§ 493.911 - Bacteriology.

§ 493.911 Bacteriology.

Cross Reference

Link to an amendment published at 87 FR 41233, July 11, 2022.

(a) Types of services offered by laboratories. In bacteriology, for proficiency testing purposes, there are five types of laboratories:

(1) Those that interpret Gram stains or perform primary inoculation, or both; and refer cultures to another laboratory appropriately certified for the subspecialty of bacteriology for identification;

(2) Those that use direct antigen techniques to detect an organism and may also interpret Gram stains or perform primary inoculation, or perform any combination of these;

(3) Those that, in addition to interpreting Gram stains, performing primary inoculations, and using direct antigen tests, also isolate and identify aerobic bacteria from throat, urine, cervical, or urethral discharge specimens to the genus level and may also perform antimicrobial susceptibility tests on selected isolated microorganisms;

(4) Those that perform the services in paragraph (a)(3) of this section and also isolate and identify aerobic bacteria from any source to the species level and may also perform antimicrobial susceptibility tests; and

(5) Those that perform the services in paragraph (a)(4) of this section and also isolate and identify anaerobic bacteria from any source.

(b)

Program content and frequency of challenge. To be approved for proficiency testing for bacteriology, the annual program must provide a minimum of five samples per testing event. There must be at least three testing events provided to the laboratory at approximately equal intervals per year. The samples may be provided to the laboratory through mailed shipments

or, at HHS' option, may be provided to HHS or its designee for on-site testing

.

For the types of laboratories specified in paragraph (a) of this section, an annual program must include samples that contain organisms that are representative of the six major groups of bacteria: anaerobes, Enterobacteriaceae, gram-positive bacilli, gram-positive cocci, gram-negative cocci, and miscellaneous gram-negative bacteria, as appropriate.

The specific organisms included in the samples may vary from year to year.

(1) The annual program must include, as applicable, samples for:

(i) Gram stain including bacterial morphology;

(ii) Direct bacterial antigen detection

, bacterial isolation and identification, Gram stain, and antimicrobial susceptibility testing.(1

;

(iii) Bacterial toxin detection; and,

(iv) Detection and identification of bacteria which includes one of the following:

(A) Detection of the presence or absence of bacteria without identification; or

(B) Identification of bacteria; and

(v) Antimicrobial susceptibility testing of select bacteria.

(2) An approved program must furnish HHS and its agents with a description of samples that it plans to include in its annual program no later than

six

6 months before each calendar year.

At least 50

The program must include bacteria commonly occurring in patient specimens and other important emerging pathogens. The program determines the reportable isolates and correct responses for antimicrobial susceptibility testing for any designated isolate. At least 25 percent of the samples must be mixtures of the principal organism and appropriate normal flora.

The program must include other important emerging pathogens (as determined by HHS) and either organisms commonly occurring in patient specimens or opportunistic pathogens.

Mixed cultures are samples that require reporting of one or more principal pathogens. Mixed cultures are not “negative” samples such as when two commensal organisms are provided in a PT sample with the intended response of “negative” or “no pathogen present.” The program must include the following two types of samples

; each type of sample must

to meet the

50

25 percent mixed culture criterion:

(i) Samples that require laboratories to report only organisms that the testing laboratory considers to be a principal pathogen that is clearly responsible for a described illness (excluding immuno-compromised patients). The program determines the reportable isolates, including antimicrobial susceptibility for any designated isolate; and

(ii) Samples that require laboratories to report all organisms present. Samples must contain multiple organisms frequently found in specimens

such as urine, blood, abscesses, and aspirates

where multiple isolates are clearly significant or where specimens are derived from immuno-compromised patients. The program determines the reportable isolates.

(

2) An

3) The content of an approved program

may

must vary over time

. For example, the types of organisms that might be included in an approved program over time are—

Anaerobes:

Bacteroides fragilis group

Clostridium perfringens

Peptostreptococcus anaerobius

Enterobacteriaceae

Citrobacter freundii

Enterobacter aerogenes

Escherichia coli

Klebsiella pneumoniae

Proteus mirabilis

Salmonella typhimurium

Serratia marcescens

Shigella sonnei

Yersinia enterocolitica

Gram-positive bacilli:

Listeria monocytogenes

Corynebacterium species CDC Group JK

Gram-positive cocci:

Staphylococcus aureus

Streptococcus Group A

Streptococcus Group B

Streptococcus Group D (S. bovis and enterococcus)

Streptococcus pneumoniae

Gram-negative cocci:

Branhamella catarrhalis

Neisseria gonorrhoeae

Neisseria meningitidis

Miscellaneous Gram-negative bacteria:

Campylobacter jejuni

Haemophilis influenza, Type B

Pseudomonas aeruginosa

(3

, as appropriate. The types of bacteria included annually must be representative of the following major groups of medically important aerobic and anaerobic bacteria, if appropriate for the sample sources:

(i) Gram-negative bacilli.

(ii) Gram-positive bacilli.

(iii) Gram-negative cocci.

(iv) Gram-positive cocci.

(4) For antimicrobial susceptibility testing, the program must provide at least

one sample

two samples per testing event

that includes gram-positive or gram-negative strains

. The program must annually provide samples that include Gram-positive organisms and samples that include Gram-negative organisms that have a predetermined pattern of

sensitivity

susceptibility or resistance to the common antimicrobial agents.

(

c

b) Evaluation of a laboratory's performance. HHS approves only those programs that assess the accuracy of a laboratory's responses in accordance with paragraphs (

c

b)(1) through (

7

9) of this section.

(1) The program determines the reportable bacterial staining and morphological characteristics to be interpreted by Gram stain. The program determines the

reportable

bacteria to be

detected

reported by direct

antigen techniques or isolation

bacterial antigen detection, bacterial toxin detection, detection of the presence or absence of bacteria without identification, identification of bacteria, and antimicrobial susceptibility testing. To determine the accuracy of

a

each of the laboratory's

response for Gram stain interpretation, direct antigen detection, identification, or antimicrobial susceptibility testing,

responses, the program must compare

the laboratory's response for each sample

each response with the response which reflects agreement of either 80 percent or more of

ten

10 or more referee laboratories or 80 percent or more of all participating laboratories.

(2) To evaluate a laboratory's response for a particular sample, the program must determine a laboratory's type of service in accordance with paragraph (a) of this section. A laboratory must isolate and

Both methods must be attempted before the program can choose to not grade a PT sample.

(2) A laboratory must identify the organisms to

the same extent it performs these procedures

highest level that the laboratory reports results on patient specimens.

(3) A laboratory's performance will be evaluated on the basis of

its final answer, for example, a laboratory specified in paragraph (a)(3) of this section will be evaluated on

the

basis of the

average of its scores for

paragraphs

paragraph (

c

b)(

3

4) through (

c)(6)

8) of this section as determined in paragraph (

c

b)(

7

9) of this section.

(

3) Since laboratories may incorrectly report the presence of organisms in addition to the correctly identified principal organism(s), the grading system must provide a means of deducting credit for additional erroneous organisms that are reported. Therefore, the

4) The performance criteria for Gram stain including bacterial morphology is staining reaction, that is, Gram positive or Gram negative and morphological description for each sample. The score is the number of correct responses for Gram stain reaction plus the number of correct responses for morphological description divided by 2 then divided by the number of samples to be tested, multiplied by 100.

(5) The performance criterion for direct bacterial antigen detection is the presence or absence of the bacterial antigen. The score is the number of correct responses divided by the number of samples to be tested, multiplied by 100.

(6) The performance criterion for bacterial toxin detection is the presence or absence of the bacterial toxin. The score is the number of correct responses divided by the number of samples to be tested multiplied by 100.

(7) The performance criterion for the detection and identification of bacteria includes one of the following:

(i) The performance criterion for the detection of the presence or absence of bacteria without identification is the correct detection of the presence or absence of bacteria without identification. The score is the number of correct responses divided by the number of samples to be tested multiplied by 100.

(ii) The performance criterion for the identification of bacteria is the total number of correct responses for

organism isolation and

bacterial identification submitted by the laboratory divided by the number of organisms present plus the number of incorrect organisms reported by the laboratory

must be

multiplied by 100 to establish a score for each sample in each testing event. Since laboratories may incorrectly report the presence of organisms in addition to the correctly identified principal organism(s), the scoring system must provide a means of deducting credit for additional erroneous organisms that are reported. For example, if a sample contained one principal organism and the laboratory reported it correctly but reported the presence of an additional organism, which was not considered reportable, the sample grade would be 1/(1+1) × 100 = 50 percent.

(

4

8) For antimicrobial susceptibility testing, a laboratory must indicate which drugs are routinely included in its test panel when testing patient samples. A laboratory's performance will be evaluated for only those

antibiotics

antimicrobials for which

service is offered

susceptibility testing is routinely performed on patient specimens. A correct response for each

antibiotic

antimicrobial will be determined as described in

§ 493.911(c

paragraph (b)(1)

using criteria such as the guidelines established by the National Committee for Clinical Laboratory Standards. Grading

of this section. Scoring for each sample is based on the number of correct susceptibility responses reported by the laboratory divided by the actual number of correct susceptibility responses determined by the program, multiplied by 100. For example, if a laboratory offers susceptibility testing

for Enterobacteriaceae

using

amikacin

three antimicrobial agents,

cephalothin,

and

tobramycin, and

the

organism in the proficiency testing sample is an Enterobacteriaceae, and the

laboratory reports correct responses for two of the three antimicrobial agents, the laboratory's grade would be 2

/

⁄3 × 100 = 67 percent.

(

5

9) The

performance criterion for qualitative antigen tests is the presence or absence of the bacterial antigen. The

score for

antigen tests is the number of correct responses divided by the number of samples to be tested for the antigen, multiplied by 100.

(6) The performance criteria for Gram stain is staining reaction, i.e., gram positive or gram negative. The score for Gram stain is the number of correct responses divided by the number of challenges to be tested, multiplied by 100.

(7) The score for

a testing event in bacteriology is the average of the scores determined under paragraphs (

c

b)(

3

4) through (

c

8)

(6)

of this section

kbased

based on the type of service offered by the laboratory.

[57 87 FR 7151, Feb. 28, 1992, as amended at 58 FR 5228, Jan. 19, 1993; 68 FR 3702, Jan. 24, 200341233, July 11, 2022]