 
    spread of the tubercle bacilli; however, some of the bacilli remain 
    dormant and viable for many years. This condition is referred to as 
    latent TB infection. Persons with latent TB infection usually have 
    positive purified protein derivative (PPD)-tuberculin skin-test 
    results, but they do not have symptoms of active TB, and they are not 
    infectious.
        In general, persons who become infected with M. tuberculosis have 
    approximately a 10% risk for developing active TB during their 
    lifetimes. This risk is greatest during the first 2 years after 
    infection. Immunocompromised persons have a greater risk for the 
    progression of latent TB infection to active TB disease; HIV infection 
    is the strongest known risk factor for this progression. Persons with 
    latent TB infection who become coinfected with HIV have approximately 
    an 8%-10% risk per year for developing active TB (8). HIV-infected 
    persons who are already severely immunosuppressed and who become newly 
    infected with M. tuberculosis have an even greater risk for developing 
    active TB (9-12).
        The probability that a person who is exposed to M. tuberculosis 
    will become infected depends primarily on the concentration of 
    infectious droplet nuclei in the air and the duration of exposure. 
    Characteristics of the TB patient that enhance transmission include (a) 
    disease in the lungs, airways, or larynx; (b) presence of cough or 
    other forceful expiratory measures; (c) presence of acid-fast bacilli 
    (AFB) in the sputum; (d) failure of the patient to cover the mouth and 
    nose when coughing or sneezing; (e) presence of cavitation on chest 
    radiograph; (f) inappropriate or short duration of chemotherapy; and 
    (g) administration of procedures that can induce coughing or cause 
    aerosolization of M. tuberculosis (e.g., sputum induction). 
    Environmental factors that enhance the likelihood of transmission 
    include (a) exposure in relatively small, enclosed spaces; (b) 
    inadequate local or general ventilation that results in insufficient 
    dilution and/or removal of infectious droplet nuclei; and (c) 
    recirculation of air containing infectious droplet nuclei. 
    Characteristics of the persons exposed to M. tuberculosis that may 
    affect the risk for becoming infected are not as well defined. In 
    general, persons who have been infected previously with M. tuberculosis 
    may be less susceptible to subsequent infection. However, reinfection 
    can occur among previously infected persons, especially if they are 
    severely immunocompromised. Vaccination with Bacille of Calmette and 
    Guerin (BCG) probably does not affect the risk for infection; rather, 
    it decreases the risk for progressing from latent TB infection to 
    active TB (13). Finally, although it is well established that HIV 
    infection increases the likelihood of progressing from latent TB 
    infection to active TB, it is unknown whether HIV infection increases 
    the risk for becoming infected if exposed to M. tuberculosis.
    C. Risk for Nosocomial Transmission of M. Tuberclosis
        Transmission of M. tuberclosis is a recognized risk in health-care 
    facilities (14-22). The magnitude of the risk varies considerably by 
    the type of health-care facility, the prevalence of TB in the 
    community, the patient population served, the HCW's occupational group, 
    the area of the health-care facility in which the HCW works, and the 
    effectiveness of TB infection-control interventions. The risk may be 
    higher in areas where patients with TB are provided care before 
    diagnosis and initiation of TB treatment and isolation precautions 
    (e.g., in clinic waiting areas and emergency departments) or where 
    diagnostic or treatment procedures that stimulate coughing are 
    performed. Nosocomial transmission of M. tuberclosis has been 
    associated with close contact with persons who have infectious TB and 
    with the performance of certain procedures (e.g., bronchoscopy [17], 
    endotracheal intubation and suctioning [18], open abscess irrigation 
    [20], and autopsy [21,22]). Sputum induction and aerosol treatments 
    that induce coughing may also increase the potential for transmission 
    of M. tuberclosis (23,24). Personnel of health-care facilities should 
    be particularly alert to the need for preventing transmission of M. 
    tuberclosis in those facilities in which immunocompromised persons 
    (e.g., HIV-infected persons) work or receive care--especially if cough-
    inducing procedures, such as sputum induction and aerosolized 
    pentamidine treatments, are being performed.
        Several TB outbreaks among persons in health-care facilities have 
    been reported recently (11,24-28; CDC, unpublished data). Many of these 
    outbreaks involved transmission of multidrug-resistant strains of M. 
    tuberclosis to both patients and HCWs. Most of the patients and some of 
    the HCWs were HIV-infected persons in whom new infection progressed 
    rapidly to active disease. Mortality associated with those outbreaks 
    was high (range: 43%-93%). Furthermore, the interval between diagnosis 
    and death was brief (range of median intervals: 4-16 weeks). Factors 
    contributing to these outbreaks included delayed diagnosis of TB, 
    delayed recognition of drug resistance, and delayed initiation of 
    effective therapy--all of which resulted in prolonged infectiousness, 
    delayed initiation and inadequate duration of TB isolation, inadequate 
    ventilation in TB isolation rooms, lapses in TB isolation practices and 
    inadequate precautions for cough-inducing procedures, and lack of 
    adequate respiratory protection. Analysis of data collected from three 
    of the health-care facilities involved in the outbreaks indicates that 
    transmission of M. tuberclosis decreased significantly or ceased 
    entirely in areas where measures similar to those in the 1990 TB 
    Guidelines were implemented (2,29-32). However, several interventions 
    were implemented simultaneously, and the effectiveness of the separate 
    interventions could not be determined.
    D. Fundamentals of TB Infection Control
        An effective TB infection-control program requires early 
    identification, isolation, and effective treatment of persons who have 
    active TB. The primary emphasis of the TB infection-control plan should 
    be on achieving these three goals. In all health-care facilities, 
    particularly those in which persons who are at high risk for TB work or 
    receive care, policies and procedures for TB control should be 
    developed, reviewed periodically, and evaluated for effectiveness to 
    determine the actions necessary to minimize the risk for transmission 
    of M. tuberclosis.
        The TB infection-control program should be based on a hierarchy of 
    control measures. The first level of the hierarchy, and that which 
    affects the largest number of persons, is using administrative measures 
    intended primarily to reduce the risk for exposing uninfected persons 
    to persons who have infectious TB. These measures include (a) 
    developing and implementing effective written policies and protocols to 
    ensure the rapid identification, isolation, diagnostic evaluation, and 
    treatment of persons likely to have TB; (b) implementing effective work 
    practices among HCWs in the health-care facility (e.g., correctly 
    wearing respiratory protection and keeping doors to isolation rooms 
    closed); (c) educating, training, and counseling HCWs about TB; and (d) 
    screening HCWs for TB infection and disease.
        The second level of the hierarchy is the use of engineering 
    controls to prevent the spread and reduce the concentration of 
    infectious droplet nuclei. These controls include (a) direct source 
    control using local exhaust ventilation, (b) controlling direction of 
    airflow to prevent contamination of air in areas adjacent to the 
    infectious source, (c) diluting and removing contaminated air via 
    general ventilation, and (d) air cleaning via air filtration or 
    ultraviolet germicidal irradiation (UVGI).
        The first two levels of the hierarchy minimize the number of areas 
    in the health-care facility where exposure to infectious TB may occur, 
    and they reduce, but do not eliminate, the risk in those few areas 
    where exposure to M. tuberculosis can still occur (e.g., rooms in which 
    patients with known or suspected infectious TB are being isolated and 
    treatment rooms in which cough-inducing or aerosol-generating 
    procedures are performed on such patients). Because persons entering 
    such rooms may be exposed to M. tuberculosis, the third level of the 
    hierarchy is the use of personal respiratory protective equipment in 
    these and certain other situations in which the risk for infection with 
    M. tuberculosis may be relatively higher.
        Specific measures to reduce the risk for transmission of M. 
    tuberculosis include the following:
         Assigning to specific persons in the health-care facility 
    the supervisory responsibility for designing, implementing, evaluating, 
    and maintaining the TB infection-control program (Section II.A).
         Conducting a risk assessment to evaluate the risk for 
    transmission of M. tuberculosis in all areas of the health-care 
    facility, developing a written TB infection-control program based on 
    the risk assessment, and periodically repeating the risk assessment to 
    evaluate the effectiveness of the TB infection-control program (Section 
    II.B).
         Developing, implementing, and enforcing policies and 
    protocols to ensure early identification, diagnostic evaluation, and 
    effective treatment of patients who may have infectious TB (Section 
    II.C; Suppl. 2).
         Providing prompt triage for and appropriate management of 
    patients in the outpatient setting who may have infectious TB (Section 
    II.D).
         Promptly initiating and maintaining TB isolation for 
    persons who may have infectious TB and who are admitted to the 
    inpatient setting (Section II.E; Suppl. 1).
         Effectively planning arrangements for discharge (Section 
    II.E).
         Developing, installing, maintaining, and evaluating 
    ventilation and other engineering controls to reduce the potential for 
    airborne exposure to M. tuberculosis (Section II.F; Suppl. 3).
         Developing, implementing, maintaining, and evaluating a 
    respiratory protection program (Section II.G; Suppl. 4).
         Using precautions while performing cough-inducing 
    procedures (Section II.H; Suppl. 3).
         Educating and training HCWs about TB, effective methods 
    for preventing transmission of M. tuberculosis, and the benefits of 
    medical screening programs (Section II.I).
         Developing and implementing a program for routine periodic 
    counseling and screening of HCWs for active TB and latent TB infection 
    (Section II.J; Suppl. 2).
         Promptly evaluating possible episodes of M. tuberculosis 
    transmission in health-care facilities, including PPD skin-test 
    conversions among HCWs, epidemiologically associated cases among HCWs 
    or patients, and contacts of patients or HCWs who have TB and who were 
    not promptly identified and isolated (Section II.K).
         Coordinating activities with the local public health 
    department, emphasizing reporting, and ensuring adequate discharge 
    follow-up and the continuation and completion of therapy (Section 
    II.L).
    
    II. Recommendations
    
    A. Assignment of Responsibility
         Supervisory responsibility for the TB infection-control 
    program should be assigned to a designated person or group of persons 
    with expertise in infection control, occupational health, and 
    engineering. These persons should be given the authority to implement 
    and enforce TB infection-control policies.
         If supervisory responsibility is assigned to a committee, 
    one person should be designated as the TB contact person. Questions and 
    problems can then be addressed to this person.
    B. Risk Assessment, Development of the TB Infection-Control Plan, and 
    Periodic Reassessment
    1. Risk Assessment
        a. General.
         TB infection-control measures for each health-care 
    facility should be based on a careful assessment of the risk for 
    transmission of M. tuberculosis in that particular setting. The first 
    step in developing the TB infection-control program should be to 
    conduct a baseline risk assessment to evaluate the risk for 
    transmission of M. tuberculosis in each area and occupational group in 
    the facility (Table 1, Figure 1). Appropriate infection-control 
    interventions can then be developed on the basis of actual risk. Risk 
    assessments should be performed for all inpatient and outpatient 
    settings (e.g., medical and dental offices).
         Regardless of risk level, the management of patients with 
    known or suspected infectious TB should not vary. However, the index of 
    suspicion for infectious TB among patients, the frequency of HCW PPD 
    skin testing, the number of TB isolation rooms, and other factors will 
    depend on whether the risk for transmission of M. tuberculosis in the 
    facility, area, or occupational group is high, intermediate, low, very 
    low, or minimal.
         The risk assessment should be conducted by a qualified 
    person or group of persons (e.g., hospital epidemiologists, infectious 
    disease specialists, pulmonary disease specialists, infection-control 
    practitioners, health-care administrators, occupational health 
    personnel, engineers, HCWs, or local public health personnel).
         The risk assessment should be conducted for the entire 
    facility and for specific areas within the facility (e.g., medical, TB, 
    pulmonary, or HIV wards; HIV, infectious disease, or pulmonary clinics; 
    and emergency departments or other areas where TB patients might 
    receive care or where cough-inducing procedures are performed). This 
    should include both inpatient and outpatient areas. In addition, risk 
    assessments should be conducted for groups of HCWs who work throughout 
    the facility rather than in a specific area (e.g., respiratory 
    therapists; bronchoscopists; environmental services, dietary, and 
    maintenance personnel; and students, interns, residents, and fellows).
         Classification of risk for a facility, for a specific 
    area, and for a specific occupational group should be based on (a) the 
    profile of TB in the community; (b) the number of infectious TB 
    patients admitted to the area or ward, or the estimated number of 
    infectious TB patients to whom HCWs in an occupational group may be 
    exposed; and (c) the results of analysis of HCW PPD test conversions 
    (where applicable) and possible person-to-person transmission of M. 
    tuberculosis (Figure 1).
         All TB infection-control programs should include periodic 
    reassessments of risk. The frequency of repeat risk assessments should 
    be based on the results of the most recent risk assessment (Table 2, 
    Figure 1).
         The ``minimal-risk'' category applies only to an entire 
    facility. A ``minimal-risk'' facility does not admit TB patients to 
    inpatient or outpatient areas and is not located in a community with TB 
    (i.e., counties or communities in which TB cases have not been reported 
    during the previous year). Thus, there is essentially no risk for 
    exposure to TB patients in the facility. This category may also apply 
    to many outpatient settings (e.g., many medical and dental offices).
    
    Table 1. Elements of a Risk Assessment for Tuberculosis (TB) in Health-
    care Facilities
    
        1. Review the community TB profile (from public health department 
    data).
        2. Review the number of TB patients who were treated in each area 
    of the facility (both inpatient and outpatient). (This information can 
    be obtained by analyzing laboratory surveillance data and by reviewing 
    discharge diagnoses or medical and infection-control records.)
        3. Review the drug-susceptibility patterns of TB isolates of 
    patients who were treated at the facility.
        4. Analyze purified protein derivative (PPD)-tuberculin skin-test 
    results of health-care workers (HCWs), by area or by occupational group 
    for HCWs not assigned to specific area (e.g., respiratory therapists).
        5. To evaluate infection-control parameters, review medical records 
    of a sample of TB patients seen at the facility.
    
    Calculate Intervals From
    
         Admission until TB suspected;
         Admission until TB evaluation performed;
         Admission until acid-fast bacilli (AFB) specimens ordered;
         AFB specimens ordered until AFB specimens collected;
         AFB specimens collected until AFB smears performed and 
    reported;
         AFB specimens collected until cultures performed and 
    reported;
         AFB specimens collected until species identification 
    conducted and reported;
         AFB specimens collected until drug-susceptibility tests 
    performed and reported;
         Admission until TB isolation initiated;
         Admission until TB treatment initiated; and
         Duration of TB isolation.
    
    Obtain the Following Additional Information
    
         Were appropriate criteria used for discontinuing 
    isolation?
         Did the patient have a history of prior admission to the 
    facility?
         Was the TB treatment regimen adequate?
         Were follow-up sputum specimens collected properly?
         Was appropriate discharge planning conducted?
        6. Perform an observational review of TB infection control 
    practices.
        7. Review the most recent environmental evaluation and maintenance 
    procedures.
    
    BILLING CODE 4163-18-P
          
    
    TN28OC94.000
    
    
    TN28OC94.001
    
    
    BILLING CODE 4163-18-C
    
                                               Table 2.--Elements of a Tuberculosis (TB) Infection-Control Program                                          
    --------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                     Risk categories                                        
                            Element                         ------------------------------------------------------------------------------------------------
                                                                Minimal       Very low          Low             Intermediate                  High          
    --------------------------------------------------------------------------------------------------------------------------------------------------------
    Assigning responsibility (Section II.A)                                                                                                                 
        Designated TB control officer or committee.........  R              R              R              R.......................  R                       
    Conducting a risk assessment (Section II.B.1)                                                                                                           
        Baseline risk assessment...........................  R              R              R              R.......................  R                       
        Community TB profile: incidence, prevalence, and     Y              Y              Y              Y.......................  Y                       
         drug-susceptibility patterns.                                                                                                                      
        Facility case surveillance (laboratory- and          C              C              C              C.......................  C                       
         discharge-diagnosis-based).                                                                                                                        
        Analysis of purified protein derivative (PPD) test   N/A            V*             Y              Every 6-12 mos..........  Every 3 mos.            
         results among health-care workers (HCWs).                                                                                                          
        Review of TB patient medical records...............  N/A            O      Y              Every 6-12 mos..........  Every 3 mos.            
        Observation of infection-control practices.........  N/A            N/A            Y              Every 6-12 mos..........  Every 3 mos.            
        Evaluation of engineering control maintenance......  OSec.          OSec.          Y              Every 6-12 mos..........  Every 3 mos.            
    Developing a TB infection control plan (Section II.B.2)                                                                                                 
        Written TB infection control plan..................  R              R              R              R.......................  R                       
    Periodically reassessing risk (Section II.B.3)                                                                                                          
        Reassessment of risk...............................  Y              Y              Y              Every 6-12 mos..........  Every 3 mos.            
    Identifying, evaluating, and initiating treatment for                                                                                                   
     patients who may have active TB (Section II.C)                                                                                                         
        Protocol (clinical prediction rules for             R              R              R              R.......................  R                       
         identifying patients who may have active TB.                                                                                                       
        Protocol for diagnostic evaluation of patients who   N/A            R              R              R.......................  R                       
         may have active TB**.                                                                                                                              
        Protocol for reporting laboratory results to         N/A            R              R              R.......................  R                       
         clinicians, infection-control practitioners,                                                                                                       
         collaborating referral facilities, and appropriate                                                                                                 
         health department(s).                                                                                                                              
        Protocol for initiating treatment of patients who    N/A            R              R              R.......................  R                       
         may have active TB**.                                                                                                                              
    Managing patients who may have TB in ambulatory-care                                                                                                    
     settings and emergency departments (Section II.D)                                                                                                      
        Triage system for identifying patients who have      R              R              R              R.......................  R                       
         active TB in emergency departments and ambulatory-                                                                                                 
         care settings.                                                                                                                                     
        Protocol for managing patients who may have active   R              R              R              R.......................  R                       
         TB in emergency departments and ambulatory-care                                                                                                    
         settings.                                                                                                                                          
        Protocol for referring patients who may have active  R              R              N/A.....  N/A     
         TB to collaborating facility.                                                      a                                                               
    Managing hospitalized patients who may have TB (Section                                                                                                 
     II.E)                                                                                                                                                  
        Appropriate number of TB isolation roomsN/ASecs. ..  N/A            N/A            R              R.......................  R                       
        Protocol for initiating TB isolation...............  N/A            N/A            R              R.......................  R                       
        Protocol for TB isolation practices................  N/A            N/A            R              R.......................  R                       
        Protocol for discontinuing TB isolation............  N/A            N/A            R              R.......................  R                       
        Protocol for discharge planning....................  N/A            N/A            R              R.......................  R                       
    Engineering controls (Suppl. 3, Section II.F)                                                                                                           
        Protocol(s) for maintenance of engineering controls  OSec.          OSec.          R              R.......................  R                       
    Respiratory protection (Suppl. 4, Section II.G)                                                                                                         
        Respiratory protection program.....................  N/A            V*             R              R.......................  R                       
    Cough-inducing and aerosol-generating procedures                                                                                                        
     (Section II.H)                                                                                                                                         
        Protocol(s) for performing cough-inducing or         O              O            R              R.......................  R                       
         aerosol-generating procedures.                                                                                                                     
        Engineering controls for performing cough-inducing   OSec.          O            R              R.......................  R                       
         or aerosol-generating procedures.                                                                                                                  
    Educating and Training HCWs (Section II.I)                                                                                                              
        Educating and training HCWs regarding TB...........  R              R              R              R.......................  R                       
    Counseling and screening HCWs (Section II.J)                                                                                                            
        Counseling HCWs regarding TB.......................  R              R              R              R.......................  R                       
        Protocol for identifying and evaluating HCWs who     R              R              R              R.......................  R                       
         have signs or symptoms of active TB.                                                                                                               
        Baseline PPD testing of HCWs.......................  O***           R              R              R.......................  R                       
        Routine periodic PPD screening of HCWs for latent    N/A            V*             Y              Every 6-12 mos..........  Every 3 mos.            
         TB infection.                                                                                                                                      
        Protocol for evaluating and managing HCWs who have   R              R              R              R.......................  R                       
         positive PPD tests.                                                                                                                                
        Protocol for managing HCWs who have active TB......  R              R              R              R.......................  R                       
    Conducting a problem evaluation (Section II.K)                                                                                                          
        Protocol for investigating PPD conversions and       R              R              R              R.......................  R                       
         active TB in HCWs.                                                                                                                                 
        Protocol for investigating possible patient-to-      R              R              R              R.......................  R                       
         patient transmission of Mycobacterium tuberculosis.                                                                                                
        Protocol for investigating possible contacts of TB   R              R              R              R.......................  R                       
         patients who were not diagnosed initially as                                                                                                       
         having TB and were not placed in isolation.                                                                                                        
    Coordination with the public health department (Section                                                                                                 
     II.L)                                                                                                                                                  
        Effective system for reporting patients who have     R              R              R              R.......................  R                       
         suspected or confirmed TB to appropriate health                                                                                                    
         department(s).                                                                                                                                     
    --------------------------------------------------------------------------------------------------------------------------------------------------------
    R=recommended; Y=yearly; C=continual; N/A=not applicable; O=optional; V=variable.                                                                       
                                                                                                                                                            
    *Because very low-risk facilities do not admit patients who may have active TB to inpatient areas, most HCWs in such facilities do not need routine     
      follow-up PPD screening after baseline PPD testing is done. However, those who are involved in the initial assessment and diagnostic evaluation of    
      patients in the ambulatory-care, emergency, and admitting departments of such facilities or in the outpatient management of patients with active TB   
      could be exposed potentially to a patient who has active TB. These HCWs may need to receive routine periodic PPD screening. Similarly, these HCWs may 
      need to be included in a respiratory protection program.                                                                                              
    Because very low-risk facilities do not admit patients suspected of having active TB, review of TB patient medical records is not applicable.   
      However, follow-up of patients who were identified during triage as possibly having active TB and referred to another institution for further         
      evaluation and management may be useful in evaluating the effectiveness of the triage system.                                                         
    Sec. Some minimal or very low-risk facilities may elect to use engineering controls (e.g., booths for cough-inducing procedures, portable high-         
      efficiency particulate [HEPA] filtration units, ultraviolet germicidal irradiation units) in triage/waiting areas. In such situations, appropriate    
      protocols for maintaining this equipment should be in place, and this maintenance should be evaluated periodically.                                   
    The criteria used in clinical prediction rules will probably vary from facility to facility depending on the prevalence of TB in the population served 
      by the facility and on the clinical, radiographic, and laboratory characteristics of TB patients examined in the facility.                            
    **The protocols should be consistent with CDC/American Thoracic Society recommendations (33).                                                           
    Protocols for referring patients who require specialized treatment (e.g., patients with multidrug-resistant TB) may be appropriate.     
    Secs. Based on maximum daily number of patients requiring TB isolation for suspected or confirmed active TB. Isolation rooms should meet the performance
      criteria specified in these guidelines.                                                                                                               
    If such procedures are used in the triage protocol(s) for identifying patients who may have active TB.                                                
    ***Minimal-risk facilities do not need to maintain an ongoing PPD skin-testing program. However, baseline PPD testing of HCWs may be advisable so that  
      if an unexpected exposure does occur, conversions can be distinguished from positive PPD test results caused by previous exposures.                   
    
         The ``very low-risk'' category generally applies only to 
    an entire facility. A very low-risk facility is one in which (a) 
    patients with active TB are not admitted to inpatient areas but may 
    receive initial assessment and diagnostic evaluation or outpatient 
    management in outpatient areas (e.g., ambulatory-care and emergency 
    departments) and (b) patients who may have active TB and need inpatient 
    care are promptly referred to a collaborating facility. In such 
    facilities, the outpatient areas in which exposure to patients with 
    active TB could occur should be assessed and assigned to the 
    appropriate low-, intermediate-, or high-risk category. Categorical 
    assignment will depend on the number of TB patients examined in the 
    area during the preceding year and whether there is evidence of 
    nosocomial transmission of M. tuberculosis in the area. If TB cases 
    have been reported in the community, but no patients with active TB 
    have been examined in the outpatient area during the preceding year, 
    the area can be designated as very low risk (e.g., many medical 
    offices).
        The referring and receiving facilities should establish a referral 
    agreement to prevent inappropriate management and potential loss to 
    follow-up of patients suspected of having TB during evaluation in the 
    triage system of a very low-risk facility.
        In some facilities in which TB patients are admitted to inpatient 
    areas, a very low-risk protocol may be appropriate for areas (e.g., 
    administrative areas) or occupational groups that have only a very 
    remote possibility of exposure to M. tuberculosis.
        The very low-risk category may also be appropriate for outpatient 
    facilities that do not provide initial assessment of persons who may 
    have TB, but do screen patients for active TB as part of a limited 
    medical screening before undertaking specialty care (e.g., dental 
    settings).
         ``Low-risk'' areas or occupational groups are those in 
    which (a) the PPD test conversion rate is not greater than that for 
    areas or groups in which occupational exposure to M. tuberculosis is 
    unlikely or than previous conversion rates for the same area or group, 
    (b) no clusters* of PPD test conversions have occurred, (c) person-to-
    person transmission of M. tuberculosis has not been detected, and (d) 
    fewer than six TB patients are examined or treated per year.
    ---------------------------------------------------------------------------
    
        *Cluster: two or more PPD skin-test conversions occurring within 
    a 3-month period among HCWs in a specific area or occupational 
    group, and epidemiologic evidence suggests occupational (nosocomial) 
    transmission.
    ---------------------------------------------------------------------------
    
         ``Intermediate-risk'' areas or occupational groups are 
    those in which (a) the PPD test conversion rate is not greater than 
    that for areas or groups in which occupational exposure to M. 
    tuberculosis is unlikely or than previous conversion rates for the same 
    area or group, (b) no clusters of PPD test conversions have occurred, 
    (c) person-to-person transmission of M. tuberculosis) has not been 
    detected, and (d) six or more patients with active TB are examined or 
    treated each year. Survey data suggest that facilities in which six or 
    more TB patients are examined or treated each year may have an 
    increased risk for transmission of M. tuberculosis (CDC, unpublished 
    data); thus, areas in which six or more patients with active TB are 
    examined or treated each year (or occupational groups in which HCWs are 
    likely to be exposed to six or more TB patients per year) should be 
    classified as ``intermediate risk.''
         ``High-risk'' areas or occupational groups are those in 
    which (a) the PPD test conversion rate is significantly greater than 
    for areas or groups in which occupational exposure to M. tuberculosis 
    is unlikely or than previous conversion rates for the same area or 
    group, and epidemiologic evaluation suggests nosocomial transmission; 
    or (b) a cluster of PPD test conversions has occurred, and 
    epidemiologic evaluation suggests nosocomial transmission of M. 
    tuberculosis; or (c) possible person-to-person transmission of M. 
    tuberculosis has been detected.
         If no data or insufficient data for adequate determination 
    of risk have been collected, such data should be compiled, analyzed, 
    and reviewed expeditiously.
        b. Community TB profile.
         A profile of TB in the community that is served by the 
    facility should be obtained from the public health department. This 
    profile should include, at a minimum, the incidence (and prevalence, if 
    available) of active TB in the community and the drug-susceptibility 
    patterns of M. tuberculosis isolates (i.e., the antituberculous agents 
    to which each isolate is susceptible and those to which it is 
    resistant) from patients in the community.
        c. Case surveillance.
         Data concerning the number of suspected and confirmed 
    active TB cases among patients and HCWs in the facility should be 
    systematically collected, reviewed, and used to estimate the number of 
    TB isolation rooms needed, to recognize possible clusters of nosocomial 
    transmission, and to assess the level of potential occupational risk. 
    The number of TB patients in specific areas of a facility can be 
    obtained from laboratory surveillance data on specimens positive for 
    AFB smears or M. tuberculosis cultures, from infection-control records, 
    and from databases containing information about hospital discharge 
    diagnoses.
         Drug-susceptibility patterns of M. tuberculosis isolates 
    from TB patients treated in the facility should be reviewed to identify 
    the frequency and patterns of drug resistance. This information may 
    indicate a need to modify the initial treatment regimen or may suggest 
    possible nosocomial transmission or increased occupational risk.
        d. Analysis of HCW PPD test screening data.
         Results of HCW PPD testing should be recorded in the 
    individual HCW's employee health record and in a retrievable aggregate 
    database of all HCW PPD test results. Personal identifying information 
    should be handled confidentially. PPD test conversion rates should be 
    calculated at appropriate intervals to estimate the risk for PPD test 
    conversions for each area of the facility and for each specific 
    occupational group not assigned to a specific area (Table 2). To 
    calculate PPD test conversion rates, the total number of previously 
    PPD-negative HCWs tested in each area or group (i.e., the denominator) 
    and the number of PPD test conversions among HCWs in each area or group 
    (the numerator) must be obtained.
         PPD test conversion rates for each area or occupational 
    group should be compared with rates for areas or groups in which 
    occupational exposure to M. tuberculosis is unlikely and with previous 
    conversion rates in the same area or group to identify areas or groups 
    where the risk for occupational PPD test conversions may be increased. 
    A low number of HCWs in a specific area may result in a greatly 
    increased rate of conversion for that area, although the actual risk 
    may not be significantly greater than that for other areas. Testing for 
    statistical significance (e.g., Fisher's exact test or chi square test) 
    may assist interpretation; however, lack of statistical significance 
    may not rule out a problem (i.e., if the number of HCWs tested is low, 
    there may not be adequate statistical power to detect a significant 
    difference). Thus, interpretation of individual situations is 
    necessary.
         An epidemiologic investigation to evaluate the likelihood 
    of nosocomial transmission should be conducted if PPD test conversions 
    are noted (Section II.K.1).
         The frequency and comprehensiveness of the HCW PPD testing 
    program should be evaluated periodically to ensure that all HCWs who 
    should be included in the program are being tested at appropriate 
    intervals. For surveillance purposes, earlier detection of transmission 
    may be enhanced if HCWs in a given area or occupational group are 
    tested on different scheduled dates rather than all being tested on the 
    same date (Section II.J.3).
        e. Review of TB patient medical records.
         The medical records of a sample of TB patients examined at 
    the facility can be reviewed periodically to evaluate infection-control 
    parameters (Table 1). Parameters to examine may include the intervals 
    from date of admission until (a) TB was suspected, (b) specimens for 
    AFB smears were ordered, (c) these specimens were collected, (d) tests 
    were performed, and (e) results were reported. Moreover, the adequacy 
    of the TB treatment regimens that were used should be evaluated.
         Medical record reviews should note previous hospital 
    admissions of TB patients before the onset of TB symptoms. Patient-to-
    patient transmission may be suspected if active TB occurs in a patient 
    who had a prior hospitalization during which exposure to another TB 
    patient occurred or if isolates from two or more TB patients have 
    identical characteristic drug-susceptibility or DNA fingerprint 
    patterns.
         Data from the case review should be used to determine if 
    there is a need to modify (a) protocols for identifying and isolating 
    patients who may have infectious TB, (b) laboratory procedures, (c) 
    administrative policies and practices, or (d) protocols for patient 
    management.
        f. Observation of TB infection-control practices.
         Assessing adherence to the policies of the TB infection-
    control program should be part of the evaluation process. This 
    assessment should be performed on a regular basis and whenever an 
    increase occurs in the number of TB patients or HCW PPD test 
    conversions. Areas at high risk for transmission of M. tuberculosis 
    should be monitored more frequently than other areas. The review of 
    patient medical records provides information on HCW adherence to some 
    of the policies of the TB infection-control program. In addition, work 
    practices related to TB isolation (e.g., keeping doors to isolation 
    rooms closed) should be observed to determine if employers are 
    enforcing, and HCWs are adhering to, these policies and if patient 
    adherence is being enforced. If these policies are not being enforced 
    or adhered to, appropriate education and other corrective action should 
    be implemented.
        g. Engineering evaluation
         Results of engineering maintenance measures should be 
    reviewed at regular intervals (Table 3). Data from the most recent 
    evaluation and from maintenance procedures and logs should be reviewed 
    carefully as part of the risk assessment.
    2. Development of the TB Infection-Control Plan
         Based on the results of the risk assessment, a written TB 
    infection-control plan should be developed and implemented for each 
    area of the facility and for each occupational group of HCWs not 
    assigned to a specific area of the facility (Table 2; Table 3).
         The occurrence of drug-resistant TB in the facility or the 
    community, or a relatively high prevalence of HIV infection among 
    patients or HCWs in the community, may increase the concern about 
    transmission of M. tuberculosis and may influence the decision 
    regarding which protocol to follow (i.e., a higher-risk classification 
    may be selected).
         Health-care facilities are likely to have a combination of 
    low-, intermediate-, and high-risk areas or occupational groups during 
    the same time period. The appropriate protocol should be implemented 
    for each area or group.
         Areas in which cough-inducing procedures are performed on 
    patients who may have active TB should, at the minimum, implement the 
    intermediate-risk protocol.
    3. Periodic Reassessment
         Follow-up risk assessment should be performed at the 
    interval indicated by the most recent risk assessment (Figure 1; Table 
    2). Based on the results of the follow-up assessment, problem 
    evaluation may need to be conducted or the protocol may need to be 
    modified to a higher- or lower-risk level.
    
    Table 3. Characteristics of an Effective Tuberculosis (TB) Infection-
    Control Program*
    
    I. Assignment of responsibility
    ---------------------------------------------------------------------------
    
        *A program such as this is appropriate for health-care 
    facilities in which there is a high risk for transmission of 
    Mycobacterium tuberculosis.
    ---------------------------------------------------------------------------
    
        A. Assign responsibility for the TB infection-control program to 
    qualified person(s).
        B. Ensure that persons with expertise in infection control, 
    occupational health, and engineering are identified and included.
    II. Risk assessment, TB infection-control plan, and periodic 
    reassessment
        A. Initial risk assessments
        1. Obtain information concerning TB in the community.
        2. Evaluate data concerning TB patients in the facility.
        3. Evaluate data concerning purified protein derivative (PPD)-
    tuberculin skin-test conversions among health-care workers (HCWs) in 
    the facility.
        4. Rule out evidence of person-to-person transmission.
        B. Written TB infection-control program
        1. Select initial risk protocol(s).
        2. Develop written TB infection-control protocols.
        C. Repeat risk assessment at appropriate intervals.
        1. Review current community and facility surveillance data and PPD-
    tuberculin skin-test results.
        2. Review records of TB patients.
        3. Observe HCW infection-control practices.
        4. Evaluate maintenance of engineering controls.
    III. Identification, evaluation, and treatment of patients who have TB
        A. Screen patients for signs and symptoms of active TB:
        1. On initial encounter in emergency department or ambulatory-care 
    setting.
        2. Before or at the time of admission.
        B. Perform radiologic and bacteriologic evaluation of patients who 
    have signs and symptoms suggestive of TB.
        C. Promptly initiate treatment.
    IV. Managing outpatients who have possible infectious TB
        A. Promptly initiate TB precautions.
        B. Place patients in separate waiting areas or TB isolation rooms.
        C. Give patients a surgical mask, a box of tissues, and 
    instructions regarding the use of these items.
    V. Managing inpatients who have possible infectious TB
        A. Promptly isolate patients who have suspected or known infectious 
    TB.
        B. Monitor the response to treatment.
        C. Follow appropriate criteria for discontinuing isolation.
    VI. Engineering recommendations
        A. Design local exhaust and general ventilation in collaboration 
    with persons who have expertise in ventilation engineering.
        B. Use a single-pass air system or air recirculation after high-
    efficiency particulate air (HEPA) filtration in areas where infectious 
    TB patients receive care.
        C. Use additional measures, if needed, in areas where TB patients 
    may receive care.
        D. Design TB isolation rooms in health-care facilities to achieve 
    6 air changes per hour (ACH) for existing facilities and 
    12 ACH for new or renovated facilities.
        E. Regularly monitor and maintain engineering controls.
        F. TB isolation rooms that are being used should be monitored daily 
    to ensure they maintain negative pressure relative to the hallway and 
    all surrounding areas.
        G. Exhaust TB isolation room air to outside or, if absolutely 
    unavoidable, recirculate after HEPA filtration.
    VII. Respiratory protection
        A. Respiratory protective devices should meet recommended 
    performance criteria.
        B. Respiratory protection should be used by persons entering rooms 
    in which patients with known or suspected infectious TB are being 
    isolated, by HCWs when performing cough-inducing or aerosol-generating 
    procedures on such patients, and by persons in other settings where 
    administrative and engineering controls are not likely to protect them 
    from inhaling infectious airborne droplet nuclei.
        C. A respiratory protection program is required at all facilities 
    in which respiratory protection is used.
    VIII. Cough-inducing procedures
        A. Do not perform such procedures on TB patients unless absolutely 
    necessary.
        B. Perform such procedures in areas that have local exhaust 
    ventilation devices (e.g., booths or special enclosures) or, if this is 
    not feasible, in a room that meets the ventilation requirements for TB 
    isolation.
        C. After completion of procedures, TB patients should remain in the 
    booth or special enclosure until their coughing subsidies.
    IX. HCW TB training and education
        A. All HCWs should receive periodic TB education appropriate for 
    their work responsibilities and duties.
        B. Training should include the epidemiology of TB in the facility.
        C. TB education should emphasize concepts of the pathogenesis of 
    and occupational risk for TB.
        D. Training should describe work practices that reduce the 
    likelihood of transmitting M. tuberculosis.
    X. HCW counseling and screening
        A. Counsel all HCWs regarding TB and TB infection.
        B. Counsel all HCWs about the increased risk to immunocompromised 
    persons for developing active TB.
        C. Perform PPD skin tests on HCWs at the beginning of their 
    employment, and repeat PPD tests at periodic intervals.
        D. Evaluate symptomatic HCWs for active TB.
    XI. Evaluate HCW PPD test conversions and possible nosocomial 
    transmission of M. tuberculosis.
    XII. Coordinate efforts with public health department(s)
         After each risk assessment, the staff responsible for TB 
    control, in conjunction with other appropriate HCWs, should review all 
    TB control policies to ensure that they are effective and meet current 
    needs.
    4. Examples of Risk Assessment
        Examples of six hypothetical situations and the means by which 
    surveillance data are used to select a TB control protocol are 
    described as follows:
        Hospital A. The overall HCW PPD test conversion rate in the 
    facility is 1.6%. No areas or HCW occupational groups have a 
    significantly greater PPD test conversion rate than areas or groups in 
    which occupational exposure to M. tuberculosis is unlikely (or than 
    previous rates for the same area or group). No clusters of PPD test 
    conversions have occurred. Patient-to-patient transmission has not been 
    detected. Patients who have TB are admitted to the facility, but no 
    area admits six or more TB patients per year. The low-risk protocol 
    will be followed in all areas.
        Hospital B. The overall HCW PPD test conversion rate in the 
    facility is 1.8%. The PPD test conversion rate for the medical 
    intensive-care unit rate is significantly higher than all other areas 
    in the facility. The problem identification process is initiated 
    (Section II.K). It is determined that all TB patients have been 
    isolated appropriately. Other potential problems are then evaluated, 
    and the cause for the higher rate is not identified. After consulting 
    the public health department TB infection-control program, the high-
    risk protocol is followed in the unit until the PPD test conversion 
    rate is similar to areas of the facility in which occupational exposure 
    to TB patients is unlikely. If the rate remains significantly higher 
    than other areas, further evaluation, including environmental and 
    procedural studies, will be performed to identify possible reasons for 
    the high conversion rate.
        Hospital C. The overall HCW PPD test conversion rate in the 
    facility is 2.4%. Rates range from 0 to 2.6% for the individual areas 
    and occupational groups. None of these rates is significantly higher 
    than rates for areas in which occupational exposure to M. tuberculosis 
    is unlikely. No particular HCW group has higher conversion rates than 
    the other groups. No clusters of HCW PPD test conversions have 
    occurred. In two of the areas, HCWs cared for more than six TB patients 
    during the preceding year. These two areas will follow the 
    intermediate-risk protocol, and all other areas will follow the low-
    risk protocol. This hospital is located in the southeastern United 
    States, and these conversion rates may reflect cross-reactivity with 
    nontuberculous mycobacteria.
        Hospital D. The overall HCW PPD test conversion rate in the 
    facility is 1.2%. In no area did HCWs care for six or more TB patients 
    during the preceding year. Three of the 20 respiratory therapists 
    tested had PPD conversions, for a rate of 15%. The respiratory 
    therapists who had PPD test conversions had spent all or part of their 
    time in the pulmonary function laboratory, where induced sputum 
    specimens were obtained. A low-risk protocol is maintained for all 
    areas and occupational groups in the facility except for respiratory 
    therapists. A problem evaluation is conducted in the pulmonary function 
    laboratory (Section II.K). It is determined that the ventilation in 
    this area is inadequate. Booths are installed for sputum induction. PPD 
    testing and the risk assessment are repeated 3 months later. If the 
    repeat testing at 3 months indicates that no more conversions have 
    occurred, the respiratory therapists will return to the low-risk 
    protocol.
        Hospital E. Hospital E is located in a community that has a 
    relatively low incidence of TB. To optimize TB services in the 
    community, the four hospitals in the community have developed an 
    agreement that one of them (e.g., Hospital G) will provide all 
    inpatient services to persons who have suspected or confirmed TB. The 
    other hospitals have implemented protocols in their ambulatory-care 
    clinics and emergency departments to identify patients who may have 
    active TB. These patients are then transferred to Hospital G for 
    inpatient care if such care is considered necessary. After discharge 
    from Hospital G, they receive follow-up care in the public health 
    department's TB clinic. During the preceding year, Hospital E has 
    identified fewer than six TB patients in its ambulatory-care and 
    emergency departments and has had no PPD test conversions or other 
    evidence of M. tuberculosis transmission among HCWs or patients in 
    these areas. These areas are classified as low risk, and all other 
    areas are classified as very low risk.
        Hospital F. Hospital F is located in a county in which no TB cases 
    have been reported during the preceding 2 years. A risk assessment 
    conducted at the facility did not identify any patients who had 
    suspected or confirmed TB during the preceding year. The facility is 
    classified as minimal risk.
    C. Identifying, Evaluating, and Initiating Treatment for Patients Who 
    May Have Active TB
        The most important factors in preventing transmission of M. 
    tuberculosis are the early identification of patients who may have 
    infectious TB, prompt implementation of TB precautions for such 
    patients, and prompt initiation of effective treatment for those who 
    are likely to have TB.
    1. Identifying Patients Who May Have Active TB
         Health-care personnel who are assigned responsibility for 
    TB infection control in ambulatory-care and inpatient settings should 
    develop, implement, and enforce protocols for the early identification 
    of patients who may have infectious TB.
         The criteria used in these protocols should be based on 
    the prevalence and characteristics of TB in the population served by 
    the specific facility. These protocols should be evaluated periodically 
    and revised according to the results of the evaluation. Review of 
    medical records of patients who were examined in the facility and 
    diagnosed as having TB may serve as a guide for developing or revising 
    these protocols.
         A diagnosis of TB may be considered for any patient who 
    has a persistent cough (i.e., a cough lasting for 3 weeks) 
    or other signs or symptoms compatible with active TB (e.g., bloody 
    sputum, night sweats, weight loss, anorexia, or fever). However, the 
    index of suspicion for TB will vary in different geographic areas and 
    will depend on the prevalence of TB and other characteristics of the 
    population served by the facility. The index of suspicion for TB should 
    be very high in geographic areas or among groups of patients in which 
    the prevalence of TB is high (Section I.B). Appropriate diagnostic 
    measures should be conducted and TB precautions implemented for 
    patients in whom active TB is suspected.
    2. Diagnostic Evaluation for Active TB
         Diagnostic measures for identifying TB should be conducted 
    for patients in whom active TB is being considered. These measures 
    include obtaining a medical history and performing a physical 
    examination, PPD skin test, chest radiograph, and microscopic 
    examination and culture of sputum or other appropriate specimens 
    (6,34,35). Other diagnostic procedures (e.g., bronchoscopy or biopsy) 
    may be indicated for some patients (36,37).
         Prompt laboratory results are crucial to the proper 
    treatment of the TB patient and to early initiation of infection 
    control. To ensure timely results, laboratories performing 
    mycobacteriologic tests should be proficient at both the laboratory and 
    administrative aspects of specimen processing. Laboratories should use 
    the most rapid methods available (e.g., fluorescent microscopy for AFB 
    smears; radiometric culture methods for isolation of mycobacteria; 
    -nitro--acetylamino--hydroxy-proprophenone 
    [NAP] test, nucleic acid probes, or high-pressure liquid chromatography 
    [HPLC] for species identification; and radiometric methods for drug-
    susceptibility testing). As other more rapid or sensitive tests become 
    available, practical, and affordable, such tests should be incorporated 
    promptly into the mycobacteriology laboratory. Laboratories that rarely 
    receive specimens for mycobacteriologic analysis should refer the 
    specimens to a laboratory that more frequently performs these tests.
         Results of AFB sputum smears should be available within 24 
    hours of specimen collection (38).
         The probability of TB is greater among patients who have 
    positive PPD test results or a history of positive PPD test results, 
    who have previously had TB or have been exposed to M. tuberculosis, or 
    who belong to a group at high risk for TB (Section I.B). Active TB is 
    strongly suggested if the diagnostic evaluation reveals AFB in sputum, 
    a chest radiograph suggestive of TB, or symptoms highly suggestive of 
    TB. TB can occur simultaneously in immunosuppressed persons who have 
    pulmonary infections caused by other organisms (e.g., Pneumocystis 
    carinii or Mycobacterium avium complex) and should be considered in the 
    diagnostic evaluation of all patients who have symptoms compatible with 
    TB (Suppl. 1; Suppl. 2).
         TB may be more difficult to diagnose among persons who 
    have HIV infection (or other conditions associated with severe 
    suppression of cell-mediated immunity) because of a nonclassical 
    clinical or radiographic presentation and/or the simultaneous 
    occurrence of other pulmonary infections (e.g., P. carinii pneumonia 
    and M. avium complex). The difficulty in diagnosing TB in HIV-infected 
    persons may be further compounded by impaired responses to PPD skin 
    tests (39,40), the possibly lower sensitivity of sputum smears for 
    detecting AFB (41), or the overgrowth of cultures with M. avium complex 
    in specimens from patients infected with both M. avium complex and M. 
    tuberculosis (42).
         Immunosuppressed patients who have pulmonary signs or 
    symptoms that are ascribed initially to infections or conditions other 
    than TB should be evaluated initially for coexisting TB. The evaluation 
    for TB should be repeated if the patient does not respond to 
    appropriate therapy for the presumed cause(s) of the pulmonary 
    abnormalities (Suppl. 1; Suppl. 2).
         Patients with suspected or confirmed TB should be reported 
    immediately to the appropriate public health department so that 
    standard procedures for identifying and evaluating TB contacts can be 
    initiated.
    3. Initiation of Treatment for Suspected or Confirmed TB
         Patients who have confirmed active TB or who are 
    considered highly likely to have active TB should be started promptly 
    on appropriate treatment in accordance with current guidelines (Suppl. 
    2) (43). In geographic areas or facilities that have a high prevalence 
    of MDR-TB, the initial regimen used may need to be enhanced while the 
    results of drug-susceptibility tests are pending. The decision should 
    be based on analysis of surveillance data.
         While the patient is in the health-care facility, anti-TB 
    drugs should be administered by directly observed therapy (DOT), the 
    process by which an HCW observes the patient swallowing the 
    medications. Continuing DOT after the patient is discharged should be 
    strongly considered. This decision and the arrangements for providing 
    outpatient DOT should be made in collaboration with the public health 
    department.
    D. Management of Patients Who May Have Active TB in Ambulatory-Care 
    Settings and Emergency Departments
         Triage of patients in ambulatory-care settings and 
    emergency departments should include vigorous efforts to promptly 
    identify patients who have active TB. HCWs who are the first points of 
    contact in facilities that serve populations at risk for TB should be 
    trained to ask questions that will facilitate identification of 
    patients with signs and symptoms suggestive of TB.
         Patients with signs or symptoms suggestive of TB should be 
    evaluated promptly to minimize the amount of time they are in 
    ambulatory-care areas. TB precautions should be followed while the 
    diagnostic evaluation is being conducted for these patients.
         TB precautions in the ambulatory-care setting should 
    include (a) placing these patients in a separate area apart from other 
    patients, and not in open waiting areas (ideally, in a room or 
    enclosure meeting TB isolation requirements); (b) giving these patients 
    surgical masks* to wear and instructing them to keep their masks on; 
    and (c) giving these patients tissues and instructing them to cover 
    their mouths and noses with the tissues when coughing or sneezing.
    ---------------------------------------------------------------------------
    
        *Surgical masks are designed to prevent the respiratory 
    secretions of the person wearing the mask from entering the air. 
    When not in a TB isolation room, patients suspected of having TB 
    should wear surgical masks to reduce the expulsion of droplet nuclei 
    into the air. These patients do not need to wear particulate 
    respirators, which are designed to filter the air before it is 
    inhaled by the person wearing the mask. Patients suspected of having 
    or known to have TB should never wear a respirator that has an 
    exhalation valve, because the device would provide no barrier to the 
    expulsion of droplet nuclei into the air.
    ---------------------------------------------------------------------------
    
         TB precautions should be followed for patients who are 
    known to have active TB and who have not completed therapy until a 
    determination has been made that they are noninfectious (Suppl. 1).
         Patients with active TB who need to attend a health-care 
    clinic should have appointments scheduled to avoid exposing HIV-
    infected or otherwise severely immunocompromised persons to M. 
    tuberculosis. This recommendation could be accomplished by designating 
    certain times of the day for appointments for these patients or by 
    treating them in areas where immunocompromised persons are not treated.
         Ventilation in ambulatory-care areas where patients at 
    high risk for TB are treated should be designed and maintained to 
    reduce the risk for transmission of M. tuberculosis. General-use areas 
    (e.g., waiting rooms) and special areas (e.g., treatment or TB 
    isolation rooms in ambulatory areas) should be ventilated in the same 
    manner as described for similar inpatient areas (Sections II.E.3, II.F; 
    Suppl. 3). Enhanced general ventilation or the use of air-disinfection 
    techniques (e.g., UVGI or recirculation of air within the room through 
    high-efficiency particulate air [HEPA] filters) may be useful in 
    general-use areas of facilities where many infectious TB patients 
    receive care (Section II.F; Suppl. 3).
         Ideally, ambulatory-care settings in which patients with 
    TB are frequently examined or treated should have a TB isolation 
    room(s) available. Such rooms are not necessary in ambulatory-care 
    settings in which patients who have confirmed or suspected TB are seen 
    infrequently. However, these facilities should have a written protocol 
    for early identification of patients with TB symptoms and referral to 
    an area or a collaborating facility where the patient can be evaluated 
    and managed appropriately. These protocols should be reviewed on a 
    regular basis and revised as necessary. The additional guidelines in 
    Section II.H should be followed in ambulatory-care settings where 
    cough-inducing procedures are performed on patients who may have active 
    TB.
    E. Management of Hospitalized Patients Who Have Confirmed or Suspected 
    TB
    1. Initiation of Isolation for TB
         In hospitals and other inpatient facilities, any patient 
    suspected of having or known to have infectious TB should be placed in 
    a TB isolation room that has currently recommended ventilation 
    characteristics (Section II.E.3; Suppl. 3). Written policies for 
    initiating isolation should specify (a) the indications for isolation, 
    (b) the person(s) authorized to initiate and discontinue isolation, (c) 
    the isolation practices to follow, (d) the monitoring of isolation, (e) 
    the management of patients who do not adhere to isolation practices, 
    and (f) the criteria for discontinuing isolation.
         In rare circumstances, placing more than one TB patient 
    together in the same room may be acceptable. This practice is sometimes 
    referred to as ``cohorting.'' Because of the risk for patients becoming 
    superinfected with drug-resistant organisms, patients with TB should be 
    placed in the same room only if all patients involved (a) have culture-
    confirmed TB, (b) have drug-susceptibility test results available on a 
    current specimen obtained during the present hospitalization, (c) have 
    identical drug-susceptibility patterns on these specimens, and (d) are 
    on effective therapy. Having isolates with identical DNA fingerprint 
    patterns is not adequate evidence for placing two TB patients together 
    in the same room, because isolates with the same DNA fingerprint 
    pattern can have different drug-susceptibility patterns.
         Pediatric patients with suspected or confirmed TB should 
    be evaluated for potential infectiousness according to the same 
    criteria as are adults (i.e., on the basis of symptoms, sputum AFB 
    smears, radiologic findings, and other criteria) (Suppl. 1). Children 
    who may be infectious should be placed in isolation until they are 
    determined to be noninfectious. Pediatric patients who may be 
    infectious include those who have laryngeal or extensive pulmonary 
    involvement, pronounced cough, positive sputum AFB smears, or cavitary 
    TB or those for whom cough-inducing procedures are performed (44).
         The source of infection for a child with TB is often a 
    member of the child's family (45). Therefore, parents and other 
    visitors of all pediatric TB patients should be evaluated for TB as 
    soon as possible. Until they have been evaluated, or the source case is 
    identified, they should wear surgical masks when in areas of the 
    facility outside of the child's room, and they should refrain from 
    visiting common areas in the facility (e.g., the cafeteria or lounge 
    areas).
         TB patients in intensive-care units should be treated the 
    same as patients in noncritical-care settings. They should be placed in 
    TB isolation and have respiratory secretions submitted for AFB smear 
    and culture if they have undiagnosed pulmonary symptoms suggestive of 
    TB.
         If readmitted to a health-care facility, patients who are 
    known to have active TB and who have not completed therapy should have 
    TB precautions applied until a determination has been made that they 
    are noninfectious (Suppl. 1).
    2. TB Isolation Practices
         Patients who are placed in TB isolation should be educated 
    about the mechanisms of M. tuberculosis transmission and the reasons 
    for their being placed in isolation. They should be taught to cover 
    their mouths and noses with a tissue when coughing or sneezing, even 
    while in the isolation room, to contain liquid drops and droplets 
    before they are expelled into the air (46).
         Efforts should be made to facilitate patient adherence to 
    isolation measures (e.g., staying in the TB isolation room). Such 
    efforts might include the use of incentives (e.g., providing them with 
    telephones, televisions, or radios in their rooms or allowing special 
    dietary requests). Efforts should also be made to address other 
    problems that could interfere with adherence to isolation (e.g., 
    management of the patient's withdrawal from addictive substances 
    [including tobacco]).
         Patients placed in isolation should remain in their 
    isolation rooms with the door closed. If possible, diagnostic and 
    treatment procedures should be performed in the isolation rooms to 
    avoid transporting patients through other areas of the facility. If 
    patients who may have infectious TB must be transported outside their 
    isolation rooms for medically essential procedures that cannot be 
    performed in the isolation rooms, they should wear surgical masks that 
    cover their mouths and noses during transport. Persons transporting the 
    patients do not need to wear respiratory protection outside the TB 
    isolation rooms. Procedures for these patients should be scheduled at 
    times when they can be performed rapidly and when waiting areas are 
    less crowded.
         Treatment and procedure rooms in which patients who have 
    infectious TB or who have an undiagnosed pulmonary disease and are at 
    high risk for active TB receive care should meet the ventilation 
    recommendations for isolation rooms (Section II.E.3; Suppl. 3). 
    Ideally, facilities in which TB patients are frequently treated should 
    have an area in the radiology department that is ventilated separately 
    for TB patients. If this is not possible, TB patients should wear 
    surgical masks and should stay in the radiology suite the minimum 
    amount of time possible, then be returned promptly to their isolation 
    rooms.
         The number of persons entering an isolation room should be 
    minimal. All persons who enter an isolation room should wear 
    respiratory protection (Section II.G; Suppl. 4). The patient's visitors 
    should be given respirators to wear while in the isolation room, and 
    they should be given general instructions on how to use their 
    respirators.
         Disposable items contaminated with respiratory secretions 
    are not associated with transmission of M. tuberculosis. However, for 
    general infection-control purposes, these items should be handled and 
    transported in a manner that reduces the risk for transmitting other 
    microorganisms to patients, HCWs, and visitors and that decreases 
    environmental contamination in the health-care facility. Such items 
    should be disposed of in accordance with hospital policy and applicable 
    regulations (Suppl. 5).
    3. The TB Isolation Room
         TB isolation rooms should be single-patient rooms with 
    special ventilation characteristics appropriate for the purposes of 
    isolation (Suppl. 3). The primary purposes of TB isolation rooms are to 
    (a) separate patients who are likely to have infectious TB from other 
    persons; (b) provide an environment that will allow reduction of the 
    concentration of droplet nuclei through various engineering methods; 
    and (c) prevent the escape of droplet nuclei from the TB isolation room 
    and treatment room, thus preventing entry of M. tuberculosis into the 
    corridor and other areas of the facility.
         To prevent the escape of droplet nuclei, the TB isolation 
    room should be maintained under negative pressure (Suppl. 3). Doors to 
    isolation rooms should be kept closed, except when patients or 
    personnel must enter or exit the room, so that negative pressure can be 
    maintained.
         Negative pressure in the room should be monitored daily 
    while the room is being used for TB isolation.
         The American Society of Heating, Refrigerating and Air-
    Conditioning Engineers, Inc. (ASHRAE) (47), the American Institute of 
    Architects (AIA) (48), and the Health Resources and Services 
    Administration (49) recommend a minimum of 6 air changes per hour (ACH) 
    for TB isolation and treatment rooms. This ventilation rate is based on 
    comfort and odor control considerations. The effectiveness of this 
    level of airflow in reducing the concentration of droplet nuclei in the 
    room, thus reducing the transmission of airborne pathogens, has not 
    been evaluated directly or adequately.
        Ventilation rates of >6 ACH are likely to produce an incrementally 
    greater reduction in the concentration of bacteria in a room than are 
    lower rates (50-52). However, accurate quantitation of decreases in 
    risk that would result from specific increases in general ventilation 
    levels has not been performed and may not be possible.
        For the purposes of reducing the concentration of droplet nuclei, 
    TB isolation and treatment rooms in existing health-care facilities 
    should have an airflow of 6 ACH. Where feasible, this 
    airflow rate should be increased to 12 ACH by adjusting or 
    modifying the ventilation system or by using auxiliary means (e.g., 
    recirculation of air through fixed HEPA filtration systems or portable 
    air cleaners) (Suppl. 3, Section II.B.5.a) (53). New construction or 
    renovation of existing health-care facilities should be designed so 
    that TB isolation rooms achieve an airflow of 12 ACH.
         Air from TB isolation rooms and treatment rooms used to 
    treat patients who have known or suspected infectious TB should be 
    exhausted to the outside in accordance with applicable federal, state, 
    and local regulations. The air should not be recirculated into the 
    general ventilation. In some instances, recirculation of air into the 
    general ventilation system from such rooms is unavoidable (i.e., in 
    existing facilities in which the ventilation system or facility 
    configuration makes venting the exhaust to the outside impossible). In 
    such cases, HEPA filters should be installed in the exhaust duct 
    leading from the room to the general ventilation system to remove 
    infectious organisms and particulates the size of droplet nuclei from 
    the air before it is returned to the general ventilation system 
    (Section II.F; Suppl. 3). Air from TB isolation and treatment rooms in 
    new or renovated facilities should not be recirculated into the general 
    ventilation system.
         Although not required, an anteroom may increase the 
    effectiveness of the isolation room by minimizing the potential escape 
    of droplet nuclei into the corridor when the door is opened. To work 
    effectively, the anteroom should have positive air pressure in relation 
    to the isolation room. The pressure relationship between the anteroom 
    and the corridor may vary according to ventilation design.
         Upper-room air UVGI may be used as an adjunct to general 
    ventilation in the isolation room (Section II.F; Suppl. 3). Air in the 
    isolation room may be recirculated within the room through HEPA filters 
    or UVGI devices to increase the effective ACH and to increase thermal 
    efficiency.
         Health-care facilities should have enough isolation rooms 
    to appropriately isolate all patients who have suspected or confirmed 
    active TB. This number should be estimated using the results of the 
    risk assessment of the health-care facility. Except for minimal-and 
    very low-risk health-care facilities, all acute-care inpatient 
    facilities should have at least one TB isolation room (Section II.B).
         Grouping isolation rooms together in one area of the 
    facility may reduce the possibility of transmitting M. tuberculosis to 
    other patients and may facilitate care of TB patients and the 
    installation and maintenance of optimal engineering (particularly 
    ventilation) controls.
    4. Discontinuation of TB Isolation
         TB isolation can be discontinued if the diagnosis of TB is 
    ruled out. For some patients, TB can be ruled out when another 
    diagnosis is confirmed. If a diagnosis of TB cannot be ruled out, the 
    patient should remain in isolation until a determination has been made 
    that the patient is noninfectious. However, patients can be discharged 
    from the health-care facility while still potentially infectious if 
    appropriate postdischarge arrangements can be ensured (Section II.E.5).
         The length of time required for a TB patient to become 
    noninfectious after starting anti-TB therapy varies considerably 
    (Suppl. 1). Isolation should be discontinued only when the patient is 
    on effective therapy, is improving clinically, and has had three 
    consecutive negative sputum AFB smears collected on different days.
         Hospitalized patients who have active TB should be 
    monitored for relapse by having sputum AFB smears examined regularly 
    (e.g., every 2 weeks). Nonadherence to therapy (i.e., failure to take 
    medications as prescribed) and the presence of drug-resistant organisms 
    are the two most common reasons why patients remain infectious despite 
    treatment. These reasons should be considered if a patient does not 
    respond clinically to therapy within 2-3 weeks.
         Continued isolation throughout the hospitalization should 
    be strongly considered for patients who have MDR-TB because of the 
    tendency for treatment failure or relapse (i.e., difficulty in 
    maintaining noninfectiousness) that has been observed in such cases.
    5. Discharge Planning
         Before a TB patient is discharged from the health-care 
    facility, the facility's staff and public health authorities should 
    collaborate to ensure continuation of therapy. Discharge planning in 
    the health-care facility should include, at a minimum, (a) a confirmed 
    outpatient appointment with the provider who will manage the patient 
    until the patient is cured, (b) sufficient medication to take until the 
    outpatient appointment, and (c) placement into case management (e.g., 
    DOT) or outreach programs of the public health department. These plans 
    should be initiated and in place before the patient's discharge.
         Patients who may be infectious at the time of discharge 
    should only be discharged to facilities that have isolation capability 
    or to their homes. Plans for discharging a patient who will return home 
    must consider whether all the household members were infected 
    previously and whether any uninfected household members are at very 
    high risk for active TB if infected (e.g., children <4 years="" of="" age="" or="" persons="" infected="" with="" hiv="" or="" otherwise="" severely="" immunocompromised).="" if="" the="" household="" does="" include="" such="" persons,="" arrangements="" should="" be="" made="" to="" prevent="" them="" from="" being="" exposed="" to="" the="" tb="" patient="" until="" a="" determination="" has="" been="" made="" that="" the="" patient="" is="" noninfectious.="" f.="" engineering="" control="" recommendations="" 1.="" general="" ventilation="" this="" section="" deals="" only="" with="" engineering="" controls="" for="" general-use="" areas="" of="" health-care="" facilities="" (e.g.,="" waiting-room="" areas="" and="" emergency="" departments).="" recommendations="" for="" engineering="" controls="" for="" specific="" areas="" of="" the="" facility="" (e.g.,="" tb="" isolation="" rooms)="" are="" contained="" in="" the="" sections="" encompassing="" those="" areas.="" details="" regarding="" ventilation="" design,="" evaluation,="" and="" supplemental="" approaches="" are="" described="" in="" supplement="" 3.=""> Health-care facilities should either (a) include as part 
    of their staff an engineer or other professional with expertise in 
    ventilation or (b) have this expertise available from a consultant who 
    is an expert in ventilation engineering and who also has hospital 
    experience. These persons should work closely with infection-control 
    staff to assist in controlling airborne infections.
         Ventilation system designs in health-care facilities 
    should meet any applicable federal, state, and local requirements.
         The direction of airflow in health-care facilities should 
    be designed, constructed, and maintained so that air flows from clean 
    areas to less-clean areas.
         Health-care facilities serving populations that have a 
    high prevalence of TB may need to supplement the general ventilation or 
    use additional engineering approaches (i.e., HEPA filtration or UVGI) 
    in general-use areas where TB patients are likely to go (e.g., waiting-
    room areas, emergency departments, and radiology suites). A single-
    pass, nonrecirculating system that exhausts air to the outside, a 
    recirculation system that passes air through HEPA filters before 
    recirculating it to the general ventilation system, or upper air UVGI 
    may be used in such areas.
    2. Additional Engineering Control Approaches
        a. HEPA filtration.
        HEPA filters may be used in a number of ways to reduce or eliminate 
    infectious droplet nuclei from room air or exhaust (Suppl. 3). These 
    methods include placement of HEPA filters (a) in exhaust ducts 
    discharging air from booths or enclosures into the surrounding room; 
    (b) in ducts or in ceiling- or wall-mounted units, for recirculation of 
    air within an individual room (fixed recirculation systems); (c) in 
    portable air cleaners; (d) in exhaust ducts to remove droplet nuclei 
    from air being discharged to the outside, either directly or through 
    ventilation equipment; and (e) in ducts discharging air from the TB 
    isolation room into the general ventilation system. In any application, 
    HEPA filters should be installed carefully and maintained meticulously 
    to ensure adequate functioning.
        The manufacturers of in-room air cleaning equipment should provide 
    documentation of the HEPA filter efficiency and the efficiency of the 
    device in lowering room air contaminant levels.
        b. UVGI.
        For general-use areas in which the risk for transmission of M. 
    tuberculosis is relatively high, UVGI lamps may be used as an adjunct 
    to ventilation for reducing the concentration of infectious droplet 
    nuclei (Suppl. 3), although the effectiveness of such units has not 
    been evaluated adequately. Ultraviolet (UV) units can be installed in a 
    room or corridor to irradiate the air in the upper portion of the room 
    (i.e., upper-room air irradiation), or they can be installed in ducts 
    to irradiate air passing through the ducts. UV units installed in ducts 
    should not be substituted for HEPA filters in ducts that discharge air 
    from TB isolation rooms into the general ventilation system. However, 
    UV units can be used in ducts that recirculate air back into the same 
    room.
        To function properly and decrease hazards to HCWs and others in the 
    health-care facility, UV lamps should be installed properly and 
    maintained adequately, which includes the monitoring of irradiance 
    levels. UV tubes should be changed according to the manufacturer's 
    instructions or when meter readings indicate tube failure. An employee 
    trained in the use and handling of UV lamps should be responsible for 
    these measures and for keeping maintenance records. Applicable safety 
    guidelines should be followed. Caution should be exercised to protect 
    HCWs, patients, visitors, and others from excessive exposure to UV 
    radiation.
    G. Respiratory Protection
         Personal respiratory protection should be used by (a) 
    persons entering rooms in which patients with known or suspected 
    infectious TB are being isolated, (b) persons present during cough-
    inducing or aerosol-generating procedures performed on such patients, 
    and (c) persons in other settings where administrative and engineering 
    controls are not likely to protect them from inhaling infectious 
    airborne droplet nuclei (Suppl. 4). These other settings include 
    transporting patients who may have infectious TB in emergency transport 
    vehicles and providing urgent surgical or dental care to patients who 
    may have infectious TB before a determination has been made that the 
    patient is noninfectious (Suppl. 1).
         Respiratory protective devices used in health-care 
    settings for protection against M. tuberculosis should meet the 
    following standard performance criteria:
        1. The ability to filter particles 1 m in size in the 
    unloaded* state with a filter efficiency of 95% (i.e., 
    filter leakage of 5%), given flow rates of up to 50 L per 
    minute.
    ---------------------------------------------------------------------------
    
        *Some filters become more efficient as they become loaded with 
    dust. Health-care settings do not have enough dust in the air to 
    load a filter on a respirator. Therefore, the filter efficiency for 
    respirators used in health-care settings must be determined in the 
    unloaded state.
    ---------------------------------------------------------------------------
    
        2. The ability to be qualitatively or quantitatively fit tested in 
    a reliable way to obtain a face-seal leakage of 10% (54,55).
        3. The ability to fit the different facial sizes and 
    characteristics of HCWs, which can usually be met by making the 
    respirators available in at least three sizes.
        4. The ability to be checked for facepiece fit, in accordance with 
    standards established by the Occupational Safety and Health 
    Administration (OSHA) and good industrial hygiene practice, by HCWs 
    each time they put on their respirators (54,55).
         The facility's risk assessment may identify a limited 
    number of selected settings (e.g., bronchoscopy performed on patients 
    suspected of having TB or autopsy performed on deceased persons 
    suspected of having had active TB at the time of death) where the 
    estimated risk for transmission of M. tuberculosis may be such that a 
    level of respiratory protection exceeding the standard performance 
    criteria is appropriate. In such circumstances, a level of respiratory 
    protection exceeding the standard criteria and compatible with patient-
    care delivery (e.g., more protective negative-pressure respirators; 
    powered air-purifying particulate respirators [PAPRs]; or positive-
    pressure air-line, half-mask respirators) should be provided by 
    employers to HCWs who are exposed to M. tuberculosis. Information on 
    these and other respirators is in the NIOSH Guide to Industrial 
    Respiratory Protection (55) and in Supplement 4 of this document.
         In some settings, HCWs may be at risk for two types of 
    exposure: (a) inhalation of M. tuberculosis and (b) mucous membrane 
    exposure to fluids that may contain bloodborne pathogens. In these 
    settings, protection against both types of exposure should be used.
         When operative procedures (or other procedures requiring a 
    sterile field) are performed on patients who may have infectious TB, 
    respiratory protection worn by the HCW should serve two functions: (a) 
    It should protect the surgical field from the respiratory secretions of 
    the HCW, and (b) it should protect the HCW from infectious droplet 
    nuclei that may be expelled by the patient or generated by the 
    procedure. Respirators with exhalation valves and most positive-
    pressure respirators do not protect the sterile field.
         Health-care facilities in which respiratory protection is 
    used to prevent inhalation of M. tuberculosis are required by OSHA to 
    develop, implement, and maintain a respiratory protection program 
    (Suppl. 4). All HCWs who use respiratory protection should be included 
    in this program. Visitors to TB patients should be given respirators to 
    wear while in isolation rooms, and they should be given general 
    instructions on how to use their respirators.
         Facilities that do not have isolation rooms and do not 
    perform cough-inducing procedures on patients who may have TB may not 
    need to have a respiratory protection program for TB. However, such 
    facilities should have written protocols for the early identification 
    of patients who have signs or symptoms of TB and procedures for 
    referring these patients to a facility where they can be evaluated and 
    managed appropriately. These protocols should be evaluated regularly 
    and revised as needed.
         Surgical masks are designed to prevent the respiratory 
    secretions of the person wearing the mask from entering the air. To 
    reduce the expulsion of droplet nuclei into the air, patients suspected 
    of having TB should wear surgical masks when not in TB isolation rooms. 
    These patients do not need to wear particulate respirators, which are 
    designed to filter the air before it is inhaled by the person wearing 
    the respirator. Patients suspected of having or known to have TB should 
    never wear a respirator that has an exhalation valve, because this type 
    of respirator does not prevent expulsion of droplet nuclei into the 
    air.
    H. Cough-Inducing and Aerosol-Generating Procedures
    1. General Guidelines
        Procedures that involve instrumentation of the lower respiratory 
    tract or induce coughing can increase the likelihood of droplet nuclei 
    being expelled into the air. These cough-inducing procedures include 
    endotracheal intubation and suctioning, diagnostic sputum induction, 
    aerosol treatments (e.g., pentamidine therapy), and bronchoscopy. Other 
    procedures that can generate aerosols (e.g., irrigation of tuberculous 
    abscesses, homogenizing or lyophilizing tissue, or other processing of 
    tissue that may contain tubercle bacilli) are also covered by these 
    recommendations.
          Cough-inducing procedures should not be performed on 
    patients who may have infectious TB unless the procedures are 
    absolutely necessary and can be performed with appropriate precautions.
         All cough-inducing procedures performed on patients who 
    may have infectious TB should be performed using local exhaust 
    ventilation devices (e.g., booths or special enclosures) or, if this is 
    not feasible, in a room that meets the ventilation requirements for TB 
    isolation.
         HCWs should wear respiratory protection when present in 
    rooms or enclosures in which cough-inducing procedures are being 
    performed on patients who may have infectious TB.
         After completion of cough-inducing procedures, patients 
    who may have infectious TB should remain in their isolation rooms or 
    enclosures and not return to common waiting areas until coughing 
    subsides. They should be given tissues and instructed to cover their 
    mouths and noses with the tissues when coughing. If TB patients must 
    recover from sedatives or anesthesia after a procedure (e.g, after a 
    bronchoscopy), they should be placed in separate isolation rooms (and 
    not in recovery rooms with other patients) while they are being 
    monitored.
         Before the booth, enclosure, or room is used for another 
    patient, enough time should be allowed to pass for at least 99% of 
    airborne contaminants to be removed. This time will vary according to 
    the efficiency of the ventilation or filtration used (Suppl. 3, Table 
    S3-1).
    2. Special Considerations for Bronchoscopy
         If performing bronchoscopy in positive-pressure rooms 
    (e.g., operating rooms) is unavoidable, TB should be ruled out as a 
    diagnosis before the procedure is performed. If the bronchoscopy is 
    being performed for the purpose of diagnosing pulmonary disease and 
    that diagnosis could include TB, the procedure should be performed in a 
    room that meets TB isolation ventilation requirements.
    3. Special Considerations for the Administration of Aerosolized 
    Pentamidine
         Patients should be screened for active TB before 
    prophylactic therapy with aerosolized pentamidine is initiated. 
    Screening should include obtaining a medical history and performing 
    skin testing and chest radiography.
         Before each subsequent treatment with aerosolized 
    pentamidine, patients should be screened for symptoms suggestive of TB 
    (e.g., development of a productive cough). If such symptoms are 
    elicited, a diagnostic evaluation for TB should be initiated.
         Patients who have suspected or confirmed active TB should 
    take, if clinically practical, oral prophylaxis for P. carinii 
    pneumonia.
    I. Education and Training of HCWs
        All HCWs, including physicians, should receive education regarding 
    TB that is relevant to persons in their particular occupational group. 
    Ideally, training should be conducted before initial assignment, and 
    the need for additional training should be reevaluated periodically 
    (e.g., once a year). The level and detail of this education will vary 
    according to the HCW's work responsibilities and the level of risk in 
    the facility (or area of the facility) in which the HCW works. However, 
    the program may include the following elements:
         The basic concepts of M. tuberculosis transmission, 
    pathogenesis, and diagnosis, including information concerning the 
    difference between latent TB infection and active TB disease, the signs 
    and symptoms of TB, and the possibility of reinfection.
         The potential for occupational exposure to persons who 
    have infectious TB in the health-care facility, including information 
    concerning the prevalence of TB in the community and facility, the 
    ability of the facility to properly isolate patients who have active 
    TB, and situations with increased risk for exposure to M. tuberculosis.
         The principles and practices of infection control that 
    reduce the risk for transmission of M. tuberculosis, including 
    information concerning the hierarchy of TB infection-control measures 
    and the written policies and procedures of the facility. Site-specific 
    control measures should be provided to HCWs working in areas that 
    require control measures in addition to those of the basic TB 
    infection-control program.
         The purpose of PPD skin testing, the significance of a 
    positive PPD test result, and the importance of participating in the 
    skin-test program.
         The principles of preventive therapy for latent TB 
    infection. These principles include the indications, use, 
    effectiveness, and the potential adverse effects of the drugs (Suppl. 
    2).
         The HCW's responsibility to seek prompt medical evaluation 
    if a PPD test conversion occurs or if symptoms develop that could be 
    caused by TB. Medical evaluation will enable HCWs who have TB to 
    receive appropriate therapy and will help to prevent transmission of M. 
    tuberculosis to patients and other HCWs.
         The principles of drug therapy for active TB.
         The importance of notifying the facility if the HCW is 
    diagnosed with active TB so that contact investigation procedures can 
    be initiated.
         The responsibilities of the facility to maintain the 
    confidentiality of the HCW while ensuring that the HCW who has TB 
    receives appropriate therapy and is noninfectious before returning to 
    duty.
         The higher risks associated with TB infection in persons 
    who have HIV infection or other causes of severely impaired cell-
    mediated immunity, including (a) the more frequent and rapid 
    development of clinical TB after infection with M. tuberculosis, (b) 
    the differences in the clinical presentation of disease, and (c) the 
    high mortality rate associated with MDR-TB in such persons.
         The potential development of cutaneous anergy as immune 
    function (as measured by CD4+ T-lymphocyte counts) declines.
         Information regarding the efficacy and safety of BCG 
    vaccination and the principles of PPD screening among BCG recipients.
         The facility's policy on voluntary work reassignment 
    options for immunocompromised HCWs.
    J. HCW Counseling, Screening, and Evaluation
        A TB counseling, screening, and prevention program for HCWs should 
    be established to protect both HCWs and patients. HCWs who have 
    positive PPD test results, PPD test conversions, or symptoms suggestive 
    of TB should be identified, evaluated to rule out a diagnosis of active 
    TB, and started on therapy or preventive therapy if indicated (5). In 
    addition, the results of the HCW PPD screening program will contribute 
    to evaluation of the effectiveness of current infection-control 
    practices.
    1. Counseling HCWs Regarding TB
         Because of the increased risk for rapid progression from 
    latent TB infection to active TB in HIV-infected or otherwise severely 
    immunocompromised persons, all HCWs should know if they have a medical 
    condition or are receiving a medical treatment that may lead to 
    severely impaired cell-mediated immunity. HCWs who may be at risk for 
    HIV infection should know their HIV status (i.e., they should be 
    encouraged to voluntarily seek counseling and testing for HIV antibody 
    status). Existing guidelines for counseling and testing should be 
    followed routinely (56). Knowledge of these conditions allows the HCW 
    to seek the appropriate preventive measures outlined in this document 
    and to consider voluntary work reassignments. Of particular importance 
    is that HCWs need to know their HIV status if they are at risk for HIV 
    infection and they work in settings where patients who have drug-
    resistant TB may be encountered.
         All HCWs should be informed about the need to follow 
    existing recommendations for infection control to minimize the risk for 
    exposure to infectious agents; implementation of these recommendations 
    will greatly reduce the risk for occupational infections among HCWs 
    (57). All HCWs should also be informed about the potential risks to 
    severely immunocompromised persons associated with caring for patients 
    who have some infectious diseases, including TB. It should be 
    emphasized that limiting exposure to TB patients is the most protective 
    measure that severely immunosuppressed HCWs can take to avoid becoming 
    infected with M. tuberculosis. HCWs who have severely impaired cell-
    mediated immunity and who may be exposed to M. tuberculosis may 
    consider a change in job setting to avoid such exposure. HCWs should be 
    advised of the option that severely immunocompromised HCWs can choose 
    to transfer voluntarily to areas and work activities in which there is 
    the lowest possible risk for exposure to M. tuberculosis. This choice 
    should be a personal decision for HCWs after they have been informed of 
    the risks to their health.
         Employers should make reasonable accommodations (e.g., 
    alternative job assignments) for employees who have a health condition 
    that compromises cell-mediated immunity and who work in settings where 
    they may be exposed to M. tuberculosis. HCWs who are known to be 
    immunocompromised should be referred to employee health professionals 
    who can individually counsel the employees regarding their risk for TB. 
    Upon the request of the immunocompromised HCW, employers should offer, 
    but not compel, a work setting in which the HCW would have the lowest 
    possible risk for occupational exposure to M. tuberculosis. Evaluation 
    of these situations should also include consideration of the provisions 
    of the Americans With Disabilities Act of 1990* and other applicable 
    federal, state, and local laws.
    ---------------------------------------------------------------------------
    
        *Americans With Disabilities Act of 1990. P.L. 101-336, 42 
    U.S.C. 12101 et seq.
    ---------------------------------------------------------------------------
    
         All HCWs should be informed that immunosuppressed HCWs 
    should have appropriate follow-up and screening for infectious 
    diseases, including TB, provided by their medical practitioner. HCWs 
    who are known to be HIV-infected or otherwise severely immunosuppressed 
    should be tested for cutaneous anergy at the time of PPD testing 
    (Suppl. 2). Consideration should be given to retesting, at least every 
    6 months, those immunocompromised HCWs who are potentially exposed to 
    M. tuberculosis because of the high risk for rapid progression to 
    active TB if they become infected.
         Information provided by HCWs regarding their immune status 
    should be treated confidentially. If the HCW requests voluntary job 
    reassignment, the confidentiality of the HCW should be maintained. 
    Facilities should have written procedures on confidential handling of 
    such information.
    2. Screening HCWs for Active TB
         Any HCW who has a persistent cough (i.e., a cough lasting 
    3 weeks), especially in the presence of other signs or 
    symptoms compatible with active TB (e.g., weight loss, night sweats, 
    bloody sputum, anorexia, or fever), should be evaluated promptly for 
    TB. The HCW should not return to the workplace until a diagnosis of TB 
    has been excluded or until the HCW is on therapy and a determination 
    has been made that the HCW is noninfectious.
    3. Screening HCWs for Latent TB Infection
         The risk assessment should identify which HCWs have 
    potential for exposure to M. tuberculosis and the frequency with which 
    the exposure may occur. This information is used to determine which 
    HCWs to include in the skin-testing program and the frequency with 
    which they should be tested (Table 2).
         If HCWs are from risks groups with increased prevalence of 
    TB, consideration may be given to including them in the skin-testing 
    program, even if they do not have potential occupational exposure to M. 
    tuberculosis, so that converters can be identified and preventive 
    therapy offered.
         Administrators of health-care facilities should ensure 
    that physicians and other personnel not paid by, but working in, the 
    facility receive skin testing at appropriate intervals for their 
    occupational group and work location.
         During the pre-employment physical or when applying for 
    hospital privileges, HCWs who have potential for exposure to M. 
    tuberculosis (Table 2), including those with a history of BCG 
    vaccination, should have baseline PPD skin testing performed (Suppl. 
    2). For HCWs who have not had a documented negative PPD test result 
    during the preceding 12 months, the baseline PPD testing should employ 
    the two-step method; this will detect boosting phenomena that might be 
    misinterpreted as a skin-test conversion. Decisions concerning the use 
    of the two-step procedure for baseline testing in a particular facility 
    should be based on the frequency of boosting in that facility.
         HCWs who have a documented history of a positive PPD test, 
    adequate treatment for disease, or adequate preventive therapy for 
    infection, should be exempt from further PPD screening unless they 
    develop signs or symptoms suggestive of TB.
         PPD-negative HCWs should undergo repeat PPD testing at 
    regular intervals as determined by the risk assessment (Section II.B). 
    In addition, these HCWs should be tested whenever they have been 
    exposed to a TB patient and appropriate precautions were not observed 
    at the time of exposure (Section II.K.3). Performing PPD testing of 
    HCWs who work in the same area or occupational group on different 
    scheduled dates (e.g., test them on their birthdays or on their 
    employment anniversary dates), rather than testing all HCWs in the area 
    or group on the same day, may lead to earlier detection of M. 
    tuberculosis transmission.
         All PPD tests should be administered, read, and 
    interpreted in accordance with current guidelines by specified trained 
    personnel (Suppl. 2). At the time their test results are read, HCWs 
    should be informed about the interpretation of both positive and 
    negative PPD test results. This information should indicate that the 
    interpretation of an induration that is 5-9 mm in diameter depends on 
    the HCW's immune status and history of exposure to persons who have 
    infectious TB. Specifically, HCWs who have indurations of 5-9 mm in 
    diameter should be advised that such results may be considered positive 
    for HCWs who are contacts of persons with infectious TB or who have HIV 
    infection or other causes of severe immunosuppression (e.g., 
    immunosuppressive therapy for organ transplantation).
         When an HCW who is not assigned regularly to a single work 
    area has a PPD test conversion, appropriate personnel should identify 
    the areas where the HCW worked during the time when infection was 
    likely to have occurred. This information can then be considered in 
    analyzing the risk for transmission in those areas.
         In any area of the facility where transmission of M. 
    tuberculosis is known to have occurred, a problem evaluation should be 
    conducted (Section II.K), and the frequency of skin testing should be 
    determined according to the applicable risk category (Section II.B).
         PPD test results should be recorded confidentially in the 
    individual HCW's employee health record and in an aggregate database of 
    all HCW PPD test results. The database can be analyzed periodically to 
    estimate the risk for acquiring new infection in specific areas or 
    occupational groups in the facility.
    4. Evaluation and Management of HCWs Who Have Positive PPD Test Results 
    or Active TB
        a. Evaluation
         All HCWs with newly recognized positive PPD test results 
    or PPD test conversions should be evaluated promptly for active TB. 
    This evaluation should include a clinical examination and a chest 
    radiograph. If the history, clinical examination, or chest radiograph 
    is compatible with active TB, additional tests should be performed 
    (Section II.C.2). If symptoms compatible with TB are present, the HCW 
    should be excluded from the workplace until either a) a diagnosis of 
    active TB is ruled out or b) a diagnosis of active TB was established, 
    the HCW is being treated, and a determination has been made that the 
    HCW is noninfectious (Suppl. 2). HCWs who do not have active TB should 
    be evaluated for preventive therapy according to published guidelines 
    (Suppl. 2).
         If an HCW's PPD test result converts to positive, a 
    history of confirmed or suspected TB exposure should be obtained in an 
    attempt to determine the potential source. When the source of exposure 
    is known, the drug-susceptibility pattern of the M. tuberculosis 
    isolated from the source should be identified so that the correct 
    curative or preventive therapy can be initiated for the HCW with the 
    PPD test conversion. The drug-susceptibility pattern should be recorded 
    in the HCW's medical record, where it will be available if the HCW 
    subsequently develops active TB and needs therapy specific for the 
    drug-susceptibility pattern.
         All HCWs, including those with histories of positive PPD 
    test results, should be reminded periodically about the symptoms of TB 
    and the need for prompt evaluation of any pulmonary symptoms suggestive 
    of TB.
        b. Routine and follow-up chest radiographs.
         Routine chest radiographs are not required for 
    asymptomatic, PPD-negative HCWs. HCWs with positive PPD test results 
    should have a chest radiograph as part of the initial evaluation of 
    their PPD test; if negative, repeat chest radiographs are not needed 
    unless symptoms develop that could be attributed to TB (58). However, 
    more frequent monitoring for symptoms of TB may be considered for 
    recent converters and other PPD-positive HCWs who are at increased risk 
    for developing active TB (e.g., HIV-infected or otherwise severely 
    immunocompromised HCWs).
        c. Workplace restrictions.
        (1) Active TB.
         HCWs with pulmonary or laryngeal TB pose a risk to 
    patients and other HCWs while they are infectious, and they should be 
    excluded from the workplace until they are noninfectious. The same work 
    restrictions apply to all HCWs regardless of their immune status.
         Before the HCW who has TB can return to the workplace, the 
    health-care facility should have documentation from the HCW's health-
    care provider that the HCW is receiving adequate therapy, the cough has 
    resolved, and the HCW has had three consecutive negative sputum smears 
    collected on different days. After work duties are resumed and while 
    the HCW remains on anti-TB therapy, facility staff should receive 
    periodic documentation from the HCW's health-care provider that the HCW 
    is being maintained on effective drug therapy for the recommended time 
    period and that the sputum AFB smears continue to be negative.
         HCWs with active laryngeal or pulmonary TB who discontinue 
    treatment before they are cured should be evaluated promptly for 
    infectiousness. If the evaluation determines that they are still 
    infectious, they should be excluded from the workplace until treatment 
    has been resumed, an adequate response to therapy has been documented, 
    and three more consecutive sputum AFB smears collected on different 
    days have been negative.
         HCWs who have TB at sites other than the lung or larynx 
    usually do not need to be excluded from the workplace if a diagnosis of 
    concurrent pulmonary TB has been ruled out.
        (2) Latent TB infection.
         HCWs receiving preventive treatment for latent TB 
    infection should not be restricted from their usual work activities.
         HCWs with latent TB infection who cannot take or who do 
    not accept or complete a full course of preventive therapy should not 
    be excluded from the workplace. These HCWs should be counseled about 
    the risk for developing active TB and instructed regularly to seek 
    prompt evaluation if signs or symptoms develop that could be caused by 
    TB.
    K. Problem Evaluation
        Epidemiologic investigations may be indicated for several 
    situations. These include, but are not limited to, (a) the occurrence 
    of PPD test conversions or active TB in HCWs; (b) the occurrence of 
    possible person-to-person transmission of M. tuberculosis; and (c) 
    situations in which patients or HCWs with active TB are not promptly 
    identified and isolated, thus exposing other persons in the facility to 
    M. tuberculosis. The general objectives of the epidemiologic 
    investigations in these situations are as follows:
        (1) To determine the likelihood that transmission of and infection 
    with M. tuberculosis has occurred in the facility;
        (2) To determine the extent to which M. tuberculosis has been 
    transmitted;
        (3) To identify those persons who have been exposed and infected, 
    enabling them to receive appropriate clinical management;
        (4) To identify factors that could have contributed to transmission 
    and infection and to implement appropriate interventions; and
        (5) To evaluate the effectiveness of any interventions that are 
    implemented and to ensure that exposure to and transmission of M. 
    tuberculosis have been terminated.
        The exact circumstances of these situations are likely to vary 
    considerably, and the associated epidemiologic investigations should be 
    tailored to the individual circumstances. The following sections 
    provide general guidance for conducting these investigations.
    1. Investigating PPD Test Conversions and Active TB in HCWs
        a. Investigating PPD test conversions in HCWs.
        PPD test conversions may be detected in HCWs as a result of a 
    contact investigation, in which case the probable source of exposure 
    and transmission is already known (Section II.K.3.), or as a result of 
    routine screening, in which case the probable source of exposure and 
    infection is not already known and may not be immediately apparent.
        If a skin-test conversion in an HCW is identified as part of 
    routine screening, the following steps should be considered (Figure 2):
         The HCW should be evaluated promptly for active TB. The 
    initial evaluation should include a thorough history, physical 
    examination, and chest radiograph. On the basis of the initial 
    evaluation, other diagnostic procedures (e.g., sputum examination) may 
    be indicated.
         If appropriate, the HCW should be placed on preventive or 
    curative therapy in accordance with current guidelines (Suppl. 2) (5).
         A history of possible exposure to M. tuberculosis should 
    be obtained from the HCW to determine the most likely source of 
    infection. When the source of infection is known, the drug-
    susceptibility pattern of the M. tuberculosis isolate from the source 
    patient should be identified to determine appropriate preventive or 
    curative therapy regimens.
         If the history suggests that the HCW was exposed to and 
    infected with M. tuberculosis outside the facility, no further 
    epidemiologic investigation to identify a source in the facility is 
    necessary.
         If the history does not suggest that the HCW was exposed 
    and infected outside the facility but does identify a probable source 
    of exposure in the facility, contacts of the suspected source patient 
    should be identified and evaluated. Possible reasons for the exposure 
    and transmission should be evaluated (Table 4), interventions should be 
    implemented to correct these causes, and PPD testing of PPD-negative 
    HCWs should be performed immediately and repeated after 3 months.
        If no additional PPD test conversions are detected on follow-up 
    testing, the investigation can be terminated.
        If additional PPD test conversions are detected on follow-up 
    testing, the possible reasons for exposure and transmission should be 
    reassessed, the appropriateness of and degree of adherence to the 
    interventions implemented should be evaluated, and PPD testing of PPD-
    negative HCWs should be repeated after another 3 months.
        If no additional PPD test conversions are detected on the second 
    round of follow-up testing, the investigation can be terminated. 
    However, if additional PPD conversions are detected on the second round 
    of follow-up testing, a high-risk protocol should be implemented in the 
    affected area or occupational group, and the public health department 
    or other persons with expertise in TB infection control should be 
    consulted.
         If the history does not suggest that the HCW was exposed 
    to and infected with M. tuberculosis outside the facility and does not 
    identify a probable source of exposure in the facility, further 
    investigation to identify the probable source patient in the facility 
    is warranted.
        The interval during which the HCW could have been infected should 
    be estimated. Generally, this would be the interval from 10 weeks 
    before the most recent negative PPD test through 2 weeks before the 
    first positive PPD test (i.e., the conversion).
        Laboratory and infection-control records should be reviewed to 
    identify all patients or HCWs who have suspected or confirmed 
    infectious TB and who could have transmitted M. tuberculosis to the 
    HCW.
        If this process does identify a likely source patient, contacts of 
    the suspected source patient should be identified and evaluated, and 
    possible reasons for the exposure and transmission should be evaluated 
    (Table 4). Interventions should be implemented to correct these causes, 
    and PPD testing of PPD-negative HCWs should be repeated after 3 months. 
    However, if this process does not identify a probable source case, PPD 
    screening results of other HCWs in the same area or occupational group 
    should be reviewed for additional evidence of M. tuberculosis 
    transmission. If sufficient additional PPD screening results are not 
    available, appropriate personnel should consider conducting additional 
    PPD screening of other HCWs in the same area or occupational group.
    
    BILLING CODE 4163-18-P
    
    TN28OC94.002
    
    
    TN28OC94.003
    
    
    BILLING CODE 4163-18-C
    
       Table 4.--Examples of Potential Problems That Can Occur When Identifying or Isolating Patients Who May Have  
                                              Infectious Tuberculosis (TB)                                          
    ----------------------------------------------------------------------------------------------------------------
           Situation                   Potential problem                              Intervention                  
    ----------------------------------------------------------------------------------------------------------------
    Patient identification   Patient with signs or symptoms not      Review triage procedures, facilities, and      
     during triage            identified.                             practices.                                    
                             Patient had no symptoms listed in       Revaluate triage protocol.                     
                              triage protocol.                                                                      
    During review of         Positive smear: results available >24   Change laboratory practices. Assess potential  
     laboratory results       hours* after submitted.                 barriers. Explore alternatives.               
                             Positive smear: results available but   Educate appropriate personnel. Review protocol 
                              action not taken promptly.              for management of positive smear results.     
                             Positive culture: results not           Change laboratory practices. Assess potential  
                              available for >3 weeks*.                barriers. Explore alternatives.               
                             Postive culture: results available but  Educate appropriate personnel. Review protocol 
                              action not taken promptly.              for management of positive culture results.   
                             Positive culture: susceptibility        Change laboratory practices. Assess potential  
                              results not available for >6 weeks*.    barriers. Explore alternatives.               
                             Positive culture: susceptibility        Educate appropriate personnel. Review protocol 
                              results available but action not        for management of positive culture            
                              taken promptly.                         susceptibility results.                       
    At time of diagnosis     Patient with signs/symptoms of TB:      Educate appropriate personnel. Evaluate        
     and during isolation     appropriate tests not ordered           protocols for TB detection.                   
                              promptly.                                                                             
                             Isolation room unavailable............  Reassess need for number of isolation rooms.   
                             Isolation not ordered or discontinued   Educate patients and appropriate personnel.    
                              too soon, or isolation policy not       Evaluate institutional barriers to            
                              followed properly (e.g., patients       implementation of isolation policy.           
                              going outside of room).                                                               
                             Personnel not properly using            Educate appropriate personnel. Evaluate        
                              respiratory protection.                 regularly scheduled re-education. Evaluate    
                                                                      institutional barriers to use of respiratory  
                                                                      protection.                                   
                             Isolation room or procedure room not    Make appropriate engineering modifications.    
                              at negative pressure reslative to       Establish protocols for regularly monitoring  
                              surrounding areas.                      and maintaining negative pressure.            
                             Inadequate air circulation............  Make appropriate engineering modifications.    
                             Door left open........................  Educate appropriate personnel and patients.    
                                                                      Evaluate self-closing doors, comfort levels in
                                                                      the room, and other measures to promote door  
                                                                      closing.                                      
    ----------------------------------------------------------------------------------------------------------------
    *These time intervals are used as examples and should not be considered absolute standards.                     
    
        If this review and/or screening does not identify additional PPD 
    conversions, nosocomial transmission is less likely, and the contact 
    investigation can probably be terminated. Whether the HCW's PPD test 
    conversion resulted from occupational exposure and infection is 
    uncertain; however, the absence of other data implicating nosocomial 
    transmission suggests that the conversion could have resulted from (a) 
    unrecognized exposure to M. tuberculosis outside the facility; (b) 
    cross-reactivity with another antigen (e.g., nontuberculous 
    mycobacteria); (c) errors in applying, reading, or interpreting the 
    test; (d) false positivity caused by the normal variability of the 
    test; or (e) false positivity caused by a defective PPD preparation.
        If this review and/or screening does identify additional PPD test 
    conversions, nosocomial transmission is more likely. In this situation, 
    the patient identification (i.e., triage) process, TB infection-control 
    policies and practices, and engineering controls should be evaluated to 
    identify problems that could have led to exposure and transmission 
    (Table 4).
        If no such problems are identified, a high-risk protocol should be 
    implemented in the affected area or occupational group, and the public 
    health department or other persons with expertise in TB infection 
    control should be consulted.
        If such problems are identified, appropriate interventions should 
    be implemented to correct the problem(s), and PPD skin testing of PPD-
    negative HCWs should be repeated after 3 months.
        If no additional PPD conversions are detected on follow-up testing, 
    the investigation can be terminated.
        If additional PPD conversions are detected on follow-up testing, 
    the possible reasons for exposure and transmission should be 
    reassessed, the appropriateness of and adherence to the interventions 
    implemented should be evaluated, and PPD skin testing of PPD-negative 
    HCWs should be repeated after another 3 months.
        If no additional PPD test conversions are detected on this second 
    round of follow-up testing, the investigation can be terminated. 
    However, if additional PPD test conversions are detected on the second 
    round of follow-up testing, a high-risk protocol should be implemented 
    in the affected area or occupational group, and the public health 
    department or other persons with expertise in TB infection control 
    should be consulted.
        b. Investigating cases of active TB in HCWs.
        If an HCW develops active TB, the following steps should be taken:
         The case should be evaluated epidemiologically, in a 
    manner similar to PPD test conversions in HCWs, to determine the 
    likelihood that it resulted from occupational transmission and to 
    identify possible causes and implement appropriate interventions if the 
    evaluation suggests such transmission.
         Contacts of the HCW (e.g., other HCWs, patients, visitors, 
    and others who have had intense exposure to the HCW) should be 
    identified and evaluated for TB infection and disease (Section II.K.3; 
    Suppl. 2). The public health department should be notified immediately 
    for consultation and to allow for investigation of community contacts 
    who were not exposed in the health-care facility.
         The public health department should notify facilities when 
    HCWs with TB are reported by physicians so that an investigation of 
    contacts can be conducted in the facility. The information provided by 
    the health department to facilities should be in accordance with state 
    or local laws to protect the confidentiality of the HCW.
    2. Investigating Possible Patient-to-Patient Transmission of M. 
    tuberculosis
        Surveillance of active TB cases in patients should be conducted. If 
    this surveillance suggests the possibility of patient-to-patient 
    transmission of M. tuberculosis (e.g., a high proportion of TB patients 
    had prior admissions during the year preceding onset of their TB, the 
    number of patients with drug-resistant TB increased suddenly, or 
    isolates obtained from multiple patients had identical and 
    characteristic drug-susceptibility or DNA fingerprint patterns), the 
    following steps should be taken:
         Review the HCW PPD test results and patient surveillance 
    data for the suspected areas to detect additional patients or HCWs with 
    PPD test conversions or active disease.
         Look for possible exposures that patients with newly 
    diagnosed TB could have had to other TB patients during previous 
    admissions. For example, were the patients admitted to the same room or 
    area, or did they receive the same procedure or go to the same 
    treatment area on the same day?
        If the evaluation thus far suggests transmission has occurred, the 
    following steps should be taken:
         Evaluate possible causes of the transmission (e.g., 
    problem with patient detection, institutional barriers to implementing 
    appropriate isolation practices, or inadequate engineering controls) 
    (Table 4).
         Ascertain whether other patients or HCWs could have been 
    exposed; if so, evaluate these persons for TB infection and disease 
    (Section II.K.3; Suppl. 2).
         Notify the public health department so they can begin a 
    community contact investigation if necessary.
    3. Investigating Contacts of Patients and HCWs Who Have Infectious TB
        If a patient who has active TB is examined in a health-care 
    facility and the illness is not diagnosed correctly, resulting in 
    failure to apply appropriate precautions, or if an HCW develops active 
    TB and exposes other persons in the facility, the following steps 
    should be taken when the illness is later diagnosed correctly:
         To identify other patients and HCWs who were exposed to 
    the source patient before isolation procedures were begun, interview 
    the source patient and all applicable personnel and review that 
    patient's medical record. Determine the areas of the facility in which 
    the source patient was hospitalized, visited, or worked before being 
    placed in isolation (e.g., outpatient clinics, hospital rooms, 
    treatment rooms, radiology and procedure areas, and patient lounges) 
    and the HCWs who may have been exposed during that time (e.g., persons 
    providing direct care, therapists, clerks, transportation personnel, 
    housekeepers, and social workers).
         The contact investigation should first determine if M. 
    tuberculosis transmission has occurred from the source patient to those 
    persons with whom the source patient had the most intense contact.
         Administer PPD tests to the most intensely exposed HCWs 
    and patients as soon as possible after the exposure has occurred. If 
    transmission did occur to the most intensely exposed persons, then 
    those persons with whom the patient had less contact should be 
    evaluated. If the initial PPD test result is negative, a second test 
    should be administered 12 weeks after the exposure was terminated.
         Those persons who were exposed to M. tuberculosis and who 
    have either a PPD test conversion or symptoms suggestive of TB should 
    receive prompt clinical evaluation and, if indicated, chest radiographs 
    and bacteriologic studies should be performed (Suppl. 2). Those persons 
    who have evidence of newly acquired infection or active disease should 
    be evaluated for preventive or curative therapy (Suppl. 2). Persons who 
    have previously had positive PPD test results and who have been exposed 
    to an infectious TB patient do not require a repeat PPD test or a chest 
    radiograph unless they have symptoms suggestive of TB.
         In addition to PPD testing those HCWs and patients who 
    have been exposed to M. tuberculosis because a patient was not isolated 
    promptly or an HCW with active TB was not identified promptly, the 
    investigation should determine why the diagnosis of TB was delayed. If 
    the correct diagnosis was made but the patient was not isolated 
    promptly, the reasons for the delay need to be defined so that 
    corrective actions can be taken.
    L. Coordination With the Public Health Department
         As soon as a patient or HCW is known or suspected to have 
    active TB, the patient or HCW should be reported to the public health 
    department so that appropriate follow-up can be arranged and a 
    community contact investigation can be performed. The health department 
    should be notified well before patient discharge to facilitate follow-
    up and continuation of therapy. A discharge plan coordinated with the 
    patient or HCW, the health department, and the inpatient facility 
    should be implemented.
         The public health department should protect the 
    confidentiality of the patient or HCW in accordance with state and 
    local laws.
         Health-care facilities and health departments should 
    coordinate their efforts to perform appropriate contact investigations 
    on patients and HCWs who have active TB.
         In accordance with state and local laws and regulations, 
    results of all AFB-positive sputum smears, cultures positive for M. 
    tuberculosis, and drug-susceptibility results on M. tuberculosis 
    isolates should be reported to the public health department as soon as 
    these results are available.
         The public health department may be able to assist 
    facilities with planning and implementing various aspects of a TB 
    infection-control program (e.g., surveillance, screening activities, 
    and outbreak investigations). In addition, the state health department 
    may be able to provide names of experts to assist with the engineering 
    aspects of TB infection control.
    M. Additional Considerations for Selected Areas in Health-Care 
    Facilities and Other Health-Care Settings
        This section contains additional information for selected areas in 
    health-care facilities and for other health-care settings.
    1. Selected Areas in Health-Care Facilities
        a. Operating rooms.
         Elective operative procedures on patients who have TB 
    should be delayed until the patient is no longer infectious.
         If operative procedures must be performed, they should be 
    done, if possible, in operating rooms that have anterooms. For 
    operating rooms without anterooms, the doors to the operating room 
    should be closed, and traffic into and out of the room should be 
    minimal to reduce the frequency of opening and closing the door. 
    Attempts should be made to perform the procedure at a time when other 
    patients are not present in the operative suite and when a minimum 
    number of personnel are present (e.g., at the end of day).
         Placing a bacterial filter on the patient endotracheal 
    tube (or at the expiratory side of the breathing circuit of a 
    ventilator or anesthesia machine if these are used) when operating on a 
    patient who has confirmed or suspected TB may help reduce the risk for 
    contaminating anesthesia equipment or discharging tubercle bacilli into 
    the ambient air.
         During postoperative recovery, the patient should be 
    monitored and should be placed in a private room that meets recommended 
    standards for ventilating TB isolation rooms.
         When operative procedures (or other procedures requiring a 
    sterile field) are performed on patients who may have infectious TB, 
    respiratory protection worn by the HCW must protect the field from the 
    respiratory secretions of the HCW and protect the HCW from the 
    infectious droplet nuclei generated by the patient. Valved or positive-
    pressure respirators do not protect the sterile field; therefore, a 
    respirator that does not have a valve and that meets the criteria in 
    Section II.G should be used.
        b. Autopsy rooms.
         Because infectious aerosols are likely to be present in 
    autopsy rooms, such areas should be at negative pressure with respect 
    to adjacent areas (Suppl. 3), and the room air should be exhausted 
    directly to the outside of the building. ASHRAE recommends that autopsy 
    rooms have ventilation that provides an airflow of 12 ACH (47), 
    although the effectiveness of this ventilation level in reducing the 
    risk for M. tuberculosis, transmission has not been evaluated. Where 
    possible, this level should be increased by means of ventilation system 
    design or by auxiliary methods (e.g., recirculation of air within the 
    room through HEPA filters) (Suppl. 3).
         Respiratory protection should be worn by personnel while 
    performing autopsies on deceased persons who may have had TB at the 
    time of death (Section II.G; Suppl. 4).
         Recirculation of HEPA-filtered air within the room or UVGI 
    may be used as a supplement to the recommended ventilation (Suppl. 3).
        c. Laboratories.
         Laboratories in which specimens for mycobacteriologic 
    studies (e.g., AFB smears and cultures) are processed should be 
    designed to conform with criteria specified by CDC and the National 
    Institutes of Health (59).
    2. Other Health-Care Settings
        TB precautions may be appropriate in a number of other types of 
    health care settings. The specific precautions that are applied will 
    vary depending on the setting. At a minimum, a risk assessment should 
    be performed yearly for these settings; a written TB infection-control 
    plan should be developed, evaluated, and revised on a regular basis; 
    protocols should be in place for identifying and managing patients who 
    may have active TB; HCWs should receive appropriate training, 
    education, and screening; protocols for problem evaluation should be in 
    place; and coordination with the public health department should be 
    arranged when necessary. Other recommendations specific to certain of 
    these settings follow.
        a. Emergency medical services.
         When EMS personnel or others must transport patients who 
    have confirmed or suspected active TB, a surgical mask should be 
    placed, if possible, over the patient's mouth and nose. Because 
    administrative and engineering controls during emergency transport 
    situations cannot be ensured, EMS personnel should wear respiratory 
    protection when transporting such patients. If feasible, the windows of 
    the vehicle should be kept open. The heating and air-conditioning 
    system should be set on a nonrecirculating cycle.
         EMS personnel should be included in a comprehensive PPD 
    screening program and should receive a baseline PPD test and follow-up 
    testing as indicated by the risk assessment. They should also be 
    included in the follow-up of contacts of a patient with infectious TB.*
    ---------------------------------------------------------------------------
    
        *The Ryan White Comprehensive AIDS Resource Emergency Act of 
    1990, P.L. 101-381, mandates notification of EMS personnel after 
    they have been exposed to infectious pulmonary TB (42 U.S.C. 300ff-
    82. 54 FR 13417 [March 21, 1994]).
    ---------------------------------------------------------------------------
    
        b. Hospices.
         Hospice patients who have confirmed or suspected TB should 
    be managed in the manner described in this document for management of 
    TB patients in hospitals. General-use and specialized areas (e.g., 
    treatment or TB isolation rooms) should be ventilated in the same 
    manner as described for similar hospital areas.
        c. Long-term care facilities.
         Recommendations published previously for preventing and 
    controlling TB in long-term care facilities should be followed (60).
         Long-term care facilities should also follow the 
    recommendations outlined in this document.
        d. Correctional facilities.
         Recommendations published previously for preventing and 
    controlling TB in correctional facilities should be followed (61).
         Prison medical facilities should also follow the 
    recommendations outlined in this document.
        e. Dental settings.
        In general, the symptoms for which patients seek treatment in a 
    dental-care setting are not likely to be caused by infectious TB. 
    Unless a patient requiring dental care coincidentally has TB, it is 
    unlikely that infectious TB will be encountered in the dental setting. 
    Furthermore, generation of droplet nuclei containing M. tuberculosis 
    during dental procedures has not been demonstrated (62). Therefore, the 
    risk for transmission of M. tuberculosis in most dental settings is 
    probably quite low. Nevertheless, during dental procedures, patients 
    and dental workers share the same air for varying periods of time. 
    Coughing may be stimulated occasionally by oral manipulations, although 
    no specific dental procedures have been classified as ``cough-
    inducing.'' In some instances, the population served by a dental-care 
    facility, or the HCWs in the facility, may be at relatively high risk 
    for TB. Because the potential exists for transmission of M. 
    tuberculosis in dental settings, the following recommendations should 
    be followed:
         A risk assessment (Section II.B) should be done 
    periodically, and TB infection-control policies for each dental setting 
    should be based on the risk assessment. The policies should include 
    provisions for detection and referral of patients who may have 
    undiagnosed active TB; management of patients with active TB, relative 
    to provision of urgent dental care; and employer-sponsored HCW 
    education, counseling, and screening.
         While taking patients' initial medical histories and at 
    periodic updates, dental HCWs should routinely ask all patients whether 
    they have a history of TB disease and symptoms suggestive of TB.
         Patients with a medical history or symptoms suggestive of 
    undiagnosed active TB should be referred promptly for medical 
    evaluation of possible infectiousness. Such patients should not remain 
    in the dental-care facility any longer than required to arrange a 
    referral. While in the dental-care facility, they should wear surgical 
    masks and should be instructed to cover their mouths and noses when 
    coughing or sneezing.
         Elective dental treatment should be deferred until a 
    physician confirms that the patient does not have infectious TB. If the 
    patient is diagnosed as having active TB, elective dental treatment 
    should be deferred until the patient is no longer infectious.
         If urgent dental care must be provided for a patient who 
    has, or is strongly suspected of having, infectious TB, such care 
    should be provided in facilities that can provide TB isolation 
    (Sections II.E and G). Dental HCWs should use respiratory protection 
    while performing procedures on such patients.
         Any dental HCW who has a persistent cough (i.e., a cough 
    lasting 3 weeks), especially in the presence of other signs 
    or symptoms compatible with active TB (e.g., weight loss, night sweats, 
    bloody sputum, anorexia, and fever), should be evaluated promptly for 
    TB. The HCW should not return to the workplace until a diagnosis of TB 
    has been excluded or until the HCW is on therapy and a determination 
    has been made that the HCW is noninfectious.
         In dental-care facilities that provide care to populations 
    at high risk for active TB, it may be appropriate to use engineering 
    controls similar to those used in general-use areas (e.g., waiting 
    rooms) of medical facilities that have a similar risk profile.
        f. Home-health-care settings.
         HCWs who provide medical services in the homes of patients 
    who have suspected or confirmed infectious TB should instruct such 
    patients to cover their mouths and noses with a tissue when coughing or 
    sneezing. Until such patients are no longer infectious, HCWs should 
    wear respiratory protection when entering these patients' homes (Suppl. 
    4).
         Precautions in the home may be discontinued when the 
    patient is no longer infectious (Suppl. 1).
         HCWs who provide health-care services in their patients' 
    homes can assist in preventing transmission of M. tuberculosis by 
    educating their patients regarding the importance of taking medications 
    as prescribed and by administering DOT.
         Cough-inducing procedures performed on patients who have 
    infectious TB should not be done in the patients' homes unless 
    absolutely necessary. When medically necessary cough-inducing 
    procedures (e.g., AFB sputum collection for evaluation of therapy) must 
    be performed on patients who may have infectious TB, the procedures 
    should be performed in a health-care facility in a room or booth that 
    has the recommended ventilation for such procedures. If these 
    procedures must be performed in a patient's home, they should be 
    performed in a well-ventilated area away from other household members. 
    If feasible, the HCW should consider opening a window to improve 
    ventilation or collecting the specimen while outside the dwelling. The 
    HCW collecting these specimens should wear respiratory protection 
    during the procedure (Section II.G).
         HCWs who provide medical services in their patients' homes 
    should be included in comprehensive employer-sponsored TB training, 
    education, counseling, and screening programs. These programs should 
    include provisions for identifying HCWs who have active TB, baseline 
    PPD skin testing, and follow-up PPD testing at intervals appropriate to 
    the degree of risk.
         Patients who are at risk for developing active TB and the 
    HCWs who provide medical services in the homes of such patients should 
    be reminded periodically of the importance of having pulmonary symptoms 
    evaluated promptly to permit early detection of and treatment for TB.
        g. Medical offices.
        In general, the symptoms of active TB are symptoms for which 
    patients are likely to seek treatment in a medical office. Furthermore, 
    the populations served by some medical offices, or the HCWs in the 
    office, may be at relatively high risk for TB. Thus, it is likely that 
    infectious TB will be encountered in a medical office. Because of the 
    potential for M. tuberculosis transmission, the following 
    recommendations should be observed:
         A risk assessment should be conducted periodically, and TB 
    infection-control policies based on results of the risk assessment 
    should be developed for the medical office. The policies should include 
    provisions for identifying and managing patients who may have 
    undiagnosed active TB; managing patients who have active TB; and 
    educating, training, counseling, and screening HCWs.
         While taking patients' initial medical histories and at 
    periodic updates, HCWs who work in medical offices should routinely ask 
    all patients whether they have a history of TB disease or have had 
    symptoms suggestive of TB.
         Patients with a medical history and symptoms suggestive of 
    active TB should receive an appropriate diagnostic evaluation for TB 
    and be evaluated promptly for possible infectiousness. Ideally, this 
    evaluation should be done in a facility that has TB isolation 
    capability. At a minimum, the patient should be provided with and asked 
    to wear a surgical mask, instructed to cover the mouth and nose with a 
    tissue when coughing or sneezing, and separated as much as possible 
    from other patients.
         Medical offices that provide evaluation or treatment 
    services for TB patients should follow the recommendations for managing 
    patients in ambulatory-care settings (Section II.D).
         If cough-inducing procedures are to be administered in a 
    medical office to patients who may have active TB, appropriate 
    precautions should be followed (Section II.H).
         Any HCW who has a persistent cough (i.e., a cough lasting 
    3 weeks), especially in the presence of other signs or 
    symptoms compatible with active TB (e.g., weight loss, night sweats, 
    bloody sputum, anorexia, or fever) should be evaluated promptly for TB. 
    HCWs with such signs or symptoms should not return to the workplace 
    until a diagnosis of TB has been excluded or until they are on therapy 
    and a determination has been made that they are noninfectious.
         HCWs who work in medical offices in which there is a 
    likelihood of exposure to patients who have infectious TB should be 
    included in employer-sponsored education, training, counseling, and PPD 
    testing programs appropriate to the level of risk in the office.
         In medical offices that provide care to populations at 
    relatively high risk for active TB, use of engineering controls as 
    described in this document for general-use areas (e.g., waiting rooms) 
    may be appropriate (Section II.F; Suppl. 3).
    
    Supplement 1: Determining the Infectiousness of a TB Patient
    
        The infectiousness of patients with TB correlates with the number 
    of organisms expelled into the air, which, in turn, correlates with the 
    following factors: (a) Disease in the lungs, airways, or larynx; (b) 
    presence of cough or other forceful expiratory measures; (c) presence 
    of acid-fast bacilli (AFB) in the sputum; (d) failure of the patient to 
    cover the mouth and nose when coughing; (e) presence of cavitation on 
    chest radiograph; (f) inappropriate or short duration of chemotherapy; 
    and (g) administration of procedures that can induce coughing or cause 
    aerosolization of M. tuberculosis (e.g., sputum induction).
        The most infectious persons are most likely those who have not been 
    treated for TB and who have either (a) pulmonary or laryngeal TB and a 
    cough or are undergoing cough-inducing procedures, (b) a positive AFB 
    sputum smear, or (c) cavitation on chest radiograph. Persons with 
    extrapulmonary TB usually are not infectious unless they have (a) 
    concomitant pulmonary disease; (b) nonpulmonary disease located in the 
    respiratory tract or oral cavity; or (c) extrapulmonary disease that 
    includes an open abscess or lesion in which the concentration of 
    organisms is high, especially if drainage from the abscess or lesion is 
    extensive (20,22). Coinfection with HIV does not appear to affect the 
    infectiousness of TB patients (63-65).
        In general, children who have TB may be less likely than adults to 
    be infectious; however, transmission from children can occur. 
    Therefore, children with TB should be evaluated for infectiousness 
    using the same parameters as for adults (i.e., pulmonary or laryngeal 
    TB, presence of cough or cough-inducing procedures, positive sputum AFB 
    smear, cavitation on chest radiograph, and adequacy and duration of 
    therapy). Pediatric patients who may be infectious include those who 
    (a) are not on therapy, (b) have just been started on therapy, or (c) 
    are on inadequate therapy, and who (a) have laryngeal or extensive 
    pulmonary involvement, (b) have pronounced cough or are undergoing 
    cough-inducing procedures, (c) have positive sputum AFB smears, or (d) 
    have cavitary TB. Children who have typical primary tuberculous lesions 
    and do not have any of the indicators of infectiousness listed 
    previously usually do not need to be placed in isolation. Because the 
    source case for pediatric TB patients often occurs in a member of the 
    infected child's family (45), parents and other visitors of all 
    pediatric TB patients should be evaluated for TB as soon as possible.
        Infection is most likely to result from exposure to persons who 
    have unsuspected pulmonary TB and are not receiving anti-TB therapy or 
    from persons who have diagnosed TB and are not receiving adequate 
    therapy. Administration of effective anti-TB therapy has been 
    associated with decreased infectiousness among persons who have active 
    TB (66). Effective therapy reduces coughing, the amount of sputum 
    produced, and the number of organisms in the sputum. However, the 
    period of time a patient must take effective therapy before becoming 
    noninfectious varies between patients (67). For example, some TB 
    patients are never infectious, whereas those with unrecognized or 
    inadequately treated drug-resistant TB may remain infectious for weeks 
    or months (24). Thus, decisions about infectiousness should be made on 
    an individual basis.
        In general, patients who have suspected or confirmed active TB 
    should be considered infectious if they (a) are coughing, (b) are 
    undergoing cough-inducing procedures, or (c) have positive AFB sputum 
    smears, and if they (a) are not on chemotherapy, (b) have just started 
    chemotherapy, or (c) have a poor clinical or bacteriologic response to 
    chemotherapy. A patient who has drug-susceptible TB and who is on 
    adequate chemotherapy and has had a significant clinical and 
    bacteriologic response to therapy (i.e., reduction in cough, resolution 
    of fever, and progressively decreasing quantity of bacilli on smear) is 
    probably no longer infectious. However, because drug-susceptibility 
    results are not usually known when the decision to discontinue 
    isolation is made, all TB patients should remain in isolation while 
    hospitalized until they have had three consecutive negative sputum 
    smears collected on different days and they demonstrate clinical 
    improvement.
    
    Supplement 2: Diagnosis and Treatment of Latent TB Infection and Active 
    TB
    
    I. Diagnostic Procedures for TB Infection and Disease
        A diagnosis of TB may be considered for any patient who has a 
    persistent cough (i.e., a cough lasting 3 weeks) or other 
    signs or symptoms compatible with TB (e.g., bloody sputum, night 
    sweats, weight loss, anorexia, or fever). However, the index of 
    suspicion for TB will vary in different geographic areas and will 
    depend on the prevalence of TB and other characteristics of the 
    population served by the facility. The index of suspicion for TB should 
    be very high in areas or among groups of patients in which the 
    prevalence of TB is high (Section I.B). Persons for whom a diagnosis of 
    TB is being considered should receive appropriate diagnostic tests, 
    which may include PPD skin testing, chest radiography, and 
    bacteriologic studies (e.g., sputum microscopy and culture).
    A. PPD Skin Testing and Anergy Testing
    1. Application and Reading of PPD Skin Tests
        The PPD skin test is the only method available for demonstrating 
    infection with M. tuberculosis. Although currently available PPD tests 
    are <100% sensitive="" and="" specific="" for="" detection="" of="" infection="" with="" m.="" tuberculosis,="" no="" better="" diagnostic="" methods="" have="" yet="" been="" devised.="" interpretation="" of="" ppd="" test="" results="" requires="" knowledge="" of="" the="" antigen="" used,="" the="" immunologic="" basis="" for="" the="" reaction="" to="" this="" antigen,="" the="" technique="" used="" to="" administer="" and="" read="" the="" test,="" and="" the="" results="" of="" epidemiologic="" and="" clinical="" experience="" with="" the="" test="" (2,5,6).="" the="" ppd="" test,="" like="" all="" medical="" tests,="" is="" subject="" to="" variability,="" but="" many="" of="" the="" variations="" in="" administering="" and="" reading="" ppd="" tests="" can="" be="" avoided="" by="" proper="" training="" and="" careful="" attention="" to="" details.="" the="" intracutaneous="" (mantoux)="" administration="" of="" a="" measured="" amount="" of="" ppd-tuberculin="" is="" currently="" the="" preferred="" method="" for="" doing="" the="" test.="" one-tenth="" milliliter="" of="" ppd="" (5="" tu)="" is="" injected="" just="" beneath="" the="" surface="" of="" the="" skin="" on="" either="" the="" volar="" or="" dorsal="" surface="" of="" the="" forearm.="" a="" discrete,="" pale="" elevation="" of="" the="" skin="" (i.e.,="" a="" wheal)="" that="" is="" 6-10="" mm="" in="" diameter="" should="" be="" produced.="" ppd="" test="" results="" should="" be="" read="" by="" designated,="" trained="" personnel="" between="" 48="" and="" 72="" hours="" after="" injection.="" patient="" or="" hcw="" self-reading="" of="" ppd="" test="" results="" should="" not="" be="" accepted="" (68).="" the="" result="" of="" the="" test="" is="" based="" on="" the="" presence="" or="" absence="" of="" an="" induration="" at="" the="" injection="" site.="" redness="" or="" erythema="" should="" not="" be="" measured.="" the="" transverse="" diameter="" of="" induration="" should="" be="" recorded="" in="" millimeters.="" 2.="" interpretation="" of="" ppd="" skin="" tests="" a.="" general.="" the="" interpretation="" of="" a="" ppd="" reaction="" should="" be="" influenced="" by="" the="" purpose="" for="" which="" the="" test="" was="" given="" (e.g.,="" epidemiologic="" versus="" diagnostic="" purposes),="" by="" the="" prevalence="" of="" tb="" infection="" in="" the="" population="" being="" tested,="" and="" by="" the="" consequences="" of="" false="" classification.="" errors="" in="" classification="" can="" be="" minimized="" by="" establishing="" an="" appropriate="" definition="" of="" a="" positive="" reaction="" (table="" s2-1).="" the="" positive-predictive="" value="" of="" ppd="" tests="" (i.e,="" the="" probability="" that="" a="" person="" with="" a="" positive="" ppd="" test="" is="" actually="" infected="" with="" m.="" tuberculosis)="" is="" dependent="" on="" the="" prevalence="" of="" tb="" infection="" in="" the="" population="" being="" tested="" and="" the="" specificity="" of="" the="" test="" (69,70).="" in="" populations="" with="" a="" low="" prevalence="" of="" tb="" infection,="" the="" probability="" that="" a="" positive="" ppd="" test="" represents="" true="" infection="" with="" m.="" tuberculosis="" is="" very="" low="" if="" the="" cut-point="" is="" set="" too="" low="" (i.e.,="" the="" test="" is="" not="" adequately="" specific).="" in="" populations="" with="" a="" high="" prevalence="" of="" tb="" infection,="" the="" probability="" that="" a="" positive="" ppd="" test="" using="" the="" same="" cut-="" point="" represents="" true="" infection="" with="" m.="" tuberculosis="" is="" much="" higher.="" to="" ensure="" that="" few="" persons="" infected="" with="" tubercle="" bacilli="" will="" be="" misclassified="" as="" having="" negative="" reactions="" and="" few="" persons="" not="" infected="" with="" tubercle="" bacilli="" will="" be="" misclassified="" as="" having="" positive="" reactions,="" different="" cut-points="" are="" used="" to="" separate="" positive="" reactions="" from="" negative="" reactions="" for="" different="" populations,="" depending="" on="" the="" risk="" for="" tb="" infection="" in="" that="" population.="" a="" lower="" cut-point="" (i.e.,="" 5="" mm)="" is="" used="" for="" persons="" in="" the="" highest="" risk="" groups,="" which="" include="" hiv-infected="" persons,="" recent="" close="" contacts="" of="" persons="" with="" tb="" (e.g.,="" in="" the="" household="" or="" in="" an="" unprotected="" occupational="" exposure="" similar="" in="" intensity="" and="" duration="" to="" household="" contact),="" and="" persons="" who="" have="" abnormal="" chest="" radiographs="" with="" fibrotic="" changes="" consistent="" with="" inactive="" tb.="" a="" higher="" cut-point="" (i.e.,="" 10="" mm)="" is="" used="" for="" persons="" who="" are="" not="" in="" the="" highest="" risk="" group="" but="" who="" have="" other="" risk="" factors="" (e.g.,="" injecting-drug="" users="" known="" to="" be="" hiv="" seronegative;="" persons="" with="" certain="" medical="" conditions="" that="" increase="" the="" risk="" for="" progression="" from="" latent="" tb="" infection="" to="" active="" tb="" [table="" s2-="" 1]);="" medically="" underserved,="" low-income="" populations;="" persons="" born="" in="" foreign="" countries="" that="" have="" a="" high="" prevalence="" of="" tb;="" and="" residents="" of="" correctional="" institutions="" and="" nursing="" homes).="" an="" even="" higher="" cut-point="" (i.e.,="" 15="" mm)="" is="" used="" for="" all="" other="" persons="" who="" have="" none="" of="" the="" above="" risk="" factors.="" recent="" ppd="" converters="" are="" considered="" members="" of="" a="" high-risk="" group.="" a="">10 mm increase in the size of the induration within a 2-
    year period is classified as a conversion from a negative to a positive 
    test result for persons <35 years="" of="" age.="" an="" increase="" of="" induration="" of="">15 mm within a 2-year period is classified as a conversion 
    for persons 35 years of age (5).
        b. HCWs.
        In general, HCWs should have their skin-test results interpreted 
    according to the recommendations in this supplement and in sections 1, 
    2, 3, and 5 of Table S2-1. However, the prevalence of TB in the 
    facility should be considered when choosing the appropriate cut-point 
    for defining a positive PPD reaction. In facilities where there is 
    essentially no risk for exposure to TB patients (i.e., minimal- or very 
    low-risk facilities [Section II.B]), an induration 15 mm may 
    be an appropriate cut-point for HCWs who have no other risk factors. In 
    other facilities where TB patients receive care, the appropriate cut-
    point for HCWs who have no other risk factors may be 10 mm.
        A recent PPD test conversion in an HCW should be defined generally 
    as an increase of 10 mm in the size of induration within a 
    2-year period. For HCWs in facilities where exposure to TB is very 
    unlikely (e.g., minimal-risk facilities), an increase of 15 
    mm within a 2-year period may be more appropriate for defining a recent 
    conversion because of the lower positive-predictive value of the test 
    in such groups.
    3. Anergy Testing
        HIV-infected persons may have suppressed reactions to PPD skin 
    tests because of anergy, particularly if their CD4+ T-lymphocyte counts 
    decline (71). Persons with anergy will have a negative PPD test 
    regardless of infection with M. tuberculosis. HIV-infected persons 
    should be evaluated for anergy in conjunction with PPD testing (72). 
    Two companion antigens (e.g., Candida antigen and tetanus toxoid) 
    should be administered in addition to PPD. Persons with 3 mm 
    of induration to any of the skin tests (including tuberculin) are 
    considered not anergic. Reactions of 5 mm to PPD are 
    considered to be evidence of TB infection in HIV-infected persons 
    regardless of the reactions to the companion antigens. If there is no 
    reaction (i.e., <3 mm="" induration)="" to="" any="" of="" the="" antigens,="" the="" person="" being="" tested="" is="" considered="" anergic.="" determination="" of="" whether="" such="" persons="" are="" likely="" to="" be="" infected="" with="" m.="" tuberculosis="" must="" be="" based="" on="" other="" epidemiologic="" factors="" (e.g.,="" the="" proportion="" of="" other="" persons="" with="" the="" same="" level="" of="" exposure="" who="" have="" positive="" ppd="" test="" results="" and="" the="" intensity="" or="" duration="" of="" exposure="" to="" infectious="" tb="" patients="" that="" the="" anergic="" person="" experienced).="" 4.="" pregnancy="" and="" ppd="" skin="" testing="" although="" thousands="" (perhaps="" millions)="" of="" pregnant="" women="" have="" been="" ppd="" skin="" tested="" since="" the="" test="" was="" devised,="" thus="" far="" no="" documented="" episodes="" of="" fetal="" harm="" have="" resulted="" from="" use="" of="" the="" tuberculin="" test="" (73).="" pregnancy="" should="" not="" exclude="" a="" female="" hcw="" from="" being="" skin="" tested="" as="" part="" of="" a="" contact="" investigation="" or="" as="" part="" of="" a="" regular="" skin-testing="" program.="" table="" s2-1.="" summary="" of="" interpretation="" of="" purified="" protein="" derivative="" (ppd)-tuberculin="" skin-test="" results="" 1.="" an="" induration="" of="">5 mm is classified as positive in:
         Persons who have human immunodeficiency virus (HIV) 
    infection or risk factors for HIV infection but unknown HIV status;
         Persons who have had recent close contact* with persons 
    who have active tuberculosis (TB);
    ---------------------------------------------------------------------------
    
        *Recent close contact implies either household or social contact 
    or unprotected occupational exposure similar in intensity and 
    duration to household contact.
    ---------------------------------------------------------------------------
    
         Persons who have fibrotic chest radiographs (consistent 
    with healed TB).
        2. An induration of 10 mm is classified as positive in 
    all persons who do not meet any of the criteria above but who have 
    other risk factors for TB, including:
    
    High-Risk Groups
    
         Injecting-drug users known to be HIV seronegative;
         Persons who have other medical conditions that reportedly 
    increase the risk for progressing from latent TB infection to active TB 
    (e.g., silicosis; gastrectomy or jejuno-ileal bypass; being 
    10% below ideal body weight; chronic renal failure with 
    renal dialysis; diabetes mellitus; high-dose corticosteroid or other 
    immuno-suppressive therapy; some hematologic disorders, including 
    malignancies such as leukemias and lymphomas; and other malignancies);
         Children <4 years="" of="" age.="" high-prevalence="" groups=""> Persons born in countries in Asia, Africa, the Caribbean, 
    and Latin America that have high prevalence of TB;
         Persons from medically underserved, low-income 
    populations;
         Residents of long-term-care facilities (e.g., correctional 
    institutions and nursing homes);
         Persons from high-risk populations in their communities, 
    as determined by local public health authorities.
        3. An induration of 15 mm is classified as positive in 
    persons who do not meet any of the above criteria.
        4. Recent converters are defined on the basis of both size of 
    induration and age of the person being tested:
         10 mm increase within a 2-year period is 
    classified as a recent conversion for persons <35 years="" of="" age;=""> 15 mm increase within a 2-year period is 
    classified as a recent conversion for persons 35 years of 
    age.
        5. PPD skin-test results in health-care workers (HCWs)
         In general, the recommendations in sections 1, 2, and 3 of 
    this table should be followed when interpreting skin-test results in 
    HCWs.
        However, the prevalence of TB in the facility should be considered 
    when choosing the appropriate cut-point for defining a positive PPD 
    reaction. In facilities where there is essentially no risk for exposure 
    to Mycobacterium tuberculosis (i.e., minimal- or very low-risk 
    facilities [Section II.B]), an induration 15 mm may be a 
    suitable cut-point for HCWs who have no other risk factors. In 
    facilities where TB patients receive care, the cut-point for HCWs with 
    no other risk factors maybe 10 mm.
         A recent conversion in an HCW should be defined generally 
    as a 10 mm increase in size of induration within a 2-year 
    period. For HCWs who work in facilities where exposure to TB is very 
    unlikely (e.g., minimal-risk facilities), an increase of 15 
    mm within a 2-year period may be more appropriate for defining a recent 
    conversion because of the lower positive-predictive value of the test 
    in such groups.
    5. BCG Vaccination and PPD Skin Testing
        BCG vaccination may produce a PPD reaction that cannot be 
    distinguished reliably from a reaction caused by infection with M. 
    tuberculosis. For a person who was vaccinated with BCG, the probability 
    that a PPD test reaction results from infection with M. tuberculosis 
    increases (a) as the size of the reaction increases, (b) when the 
    person is a contact of a person with TB, (c) when the person's country 
    of origin has a high prevalence of TB, and (d) as the length of time 
    between vaccination and PPD testing increases. For example, a PPD test 
    reaction of 10 mm probably can be attributed to M. 
    tuberculosis infection in an adult who was vaccinated with BCG as a 
    child and who is from a country with a high prevalence of TB (74,75).
    6. The Booster Phenomenon
        The ability of persons who have TB infection to react to PPD may 
    gradually wane. For example, if tested with PPD, adults who were 
    infected during their childhood may have a negative reaction. However, 
    the PPD could boost the hypersensitivity, and the size of the reaction 
    could be larger on a subsequent test. This boosted reaction may be 
    misinterpreted as a PPD test conversion from a newly acquired 
    infection. Misinterpretation of a boosted reaction as a new infection 
    could result in unnecessary investigations of laboratory and patient 
    records in an attempt to identify the source case and in unnecessary 
    prescription of preventive therapy for HCWs. Although boosting can 
    occur among persons in any age group, the likelihood of the reaction 
    increases with the age of the person being tested (6,76).
        When PPD testing of adults is to be repeated periodically (as in 
    HCW skin-testing programs), two-step testing can be used to reduce the 
    likelihood that a boosted reaction is misinterpreted as a new 
    infection. Two-step testing should be performed on all newly employed 
    HCWs who have an initial negative PPD test result at the time of 
    employment and have not had a documented negative PPD test result 
    during the 12 months preceding the initial test. A second test should 
    be performed 1-3 weeks after the first test. If the second test result 
    is positive, this is most likely a boosted reaction, and the HCW should 
    be classified as previously infected. If the second test result remains 
    negative, the HCW is classified as uninfected, and a positive reaction 
    to a subsequent test is likely to represent a new infection with M. 
    tuberculosis.
    B. Chest Radiography
        Patients who have positive skin-test results or symptoms suggestive 
    of TB should be evaluated with a chest radiograph regardless of PPD 
    test results. Radiographic abnormalities that strongly suggest active 
    TB include upper-lobe infiltration, particularly if cavitation is seen 
    (77), and patchy or nodular infiltrates in the apical or subapical 
    posterior upper lobes or the superior segment of the lower lobe. If 
    abnormalities are noted, or if the patient has symptoms suggestive of 
    extrapulmonary TB, additional diagnostic tests should be conducted.
        The radiographic presentation of pulmonary TB in HIV-infected 
    patients may be unusual (78). Typical apical cavitary disease is less 
    common among such patients. They may have infiltrates in any lung zone, 
    a finding that is often associated with mediastinal and/or hilar 
    adenopathy, or they may have a normal chest radiograph, although this 
    latter finding occurs rarely.
    C. Bacteriology
        Smear and culture examination of at least three sputum specimens 
    collected on different days is the main diagnostic procedure for 
    pulmonary TB (6). Sputum smears that fail to demonstrate AFB do not 
    exclude the diagnosis of TB. In the United States, approximately 60% of 
    patients with positive sputum cultures have positive AFB sputum smears. 
    HIV-infected patients who have pulmonary TB may be less likely than 
    immunocompetent patients to have AFB present on sputum smears, which is 
    consistent with the lower frequency of cavitary pulmonary disease 
    observed among HIV-infected persons (39,41).
        Specimens for smear and culture should contain an adequate amount 
    of expectorated sputum but not much saliva. If a diagnosis of TB cannot 
    be established from sputum, a bronchoscopy may be necessary (36,37). In 
    young children who cannot produce an adequate amount of sputum, gastric 
    aspirates may provide an adequate specimen for diagnosis.
        A culture of sputum or other clinical specimen that contains M. 
    tuberculosis provides a definitive diagnosis of TB. Conventional 
    laboratory methods may require 4-8 weeks for species identification; 
    however, the use of radiometric culture techniques and nucleic acid 
    probes facilitates more rapid detection and identification of 
    mycobacteria (79,80). Mixed mycobacterial infection, either 
    simultaneous or sequential, can obscure the identification of M. 
    tuberculosis during the clinical evaluation and the laboratory analysis 
    (42). The use of nucleic acid probes for both M. avium complex and M. 
    tuberculosis may be useful for identifying mixed mycobacterial 
    infections in clinical specimens.
    
    II. Preventive Therapy for Latent TB Infection and Treatment of Active 
    TB
    
    A. Preventive Therapy for Latent TB Infection
        Determining whether a person with a positive PPD test reaction or 
    conversion is a candidate for preventive therapy must be based on (a) 
    the likelihood that the reaction represents true infection with M. 
    tuberculosis (as determined by the cut-points), (b) the estimated risk 
    for progression from latent infection to active TB, and (c) the risk 
    for hepatitis associated with taking isoniazid (INH) preventive therapy 
    (as determined by age and other factors).
        HCWs with positive PPD test results should be evaluated for 
    preventive therapy regardless of their ages if they (a) are recent 
    converters, (b) are close contacts of persons who have active TB, (c) 
    have a medical condition that increases the risk for TB, (d) have HIV 
    infection, or (e) use injecting drugs (5). HCWs with positive PPD test 
    results who do not have these risk factors should be evaluated for 
    preventive therapy if they are <35 years="" of="" age.="" preventive="" therapy="" should="" be="" considered="" for="" anergic="" persons="" who="" are="" known="" contacts="" of="" infectious="" tb="" patients="" and="" for="" persons="" from="" populations="" in="" which="" the="" prevalence="" of="" tb="" infection="" is="" very="" high="" (e.g.,="" a="" prevalence="" of="">10%).
        Because the risk for INH-associated hepatitis may be increased 
    during the peripartum period, the decision to use preventive therapy 
    during pregnancy should be made on an individual basis and should 
    depend on the patient's estimated risk for progression to active 
    disease. In general, preventive therapy can be delayed until after 
    delivery. However, for pregnant women who were probably infected 
    recently or who have high-risk medical conditions, especially HIV 
    infection, INH preventive therapy should begin when the infection is 
    documented (81-84). No evidence suggests that INH poses a carcinogenic 
    risk to humans (85-87).
        The usual preventive therapy regimen is oral INH 300 mg daily for 
    adults and 10 mg/kg/day for children (88). The recommended duration of 
    therapy is 12 months for persons with HIV infection and 9 months for 
    children. Other persons should receive INH therapy for 6-12 months. For 
    persons who have silicosis or a chest radiograph demonstrating inactive 
    fibrotic lesions and who have no evidence of active TB, acceptable 
    regimens include (a) 4 months of INH plus rifampin or (b) 12 months of 
    INH, providing that infection with INH-resistant organisms is unlikely 
    (33). For persons likely to be infected with MDR-TB, alternative 
    multidrug preventive therapy regimens should be considered (89).
        All persons placed on preventive therapy should be educated 
    regarding the possible adverse reactions associated with INH use, and 
    they should be questioned carefully at monthly intervals by qualified 
    personnel for signs or symptoms consistent with liver damage or other 
    adverse effects (81-84,88,90,91). Because INH-associated hepatitis 
    occurs more frequently among persons >35 years of age, a transaminase 
    measurement should be obtained from persons in this age group before 
    initiation of INH therapy and then obtained monthly until treatment has 
    been completed. Other factors associated with an increased risk for 
    hepatitis include daily alcohol use, chronic liver disease, and 
    injecting-drug use. In addition, postpubertal black and Hispanic women 
    may be at greater risk for hepatitis or drug interactions (92). More 
    careful clinical monitoring of persons with these risk factors and 
    possibly more frequent laboratory monitoring should be considered. If 
    any of these tests exceeds three to five times the upper limit of 
    normal, discontinuation of INH should be strongly considered. Liver 
    function tests are not a substitute for monthly clinical evaluations or 
    for the prompt assessment of signs or symptoms of adverse reactions 
    that could occur between the regularly scheduled evaluations (33).
        Persons who have latent TB infection should be advised that they 
    can be reinfected with another strain of M. tuberculosis (93).
    B. Treatment of Patients Who Have Active TB
        Drug-susceptibility testing should be performed on all initial 
    isolates from patients with TB. However, test results may not be 
    available for several weeks, making selection of an initial regimen 
    difficult, especially in areas where drug-resistant TB has been 
    documented. Current recommendations for therapy and dosage schedules 
    for the treatment of drug-susceptible TB should be followed (Table S2-
    2; Table S2-3) (43). Streptomycin is contraindicated in the treatment 
    of pregnant women because of the risk for ototoxicity to the fetus. In 
    geographic areas or facilities in which drug-resistant TB is highly 
    prevalent, the initial treatment regimen used while results of drug-
    susceptibility tests are pending may need to be expanded. This decision 
    should be based on analysis of surveillance data.
        When results from drug-susceptibility tests become available, the 
    regimen should be adjusted appropriately (94-97). If drug resistance is 
    present, clinicians unfamiliar with the management of patients with 
    drug-resistant TB should seek expert consultation.
        For any regimen to be effective, adherence to the regimen must be 
    ensured. The most effective method of ensuring adherence is the use of 
    DOT after the patient has been discharged from the hospital (43,91). 
    This practice should be coordinated with the public health department.
    
                                   Table S2-2.--Regimen Options for the Treatment of Tuberculosis (TB) in Children and Adults                               
    --------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Initial treatment phase            Continuation treatment phase                                
                                              Total    ---------------------------------------------------------------------------                          
      Option           Indication          duration of                      Interval and                                                    Comments        
                                             therapy         Drugs*           duration        Drugs*       Interval and duration                            
    --------------------------------------------------------------------------------------------------------------------------------------------------------
    1........  Pulmonary and              6 mos.......  INH.............  Daily for 8 wks  INH.........  Daily or two or three     EMB or SM should 
                extrapulmonary TB in                    RIF                                RIF            times wkly for    be continued until      
                adults and children.                    PZA                                               16 wksSec. .              susceptibility to INH   
                                                        EMB or SM                                                                   and RIF is demonstrated.
                                                                                                                                   In areas where   
                                                                                                                                    primary INH resistance  
                                                                                                                                    is <4%, emb="" or="" sm="" may="" not="" be="" necessary="" for="" patients="" with="" no="" individual="" risk="" factors="" for="" drug="" resistance.="" 2........="" pulmonary="" and="" 6="" mos.......="" inh.............="" daily="" for="" 2="" inh.........="" two="" times="">    Regimen should be
                extrapulmonary TB in                    RIF                wks, then two   RIF            for 16 wksSec. .          directly observed.      
                adults and children.                    PZA                times                                                   After the initial
                                                        EMB or SM          wkly                                             phase, EMB or SM should 
                                                                           for 6 wks.                                               be continued until      
                                                                                                                                    susceptibility to INH   
                                                                                                                                    and RIF is demonstrated,
                                                                                                                                    unless drug resistance  
                                                                                                                                    is unlikely.            
    3........  Pulmonary and              6 mos.......  INH.............                                                                                    
                extrapulmonary TB in                    RIF                                                                                                 
                adults and children.                    PZA                                                                                                 
                                                        EMB or SM                                                                                           
    (2)3       Regimen should be                                                                                                                    
     times      directly observed..                                                                                                                         
     wklyContinue all four                                                                                                                    
     g for 6    drugs for 6 mos..                                                                                                                          
     mosSec.   This regimen has                                                                                                                     
                been shown to be                                                                                                                            
                effective for INH-                                                                                                                          
                resistant TB..                                                                                                                              
    4........  Smear- and culture-        4 mos.......  INH.............  Follow option    INH.........  Daily or two or three     Continue all four
                negative pulmonary TB in                RIF                1, 2, or 3 for  RIF            times wkly for    drugs for 4 mos.        
                adults.                                 PZA                8 wks.          PZA            8 wks.                   If drug          
                                                        EMB or SM                          EMB or SM                                resistance is unlikely  
                                                                                                                                    (primary INH resistance 
                                                                                                                                    <4% and="" patient="" has="" no="" individual="" risk="" factors="" for="" drug="" resistance),="" emb="" or="" sm="" may="" not="" be="" necessary="" and="" pza="" may="" be="" discontinued="" after="" 2="" mos.="" 5........="" pulmonary="" and="" 9="" mos.......="" inh.............="" daily="" for="" 8="" wks="" inh.........="" daily="" or="" two="" times="">EMB or SM should 
                extrapulmonary TB in                    RIF                                RIF            wkly for 24       be continued until      
                adults and children when                EMB or                                            wksSec. .                 susceptibility to INH   
                PZA is contraindicated.                 SM**                                                                        and RIF is demonstrated.
                                                                                                                                   In areas where   
                                                                                                                                    primary INH resistance  
                                                                                                                                    is <4%, emb="" or="" sm="" may="" not="" be="" necessary="" for="" patients="" with="" no="" individual="" risk="" factors="" for="" drug="" resistance.="" --------------------------------------------------------------------------------------------------------------------------------------------------------="" *emb="ethambutol;" inh="isoniazid;" pza="pyrazinamide;" rif="rifampin;" sm="streptomycin.">All regimens administered intermittently should be directly observed.                                                                           
    Sec. For infants and children with miliary TB, bone and joint TB, or TB meningitis, treatment should last at least 12 months. For adults with these     
      forms of extrapulmonary TB, response to therapy should be monitored closely. If response is slow or suboptimal, treatment may be prolonged on a case- 
      by-case basis.                                                                                                                                        
    Some evidence suggests that SM may be discontinued after 4 months if the isolate is susceptible to all drugs.                                          
    **Avoid treating pregnant women with SM because of the risk of ototoxicity to the fetus.                                                                
                                                                                                                                                            
    Note: For all patients, if drug-susceptibility results show resistance to any of the first-line drugs, or if the patient remains symptomatic or smear-  
      or culture-positive after 3 months, consult a TB medical expert.                                                                                      
    
    
                              Table S2-3.--Dosage Recommendations for the Initial Treatment of Tuberculosis in Children* and Adults                         
    --------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    Dosage schedule                                                         
                         -----------------------------------------------------------------------------------------------------------------------------------
            Drug                   Daily dose (maximum dose)               Two doses per week (maximum dose)          Three doses per week (maximum dose)   
                         -----------------------------------------------------------------------------------------------------------------------------------
                                Children               Adults               Children               Adults               Children               Adults       
    --------------------------------------------------------------------------------------------------------------------------------------------------------
    Isoniazid...........  10-20 mg/kg (300 mg)  5 mg/kg (300 mg)....  20-40 mg/kg (900 mg)  15 mg/kg (900 mg)...  20-40 mg/kg (900 mg)  15 mg/kg) (900 mg)  
    Rifampin............  10-20 mg/kg (600 mg)  10 mg/kg (600 mg)...  10-20 mg/kg (600 mg)  10 mg/kg (600 mg)...  10-20 mg/kg (600 mg)  10 mg/kg (600 mg)   
    Pyrazinamide........  15-30 mg/kg (2 gm)..  15-30 mg/kg (2 gm)..  50-70 mg/kg (4 gm)..  50-70 mg/kg (4 gm)..  50-70 mg/kg (3 gm)..  50-70 mg/kg (3 gm)  
    Ethambutol..........  15-25 mg/kg.........  15-25 mg/kg.........  50 mg/kg............  50 mg/kg............  25-40 mg/kg.........  25-30 mg/kg         
    Streptomycin........  20-40 mg/kg (1 gm)..  15 mg/kg (1 gm).....  20-40 mg/kg (1.5 gm)  20-40 mg/kg (1.5 gm)  20-40 mg/kg (1.5 gm)  20-40 mg/kg (1.5 gm)
    --------------------------------------------------------------------------------------------------------------------------------------------------------
    *Persons 12 years of age.                                                                                                                    
    
    Supplement 3: Engineering Controls
    
    I. Introduction
        This supplement provides information regarding the use of 
    ventilation (Section II) and UVGI (Section III) for preventing the 
    transmission of M. tuberculosis in health-care facilities. The 
    information provided is primarily conceptual and is intended to educate 
    staff in the health-care facility concerning engineering controls and 
    how these controls can be used as part of the TB infection-control 
    program. This supplement should not be used in place of consultation 
    with experts, who can assume responsibility for advising on ventilation 
    system design and selection, installation, and maintenance of 
    equipment.
        The recommendations for engineering controls include (a) local 
    exhaust ventilation (i.e., source control), (b) general ventilation, 
    and (c) air cleaning. General ventilation considerations include (a) 
    dilution and removal of contaminants, (b) airflow patterns within 
    rooms, (c) airflow direction in facilities, (d) negative pressure in 
    rooms, and (e) TB isolation rooms. Air cleaning or disinfection can be 
    accomplished by filtration of air (e.g., through HEPA filters) or by 
    UVGI.
    II. Ventilation
        Ventilation systems for health-care facilities should be designed, 
    and modified when necessary, by ventilation engineers in collaboration 
    with infection-control and occupational health staff. Recommendations 
    for designing and operating ventilation systems have been published by 
    ASHRAE (47), AIA (48), and the American Conference of Governmental 
    Industrial Hygienists, Inc. (98).
        As part of the TB infection-control plan, health-care facility 
    personnel should determine the number of TB isolation rooms, treatment 
    rooms, and local exhaust devices (i.e., for cough-inducing or aerosol-
    generating procedures) that the facility needs. The locations of these 
    rooms and devices will depend on where in the facility the ventilation 
    conditions recommended in this document can be achieved. Grouping 
    isolation rooms together in one area of the facility may facilitate the 
    care of TB patients and the installation and maintenance of optimal 
    engineering controls (particularly ventilation).
        Periodic evaluations of the ventilation system should review the 
    number of TB isolation rooms, treatment rooms, and local exhaust 
    devices needed and the regular maintenance and monitoring of the local 
    and general exhaust systems (including HEPA filtration systems if they 
    are used).
        The various types and conditions of ventilation systems in health-
    care facilities and the individual needs of these facilities preclude 
    the ability to provide specific instructions regarding the 
    implementation of these recommendations. Engineering control methods 
    must be tailored to each facility on the basis of need and the 
    feasibility of using the ventilation and air-cleaning concepts 
    discussed in this supplement.
    A. Local Exhaust Ventilation
        Purpose: To capture airborne contaminants at or near their source 
    (i.e., the source control method) and remove these contaminants without 
    exposing persons in the area to infectious agents (98).
        Source control techniques can prevent or reduce the spread of 
    infectious droplet nuclei into the general air circulation by 
    entrapping infectious droplet nuclei as they are being emitted by the 
    patient (i.e., the source). These techniques are especially important 
    when performing procedures likely to generate aerosols containing 
    infectious particles and when infectious TB patients are coughing or 
    sneezing.
        Local exhaust ventilation is a preferred source control technique, 
    and it is often the most efficient way to contain airborne contaminants 
    because it captures these contaminants near their source before they 
    can disperse. Therefore, the technique should be used, if feasible, 
    wherever aerosol-generating procedures are performed. Two basic types 
    of local exhaust devices use hoods: (a) The enclosing type, in which 
    the hood either partially or fully encloses the infectious source; and 
    (b) the exterior type, in which the infectious source is near but 
    outside the hood. Fully enclosed hoods, booths, or tents are always 
    preferable to exterior types because of their superior ability to 
    prevent contaminants from escaping into the HCW's breathing zone. 
    Descriptions of both enclosing and exterior devices have been published 
    previously (98).
    1. Enclosing Devices
        The enclosing type of local exhaust ventilation device includes 
    laboratory hoods used for processing specimens that could contain 
    viable infectious organisms, booths used for sputum induction or 
    administration of aerosolized medications (e.g., aerosolized 
    pentamidine) (Figure S3-1), and tents or hoods made of vinyl or other 
    materials used to enclose and isolate a patient. These devices are 
    available in various configurations. The most simple of these latter 
    devices is a tent that is placed over the patient; the tent has an 
    exhaust connection to the room discharge exhaust system. The most 
    complex device is an enclosure that has a sophisticated self-contained 
    airflow and recirculation system.
        Both tents and booths should have sufficient airflow to remove at 
    least 99% of airborne particles during the interval between the 
    departure of one patient and the arrival of the next (99). The time 
    required for removing a given percentage of airborne particles from an 
    enclosed space depends on several factors. These factors include the 
    number of ACH, which is determined by the number of cubic feet of air 
    in the room or booth and the rate at which air is entering the room or 
    booth at the intake source; the location of the ventilation inlet and 
    outlet; and the physical configuration of the room or booth (Table S3-
    1).
    
    TN28OC94.004
    
    2. Exterior Devices
        The exterior type of local exhaust ventilation device is usually a 
    hood very near, but not enclosing, the infectious patient. The airflow 
    produced by these devices should be sufficient to prevent cross-
    currents of air near the patient's face from causing escape of droplet 
    nuclei. Whenever possible, the patient should face directly into the 
    hood opening so that any coughing or sneezing is directed into the 
    hood, where the droplet nuclei are captured. The device should maintain 
    an air velocity of  200 feet per minute at the patient's 
    breathing zone to ensure capture of droplet nuclei.
    3. Discharge Exhaust From Booths, Tents, and Hoods
        Air from booths, tents, and hoods may be discharged into the room 
    in which the device is located or it may be exhausted to the outside. 
    If the air is discharged into the room, a HEPA filter should be 
    incorporated at the discharge duct or vent of the device. The exhaust 
    fan should be located on the discharge side of the HEPA filter to 
    ensure that the air pressure in the filter housing and booth is 
    negative with respect to adjacent areas. Uncontaminated air from the 
    room will flow into the booth through all openings, thus preventing 
    infectious droplet nuclei in the booth from escaping into the room. 
    Most commercially available booths, tents, and hoods are fitted with 
    HEPA filters, in which case additional HEPA filtration is not needed.
        If the device does not incorporate a HEPA filter, the air from the 
    device should be exhausted to the outside in accordance with 
    recommendations for isolation room exhaust (Suppl. 3, Section II.B.5). 
    (See Supplement 3, Section II.C, for information regarding 
    recirculation of exhaust air.)
    
    Table S3-1.--Air Changes Per Hour (ACH) and Time in Minutes Required for
      Removal Efficiencies of 90%, 99%, and 99.9% of Airborne Contaminants* 
    ------------------------------------------------------------------------
                                                     Minutes required for a 
                                                     removal efficiency of: 
                         ACH                      --------------------------
                                                     90%      99%     99.9% 
    ------------------------------------------------------------------------
    1............................................      138      276      414
    2............................................       69      138      207
    3............................................       46       92      138
    4............................................       35       69      104
    5............................................       28       55       83
    6............................................       23       46       69
    7............................................       20       39       59
    8............................................       17       35       52
    9............................................       15       31       46
    10...........................................       14       28       41
    11...........................................       13       25       38
    12...........................................       12       23       35
    13...........................................       11       21       32
    14...........................................       10       20       30
    15...........................................        9       18       28
    16...........................................        9       17       26
    17...........................................        8       16       24
    18...........................................        8       15       23
    19...........................................        7       15       22
    20...........................................        7       14       21
    25...........................................        6       11       17
    30...........................................        5        9       14
    35...........................................        4        8       12
    40...........................................        3        7       10
    45...........................................        3        6        9
    50...........................................        3        6       8 
    ------------------------------------------------------------------------
    *This table has been adapted from the formula for the rate of purging   
      airborne contaminants (99). Values have been derived from the formula 
      t1 = [In C2  C1)  (Q  V)]  x  60, with T1 = 0 
      and C2  C1 - (removal efficiency  100), and where:    
    t1 = initial timepoint                                                  
    C1 = initial concentration of contaminant                               
    C2 = final concentration of contaminants                                
    Q = air flow rate (cubic feet per hour)                                 
    V = room volume (cubic feet)                                            
    Q  V = ACH                                                      
    The times given assume perfect mixing of the air within the space (i.e.,
      mixing factor = 1). However, perfect mixing usually does not occur,   
      and the mixing factor could be as high as 10 if air distribution is   
      very poor (98). The required time is derived by multiplying the       
      appropriate time from the table by the mixing factor that has been    
      determined for the booth or room. The factor and required time should 
      be included in the operating instructions provided by the manufacturer
      of the booth or enclosure, and these instructions should be followed. 
    
    B. General Ventilation
        General ventilation can be used for several purposes, including 
    diluting and removing contaminated air, controlling airflow patterns 
    within rooms, and controlling the direction of airflow throughout a 
    facility. Information on these topics is contained in the following 
    sections.
    1. Dilution and Removal
        Purpose: To reduce the concentration of contaminants in the air.
        General ventilation maintains air quality by two processes: 
    dilution and removal of airborne contaminants. Uncontaminated supply 
    (i.e., incoming) air mixes with the contaminated room air (i.e., 
    dilution), which is subsequently removed from the room by the exhaust 
    system (i.e., removal). These processes reduce the concentration of 
    droplet nuclei in the room air.
        a. Types of general ventilation systems.
        Two types of general ventilation systems can be used for dilution 
    and removal of contaminated air: the single-pass system and the 
    recirculating system. In a single-pass system, the supply air is either 
    outside air that has been appropriately heated and cooled or air from a 
    central system that supplies a number of areas. After air passes 
    through the room (or area), 100% of that air is exhausted to the 
    outside. The single-pass system is the preferred choice in areas where 
    infectious airborne droplet nuclei are known to be present (e.g., TB 
    isolation rooms or treatment rooms) because it prevents contaminated 
    air from being recirculated to other areas of the facility.
        In a recirculating system, a small portion of the exhaust air is 
    discharged to the outside and is replaced with fresh outside air, which 
    mixes with the portion of exhaust air that was not discharged to the 
    outside. The resulting mixture, which can contain a large proportion of 
    contaminated air, is then recirculated to the areas serviced by the 
    system. This air mixture could be recirculated into the general 
    ventilation, in which case contaminants may be carried from 
    contaminated areas to uncontaminated areas. Alternatively, the air 
    mixture could also be recirculated within a specific room or area, in 
    which case other areas of the facility will not be affected (Suppl. 3, 
    Section II.C.3).
        b. Ventilation rates.
        Recommended general ventilation rates for health-care facilities 
    are usually expressed in number of ACH. This number is the ratio of the 
    volume of air entering the room per hour to the room volume and is 
    equal to the exhaust airflow (Q [cubic feet per minute]) divided by the 
    room volume (V [cubic feet]) multiplied by 60 (i.e., ACH = Q  V 
     x  60).
        The feasibility of achieving specific ventilation rates depends on 
    the construction and operational requirements of the ventilation system 
    (e.g., the energy requirements to move and to heat or cool the air). 
    The feasibility of achieving specific ventilation rates may also be 
    different for retrofitted facilities and newly constructed facilities. 
    The expense and effort of achieving specific higher ventilation rates 
    for new construction may be reasonable, whereas retrofitting an 
    existing facility to achieve similar ventilation rates may be more 
    difficult. However, achieving higher ventilation rates by using 
    auxiliary methods (e.g., room-air recirculation) in addition to exhaust 
    ventilation may be feasible in existing facilities (Suppl. 3, Section 
    II.C).
    2. Airflow Patterns Within Rooms (Air Mixing)
        Purpose: To provide optimum airflow patterns and prevent both 
    stagnation and short-circuiting of air.
        General ventilation systems should be designed to provide optimal 
    patterns of airflow within rooms and prevent air stagnation or short-
    circuiting of air from the supply to the exhaust (i.e., passage of air 
    directly from the air supply to the air exhaust). To provide optimal 
    airflow patterns, the air supply and exhaust should be located such 
    that clean air first flows to parts of the room where HCWs are likely 
    to work, and then flows across the infectious source and into the 
    exhaust. In this way, the HCW is not positioned between the infectious 
    source and the exhaust location. Although this configuration may not 
    always be possible, it should be used whenever feasible. One way to 
    achieve this airflow pattern is to supply air at the side of the room 
    opposite the patient and exhaust it from the side where the patient is 
    located. Another method, which is most effective when the supply air is 
    cooler than the room air, is to supply air near the ceiling and exhaust 
    it near the floor (Figure S3-2). Airflow patterns are affected by large 
    air temperature differentials, the precise location of the supply and 
    exhausts, the location of furniture, the movement of HCWs and patients, 
    and the physical configuration of the space. Smoke tubes can be used to 
    visualize airflow patterns in a manner similar to that described for 
    estimating room air mixing.
    
    TN28OC94.005
    
          
        Adequate air mixing, which requires that an adequate number of ACH 
    be provided to a room (Suppl. 3, Section II.B.1), must be ensured to 
    prevent air stagnation within the room. However, the air will not 
    usually be changed the calculated number of times per hour because the 
    airflow patterns in the room may not permit complete mixing of the 
    supply and room air in all parts of the room. This results in an 
    ``effective'' airflow rate in which the supplied airflow may be less 
    than required for proper ventilation. To account for this variation, a 
    mixing factor (which ranges from 1 for perfect mixing to 10 for poor 
    mixing) is applied as a multiplier to determine the actual supply 
    airflow (i.e., the recommended ACH multiplied by the mixing factor 
    equals the actual required ACH) (51,98). The room air supply and 
    exhaust system should be designed to achieve the lowest mixing factor 
    possible. The mixing factor is determined most accurately by 
    experimentally testing each space configuration, but this procedure is 
    complex and time-consuming. A reasonably good qualitative measure of 
    mixing can be estimated by an experienced ventilation engineer who 
    releases smoke from smoke tubes at a number of locations in the room 
    and observes the movement of the smoke. Smoke movement in all areas of 
    the room indicates good mixing. Stagnation of air in some areas of the 
    room indicates poor mixing, and movement of the supply and exhaust 
    openings or redirection of the supply air is necessary.
    3. Airflow Direction in the Facility
        Purpose: To contain contaminated air in localized areas in a 
    facility and prevent its spread to uncontaminated areas.
        a. Directional airflow.
        The general ventilation system should be designed and balanced so 
    that air flows from less contaminated (i.e., more clean) to more 
    contaminated (less clean) areas (47,48). For example, air should flow 
    from corridors (cleaner areas) into TB isolation rooms (less clean 
    areas) to prevent spread of contaminants to other areas. In some 
    special treatment rooms in which operative and invasive procedures are 
    performed, the direction of airflow is from the room to the hallway to 
    provide cleaner air during these procedures. Cough-inducing or aerosol-
    generating procedures (e.g., bronchoscopy and irrigation of tuberculous 
    abscesses) should not be performed in rooms with this type of airflow 
    on patients who may have infectious TB.
        b. Negative pressure for achieving directional airflow.
        The direction of airflow is controlled by creating a lower 
    (negative) pressure in the area into which the flow of air is desired. 
    For air to flow from one area to another, the air pressure in the two 
    areas must be different. Air will flow from a higher pressure area to a 
    lower pressure area. The lower pressure area is described as being at 
    negative* pressure relative to the higher pressure area. Negative 
    pressure is attained by exhausting air from an area at a higher rate 
    than air is being supplied. The level of negative pressure necessary to 
    achieve the desired airflow will depend on the physical configuration 
    of the ventilation system and area, including the airflow path and flow 
    openings, and should be determined on an individual basis by an 
    experienced ventilation engineer.
    ---------------------------------------------------------------------------
    
        *Negative is defined relative to the air pressure in the area 
    from which air is to flow.
    ---------------------------------------------------------------------------
    
    4. Achieving Negative Pressure in a Room
        Purpose: To control the direction of airflow between the room and 
    adjacent areas, thereby preventing contaminated air from escaping from 
    the room into other areas of the facility.
        a. Pressure differential.
        The minimum pressure difference necessary to achieve and maintain 
    negative pressure that will result in airflow into the room is very 
    small (0.001 inch of water). Higher pressures ( 0.001 inch 
    of water) are satisfactory; however, these higher pressures may be 
    difficult to achieve. The actual level of negative pressure achieved 
    will depend on the difference in the ventilation exhaust and supply 
    flows and the physical configuration of the room, including the airflow 
    path and flow openings. If the room is well sealed, negative pressures 
    greater than the minimum of 0.001 inch of water may be readily 
    achieved. However, if rooms are not well sealed, as may be the case in 
    many facilities (especially older facilities), achieving higher 
    negative pressures may require exhaust/supply flow differentials beyond 
    the capability of the ventilation system.
        To establish negative pressure in a room that has a normally 
    functioning ventilation system, the room supply and exhaust airflows 
    are first balanced to achieve an exhaust flow of either 10% or 50 cubic 
    feet per minute (cfm) greater than the supply (whichever is the 
    greater). In most situations, this specification should achieve a 
    negative pressure of at least 0.001 inch of water. If the minimum 0.001 
    inch of water is not achieved and cannot be achieved by increasing the 
    flow differential (within the limits of the ventilation system), the 
    room should be inspected for leakage (e.g., through doors, windows, 
    plumbing, and equipment wall penetrations), and corrective action 
    should be taken to seal the leaks.
        Negative pressure in a room can be altered by changing the 
    ventilation system operation or by the opening and closing of the 
    room's doors, corridor doors, or windows. When an operating 
    configuration has been established, it is essential that all doors and 
    windows remain properly closed in the isolation room and other areas 
    (e.g., doors in corridors that affect air pressure) except when persons 
    need to enter or leave the room or area.
        b. Alternate methods for achieving negative pressure.
        Although an anteroom is not a substitute for negative pressure in a 
    room, it may be used to reduce escape of droplet nuclei during opening 
    and closing of the isolation room door. Some anterooms have their own 
    air supply duct, but others do not. The TB isolation room should have 
    negative pressure relative to the anteroom, but the air pressure in the 
    anteroom relative to the corridor may vary depending on the building 
    design. This should be determined, in accordance with applicable 
    regulations, by a qualified ventilation engineer.
        If the existing ventilation system is incapable of achieving the 
    desired negative pressure because the room lacks a separate ventilation 
    system or the room's system cannot provide the proper airflow, steps 
    should be taken to provide a means to discharge air from the room. The 
    amount of air to be exhausted will be the same as discussed previously 
    (Suppl. 3, Section II.B.4.a).
        Fixed room-air recirculation systems (i.e., systems that 
    recirculate the air in an entire room) may be designed to achieve 
    negative pressure by discharging air outside the room (Suppl. 3, 
    Section II.C.3).
        Some portable room-air recirculation units (Suppl. 3, Section 
    II.C.3.b.) are designed to discharge air to the outside to achieve 
    negative pressure. Air cleaners that can accomplish this must be 
    designed specifically for this purpose.
        A small centrifugal blower (i.e., exhaust fan) can be used to 
    exhaust air to the outside through a window or outside wall. This 
    approach may be used as an interim measure to achieve negative 
    pressure, but it provides no fresh air and suboptimal dilution.
        Another approach to achieving the required pressure difference is 
    to pressurize the corridor. Using this method, the corridor's general 
    ventilation system is balanced to create a higher air pressure in the 
    corridor than in the isolation room; the type of balancing necessary 
    depends on the configuration of the ventilation system. Ideally, the 
    corridor air supply rate should be increased while the corridor exhaust 
    rate is not increased. If this is not possible, the exhaust rate should 
    be decreased by resetting appropriate exhaust dampers. Caution should 
    be exercised, however, to ensure that the exhaust rate is not reduced 
    below acceptable levels. This approach requires that all settings used 
    to achieve the pressure balance, including doors, be maintained. This 
    method may not be desirable if the corridor being pressurized has rooms 
    in which negative pressure is not desired. In many situations, this 
    system is difficult to achieve, and it should be considered only after 
    careful review by ventilation personnel.
        c. Monitoring negative pressure.
        The negative pressure in a room can be monitored by visually 
    observing the direction of airflow (e.g., using smoke tubes) or by 
    measuring the differential pressure between the room and its 
    surrounding area.
        Smoke from a smoke tube can be used to observe airflow between 
    areas or airflow patterns within an area. To check the negative 
    pressure in a room by using a smoke tube, hold the smoke tube near the 
    bottom of the door and approximately 2 inches in front of the door, or 
    at the face of a grille or other opening if the door has such a 
    feature, and generate a small amount of smoke by gently squeezing the 
    bulb (Figure S3-3). The smoke tube should be held parallel to the door, 
    and the smoke should be issued from the tube slowly to ensure the 
    velocity of the smoke from the tube does not overpower the air 
    velocity. The smoke will travel in the direction of airflow. If the 
    room is at negative pressure, the smoke will travel under the door and 
    into the room (e.g., from higher to lower pressure). If the room is not 
    at negative pressure, the smoke will be blown outward or will stay 
    stationary. This test must be performed while the door is closed. If 
    room air cleaners are being used in the room, they should be running. 
    The smoke is irritating if inhaled, and care should be taken not to 
    inhale it directly from the smoke tube. However, the quantity of smoke 
    issued from the tube is minimal and is not detectable at short 
    distances from the tube.
        Differential pressure-sensing devices also can be used to monitor 
    negative pressure; they can provide either periodic (noncontinuous) 
    pressure measurements or continuous pressure monitoring. The continuous 
    monitoring component may simply be a visible and/or audible warning 
    signal that air pressure is low. In addition, it may also provide a 
    pressure readout signal, which can be recorded for later verification 
    or used to automatically adjust the facility's ventilation control 
    system.
    
    TN28OC94.006
    
        Pressure-measuring devices should sense the room pressure just 
    inside the airflow path into the room (e.g., at the bottom of the 
    door). Unusual airflow patterns within the room can cause pressure 
    variations; for example, the air can be at negative pressure at the 
    middle of a door and at positive pressure at the bottom of the same 
    door (Figure S3-4). If the pressure-sensing ports of the device cannot 
    be located directly across the airflow path, it will be necessary to 
    validate that the negative pressure at the sensing point is and remains 
    the same as the negative pressure across the flow path.
        Pressure-sensing devices should incorporate an audible warning with 
    a time delay to indicate that a door is open. When the door to the room 
    is opened, the negative pressure will decrease. The time-delayed signal 
    should allow sufficient time for persons to enter or leave the room 
    without activating the audible warning.
    
    TN28OC94.007
    
        A potential problem with using pressure-sensing devices is that the 
    pressure differentials used to achieve the low negative pressure 
    necessitate the use of very sensitive mechanical devices, electronic 
    devices, or pressure gauges to ensure accurate measurements. Use of 
    devices that cannot measure these low pressures (i.e., pressures as low 
    as 0.001 inch of water) will require setting higher negative pressures 
    that may be difficult and, in some instances, impractical to achieve 
    (Suppl. 3, Section II.B.4).
        Periodic checks are required to ensure that the desired negative 
    pressure is present and that the continuous monitoring devices, if 
    used, are operating properly. If smoke tubes or other visual checks are 
    used, TB isolation rooms and treatment rooms should be checked 
    frequently for negative pressure. Rooms undergoing changes to the 
    ventilation system should be checked daily. TB isolation rooms should 
    be checked daily for negative pressure while being used for TB 
    isolation. If these rooms are not being used for patients who have 
    suspected or confirmed TB but potentially could be used for such 
    patients, the negative pressure in the rooms should be checked monthly. 
    If pressure-sensing devices are used, negative pressure should be 
    verified at least once a month by using smoke tubes or taking pressure 
    measurements.
    C. HEPA Filtration
        Purpose: To remove contaminants from the air.
        HEPA filtration can be used as a method of air cleaning that 
    supplements other recommended ventilation measures. For the purposes of 
    these guidelines, HEPA filters are defined as air-cleaning devices that 
    have a demonstrated and documented minimum removal efficiency of 99.97% 
    of particles greater than or equal to 0.3 m in diameter. HEPA 
    filters have been shown to be effective in reducing the concentration 
    of Aspergillus spores (which range in size from 1.5 m to 6 
    m) to below measurable levels (100-102). The ability of HEPA 
    filters to remove tubercle bacilli from the air has not been studied, 
    but M. tuberculosis droplet nuclei probably range from 1 m to 
    5 m in diameter (i.e., approximately the same size as 
    Aspergillus spores). Therefore, HEPA filters can be expected to remove 
    infectious droplet nuclei from contaminated air. HEPA filters can be 
    used to clean air before it is exhausted to the outside, recirculated 
    to other areas of a facility, or recirculated within a room. If the 
    device is not completely passive (e.g., it utilizes techniques such as 
    electrostatics) and the failure of the electrostatic components permits 
    loss of filtration efficiency to less than 99.97%, the device should 
    not be used in systems that recirculate air back into the general 
    facility ventilation system from TB isolation rooms and treatment rooms 
    in which procedures are performed on patients who may have infectious 
    TB (Suppl. 3, Section II.C.2).
        HEPA filters can be used in a number of ways to reduce or eliminate 
    infectious droplet nuclei from room air or exhaust. These methods 
    include placement of HEPA filters (a) in exhaust ducts to remove 
    droplet nuclei from air being discharged to the outside, either 
    directly or through ventilation equipment; (b) in ducts discharging 
    room air into the general ventilation system; and (c) in fixed or 
    portable room-air cleaners. The effectiveness of portable HEPA room-air 
    cleaning units has not been evaluated adequately, and there is probably 
    considerable variation in their effectiveness. HEPA filters can also be 
    used in exhaust ducts or vents that discharge air from booths or 
    enclosures into the surrounding room (Suppl. 3, Section II.A.3). In any 
    application, HEPA filters should be installed carefully and maintained 
    meticulously to ensure adequate function.
        Manufacturers of room-air cleaning equipment should provide 
    documentation of the HEPA filter efficiency and the efficiency of the 
    installed device in lowering room-air contaminant levels.
    1. Use of HEPA Filtration When Exhausting Air to the Outside
        HEPA filters can be used as an added safety measure to clean air 
    from isolation rooms and local exhaust devices (i.e., booths, tents, or 
    hoods used for cough-inducing procedures) before exhausting it directly 
    to the outside, but such use is unnecessary if the exhaust air cannot 
    re-enter the ventilation system supply. The use of HEPA filters should 
    be considered wherever exhaust air could possibly reenter the system.
        In many instances, exhaust air is not discharged directly to the 
    outside; rather, the air is directed through heat-recovery devices 
    (e.g., heat wheels). Heat wheels are often used to reduce the costs of 
    operating ventilation systems (103). If such units are used with the 
    system, a HEPA filter should also be used. As the wheel rotates, energy 
    is transferred into or removed from the supply inlet air stream. The 
    HEPA filter should be placed upstream from the heat wheel because of 
    the potential for leakage across the seals separating the inlet and 
    exhaust chambers and the theoretical possibility that droplet nuclei 
    could be impacted on the wheel by the exhaust air and subsequently 
    stripped off into the supply air.
    2. Recirculation of HEPA-Filtered Air to Other Areas of a Facility
        Air from TB isolation rooms and treatment rooms used to treat 
    patients who have confirmed or suspected infectious TB should be 
    exhausted to the outside in accordance with applicable Federal, state, 
    and local regulations. The air should not be recirculated into the 
    general ventilation. In some instances, recirculation of air into the 
    general ventilation system from such rooms is unavoidable (i.e., in 
    existing facilities in which the ventilation system or facility 
    configuration makes venting the exhaust to the outside impossible). In 
    such cases, HEPA filters should be installed in the exhaust duct 
    leading from the room to the general ventilation system to remove 
    infectious organisms and particulates the size of droplet nuclei from 
    the air before it is returned to the general ventilation system 
    (Section II.F; Suppl. 3). Air from TB isolation rooms and treatment 
    rooms in new or renovated facilities should not be recirculated into 
    the general ventilation system.
    3. Recirculation of HEPA-Filtered Air Within a Room
        Individual room-air recirculation can be used in areas where there 
    is no general ventilation system, where an existing system is incapable 
    of providing adequate airflow, or where an increase in ventilation is 
    desired without affecting the fresh air supply or negative pressure 
    system already in place. Recirculation of HEPA-filtered air within a 
    room can be achieved in several ways: (a) by exhausting air from the 
    room into a duct, filtering it through a HEPA filter installed in the 
    duct, and returning it to the room (Figure S3-5); (b) by filtering air 
    through HEPA recirculation systems mounted on the wall or ceiling of 
    the room (Figure S3-6); or (c) by filtering air through portable HEPA 
    recirculation systems. In this document, the first two of these 
    approaches are referred to as fixed room-air recirculation systems, 
    because the HEPA filter devices are fixed in place and are not easily 
    movable.
    
    BILLING CODE 4163-18-P
    
    TN28OC94.008
    
    
    BILLING CODE 4163-18-C
        a. Fixed room-air recirculation systems.
        The preferred method of recirculating HEPA-filtered air within a 
    room is a built-in system, in which air is exhausted from the room into 
    a duct, filtered through a HEPA filter, and returned to the room 
    (Figure S3-5). This technique may be used to add air changes in areas 
    where there is a recommended minimum ACH that is difficult to meet with 
    general ventilation alone. The air does not have to be conditioned, 
    other than by the filtration, and this permits higher airflow rates 
    than the general ventilation system can usually achieve. An alternative 
    is the use of HEPA filtration units that are mounted on the wall or 
    ceiling of the room (Figure S3-7). Fixed recirculation systems are 
    preferred over portable (free-standing) units because they can be 
    installed and maintained with a greater degree of reliability.
        b. Portable room-air recirculation units.
        Portable HEPA filtration units may be considered for recirculating 
    air within rooms in which there is no general ventilation system, where 
    the system is incapable of providing adequate airflow, or where 
    increased effectiveness in room airflow is desired. Effectiveness 
    depends on circulating as much of the air in the room as possible 
    through the HEPA filter, which may be difficult to achieve and 
    evaluate. The effectiveness of a particular unit can vary depending on 
    the room's configuration, the furniture and persons in the room, and 
    placement of the HEPA filtration unit and the supply and exhaust 
    grilles. Therefore, the effectiveness of the portable unit may vary 
    considerably in rooms with different configurations or in the same room 
    if moved from one location to another in the room. If portable units 
    are used, caution should be exercised to ensure they can recirculate 
    all or nearly all of the room air through the HEPA filter. Some 
    commercially available units may not be able to meet this requirement 
    because of design limitations or insufficient airflow capacity. In 
    addition, units should be designed and operated to ensure that persons 
    in the room cannot interfere with or otherwise compromise the 
    functioning of the unit. Portable HEPA filtration units have not been 
    evaluated adequately to determine their role in TB infection-control 
    programs.
        Portable HEPA filtration units should be designed to achieve the 
    equivalent of 12 ACH. They should also be designed to ensure 
    adequate air mixing in all areas of the hospital rooms in which they 
    are used, and they should not interfere with the current ventilation 
    system.
        Some HEPA filtration units employ UVGI for disinfecting air after 
    HEPA filtration. However, whether exposing the HEPA-filtered air to UV 
    irradiation further decreases the concentration of contaminants is not 
    known.
        c. Evaluation of room-air recirculation systems and units.
        Detailed and accurate evaluations of room-air recirculation systems 
    and units require the use of sophisticated test equipment and lengthy 
    test procedures that are not practical. However, an estimate of the 
    unit's ability to circulate the air in the room can be made by 
    visualizing airflow patterns as was described previously for estimating 
    room air mixing (Suppl. 3, Section II.B.1). If the air movement is good 
    in all areas of the room, the unit should be effective.
    4. Installing, Maintaining, and Monitoring HEPA Filters
        Proper installation and testing and meticulous maintenance are 
    critical if a HEPA filtration system is used (104), especially if the 
    system used recirculates air to other parts of the facility. Improper 
    design, installation, or maintenance could allow infectious particles 
    to circumvent filtration and escape into the general ventilation system 
    (47). HEPA filters should be installed to prevent leakage between 
    filter segments and between the filter bed and its frame. A regularly 
    scheduled maintenance program is required to monitor the HEPA filter 
    for possible leakage and for filter loading. A quantitative leakage and 
    filter performance test (e.g., the dioctal phthalate [DOP] penetration 
    test [105]) should be performed at the initial installation and every 
    time the filter is changed or moved. The test should be repeated every 
    6 months for filters in general-use areas and in areas with systems 
    that exhaust air that is likely to be contaminated with M. tuberculosis 
    (e.g, TB isolation rooms).
        A manometer or other pressure-sensing device should be installed in 
    the filter system to provide an accurate and objective means of 
    determining the need for filter replacement. Pressure drop 
    characteristics of the filter are supplied by the manufacturer of the 
    filter. Installation of the filter should allow for maintenance that 
    will not contaminate the delivery system or the area served. For 
    general infection-control purposes, special care should be taken to not 
    jar or drop the filter element during or after removal.
        The scheduled maintenance program should include procedures for 
    installation, removal, and disposal of filter elements. HEPA filter 
    maintenance should be performed only by adequately trained personnel. 
    Appropriate respiratory protection should be worn while performing 
    maintenance and testing procedures. In addition, filter housing and 
    ducts leading to the housing should be labelled clearly with the words 
    ``Contaminated Air'' (or a similar warning).
        When a HEPA filter is used, one or more lower efficiency disposable 
    prefilters installed upstream will extend the useful life of the HEPA 
    filter. A disposable filter can increase the life of a HEPA filter by 
    25%. If the disposable filter is followed by a 90% extended surface 
    filter, the life of the HEPA filter can be extended almost 900% (98). 
    These prefilters should be handled and disposed of in the same manner 
    as the HEPA filter.
    D. TB Isolation Rooms and Treatment Rooms
        Purpose: To separate patients who are likely to have infectious TB 
    from other persons, to provide an environment that will allow reduction 
    of the concentration of droplet nuclei through various engineering 
    methods, and to prevent the escape of droplet nuclei from such rooms 
    into the corridor and other areas of the facility using directional 
    airflow.
        A hierarchy of ventilation methods used to achieve a reduction in 
    the concentration of droplet nuclei and to achieve directional airflow 
    using negative pressure has been developed (Table S3-2). The methods 
    are listed in order from the most desirable to the least desirable. The 
    method selected will depend on the configuration of the isolation room 
    and the ventilation system in the facility; the determination should be 
    made in consultation with a ventilation engineer.
    
       Table S3-2.--Hierarchy of Ventilation Methods for Tuberculosis (TB)  
                       Isolation Rooms and Treatment Rooms                  
    ------------------------------------------------------------------------
     Reducing concentration of airborne  Achieving directional airflow using
             tubercle bacilli*                negative pressure     
    ------------------------------------------------------------------------
    1. Facility heating, ventilation,    1. Facility HVAC system.           
     and air-conditioning (HVAC) system.                                    
    2. Fixed room-air high-efficiency    2. Bleed airSec.  from fixed room- 
     particulate air (HEPA)               air HEPA recirculation system.    
     recirculation system.                                                  
    3. Wall- or ceiling-mounted room-    3. Bleed air from wall- or ceiling-
     air HEPA recirculation system.       mounted room-air HEPA             
                                          recirculation system.             
    4. Portable room-air HEPA            4. Bleed air from portable room-air
     recirculation unit.                 HEPA recirculation unit.         
                                         5. Exhaust air from room through   
                                          window-mounted fan.**             
    ------------------------------------------------------------------------
    *Ventilation methods are used to reduce the concentration of airborne   
      tubercle bacilli. If the facility HVAC system cannot achieve the      
      recommended ventilation rate, auxiliary room-air recirculation methods
      may be used. These methods are listed in order from the most desirable
      to the least desirable. Ultraviolet germicidal irradiation may be used
      as a supplement to any of the ventilation methods for air cleaning.   
    Directional airflow using negative pressure can be achieved with
      the facility HVAC system and/or the auxiliary air-recirculation-      
      cleaning systems. These methods are listed in order from the most     
      desirable to the least desirable.                                     
    Sec. To remove the amount of return air necessary to achieve negative   
      pressure.                                                             
    The effectiveness of portable room-air HEPA recirculation units can    
      vary depending on the room's configuration, the furniture and persons 
      in the room, the placement of the unit, the supply and exhaust        
      grilles, and the achievable ventilation rates and air mixing. Units   
      should be designed and operated to ensure that persons in the room    
      cannot interfere with or otherwise compromise the function of the     
      unit. Fixed recirculating systems are preferred over portable units in
      TB isolation rooms of facilities in which services are provided       
      regularly to TB patients.                                             
    **This method simply achieves negative pressure and should be used only 
      as a temporary measure.                                               
    
    1. Preventing the Escape of Droplet Nuclei From the Room
        Rooms used for TB isolation should be single-patient rooms with 
    negative pressure relative to the corridor or other areas connected to 
    the room. Doors between the isolation room and other areas should 
    remain closed except for entry into or exit from the room. The room's 
    openings (e.g., windows and electrical and plumbing entries) should be 
    sealed as much as possible. However, a small gap of \1/8\ to \1/2\ inch 
    should be at the bottom of the door to provide a controlled airflow 
    path. Proper use of negative pressure will prevent contaminated air 
    from escaping the room.
    2. Reducing the Concentration of Droplet Nuclei in the Room
        ASHRAE (47), AIA (48), and the Health Resources and Services 
    Administration (49) recommend a minimum of 6 ACH for TB isolation rooms 
    and treatment rooms. This ventilation rate is based on comfort- and 
    odor-control considerations. The effectiveness of this level of airflow 
    in reducing the concentration of droplet nuclei in the room, thus 
    reducing the transmission of airborne pathogens, has not been evaluated 
    directly or adequately.
        Ventilation rates >6 ACH are likely to produce an incrementally 
    greater reduction in the concentration of bacteria in a room than are 
    lower rates (50-52). However, accurate quantitation of decreases in 
    risk that would result from specific increases in general ventilation 
    levels has not been performed and may not be possible.
        To reduce the concentration of droplet nuclei, TB isolation rooms 
    and treatment rooms in existing health-care facilities should have an 
    airflow of 6 ACH. Where feasible, this airflow rate should 
    be increased to 12 ACH by adjusting or modifying the 
    ventilation system or by using auxiliary means (e.g., recirculation of 
    air through fixed HEPA filtration units or portable air cleaners) 
    (Suppl. 3, Section II.C) (53). New construction or renovation of 
    existing health-care facilities should be designed so that TB isolation 
    rooms achieve an airflow of 12 ACH.
    3. Exhaust From TB Isolation Rooms and Treatment Rooms
        Air from TB isolation rooms and treatment rooms in which patients 
    with infectious TB may be examined should be exhausted directly to the 
    outside of the building and away from air-intake vents, persons, and 
    animals in accordance with federal, state, and local regulations 
    concerning environmental discharges. (See Suppl. 3, Section II.C, for 
    information regarding recirculation of exhaust air.) Exhaust ducts 
    should not be located near areas that may be populated (e.g., near 
    sidewalks or windows that could be opened). Ventilation system exhaust 
    discharges and inlets should be designed to prevent reentry of 
    exhausted air. Wind blowing over a building creates a highly turbulent 
    recirculation zone, which can cause exhausted air to reenter the 
    building (Figure S3-7). Exhaust flow should be discharged above this 
    zone (Suppl. 3, Section II.C.1). Design guidelines for proper placement 
    of exhaust ducts can be found in the 1989 ASHRAE Fundamentals Handbook 
    (106). If recirculation of air from such rooms into the general 
    ventilation system is unavoidable, the air should be passed through a 
    HEPA filter before recirculation (Suppl. 3, Section II.C.2).
    
    TN28OC94.009
    
    4. Alternatives to TB Isolation Rooms
        Isolation can also be achieved by use of negative-pressure 
    enclosures (e.g, tents or booths) (Suppl. 3, Section II.A.1). These can 
    be used to provide patient isolation in areas such as emergency rooms 
    and medical testing and treatment areas and to supplement isolation in 
    designated isolation rooms.
    
    III. UVGI
    
        Purpose: To kill or inactivate airborne tubercle bacilli.
        Research has demonstrated that UVGI is effective in killing or 
    inactivating tubercle bacilli under experimental conditions (66,107-
    110) and in reducing transmission of other infections in hospitals 
    (111), military housing (112), and classrooms (113-115). Because of the 
    results of numerous studies (116-120) and the experiences of TB 
    clinicians and mycobacteriologists during the past several decades, the 
    use of UVGI has been recommended as a supplement to other TB infection-
    control measures in settings where the need for killing or inactivating 
    tubercle bacilli is important (2,4,121-125).
        UV radiation is defined as that portion of the electromagnetic 
    spectrum described by wavelengths from 100 to 400 nm. For convenience 
    of classification, the UV spectrum has been separated into three 
    different wavelength bands: UV-A (long wavelengths, range: 320-400 nm), 
    UV-B (midrange wavelengths, range: 290-320 nm), and UV-C (short 
    wavelengths, range: 100-290 nm) (126). Commercially available UV lamps 
    used for germicidal purposes are low-pressure mercury vapor lamps (127) 
    that emit radiant energy in the UV-C range, predominantly at a 
    wavelength of 253.7 nm (128).
    A. Applications
        UVGI can be used as a method of air disinfection to supplement 
    other engineering controls. Two systems of UVGI can be used for this 
    purpose: duct irradiation and upper-room air irradiation.
    1. Duct Irradiation
        Purpose: To inactivate tubercle bacilli without exposing persons to 
    UVGI.
        In duct irradiation systems, UV lamps are placed inside ducts that 
    remove air from rooms to disinfect the air before it is recirculated. 
    When UVGI duct systems are properly designed, installed, and 
    maintained, high levels of UV radiation may be produced in the duct 
    work. The only potential for human exposure to this radiation occurs 
    during maintenance operations.
        Duct irradiation may be used:
         In a TB isolation room or treatment room to recirculate 
    air from the room, through a duct containing UV lamps, and back into 
    the room. This recirculation method can increase the overall room 
    airflow but does not increase the supply of fresh outside air to the 
    room.
         In other patients' rooms and in waiting rooms, emergency 
    rooms, and other general-use areas of a facility where patients with 
    undiagnosed TB could potentially contaminate the air, to recirculate 
    air back into the general ventilation. Duct-irradiation systems are 
    dependent on airflow patterns within a room that ensure that all or 
    nearly all of the room air circulates through the duct.
    2. Upper-Room Air Irradiation
        Purpose: To inactivate tubercle bacilli in the upper part of the 
    room, while minimizing radiation exposure to persons in the lower part 
    of the room.
        In upper-room air irradiation, UVGI lamps are suspended from the 
    ceiling or mounted on the wall. The bottom of the lamp is shielded to 
    direct the radiation upward but not downward. The system depends on air 
    mixing to take irradiated air from the upper to the lower part of the 
    room, and nonirradiated air from the lower to the upper part. The 
    irradiated air space is much larger than that in a duct system.
        UVGI has been effective in killing bacteria under conditions where 
    air mixing was accomplished mainly by convection. For example, BCG was 
    atomized in a room that did not have supplemental ventilation (120), 
    and in another study a surrogate bacteria, Serratia marcesens, was 
    aerosolized in a room with a ventilation rate of 6 ACH (129). These 
    reports estimated the effect of UVGI to be equivalent to 10 and 39 ACH, 
    respectively, for the organisms tested, which are less resistant to 
    UVGI than M. tuberculosis (120). The addition of fans or some heating/
    air conditioning arrangements may double the effectiveness of UVGI 
    lamps (130-132). Greater rates of ventilation, however, may decrease 
    the length of time the air is irradiated, thus decreasing the killing 
    of bacteria (117,129). The optimal relationship between ventilation and 
    UVGI is not known. Air irradiation lamps used in corridors have been 
    effective in killing atomized S. marcesens (133). Use of UVGI lamps in 
    an outpatient room has reduced culturable airborne bacteria by 14%-19%. 
    However, the irradiation did not reduce the concentration of gram-
    positive, rod-shaped bacteria; although fast-growing mycobacteria were 
    cultured, M. tuberculosis could not be recovered from the room's air 
    samples because of fungal overgrowth of media plates (134).
        Upper-room air UVGI irradiation may be used:
         In isolation or treatment rooms as a supplemental method 
    of air cleaning.
         In other patients' rooms and in waiting rooms, emergency 
    rooms, corridors, and other central areas of a facility where patients 
    with undiagnosed TB could potentially contaminate the air. Determinants 
    of UVGI effectiveness include room configuration, UV lamp placement, 
    and the adequacy of airflow patterns in bringing contaminated air into 
    contact with the irradiated upper-room space. Air mixing may be 
    facilitated by supplying cool air near the ceiling in rooms where 
    warmer air (or a heating device) is present below. The ceiling should 
    be high enough for a large volume of upper-room air to be irradiated 
    without HCWs and patients being overexposed to UV radiation.
    B. Limitations
        Because the clinical effectiveness of UV systems varies, and 
    because of the risk for transmission of M. tuberculosis if a system 
    malfunctions or is maintained improperly, UVGI is not recommended for 
    the following specific applications:
        1. Duct systems using UVGI are not recommended as a substitute for 
    HEPA filters if air from isolation rooms must be recirculated to other 
    areas of a facility.
        2. UVGI alone is not recommended as a substitute for HEPA 
    filtration or local exhaust of air to the outside from booths, tents, 
    or hoods used for cough-inducing procedures.
        3. UVGI is not a substitute for negative pressure.
        The use of UV lamps and HEPA filtration in a single unit would not 
    be expected to have any infection-control benefits not provided by use 
    of the HEPA filter alone.
        The effectiveness of UVGI in killing airborne tubercle bacilli 
    depends on the intensity of UVGI, the duration of contact the organism 
    has with the irradiation, and the relative humidity (66,108,111). 
    Humidity can have an adverse effect on UVGI effectiveness at levels 
    >70% relative humidity for S. marcescens (135). The interaction of 
    these factors has not been fully defined, however, making precise 
    recommendations for individual UVGI installations difficult to develop.
        Old lamps or dust-covered UV lamps are less effective; therefore, 
    regular maintenance of UVGI systems is crucial.
    C. Safety Issues
        Short-term overexposure to UV radiation can cause erythema and 
    keratoconjunctivitis (136,137). Broad-spectrum UV radiation has been 
    associated with increased risk for squamous and basal cell carcinomas 
    of the skin (138). UV-C was recently classified by the International 
    Agency for Research on Cancer as ``probably carcinogenic to humans 
    (Group 2A)'' (138). This classification is based on studies suggesting 
    that UV-C radiation can induce skin cancers in animals; DNA damage, 
    chromosomal aberrations and sister chromatid exchange and 
    transformation in human cells in vitro; and DNA damage in mammalian 
    skin cells in vivo. In the animal studies, a contribution of UV-B to 
    the tumor effects could not be excluded, but the effects were greater 
    than expected for UV-B alone (138). Although some recent studies have 
    demonstrated that UV radiation can activate HIV gene promoters (i.e., 
    the genes in HIV that prompt replication of the virus) in laboratory 
    samples of human cells (139-144), the implications of these in vitro 
    findings for humans are unknown.
        In 1972, the National Institute for Occupational Safety and Health 
    (NIOSH) published a recommended exposure limit (REL) for occupational 
    exposure to UV radiation (136). The REL is intended to protect workers 
    from the acute effects of UV exposure (e.g., erythema and 
    photokeratoconjunctivitis). However, photosensitive persons and those 
    exposed concomitantly to photoactive chemicals may not be protected by 
    the recommended standard. If proper procedures are not followed, HCWs 
    performing maintenance on such fixtures are at risk for exposure to UV 
    radiation. Because UV fixtures used for upper-room air irradiation are 
    present in rooms, rather than hidden in ducts, safety may be much more 
    difficult to achieve and maintain. Fixtures must be designed and 
    installed to ensure that UV exposure to persons in the room (including 
    HCWs and inpatients) are below current safe exposure levels. Recent 
    health hazard evaluations conducted by CDC have noted problems with 
    overexposure of HCWs to UVGI and with inadequate maintenance, training, 
    labelling, and use of personal protective equipment (145-147).
        The current number of persons who are properly trained in UVGI 
    system design and installation is limited. CDC strongly recommends that 
    a competent UVGI system designer be consulted to address safety 
    considerations before such a system is procured and installed. Experts 
    who might be consulted include industrial hygienists, engineers, and 
    health physicists. Principles for the safe installation of UV lamp 
    fixtures have been developed and can be used as guidelines (148,149).
        If UV lamps are being used in a facility, the general TB education 
    of HCWs should include:
        1. The basic principles of UVGI systems (i.e., how they work and 
    what their limitations are).
        2. The potential hazardous effects of UVGI if overexposure occurs.
        3. The potential for photosensitivity associated with certain 
    medical conditions or use of some medications.
        4. The importance of general maintenance procedures for UVGI 
    fixtures.
        Exposure to UV intensities above the REL should be avoided. 
    Lightweight clothing made of tightly woven fabric and UV-absorbing 
    sunscreens with solar-protection factors (SPFs) 15 may help 
    protect photosensitive persons. HCWs should be advised that any eye or 
    skin irritation that develops after UV exposure should be examined by 
    occupational health staff.
    D. Exposure Criteria for UV Radiation
        The NIOSH REL for UV radiation is wavelength dependent because 
    different wavelengths of UV radiation have different adverse effects on 
    the skin and eyes (136). Relative spectral effectiveness (S) 
    is used to compare various UV sources with a source producing UV 
    radiation at 270 nm, the wavelength of maximum ocular sensitivity. For 
    example, the S at 254 nm is 0.5; therefore, twice as much 
    energy is required at 254 nm to produce an identical biologic effect at 
    270 nm (136). Thus, at 254 nm, the NIOSH REL is 0.006 joules per square 
    centimeter (J/cm\2\); and at 270 nm, it is 0.003 J/cm\2\.
        For germicidal lamps that emit radiant energy predominantly at a 
    wavelength of 254 nm, proper use of the REL requires that the measured 
    irradiance level (E) in microwatts per square centimeter (W/
    cm2) be multiplied by the relative spectral effectiveness at 254 
    nm (0.5) to obtain the effective irradiance (Eeff). The maximum 
    permissible exposure time can then be determined for selected values of 
    Eeff (Table S3-3), or it can be calculated (in seconds) by 
    dividing 0.003 J/cm2 (the NIOSH REL at 270 nm) by Eeff in 
    W/cm2 (136,150).
        To protect HCWs who are exposed to germicidal UV radiation for 8 
    hours per workday, the measured irradiance (E) should be 0.2 
    W/cm2. This is calculated by obtaining Eeff (0.1 
    W/cm2) (Table S3-3) and then dividing this value by 
    S (0.5). 
    
     Table S3-3.--Maximum Permissible Exposure Times* for Selected Values of
                              Effective Irradiance                          
    ------------------------------------------------------------------------
                                                                 Effective  
                                                                irradiance  
               Permissible exposure time per day              (Eeff)
                                                               (W/ 
                                                                   cm2)     
    ------------------------------------------------------------------------
    8 hrs...................................................            0.1 
    4 hrs...................................................            0.2 
    2 hrs...................................................            0.4 
    1 hr....................................................            0.8 
    30 min..................................................            1.7 
    15 min..................................................            3.3 
    10 min..................................................            5.0 
    5 min...................................................           10.0 
    1 min...................................................           50.0 
    30 sec..................................................         100.0  
    ------------------------------------------------------------------------
    *Permissible exposure times are designed to prevent acute effects of    
      irradiation to skin and eyes (136). These recommended limits are      
      wavelength dependent because different wavelengths of ultraviolet (UV)
      radiation have different adverse effects on these organs.             
    Relative spectral effectiveness (S) is used to compare 
      various UV sources with a source producing UV radiation at 270 nm, the
      wavelength of maximum ocular sensitivity. For example, the relative   
      spectral effectiveness at 254 nm is 0.5; therefore, twice as much     
      energy is required at 254 nm to produce an identical biologic effect  
      at 270 nm. At 254 nm, the NIOSH REL is 0.006 joules per square        
      centimeter (J/cm2); and at 270 nm, it is 0.003 J/cm2. For germicidal  
      lamps that emit radiant energy predominantly at a wavelength of 254   
      nm, proper use of the REL requires that the measured irradiance level 
      (E) in microwatts per square centimeter (W/cm2) be multiplied
      by the relative spectral effectiveness at 254 nm (0.5) to obtain Eeff.
      The maximum permissible exposure time can be calculated (in seconds)  
      by dividing 0.003 J/cm2 (the NIOSH REL at 270 nm) by Eeff in W/cm2 (136,150). To protect health-care workers who are exposed to  
      germicidal UV radiation for 8 hours per work day, the measured        
      irradiance (E) should be 0.2 W/cm2, which is      
      calculated by obtaining Eeff (0.1 W/cm2), then dividing this 
      value by S (0.5).                                            
    
    E. Maintenance and Monitoring
    1. Labelling and Posting
        Warning signs should be posted on UV lamps and wherever high-
    intensity (i.e., UV exposure greater than the REL) germicidal UV 
    irradiation is present (e.g., upper-room air space and accesses to 
    ducts [if duct irradiation is used]) to alert maintenance staff or 
    other HCWs of the hazard. Some examples are shown below:
    CAUTION
    ULTRAVIOLET ENERGY: TURN OFF LAMPS BEFORE ENTERING UPPER ROOM
    CAUTION
    ULTRAVIOLET ENERGY: PROTECT EYES & SKIN
    2. Maintenance
        Because the intensity of UV lamps fluctuates as they age, a 
    schedule for replacing the lamps should be developed. The schedule can 
    be determined from either a time/use log or a system based on 
    cumulative time. The tube should be checked periodically for dust 
    build-up, which lessens the output of UVGI. If the tube is dirty, it 
    should be allowed to cool, then cleaned with a damp cloth. Tubes should 
    be replaced if they stop glowing or if they flicker to an objectionable 
    extent. Maintenance personnel must turn off all UV tubes before 
    entering the upper part of the room or before accessing ducts for any 
    purpose. Only a few seconds of direct exposure to the intense UV 
    radiation in the upper-room air space or in ducts can cause burns. 
    Protective equipment (e.g., gloves and goggles [and/or face shields]) 
    should be worn if exposure greater than the recommended standard is 
    anticipated.
        Banks of UVGI tubes can be installed in ventilating ducts. Safety 
    devices should be used on access doors to eliminate hazard to 
    maintenance personnel. For duct irradiation systems, the access door 
    for servicing the lamps should have an inspection window* through which 
    the lamps are checked periodically for dust build-up and 
    malfunctioning. The access door should have a warning sign written in 
    languages appropriate for maintenance personnel to alert them to the 
    health hazard of looking directly at bare tubes. The lock for this door 
    should have an automatic electric switch or other device that turns off 
    the lamps when the door is opened.
    ---------------------------------------------------------------------------
    
        *Ordinary glass (not quartz) is sufficient to filter out UV 
    radiation.
    ---------------------------------------------------------------------------
    
        Two types of fixtures are used in upper-room air irradiation: wall-
    mounted fixtures that have louvers to block downward radiation and 
    ceiling-mounted fixtures that have baffles to block radiation below the 
    horizontal plane of the UV tube. The actual UV tube in either type of 
    fixture must not be visible from any normal position in the room. Light 
    switches that can be locked should be used, if possible, to prevent 
    injury to personnel who might unintentionally turn the lamps on during 
    maintenance procedures. In most applications, properly shielding the UV 
    lamps to provide protection from most, if not all, of the direct UV 
    radiation is not difficult. However, radiation reflected from glass, 
    polished metal, and high-gloss ceramic paints can be harmful to persons 
    in the room, particularly if more than one UV lamp is in use. Surfaces 
    in irradiated rooms that can reflect UVGI into occupied areas of the 
    room should be covered with non-UV reflecting material.
    3. Monitoring
        A regularly scheduled evaluation of the UV intensity to which HCWs, 
    patients, and others are exposed should be conducted.
        UV measurements should be made in various locations within a room 
    using a detector designed to be most sensitive at 254 nm. Equipment 
    used to measure germicidal UV radiation should be maintained and 
    calibrated on a regular schedule.
        A new UV installation must be carefully checked for hot spots 
    (i.e., areas of the room where the REL is exceeded) by an industrial 
    hygienist or other person knowledgeable in making UV measurements. UV 
    radiation levels should not exceed those in the recommended guidelines.
    
    Supplement 4: Respiratory Protection
    
    I. Considerations for Selection of Respirators
        Personal respiratory protection should be used by (a) persons 
    entering rooms where patients with known or suspected infectious TB are 
    being isolated, (b) persons present during cough-inducing or aerosol-
    generating procedures performed on such patients, and (c) persons in 
    other settings where administrative and engineering controls are not 
    likely to protect them from inhaling infectious airborne droplet 
    nuclei. These other settings should be identified on the basis of the 
    facility's risk assessment.
        Although data regarding the effectiveness of respiratory protection 
    from many hazardous airborne materials have been collected, the precise 
    level of effectiveness in protecting HCWs from M. tuberculosis 
    transmission in health-care settings has not been determined. 
    Information concerning the transmission of M. tuberculosis is 
    incomplete. Neither the smallest infectious dose of M. tuberculosis nor 
    the highest level of exposure to M. tuberculosis at which transmission 
    will not occur has been defined conclusively (59,151,152). Furthermore, 
    the size distribution of droplet nuclei and the number of particles 
    containing viable M. tuberculosis that are expelled by infectious TB 
    patients have not been defined adequately, and accurate methods of 
    measuring the concentration of infectious droplet nuclei in a room have 
    not been developed.
        Nevertheless, in certain settings the administrative and 
    engineering controls may not adequately protect HCWs from airborne 
    droplet nuclei (e.g., in TB isolation rooms, treatment rooms in which 
    cough-inducing or aerosol-generating procedures are performed, and 
    ambulances during the transport of infectious TB patients). Respiratory 
    protective devices used in these settings should have characteristics 
    that are suitable for the organism they are protecting against and the 
    settings in which they are used.
    A. Performance Criteria for Personal Respirators for Protection Against 
    Transmission of M. tuberculosis
        Respiratory protective devices used in health-care settings for 
    protection against M. tuberculosis should meet the following standard 
    criteria. These criteria are based on currently available information, 
    including (a) data on the effectiveness of respiratory protection 
    against noninfectious hazardous materials in workplaces other than 
    health-care settings and on an interpretation of how these data can be 
    applied to respiratory protection against M. tuberculosis; (b) data on 
    the efficiency of respirator filters in filtering biological aerosols; 
    (c) data on face-seal leakage; and (d) data on the characteristics of 
    respirators that were used in conjunction with administrative and 
    engineering controls in outbreak settings where transmission to HCWs 
    and patients was terminated.
        1. The ability to filter particles 1 um in size in the unloaded 
    state with a filter efficiency of 95% (i.e., filter leakage 
    of 5%), given flow rates of up to 50 L per minute.
        Available data suggest that infectious droplet nuclei range in size 
    from 1 m to 5 m; therefore, respirators used in 
    health-care settings should be able to efficiently filter the smallest 
    particles in this range. Fifty liters per minute is a reasonable 
    estimate of the highest airflow rate an HCW is likely to achieve during 
    breathing, even while performing strenuous work activities.
        2. The ability to be qualitatively or quantitatively fit tested in 
    a reliable way to obtain a face-seal leakage of 10% (54,55).
        3. The ability to fit the different facial sizes and 
    characteristics of HCWs, which can usually be met by making the 
    respirators available in at least three sizes.
        4. The ability to be checked for facepiece fit, in accordance with 
    OSHA standards and good industrial hygiene practice, by HCWs each time 
    they put on their respirators (54,55).
        In some settings, HCWs may be at risk for two types of exposure: 
    (a) inhalation of M. tuberculosis and (b) mucous membrane exposure to 
    fluids that may contain bloodborne pathogens. In these settings, 
    protection against both types of exposure should be used.
        When operative procedures (or other procedures requiring a sterile 
    field) are performed on patients who may have infectious TB, 
    respiratory protection worn by the HCW should serve two functions: (a) 
    it should protect the surgical field from the respiratory secretions of 
    the HCW and (b) it should protect the HCW from infectious droplet 
    nuclei that may be expelled by the patient or generated by the 
    procedure. Respirators with expiration valves and positive-pressure 
    respirators do not protect the sterile field; therefore, a respirator 
    that does not have a valve and that meets the criteria in Supplement 4, 
    Section I.A, should be used.
    B. Specific Respirators
        The OSHA respiratory protection standard requires that all 
    respiratory protective devices used in the workplace be certified by 
    NIOSH.* NIOSH-approved HEPA respirators are the only currently 
    available air-purifying respirators that meet or exceed the standard 
    performance criteria stated above. However, the NIOSH certification 
    procedures are currently being revised (153). Under the proposed 
    revision, filter materials would be tested at a flow rate of 85 L/min 
    for penetration by particles with a median aerodynamic diameter of 0.3 
    m and, if certified, would be placed in one of the following 
    categories: type A, which has 99.97% efficiency (similar to 
    current HEPA filter media); type B, 99% efficiency; or type 
    C, 95% efficiency. According to this proposed scheme, type C 
    filter material would meet or exceed the standard performance criteria 
    specified in this document.
    ---------------------------------------------------------------------------
    
        *29 CFR 1910.134.
    ---------------------------------------------------------------------------
    
        The facility's risk assessment may identify a limited number of 
    selected settings (e.g., bronchoscopy performed on patients suspected 
    of having TB or autopsy performed on deceased persons suspected of 
    having had active TB at the time of death) where the estimated risk for 
    transmission of M. tuberculosis may be such that a level of respiratory 
    protection exceeding the standard criteria is appropriate. In such 
    circumstances, a level of respiratory protection exceeding the standard 
    criteria and compatible with patient-care delivery (e.g., negative-
    pressure respirators that are more protective; powered air-purifying 
    particulate respirators [PAPRs]; or positive-pressure airline, half-
    mask respirators) should be provided by employers to HCWs who are 
    exposed to M. tuberculosis. Information on these and other respirators 
    may be found in the NIOSH Guide to Industrial Respiratory Protection 
    (55).
    C. The Effectiveness of Respiratory Protective Devices
        The following information, which is based on experience with 
    respiratory protection in the industrial setting, summarizes the 
    available data about the effectiveness of respiratory protection 
    against hazardous airborne materials. Data regarding protection against 
    transmission of M. tuberculosis are not available.
        The parameters used to determine the effectiveness of a respiratory 
    protective device are face-seal efficacy and filter efficacy.
    1. Face-Seal Leakage
        Face-seal leakage compromises the ability of particulate 
    respirators to protect HCWs from airborne materials (154-156). A proper 
    seal between the respirator's sealing surface and the face of the 
    person wearing the respirator is essential for effective and reliable 
    performance of any negative-pressure respirator. This seal is less 
    critical, but still important, for positive-pressure respirators. Face-
    seal leakage can result from various factors, including incorrect 
    facepiece size or shape, incorrect or defective facepiece sealing-lip, 
    beard growth, perspiration or facial oils that can cause facepiece 
    slippage, failure to use all the head straps, incorrect positioning of 
    the facepiece on the face, incorrect head strap tension or position, 
    improper respirator maintenance, and respirator damage.
        Every time a person wearing a negative-pressure particulate 
    respirator inhales, a negative pressure (relative to the workplace air) 
    is created inside the facepiece. Because of this negative pressure, air 
    containing contaminants can take a path of least resistance into the 
    respirator--through leaks at the face-seal interface--thus avoiding the 
    higher-resistance filter material. Currently available, cup-shaped, 
    disposable particulate respirators have from 0 to 20% face-seal leakage 
    (55,154). This face-seal leakage results from the variability of the 
    human face and from limitations in the respirator's design, 
    construction, and number of sizes available. The face-seal leakage is 
    probably higher if the respirator is not fitted properly to the HCW's 
    face, tested for an adequate fit by a qualified person, and then 
    checked for fit by the HCW every time the respirator is put on. Face-
    seal leakage may be reduced to less than <10% with="" improvements="" in="" design,="" a="" greater="" variety="" in="" available="" sizes,="" and="" appropriate="" fit="" testing="" and="" fit="" checking.="" in="" comparison="" with="" negative-pressure="" respirators,="" positive-pressure="" respirators="" produce="" a="" positive="" pressure="" inside="" the="" facepiece="" under="" most="" conditions="" of="" use.="" for="" example,="" in="" a="" papr,="" a="" blower="" forcibly="" draws="" ambient="" air="" through="" hepa="" filters,="" then="" delivers="" the="" filtered="" air="" to="" the="" facepiece.="" this="" air="" is="" blown="" into="" the="" facepiece="" at="" flow="" rates="" that="" generally="" exceed="" the="" expected="" inhalation="" flow="" rates.="" the="" positive="" pressure="" inside="" the="" facepiece="" reduces="" face-seal="" leakage="" to="" low="" levels,="" particularly="" during="" the="" relatively="" low="" inhalation="" rates="" expected="" in="" health-care="" settings.="" paprs="" with="" a="" tight-fitting="" facepiece="" have=""><2% face-seal="" leakage="" under="" routine="" conditions="" (55).="" powered-air="" respirators="" with="" loose-fitting="" facepieces,="" hoods,="" or="" helmets="" have=""><4% face-seal="" leakage="" under="" routine="" conditions="" (55).="" thus,="" a="" papr="" may="" offer="" lower="" levels="" of="" face-seal="" leakage="" than="" nonpowered,="" half-mask="" respirators.="" full="" facepiece,="" nonpowered="" respirators="" have="" the="" same="" leakage="" (i.e.,=""><2%) as="" paprs.="" another="" factor="" contributing="" to="" face-seal="" leakage="" of="" cup-shaped,="" disposable="" respirators="" is="" that="" some="" of="" these="" respirators="" are="" available="" in="" only="" one="" size.="" a="" single="" size="" may="" produce="" higher="" leakage="" for="" persons="" who="" have="" smaller="" or="" difficult-to-fit="" faces="" (157).="" the="" facepieces="" used="" for="" some="" reusable="" (including="" hepa="" and="" replaceable="" filter,="" negative-="" pressure)="" and="" all="" positive-pressure="" particulate="" air-purifying="" respirators="" are="" available="" in="" as="" many="" as="" three="" different="" sizes.="" 2.="" filter="" leakage="" aerosol="" leakage="" through="" respirator="" filters="" depends="" on="" at="" least="" five="" independent="" variables:="" (a)="" the="" filtration="" characteristics="" for="" each="" type="" of="" filter,="" (b)="" the="" size="" distribution="" of="" the="" droplets="" in="" the="" aerosol,="" (c)="" the="" linear="" velocity="" through="" the="" filtering="" material,="" (d)="" the="" filter="" loading="" (i.e.,="" the="" amount="" of="" contaminant="" deposited="" on="" the="" filter),="" and="" (e)="" any="" electrostatic="" charges="" on="" the="" filter="" and="" on="" the="" droplets="" in="" the="" aerosol="" (158).="" when="" hepa="" filters="" are="" used="" in="" particulate="" air-purifying="" respirators,="" filter="" efficiency="" is="" so="" high="" (i.e.,="" effectively="" 100%)="" that="" filter="" leakage="" is="" not="" a="" consideration.="" therefore,="" for="" all="" hepa-filter="" respirators,="" virtually="" all="" inward="" leakage="" of="" droplet="" nuclei="" occurs="" at="" the="" respirator's="" face="" seal.="" 3.="" fit="" testing="" fit="" testing="" is="" part="" of="" the="" respiratory="" protection="" program="" required="" by="" osha="" for="" all="" respiratory="" protective="" devices="" used="" in="" the="" workplace.="" a="" fit="" test="" determines="" whether="" a="" respiratory="" protective="" device="" adequately="" fits="" a="" particular="" hcw.="" the="" hcw="" may="" need="" to="" be="" fit="" tested="" with="" several="" devices="" to="" determine="" which="" device="" offers="" the="" best="" fit.="" however,="" fit="" tests="" can="" detect="" only="" the="" leakage="" that="" occurs="" at="" the="" time="" of="" the="" fit="" testing,="" and="" the="" tests="" cannot="" distinguish="" face-seal="" leakage="" from="" filter="" leakage.="" determination="" of="" facepiece="" fit="" can="" involve="" qualitative="" or="" quantitative="" tests="" (55).="" a="" qualitative="" test="" relies="" on="" the="" subjective="" response="" of="" the="" hcw="" being="" fit="" tested.="" a="" quantitative="" test="" uses="" detectors="" to="" measure="" inward="" leakage.="" disposable,="" negative-pressure="" particulate="" respirators="" can="" be="" qualitatively="" fit="" tested="" with="" aerosolized="" substances="" that="" can="" be="" tasted,="" although="" the="" results="" of="" this="" testing="" are="" limited="" because="" the="" tests="" depend="" on="" the="" subjective="" response="" of="" the="" hcw="" being="" tested.="" quantitative="" fit="" testing="" of="" disposable="" negative-pressure="" particulate="" respirators="" can="" best="" be="" performed="" if="" the="" manufacturer="" provides="" a="" test="" respirator="" with="" a="" probe="" for="" this="" purpose.="" replaceable="" filter,="" negative-pressure="" particulate="" respirators="" and="" all="" positive-pressure="" particulate="" respirators="" can="" be="" fit="" tested="" reliably,="" both="" qualitatively="" and="" quantitatively,="" when="" fitted="" with="" hepa="" filters.="" 4.="" fit="" checking="" a="" fit="" check="" is="" a="" maneuver="" that="" an="" hcw="" performs="" before="" each="" use="" of="" the="" respiratory="" protective="" device="" to="" check="" the="" fit.="" the="" fit="" check="" can="" be="" performed="" according="" to="" the="" manufacturer's="" facepiece="" fitting="" instructions="" by="" using="" the="" applicable="" negative-pressure="" or="" positive-="" pressure="" test.="" some="" currently="" available="" cup-shaped,="" disposable="" negative-pressure="" particulate="" respirators="" cannot="" be="" fit="" checked="" reliably="" by="" persons="" wearing="" the="" devices="" because="" occluding="" the="" entire="" surface="" of="" the="" filter="" is="" difficult.="" strategies="" for="" overcoming="" these="" limitations="" are="" being="" developed="" by="" respirator="" manufacturers.="" 5.="" reuse="" of="" respirators="" conscientious="" respirator="" maintenance="" should="" be="" an="" integral="" part="" of="" an="" overall="" respirator="" program.="" this="" maintenance="" applies="" both="" to="" respirators="" with="" replaceable="" filters="" and="" respirators="" that="" are="" classified="" as="" disposable="" but="" that="" are="" reused.="" manufacturers'="" instructions="" for="" inspecting,="" cleaning,="" and="" maintaining="" respirators="" should="" be="" followed="" to="" ensure="" that="" the="" respirator="" continues="" to="" function="" properly="" (55).="" when="" respirators="" are="" used="" for="" protection="" against="" noninfectious="" aerosols="" (e.g.,="" wood="" dust),="" which="" may="" be="" present="" in="" the="" air="" in="" heavy="" concentrations,="" the="" filter="" material="" may="" become="" occluded="" with="" airborne="" material.="" this="" occlusion="" may="" result="" in="" an="" uncomfortable="" breathing="" resistance.="" in="" health-care="" settings="" where="" respirators="" are="" used="" for="" protection="" against="" biological="" aerosols,="" the="" concentration="" of="" infectious="" particles="" in="" the="" air="" is="" probably="" low;="" thus,="" the="" filter="" material="" in="" a="" respirator="" is="" very="" unlikely="" to="" become="" occluded="" with="" airborne="" material.="" in="" addition,="" there="" is="" no="" evidence="" that="" particles="" impacting="" on="" the="" filter="" material="" in="" a="" respirator="" are="" re-aerosolized="" easily.="" for="" these="" reasons,="" the="" filter="" material="" used="" in="" respirators="" in="" the="" health-care="" setting="" should="" remain="" functional="" for="" weeks="" to="" months.="" respirators="" with="" replaceable="" filters="" are="" reusable,="" and="" a="" respirator="" classified="" as="" disposable="" may="" be="" reused="" by="" the="" same="" hcw="" as="" long="" as="" it="" remains="" functional.="" before="" each="" use,="" the="" outside="" of="" the="" filter="" material="" should="" be="" inspected.="" if="" the="" filter="" material="" is="" physically="" damaged="" or="" soiled,="" the="" filter="" should="" be="" changed="" (in="" the="" case="" of="" respirators="" with="" replaceable="" filters)="" or="" the="" respirator="" discarded="" (in="" the="" case="" of="" disposable="" respirators).="" infection-control="" personnel="" should="" develop="" standard="" operating="" procedures="" for="" storing,="" reusing,="" and="" disposing="" of="" respirators="" that="" have="" been="" designated="" as="" disposable="" and="" for="" disposing="" of="" replaceable="" filter="" elements.="" ii.="" implementing="" a="" personal="" respiratory="" protection="" program="" if="" personal="" respiratory="" protection="" is="" used="" in="" a="" health-care="" setting,="" osha="" requires="" that="" an="" effective="" personal="" respiratory="" protection="" program="" be="" developed,="" implemented,="" administered,="" and="" periodically="" reevaluated="" (54,55).="" all="" hcws="" who="" need="" to="" use="" respirators="" for="" protection="" against="" infection="" with="" m.="" tuberculosis="" should="" be="" included="" in="" the="" respiratory="" protection="" program.="" visitors="" to="" tb="" patients="" should="" be="" given="" respirators="" to="" wear="" while="" in="" isolation="" rooms,="" and="" they="" should="" be="" given="" general="" instructions="" on="" how="" to="" use="" their="" respirators.="" the="" number="" of="" hcws="" included="" in="" the="" respiratory="" protection="" program="" in="" each="" facility="" will="" vary="" depending="" on="" (a)="" the="" number="" of="" potentially="" infectious="" tb="" patients,="" (b)="" the="" number="" of="" rooms="" or="" areas="" to="" which="" patients="" with="" suspected="" or="" confirmed="" infectious="" tb="" are="" admitted,="" and="" (c)="" the="" number="" of="" hcws="" needed="" in="" these="" rooms="" or="" areas.="" where="" respiratory="" protection="" programs="" are="" required,="" they="" should="" include="" enough="" hcws="" to="" provide="" adequate="" care="" for="" a="" patient="" with="" known="" or="" suspected="" tb="" should="" such="" a="" patient="" be="" admitted="" to="" the="" facility.="" however,="" administrative="" measures="" should="" be="" used="" to="" limit="" the="" number="" of="" hcws="" who="" need="" to="" enter="" these="" rooms="" or="" areas,="" thus="" limiting="" the="" number="" of="" hcws="" who="" need="" to="" be="" included="" in="" the="" respiratory="" protection="" program.="" information="" regarding="" the="" development="" and="" management="" of="" a="" respiratory="" protection="" program="" is="" available="" in="" technical="" training="" courses="" that="" cover="" the="" basics="" of="" personal="" respiratory="" protection.="" such="" courses="" are="" offered="" by="" various="" organizations,="" such="" as="" niosh,="" osha,="" and="" the="" american="" industrial="" hygiene="" association.="" similar="" courses="" are="" available="" from="" private="" contractors="" and="" universities.="" to="" be="" effective="" and="" reliable,="" respiratory="" protection="" programs="" must="" contain="" at="" least="" the="" following="" elements="" (55,154):="" 1.="" assignment="" of="" responsibility.="" supervisory="" responsibility="" for="" the="" respiratory="" protection="" program="" should="" be="" assigned="" to="" designated="" persons="" who="" have="" expertise="" in="" issues="" relevant="" to="" the="" program,="" including="" infectious="" diseases="" and="" occupational="" health.="" 2.="" standard="" operating="" procedures.="" written="" standard="" operating="" procedures="" should="" contain="" information="" concerning="" all="" aspects="" of="" the="" respiratory="" protection="" program.="" 3.="" medical="" screening.="" hcws="" should="" not="" be="" assigned="" a="" task="" requiring="" use="" of="" respirators="" unless="" they="" are="" physically="" able="" to="" perform="" the="" task="" while="" wearing="" the="" respirator.="" hcws="" should="" be="" screened="" for="" pertinent="" medical="" conditions="" at="" the="" time="" they="" are="" hired,="" then="" rescreened="" periodically="" (55).="" the="" screening="" could="" occur="" as="" infrequently="" as="" every="" 5="" years.="" the="" screening="" process="" should="" begin="" with="" a="" general="" screening="" (e.g.,="" a="" questionnaire)="" for="" pertinent="" medical="" conditions,="" and="" the="" results="" of="" the="" screening="" should="" then="" be="" used="" to="" identify="" hcws="" who="" need="" further="" evaluation.="" routine="" physical="" examination="" or="" testing="" with="" chest="" radiographs="" or="" spirometry="" is="" not="" necessary="" or="" required.="" few="" medical="" conditions="" preclude="" the="" use="" of="" most="" negative-pressure="" particulate="" respirators.="" hcws="" who="" have="" mild="" pulmonary="" or="" cardiac="" conditions="" may="" report="" discomfort="" with="" breathing="" when="" wearing="" negative-="" pressure="" particulate="" respirators,="" but="" these="" respirators="" are="" unlikely="" to="" have="" adverse="" health="" effects="" on="" the="" hcws.="" those="" hcws="" who="" have="" more="" severe="" cardiac="" or="" pulmonary="" conditions="" may="" have="" more="" difficulty="" than="" hcws="" with="" similar="" but="" milder="" conditions="" if="" performing="" duties="" while="" wearing="" negative-pressure="" respirators.="" furthermore,="" these="" hcws="" may="" be="" unable="" to="" use="" some="" paprs="" because="" of="" the="" added="" weight="" of="" these="" respirators.="" 4.="" training.="" hcws="" who="" wear="" respirators="" and="" the="" persons="" who="" supervise="" them="" should="" be="" informed="" about="" the="" necessity="" for="" wearing="" respirators="" and="" the="" potential="" risks="" associated="" with="" not="" doing="" so.="" this="" training="" should="" also="" include="" at="" a="" minimum:=""> The nature, extent, and specific hazards of M. 
    tuberculosis transmission in their respective health-care facility.
         A description of specific risks for TB infection among 
    persons exposed to M. tuberculosis, of any subsequent treatment with 
    INH or other chemoprophylactic agents, and of the possibility of active 
    TB disease.
         A description of engineering controls and work practices 
    and the reasons why they do not eliminate the need for personal 
    respiratory protection.
         An explanation for selecting a particular type of 
    respirator, how the respirator is properly maintained and stored, and 
    the operation, capabilities, and limitations of the respirator 
    provided.
         Instruction in how the HCW wearing the respirator should 
    inspect, put on, fit check, and correctly wear the provided respirator 
    (i.e., achieve and maintain proper face-seal fit on the HCW's face).
         An opportunity to handle the provided respirator and learn 
    how to put it on, wear it properly, and check the important parts.
         Instruction in how to recognize an inadequately 
    functioning respirator.
        5. Face-seal fit testing and fit checking. HCWs should undergo fit 
    testing to identify a respirator that adequately fits each individual 
    HCW. The HCW should receive fitting instructions that include 
    demonstrations and practice in how the respirator should be worn, how 
    it should be adjusted, and how to determine if it fits properly. The 
    HCW should be taught to check the facepiece fit before each use.
        6. Respirator inspection, cleaning, maintenance, and storage. 
    Conscientious respirator maintenance should be an integral part of an 
    overall respirator program. This maintenance applies both to 
    respirators with replaceable filters and respirators that are 
    classified as disposable but that are reused. Manufacturers' 
    instructions for inspecting, cleaning, and maintaining respirators 
    should be followed to ensure that the respirator continues to function 
    properly (55).
        7. Periodic evaluation of the personal respiratory protection 
    program. The program should be evaluated completely at least once a 
    year, and both the written operating procedures and program 
    administration should be revised as necessary based on the results of 
    the evaluation. Elements of the program that should be evaluated 
    include work practices and employee acceptance of respirator use (i.e., 
    subjective comments made by employees concerning comfort during use and 
    interference with duties).
    
    Supplement 5: Decontamination--Cleaning, Disinfecting, and Sterilizing 
    of Patient-Care Equipment
    
        Equipment used on patients who have TB is usually not involved in 
    the transmission of M. tuberculosis, although transmission by 
    contaminated bronchoscopes has been demonstrated (159,160). Guidelines 
    for cleaning, disinfecting, and sterilizing equipment have been 
    published (161,162). The rationale for cleaning, disinfecting, or 
    sterilizing patient-care equipment can be understood more readily if 
    medical devices, equipment, and surgical materials are divided into 
    three general categories. These categories--critical, semicritical, and 
    noncritical items--are defined by the potential risk for infection 
    associated with their use (163,164).
        Critical items are instruments that are introduced directly into 
    the bloodstream or into other normally sterile areas of the body (e.g., 
    needles, surgical instruments, cardiac catheters, and implants). These 
    items should be sterile at the time of use.
        Semicritical items are those that may come in contact with mucous 
    membranes but do not ordinarily penetrate body surfaces (e.g., 
    noninvasive flexible and rigid fiberoptic endoscopes or bronchoscopes, 
    endotracheal tubes, and anesthesia breathing circuits). Although 
    sterilization is preferred for these instruments, high-level 
    disinfection that destroys vegetative microorganisms, most fungal 
    spores, tubercle bacilli, and small nonlipid viruses may be used. 
    Meticulous physical cleaning of such items before sterilization or 
    high-level disinfection is essential.
        Noncritical items are those that either do not ordinarily touch the 
    patient or touch only the patient's intact skin (e.g., crutches, 
    bedboards, blood pressure cuffs, and various other medical 
    accessories). These items are not associated with direct transmission 
    of M. tuberculosis, and washing them with detergent is usually 
    sufficient.
        Health-care facility policies should specify whether cleaning, 
    disinfecting, or sterilizing an item is necessary to decrease the risk 
    for infection. Decisions about decontamination processes should be 
    based on the intended use of the item, not on the diagnosis of the 
    patient for whom the item was used. Selection of chemical disinfectants 
    depends on the intended use, the level of disinfection required, and 
    the structure and material of the item to be disinfected.
        Although microorganisms are ordinarily found on walls, floors, and 
    other environmental surfaces, these surfaces are rarely associated with 
    transmission of infections to patients or HCWs. This is particularly 
    true with organisms such as M. tuberculosis, which generally require 
    inhalation by the host for infection to occur. Therefore, extraordinary 
    attempts to disinfect or sterilize environmental surfaces are not 
    indicated. If a detergent germicide is used for routine cleaning, a 
    hospital-grade, EPA-approved germicide/disinfectant that is not 
    tuberculocidal can be used. The same routine daily cleaning procedures 
    used in other rooms in the facility should be used to clean TB 
    isolation rooms, and personnel should follow isolation practices while 
    cleaning these rooms. For final cleaning of the isolation room after a 
    patient has been discharged, personal protective equipment is not 
    necessary if the room has been ventilated for the appropriate amount of 
    time (Table S3-1).
    
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    Glossary
    
        This glossary contains many of the terms used in the guidelines, as 
    well as others that are encountered frequently by persons who implement 
    TB infection-control programs. The definitions given are not dictionary 
    definitions but are those most applicable to usage relating to TB.
        Acid-fast bacilli (AFB): Bacteria that retain certain dyes after 
    being washed in an acid solution. Most acid-fast organisms are 
    mycobacteria. When AFB are seen on a stained smear of sputum or other 
    clinical specimen, a diagnosis of TB should be suspected; however, the 
    diagnosis of TB is not confirmed until a culture is grown and 
    identified as M. tuberculosis.
        Adherence: Refers to the behavior of patients when they follow all 
    aspects of the treatment regimen as prescribed by the medical provider, 
    and also refers to the behavior of HCWs and employers when they follow 
    all guidelines pertaining to infection control.
        Aerosol: The droplet nuclei that are expelled by an infectious 
    person (e.g., by coughing or sneezing); these droplet nuclei can remain 
    suspended in the air and can transmit M. tuberculosis to other persons.
        AIA: The American Institute of Architects, a professional body that 
    develops standards for building ventilation.
        Air changes: The ratio of the volume of air flowing through a space 
    in a certain period of time (i.e., the airflow rate) to the volume of 
    that space (i.e., the room volume); this ratio is usually expressed as 
    the number of air changes per hour (ACH).
        Air mixing: The degree to which air supplied to a room mixes with 
    the air already in the room, usually expressed as a mixing factor. This 
    factor varies from 1 (for perfect mixing) to 10 (for poor mixing), and 
    it is used as a multiplier to determine the actual airflow required 
    (i.e., the recommended ACH multiplied by the mixing factor equals the 
    actual ACH required).
        Alveoli: The small air sacs in the lungs that lie at the end of the 
    bronchial tree; the site where carbon dioxide in the blood is replaced 
    by oxygen from the lungs and where TB infection usually begins.
        Anergy; The inability of a person to react to skin-test antigens 
    (even if the person is infected with the organisms tested) because of 
    immunosuppression.
        Anteroom: A small room leading from a corridor into an isolation 
    room; this room can act as an airlock, preventing the escape of 
    contaminants from the isolation room into the corridor.
        Area: A structural unit (e.g., a hospital ward or laboratory) or 
    functional unit (e.g., an internal medicine service) in which HCWs 
    provide services to and share air with a specific patient population or 
    work with clinical specimens that may contain viable M tuberculosis 
    organisms. The risk for exposure to M tuberculosis in a given area 
    depends on the prevalence of TB in the population served and the 
    characteristics of the environment.
        ASHRAE: The American Society of Heating, Refrigerating and Air-
    Conditioning Engineers, Inc., a professional body that develops 
    standards for building ventilation.
        Asymptomatic: Without symptoms, or producing no symptoms.
        Bacillus of Calmette and Guerin (BCG) vaccine: A TB vaccine used in 
    many parts of the world.
        BACTEC: One of the most often used radiometric methods 
    for detecting the early growth of mycobacteria in culture. It provides 
    rapid growth (in 7-14 days) and rapid drug-susceptibility testing (in 
    5-6 days). When BACTEC is used with rapid species 
    identification methods, M. tuberculosis can be identified within 10-14 
    days of specimen collection.
        Booster phenomenon: A phenomenon in which some persons (especially 
    older adults) who are skin tested many years after infection with M. 
    tuberculosis have a negative reaction to an initial skin test, followed 
    by a positive reaction to a subsequent skin test. The second (i.e., 
    positive) reaction is caused by a boosted immune response. Two-step 
    testing is used to distinguish new infections from boosted reactions 
    (see Two-step testing).
        Bronchoscopy: A procedure for examining the respiratory tract that 
    requires inserting an instrument (a bronchoscope) through the mouth or 
    nose and into the trachea. The procedure can be used to obtain 
    diagnostic specimens.
        Capreomycin: An injectable, second-line anti-TB drug used primarily 
    for the treatment of drug-resistant TB.
        Cavity: A hole in the lung resulting from the destruction of 
    pulmonary tissue by TB or other pulmonary infections or conditions. TB 
    patients who have cavities in their lungs are referred to as having 
    cavitary disease, and they are often more infectious than TB patients 
    without cavitary disease.
        Chemotherapy: Treatment of an infection or disease by means of oral 
    or injectable drugs.
        Cluster: Two or more PPD skin-test conversions occurring within a 
    3-month period among HCWs in a specific area or occupational group, and 
    epidemiologic evidence suggests occupational (nosocomial) transmission.
        Contact: A person who has shared the same air with a person who has 
    infectious TB for a sufficient amount of time to allow possible 
    transmission of M. tuberculosis.
        Conversion, PPD: See PPD test conversion.
        Culture: The process of growing bacteria in the laboratory so that 
    organisms can be identified.
        Cycloserine: A second-line, oral anti-TB drug used primarily for 
    treating drug-resistant TB.
        Directly observed therapy (DOT): An adherence-enhancing strategy in 
    which an HCW or other designated person watches the patient swallow 
    each does of medication.
        DNA probe: A technique that allows rapid and precise identification 
    of mycobacteria (e.g., M. tuberculosis and M. bovis) that are grown in 
    culture. The identification can often be completed in 2 hours.
        Droplet nuclei: Microscopic particles (i.e., 1-5 m in 
    diameter) produced when a person coughs, sneezes, shouts, or sings. The 
    droplets produced by an infectious TB patient can carry tubercle 
    bacilli and can remain suspended in the air for prolonged periods of 
    time and be carried on normal air currents in the room.
        Drug resistance, acquired: A resistance to one or more anti-TB 
    drugs that develops while a patient is receiving therapy and which 
    usually results from the patient's nonadherence to therapy or the 
    prescription of an inadequate regimen by a health-care provider.
        Drug resistance, primary: A resistance to one or more anti-TB drugs 
    the exists before a patient is treated with the drug(s). Primary 
    resistance occurs in persons exposed to and infected with a drug-
    resistant strain of M. tuberculosis.
        Drug-susceptibility pattern: The anti-TB drugs to which the 
    tubercle bacilli cultured from a TB patient are susceptible or 
    resistant based on drug-susceptibility tests.
        Drug-susceptibility tests: Laboratory tests that determine whether 
    tubercle bacilli cultured from a patient are susceptible or resistant 
    to various anti-TB drugs.
        Ethambutol: A first-line, oral anti-TB drug sometimes used 
    concomitantly with INH, rifampin, and pyrazinamide.
        Ethionamide: A second-line, oral anti-TB drug used primarily for 
    treating drug-resistant TB.
        Exposure: The condition of being subjected to something (e.g., 
    infectious agents) that could have a harmful effect. A person exposed 
    to M. tuberculosis does not necessarily become infected (see 
    Transmission).
        First-line drugs: The most often used anti-TB drugs (i.e., INH, 
    rifampin, pyrazinamide, ethambutol, and streptomycin).
        Fixed room-air HEPA recirculation systems: Nonmobile devices or 
    systems that remove airborne contaminants by recirculating air through 
    a HEPA filter. These may be built into the room and permanently ducted 
    or may be mounted to the wall or ceiling within the room. In either 
    situation, they are fixed in place and are not easily movable.
        Fluorochrome stain: A technique for staining a clinical specimen 
    with fluorescent dyes to perform a microscopic examination (smear) for 
    mycobacteria. This technique is preferable to other staining techniques 
    because the mycobacteria can be seen easily and the slides can be read 
    quickly.
        Fomites: Linens, books, dishes, or other objects used or touched by 
    a patient. These objects are not involved in the transmission of M. 
    tuberculosis.
        Gastric aspirate: A procedure sometimes used to obtain a specimen 
    for culture when a patient cannot cough up adequate sputum. A tube is 
    inserted through the mouth or nose and into the stomach to recover 
    sputum that was coughed into the throat and then swallowed. This 
    procedure is particularly useful for diagnosis in children, who are 
    often unable to cough up sputum.
        High-efficiency particulate air (HEPA) filter: A specialized filter 
    that is capable of removing 99.97% of particles 0.3 
    m in diameter and that may assist in controlling the 
    transmission of M. tuberculosis. Filters may be used in ventilation 
    systems to remove particles from the air or in personal respirators to 
    filter air before it is inhaled by the person wearing the respirator. 
    The use of HEPA filters in ventilation systems requires expertise in 
    installation and maintenance.
        Human immunodeficiency virus (HIV) infection: Infection with the 
    virus that causes acquired immunodeficiency syndrome (AIDS). HIV 
    infection is the most important risk factor for the progression of 
    latent TB infection to active TB.
        Immunosuppressed: A condition in which the immune system is not 
    functioning normally (e.g., severe cellular immunosuppression resulting 
    from HIV infection or immunosuppressive therapy). Immunosuppressed 
    persons are at greatly increased risk for developing active TB after 
    they have been infected with M. tuberculosis. No data are available 
    regarding whether these persons are also at increased risk for 
    infection with M. tuberculosis after they have been exposed to the 
    organism.
        Induration: An area of swelling produced by an immune response to 
    an antigen. In tuberculin skin testing or anergy testing, the diameter 
    of the indurated area is measured 48-72 hours after the injection, and 
    the result is recorded in millimeters.
        Infection: The condition in which organisms capable of causing 
    disease (e.g., M. tuberculosis) enter the body and elicit a response 
    from the host's immune defenses. TB infection may or may not lead to 
    clinical disease.
        Infectious: Capable of transmitting infection. When persons who 
    have clinically active pulmonary or laryngeal TB disease cough or 
    sneeze, they can expel droplets containing M. tuberculosis into the 
    air. Persons whose sputum smears are positive for AFB are probably 
    infectious.
        Injectable: A medication that is usually administered by injection 
    into the muscle (intramuscular [IM]) or the bloodstream (intravenous 
    [IV]).
        Intermittent therapy: Therapy administered either two or three 
    times per week, rather than daily. Intermittent therapy should be 
    administered only under the direct supervision of an HCW or other 
    designated person (see Directly observed therapy [DOT]).
        Intradermal: Within the layers of the skin.
        Isoniazid (INH): A first-line, oral drug used either done as 
    preventive therapy or in combination with several other drugs to treat 
    TB disease.
        Kanamycin: An injectable, second-line anti-TB drug used primarily 
    for treatment of drug-resistant TB.
        Latent TB infection: Infection with M. tuberculosis, usually 
    detected by a positive PPD skin-test result, in a person who has no 
    symptoms of active TB and who is not infectious.
        Mantoux test: A method of skin testing that is performed by 
    injecting 0.1 mL of PPD-tuberculin containing 5 tuberculin units into 
    the dermis (i.e., the second layer of skin) of the forearm with a 
    needle and syringe. This test is the most reliable and standardized 
    technique for tuberculin testing (see Tuberculin skin test and Purified 
    protein derivative [PPD]-tuberculin test).
        Multidrug-resistant tuberculosis (MDR-TB): Active TB caused by M. 
    tuberculosis organisms that are resistant to more than one anti-TB 
    drug; in practice, often refers to organisms that are resistant to both 
    INH and rifampin with or without resistance to other drugs (see Drug 
    resistance, acquired and Drug resistance, primary).
        M. tuberculosis complex: A group of closely related mycobacterial 
    species that can cause active TB (e.g., M. tuberculosis, M. bovis, and 
    M. africanum); most TB in the United States is caused by M. 
    tuberculosis.
        Negative pressure: The relative air pressure difference between two 
    areas in a healthcare facility. A room that is at negative pressure has 
    a lower pressure than adjacent areas, which keeps air from flowing out 
    of the room and into adjacent rooms or areas.
        Nosocomial: An occurrence, usually an infection, that is acquired 
    in a hospital or as a result of medical care.
        Para-aminosalicylic acid: A second-line, oral anti-TB drug used for 
    treating drug-resistant TB.
        Pathogenesis: The pathologic, physiologic, or biochemical process 
    by which a disease develops.
        Pathogenicity: The quality of producing or the ability to produce 
    pathologic changes or disease. Some nontuberculous mycobacteria are 
    pathogenic (e.g., Mycobacterium kansasii), and others are not (.e.g., 
    Mycobacterium phlei).
        Portable room-air HEPA recirculation units: Free-standing portable 
    devices that remove airborne contaminants by recirculating air through 
    a HEPA filter.
        Positive PPD reaction: A reaction to the purified protein 
    derivative (PPD)-tuberculin skin test that suggests the person tested 
    is infected with M. tuberculosis. The person interpreting the skin-test 
    reaction determines whether it is positive on the basis of the size of 
    the induration and the medical history and risk factors of the person 
    being tested.
        Preventive therapy: Treatment of latent TB infection used to 
    prevent the progression of latent infection to clinically active 
    disease.
        Purified protein derivative (PPD)-tuberculin: A purified tuberculin 
    preparation that was developed in the 1930s and that was derived from 
    old tuberculin. The standard Mantoux test uses 0.1 mL of PPD 
    standardized to 5 tuberculin units.
        Purified protein derivative (PPD)-tuberculin test: A method used to 
    evaluate the likelihood that a person is infected with M. tuberculosis. 
    A small dose of tuberculin (PPD) is injected just beneath the surface 
    of the skin, and the area is examined 48-72 hours after the injection. 
    A reaction is measured according to the size of the induration. The 
    classification of a reaction as positive or negative depends on the 
    patient's medical history and various risk factors (see Mantoux test).
        Purified protein derivative (PPD)-tuberculin test conversion: A 
    change in PPD test results from negative to positive. A conversion 
    within a 2-year period is usually interpreted as new M. tuberculosis 
    infection, which carries an increased risk for progression to active 
    disease. A booster reaction may be misinterpreted as a new infection 
    (see Booster phenomenon and Two-step testing).
        Pyrazinamide: A first-line, oral anti-TB drug used in treatment 
    regimens.
        Radiography: A method of viewing the respiratory system by using 
    radiation to transmit an image of the respiratory system to film. A 
    chest radiograph is taken to view the respiratory system of a person 
    who is being evaluated for pulmonary TB. Abnormalities (e.g., lesions 
    or cavities in the lungs and enlarged lymph nodes) may indicate the 
    presence of TB.
        Radiometric method: A method for culturing a specimen that allows 
    for rapid detection of bacterial growth by measuring production of 
    CO2 by viable organisms; also a method of rapidly performing 
    susceptibility testing of M. tuberculosis.
        Recirculation: Ventilation in which all or most of the air that is 
    exhausted from an area is returned to the same area or other areas of 
    the facility.
        Regimen: Any particular TB treatment plan that specifies which 
    drugs are used, in what doses, according to what schedule, and for how 
    long.
        Registry: A record-keeping method for collecting clinical, 
    laboratory, and radiographic data concerning TB patients so that the 
    data can be organized and made available for epidemiologic study.
        Resistance: The ability of some strains of bacteria, including M. 
    tuberculosis, to grow and multiply in the presence of certain drugs 
    that ordinarily kill them; such strains are referred to as drug-
    resistant strains.
        Rifampin: A first-line, oral anti-TB drug that, when used 
    concomitantly with INH and pyrazinamide, provides the basis for short-
    course therapy.
        Room-air HEPA recirculation systems and units: Devices (either 
    fixed or portable) that remove airborne contaminants by recirculating 
    air through a HEPA filter.
        Second-line drugs: Anti-TB drugs used when the first-line drugs 
    cannot be use (e.g., for drug-resistant TB or because of adverse 
    reactions to the first-line drugs). Examples are cycloserine, 
    ethionamide, and capreomycin.
        Single-pass ventilation: Ventilation in which 100% of the air 
    supplied to an area is exhausted to the outside.
        Smear (AFB smear): A laboratory technique for visualizing 
    mycobacteria. The specimen is smeared onto a slide and stained, then 
    examined using a microscope. Smear results should be available within 
    24 hours. In TB, a large number of mycobacteria seen on an AFB smear 
    usually indicates infectiousness. However, a positive result is not 
    diagnostic of TB because organisms other than M. tuberculosis may be 
    seen on an AFB smear (e.g., nontuberculous mycobacteria).
        Source case: A case of TB in an infectious person who has 
    transmitted M. tuberculosis to another person or persons.
        Source control: Controlling a contaminant at the source of its 
    generation, which prevents the spread of the contaminant to the general 
    work space.
        Specimen: Any body fluid, secretion, or tissue sent to a laboratory 
    where smears and cultures for M. tuberculosis will be performed (e.g., 
    sputum, urine, spinal fluid, and material obtained at biopsy).
        Sputum: Phlegm coughed up from deep within the lungs. If a patient 
    has pulmonary disease, an examination of the sputum by smear and 
    culture can be helpful in evaluating the organism responsible for the 
    infection. Sputum should not be confused with saliva or nasal 
    secretions.
        Sputum induction: A method used to obtain sputum from a patient who 
    is unable to cough up a specimen spontaneously. The patient inhales a 
    saline mist, which stimulates a cough from deep within the lungs.
        Sputum smear, positive: AFB are visible on the sputum smear when 
    viewed under a microscope. Persons with a sputum smear positive for AFB 
    are considered more infectious than those with smear-negative sputum.
        Streptomycin: A first-line, injectable anti-TB drug.
        Symptomatic: Having symptoms that may indicate the presence of TB 
    or another disease (see Asymptomatic).
        TB case: A particular episode of clinically active TB. This term 
    should be used only to refer to the disease itself, not the patient 
    with the disease. By law, cases of TB must be reported to the local 
    health department.
        TB infection: A condition in which living tubercle bacilli are 
    present in the body but the disease is not clinically active. Infected 
    persons usually have positive tuberculin reactions, but they have no 
    symptoms related to the infection and are not infectious. However, 
    infected persons remain at lifelong risk for developing disease unless 
    preventive therapy is given.
        Transmission: The spread of an infectious agent from one person to 
    another. The likelihood of transmission is directly related to the 
    duration and intensity of exposure to M. tuberculosis (see Exposure).
        Treatment failures: TB disease in patients who do not respond to 
    chemotherapy and in patients whose disease worsens after having 
    improved initially.
        Tubercle bacilli: M. tuberculosis organisms.
        Tuberculin skin test: A method used to evaluate the likelihood that 
    a person is infected with M. tuberculosis. A small dose of PPD-
    tuberculin is injected just beneath the surface of the skin, and the 
    area is examined 48-72 hours after the injection. A reaction is 
    measured according to the size of the induration. The classification of 
    a reaction as positive or negative depends on the patient's medical 
    history and various risk factors (see Mantoux test, PPD test).
        Tuberculosis (TB): A clinically active, symptomatic disease caused 
    by an organism in the M. tuberculosis complex (usually M. tuberculosis 
    or, rarely, M. bovis or M. africanum).
        Two-step testing: A procedure used for the baseline testing of 
    persons who will periodically receive tuberculin skin tests (e.g., 
    HCWs) to reduce the likelihood of mistaking a boosted reaction for a 
    new infection. If the initial tuberculin-test result is classified as 
    negative, a second test is repeated 1-3 weeks later. If the reaction to 
    the second test is positive, it probably represents a boosted reaction. 
    If the second test result is also negative, the person is classified as 
    not infected. A positive reaction to a subsequent test would indicate 
    new infection (i.e., a skin-test conversion) in such a person.
        Ultraviolet germicidal irradiation (UVGI): The use of ultraviolet 
    radiation to kill or inactivate microorganisms.
        Ultraviolet germicidal irradiation (UVGI) lamps: Lamps that kill or 
    inactivate microorganisms by emitting ultraviolet germicidal radiation, 
    predominantly at a wavelength of 254 nm (intermediate light waves 
    between visible light and X-rays). UVGI lamps can be used in ceiling or 
    wall fixtures or within air ducts of ventilation systems.
        Ventilation, dilution: An engineering control technique to dilute 
    and remove airborne contaminants by the flow of air into and out of an 
    area. Air that contains droplet nuclei is removed and replaced by 
    contaminant-free air. If the flow is sufficient, droplet nuclei become 
    dispersed, and their concentration in the air is diminished.
        Ventilation, local exhaust: Ventilation used to capture and remove 
    airborne contaminants by enclosing the contaminant source (i.e., the 
    patient) or by placing an exhaust hood close to the contaminant source.
        Virulence: The degree of pathogenicity of a micoorganism as 
    indicated by the severity of the disease produced and its ability to 
    invade the tissues of a host. M. tuberculosis is a virulent organism.
    
    Index
    
    Acid-fast bacilli smears (see Smears, AFB)
    Acquired immunodeficiency syndrome (see HIV infection)
    Administrative controls
    Aerosol therapy
    Aerosolized pentamidine
        Booths for administration
        Patient screening
        Risk for nonsocomial transmission of M. tuberculosis
        Tents for administration
    AFB smears (see Smears, AFB)
    AIDS (see HIV infection)
    Air changes per hour (ACH)
        ASHRAE recommendations
        Determining
        Removal efficiencies
    Airflow
        Monitoring direction
    Ambulatory-care settings/areas
        Management of patients
    American Conference of Governmental Industrial Hygienists, Inc. 
    (ACGIH)
    American Institute of Architects (AIA)
    American Society of Heating, Refrigerating and Air-Conditioning 
    Engineers, Inc. (ASHRAE)
    Americans With Disabilities Act of 1990
    Anergy testing
    Anesthesia considerations
    Anterooms
        Negative pressure for
    Assignment of responsibility
    Autopsy
        Risk for nonsocomial transmission of M. tuberculosis
    Autopsy rooms
        HEPA filtration
        Respiratory protection
        UVGI
    Bacteriology
        Collecting specimens
        Mixed mycobacterial infection
    BCG (Bacille of Calmette and Guerin) vaccine
        Skin testing
        Vaccination
    Bronchoscopy
        Ventilation
    Chest radiography (see Diagnosis of TB)
    Cluster (see PPD testing)
    Cohorting
    Community TB profile
    Confidentiality
    Contact investigation
    Correctional facilities
    Cough-inducing procedures
        Bronchoscopy
        General guidelines
        Home-health-care settings
        In ambulatory-care areas
        Patient recovery from
        Pentamidine, aerosolized
        Respiratory protection
        Risk for nonsocomial transmission of M. tuberculosis
    Sputum induction
    Counseling
        Immunocompromised workers
    Culture methods
        Radiometric
    Decontamination of patient-care equipment
        Supplement 5--Decontamination, disinfecting, and sterilizing of 
    patient-care equipment
    Dental care
    Dental settings
        Infection-control precautions, TB
        PPD screening program
        Risk assessment
    Diagnosis of TB
        Anergy testing
        Bacteriology (see Smears, AFB and Culture methods)
        Before aerosol therapy
        Bronchoscopy
        Chest radiograph
        Culturing
        DNA probes
        Fluorescent microscopy
        High-pressure liquid chromatography
        Hospitalized patients
        Index of suspicion
        Mantoux technique
        Medical history
        NAP test
        Nucleic acid probes
        PPD testing
        Radiometric culture
        Smears
        Supplement 2--Diagnosis and treatment of latent TB infection and 
    active TB
        With anergy
        With immunocompromising conditions
        With simultaneous pulmonary infection
    Directly observed therapy (DOT)
        Home-health-care settings
        Public health department
    Discharge planning
    Drug-resistant TB
    Drug-susceptibility testing
        On initial isolates
        Radiometric methods
        Reporting to public health department
    Education and training
    Emergency medical services
        PPD screening program
        Respiratory protection
    Emergency departments
        Management of patients
    Endotracheal intubation
    Engineering controls
    Epidemiology, pathogenesis, and transmission of M. tuberculosis
    Executive Summary
    General ventilation
        Dilution and removal
        Facility airflow direction
        Mixing factor
        Negative pressure
        Recirculating systems
        Room airflow patterns
        Short-circuitingl
        Single-pass systems
    Glossary
    Health-care facility, definition
    Health-care worker(s) (HCW[s])
        Confidentiality
        Counseling
        Risk for infection
        Risk for infection and disease in immunocompromised HCWs
        Job reassignment
        Definition
        Education and training
        Evaluating PPD conversions
        Evaluating positive PPD-test results
        Immunocompromised
        Preventive therapy
        Screening for active TB
        Screening for latent TB infection
        Training
        Workplace restrictions
        Active TB
        Latent TB infection
    Health department
        Case notification
    Health Resources and Services Administration
    Heat wheel energy recovery units,
        HEPA filtration for
    Hierarchy of controls
    High-efficiency particulate (HEPA) filtration
        Autopsy rooms
        Disposable prefilters to extend life
        DOP penetration test
        Efficiency
        Enclosing booth use
        In ambulatory-care areas
        Individual room-air recirculation
        Installation, maintenance, and monitoring
        Longevity
        Pressure-sensing device to determine replacement need
        Recirculation of HEPA-filtered air within a room
        Evaluation
        Fixed room-air recirculation systems
        Portable room-air recirculation units
        Recirculation of HEPA-filtered air to other areas of facility
        Use when exhausting air to the outside
    High-risk area
    HIV infection
        Anergy testing
        Cell-mediated immunity, impaired
        Chest radiography
        Coinfection with M. tuberculosis
        Counseling HIV-infected HCWs
        Evaluation of PPD skin-test results
        Likelihood of infection after exposure to M. tuberculosis
        Progression from latent TB infection to active TB
        Smears, AFB
    Home-health-care settings
        Cough-inducing procedures
        PPD screening program
        Respiratory protection
    Hospices
    Human immunodeficiency virus (see HIV infection)
    Infection control
        Development of the TB infection-control plan
        Engineering controls
        Evaluation of engineering controls
        Fundamentals
        Hierarchy of control measures
        Observation of infection-control practices
    Infection-control practices, evaluating effectiveness
    Infectiousness
        Determining
        Factors determining
        In HIV-infected patients
        Length of, on therapy
        Monitoring
        Pediatric patients
        Supplement 1--Determining the infectiousness of a TB patient
        Noninfectiousness
    Intensive-care units
    Intermediate-risk area
    Isolation practices
        Dental settings
        Discontinuation
        Facilitating patient adherence
        For multidrug-resistant TB
        Initiation
        Intensive-care units
        Keeping door to room closed
        Long-term-care facilities
        Minimizing access to room
        Patient education
        Pediatric patients
        Visitors
    Isolation rooms
        Air changes per hour (ACH)
        Air exhaust
        Anteroom
        Grouping
        HEPA filtration
        Keeping door to room closed
        Negative pressure
        Number required
        Purpose
        Ultraviolet germicidal irradiation (UVGI)
    Isoniazid (INH)
        During pregnancy
        Hepatitis
        Monitoring for adverse reactions
        Preventive therapy regimen
    Laboratories
    Local exhaust ventilation
        Discharge from booths, tents, and hoods
        Exterior devices
        Into TB isolation rooms
    Long-term-care facilities
    Low-risk area
    Medical offices
    Medical record review
    Minimal-risk facility
    Mycobacterium avium complex
    National Institute for Occupational Safety and Health (NIOSH)
    Negative pressure
        Alternate methods for achieving
        Definition
        Monitoring
        Pressure differential required
        Pressure-sensing devices
        Pressurizing the corridor
        Smoke-tube testing
        TB isolation rooms
        Tents and booths
    Nosocomial transmission
        Factors promoting
    Occupational groups
    Occupational Safety and Health Administration (OSHA)
    Operating rooms
        Anterooms
        Respiratory protection
        Ventilation
    OSHA respiratory protection standard
    Outbreaks of TB in health-care facilities
    Patient-to-patient transmission
        Cohorting
        Investigating
    Pediatric patients
    Pneumocystis carinii
    PPD reading
        Cut-points for risk groups
    PPD testing
        Analysis of increased conversion rate
        Anergy
        BCG vaccination
        Booster phenomenon
        Cluster
        Contact investigation
        Conversions
        Dental settings
        Emergency medical services
        Evaluating PPD conversions
        Frequency
        HCWs with positive PPD tests
        Home-health-care settings
        Immunocompromised workers
        Interpretation of results
        Mantoux technique
        Occupational group
        Persons with HIV infection
        Positive-predictive value
        Pregnancy
        Recent PPD converters
        Recording results
        Self-reading results
        Staggered testing
        Two-step testing
    Preventive therapy
        Drug-susceptibility testing
        For anergic persons
        Monitoring
        Pregnancy
        Regimens
    Problem evaluation
        Active TB in HCWs
        Contact investigation
        Patient-to-patient transmission
        PPD test conversions in HCWs
    Pubic health department
        Contact investigation
        Coordination
        Directly observed therapy (DOT)
        Discharge planning
        Providing assistance
        Reporting
    Radiographs
    Radiology department
    Re-entrainment
    Recommendations
        Aerosolized pentamidine
        AFB smears
        Analysis of PPD screening data
        Anergy testing
        Anterooms
        Autopsy rooms
        Bronchoscopy
        Case surveillance
        Community TB profile
        Contact investigation
        Correctional facilities
        Cough-inducing procedures
        Development of the TB infection-control plan
        Diagnosis
        Discharge planning
        Drug-susceptibility testing
        Emergency departments
        Emergency medical services
        Engineering controls
        Environmental/engineering evaluation
        HCW counseling
        HCW screening
        HEPA filtration
        Home-health-care settings
        Hospices
        Identification of patients who may have active TB
        Immunocompromised persons
        Infectiousness
        Initiation of TB isolation
        Initiation of treatment
        Isolation practices
        Correctional facilities
        Dental settings
        Discontinuation of
        Laboratories
        Long-term-care facilities
        Managing hospitalized patients
        Managing patients
        In ambulatory-care settings
        In correctional facilities
        In dental settings
        In emergency departments
        In emergency medical services settings
        In home-health-care settings
        In hospices
        In medical offices
        Mantoux technique
        Medical offices
        Multidrug-resistant tuberculosis (MDR-TB)
        Observation of infection-control practices
        Operating rooms
        Patient transport
        Periodic reassessment
        Preventive therapy for TB infection
        Problem evaluation
        Radiology department
        Radiometric culture
        Review of TB patient medical records
        Risk assessment
        Training
        Treatment for active TB
        Treatment for latent TB
        Triage
        UVGI
        UVGI maintenance
        Ventilation
        Waiting areas
        Workplace restrictions
    Respiratory protection
        Cleaning
        Cough-inducing procedures
        Dental settings
        Effectiveness
        Emergency medical services
        Face-seal leakage
        Filter leakage
        Fit checking
        Fit testing
        Home-health-care settings
        Maintenance
        Medical screening
        Negative-pressure respirators
        NIOSH
        Operating rooms
        OSHA respiratory protection standard
        Performance criteria
        Positive-pressure respirators
        Respiratory protection program
        Reuse of respirators
        Storage
        Supplement 4--Respiratory protection
        Surgery
        Surgical masks for patients
        Training
        Visitors of TB patients
    Respiratory protection program
        Elements
        Periodic evaluation
    Risk assessment
        Case surveillance
        Community TB profile
        Elements of a risk assessment
        Examples
        How to perform
        Levels of risk
        Periodic reassessment
        Review of TB patient medical records
        Risk area definitions
        Who should conduct
    Risk factors for disease progression
    Risk groups
    Signs and symptoms of active TB
    Skin testing (see PPD testing)
    Smears, AFB
    Smoke-tube testing
    Smoke tubes
    Source control
    Sputum induction
    Surgical masks
        For patient transport
        For patients in ambulatory-care areas or emergency departments
        Visitors of TB patients
    TB infection-control program
        Assigning supervisory responsibility
        Elements of a TB infection-control program
    TB isolation rooms
        Achieving negative pressure
        Anterooms
        Cohorting
        Exhaust
        Grouping
        HEPA filtration
        In ambulatory-care areas
        Negative pressure
        Purpose
        Ventilation
    TB patient scheduling
    Tissues
        For hospitalized patients
        For patients in ambulatory-care areas or emergency departments
        Home-health-care settings
    Transporting TB patients
    Treatment for TB
        Adherence
        Directly observed therapy (DOT)
        Dosage recommendations for children and adults
        Drug susceptibility
        For active TB
        For latent TB infection
        During pregnancy
        For active TB
        For latent TB infection
        Initiation of
        Preventive therapy
        Regimen options for children and adults
        Supplement 2--Diagnosis and treatment for latent TB infection 
    and active TB
        Treatment for active TB
    Triage
    Tuberculin skin test (see PPD testing)
    Ultraviolet germicidal irradiation (UVGI)
        Activation of HIV gene promoters
        Applications
        Autopsy rooms
        Carcinogenicity
        Definition
        Determining maximum permissible exposure times
        Duct irradiation
        Educating HCWs
        Effectiveness
        Exposure criteria for UV radiation
        HCW training issues
        In ambulatory-care settings
        Installation
        Labelling and posting caution signs
        Limitations
        Maintenance
        Monitoring
        Obtaining consultation before installation
        Precautions
        Recommended exposure limits (RELs)
        Safety issues
        Upper-room air irradiation
        UV radiation, definition
    Ventilation
        Air changes per hour (ACH)
        Airflow patterns
        Ambulatory-care areas
        Anterooms
        Autopsy rooms
        Correctional facilities
        Dilution and removal
        Direction of airflow
        Discharge from booths, tents, and hoods
        Emergency departments
        Emergency medical services
        Enclosing devices
        Engineers
        Evaluation
        Exhaust
        General ventilation
        HEPA filter installation, maintenance, and monitoring
        Home-health-care settings
        Hospices
        Local exhaust ventilation
        Discharge exhaust
        Enclosing devices
        Exterior devices
        Maintenance
        Monitoring
        Mixing factor
        Negative pressure
        Operating rooms
        Periodic evaluation
        Positive-pressure rooms
        Pressure-sensing devices
        Pressurizing the corridor to induce negative pressure
        Radiology department
        Rates (see Air changes per hour [ACH])
        Recirculation of HEPA filtered air
        Fixed
        Portable
        Re-entrainment
        Short-circuiting
        Single-pass system
        Source control methods
        Stagnation
        Supplement 3--Engineering issues in TB control
        TB isolation rooms
        Tents and booths (see Local exhaust ventilation)
        Treatment rooms
        Ventilation rates
        Waiting-room areas
    Very low-risk area or facility
    Visitors
        Contact investigation
        Pediatric patients
        Protection against UVGI
        Respiratory protection for
    Waiting-room areas
    Workplace reassignment
    Workplace restrictions
        Active TB
        Extrapulmonary TB
        Latent TB infection
        Nonadherence to preventive therapy
        Nonadherence to treatment
        Return to work
    
    List of Tables
    
    Table 1. Elements of a risk assessment for tuberculosis (TB) in 
    health-care facilities
    Table 2. Elements of a tuberculosis (TB) infection-control program
    Table 3. Characteristics of an effective tuberculosis (TB) 
    infection-control program
    Table 4. Examples of potential problems that can occur when 
    identifying or isolating patients who may have infectious 
    tuberculosis (TB)
    Table S2-1. Summary of interpretation of purified protein derivative 
    (PPD)-tuberculin skin-test results
    Table S2-2. Regimen options for the treatment of tuberculosis (TB) 
    in children and adults
    Table S2-3. Dosage recommendations for the initial treatment of 
    tuberculosis in children and adults
    Table S3-1. Air changes per hour (ACH) and time in minutes required 
    for removal efficiencies of 90%, 99%, and 99.9% of airborne 
    contaminants
    Table S3-2. Hierarchy of ventilation methods for tuberculosis (TB) 
    isolation rooms and treatment rooms
    Table S3-3. Maximum permissible exposure times for selected values 
    of effective irradiance
    
    List of Figures
    
    Figure 1. Protocol for conducting a tuberculosis (TB) risk 
    assessment in a health-care facility
    Figure 2. Protocol for investigating purified protein derivative 
    (PPD)-tuberculin skin-test conversions in health-care workers (HCWs)
    Figure S3-1. An enclosing booth designed to sweep air past a patient 
    who has active tuberculosis and entrap the infectious droplet nuclei 
    in a high-efficiency particulate air (HEPA) filter
    Figure S3-2. Room airflow patterns designed to provide mixing of air 
    and prevent passage of air directly from the air supply to the 
    exhaust
    Figure S3-3. Smoke-tube testing and anemometer placement to 
    determine the direction of airflow into and out of a room
    Figure S3-4. Cross-sectional view of a room showing the location of 
    negative pressure measurement
    Figure S3-5. Fixed, ducted room-air recirculation system using a 
    high-efficiency particulate air (HEPA) filter inside an air duct
    Figure S3-6. Fixed ceiling-mounted room-air recirculation system 
    using a high-efficiency particulate air (HEPA) filter
    Figure S3-7. Air recirculation zone created by wind blowing over a 
    building
    
    [FR Doc. 94-26598 Filed 10-27-94; 8:45 am]
    BILLING CODE 4163-18-P
    
    
    

Document Information

Published:
10/28/1994
Department:
Centers for Disease Control and Prevention
Entry Type:
Uncategorized Document
Action:
Notice of Final Revisions to the ``Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities, 1994.''
Document Number:
94-26598
Dates:
October 28, 1994.
Pages:
0-0 (None pages)
Docket Numbers:
Federal Register: October 28, 1994