Acid-Fast Bacillus (AFB) Culture and AFB Stain with Reflex to Mycobacterium tuberculosis Complex Detection and Rifampin Resistance by PCR

Respiratory specimens under 5 mL are suboptimal and may compromise recovery of AFB from culture. Stain may not be performed on low volume samples.

Eswabs are considered suboptimal and may have reduced sensitivity for AFB diagnosis.

Preferred acceptable specimens: Tissue, pus, drainage, or wound aspirates submitted in sterile containers. Please submit an Eswab specimen only when tissue biopsy or fluid aspiration is not feasible for specimens collected surgically. Eswabs are not acceptable for respiratory fluid specimens (eg, sputum) and body fluids, and testing will be canceled.
Positive cultures are reported as soon as detected. AFB stain, AFB identification of positives, and susceptibility tests are billed separately from culture. Identification of positive culture is billed by matrix-assisted laser desorption ionization (MALDI), PCR, and/or sequencing tests performed.

The laboratory should be notified when the presence of Mycobacterium genavense or Mycobacterium haemophilum is suspected, as these organisms will not grow on media routinely used for Mycobacterium isolation.

The laboratory should be notified when M. xenopii is suspected, as this organism requires a different temperature from routine culture setup.

The laboratory should be notified if the specimen is from a cystic fibrosis patient, as these specimens need additional decontamination from routine culture setup.

Susceptibility will be performed on organisms isolated from a sterile source and isolates of Mycobacterium tuberculosis complex, M. chelonae, M. abscesses, M. fortuitum complex, M. immunogenum, M. mucogenicum. Susceptibility testing will be performed by request only on M. kansasii and M. marinum. Susceptibility testing of M. gordonae is inappropriate.

For AFB susceptibility information, refer to Antimicrobial Susceptibility - AFB Mycobacteria (ARUP test code 0060217).

For AFB culture on blood refer to Culture, Acid-Fast Bacillus, Blood (ARUP test code 0060060).

After a positive result, repeat orders for Mycobacterium tuberculosis Complex Detection and Rifampin Resistance by PCR will continue to yield a positive result and repeat testing is not clinically indicated.