§ 493.913 Mycobacteriology. ( a ) *Program content and frequency of challenge.* To be approved for proficiency testing for mycobacteriology, the annual program must provide a minimum of five samples per testing event. There must be at least two testing events provided to the laboratory at approximately equal intervals per year. The samples may be provided through mailed shipments. The specific organisms included in the samples may vary from year to year. ( 1 ) The annual program must include, as applicable, samples for: ( i ) Acid-fast stain; and
( ii ) Detection and identification of mycobacteria which includes one of the following: ( A ) Detection of the presence or absence of mycobacteria without identification; or
( B ) Identification of mycobacteria.
( 2 ) An approved program must furnish HHS and its agents with a description of the samples it plans to include in its annual program no later than 6 months before each calendar year. At least 25 percent of the samples must be mixtures of the principal mycobacteria and appropriate normal flora. The program must include mycobacteria commonly occurring in patient specimens and other important emerging mycobacteria. The program determines the reportable isolates and correct responses.
( 3 ) The content of an approved program may vary over time, as appropriate. The mycobacteria included annually must contain species representative of the following major groups of medically important mycobacteria, if appropriate for the sample sources: ( i ) *Mycobacterium tuberculosis* complex; and
( ii ) *Mycobacterium* other than tuberculosis (MOTT).
( 4 ) The program must provide at least five samples per testing event that include challenges that contain acid-fast organisms and challenges that do not contain acid-fast organisms.
( b ) *Evaluation of a laboratory's performance.* HHS approves only those programs that assess the accuracy of a laboratory's response in accordance with paragraphs (b)(1) through (6) of this section. ( 1 ) The program determines the reportable mycobacteria to be detected by acid-fast stain. The program determines the mycobacteria to be reported by detection of the presence or absence of mycobacteria without identification, and identification of mycobacteria. To determine the accuracy of each of the laboratory's responses, the program must compare each response with the response that reflects agreement of either 80 percent or more of 10 or more referee laboratories or 80 percent or more of all participating laboratories. Both methods must be attempted before the program can choose to not grade a PT sample.
( 2 ) A laboratory must detect and identify the organisms to the highest level that the laboratory reports results on patient specimens.
( 3 ) A laboratory's performance will be evaluated on the basis of the average of its scores for paragraph (b)(4) through (5) of this section as determined in paragraph (b)(6) of this section.
( 4 ) The performance criterion for acid-fast stains is positive or negative or the presence or absence of acid-fast organisms. The score is the number of correct responses divided by the number of samples to be tested, multiplied by 100.
( 5 ) The performance criterion for the detection and identification of mycobacteria includes one of the following: ( i ) The performance criterion for the detection of the presence or absence of mycobacteria without identification is the correct detection of the presence or absence of mycobacteria 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 mycobacteria is the total number of correct responses for mycobacterial identification submitted by the laboratory divided by the number of organisms present plus the number of incorrect organisms reported by the laboratory multiplied by 100 to establish a score for each sample in each testing event. Since laboratories may incorrectly report the presence of mycobacteria in addition to the correctly identified principal organism(s), the scoring system must provide a means of deducting credit for additional erroneous organisms 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.
( 6 ) The score for a testing event in mycobacteriology is the average of the scores determined under paragraphs (b)(4) through (5) of this section based on the type of service offered by the laboratory.
[87 FR 41234, July 11, 2022]