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Advanced Diagnostic Laboratories

TB NAAT, Smear, Culture, and Identification of Acid Fast Bacilli

Test Code



This test represents the full workup for acid fast bacilli and partially acid fast organisms from a clinical specimen, especially if there is unknown or potential risk of M. tuberculosis infection.

This algorithm includes the following components: nucleic acid amplification testing (NAAT), acid fast smear, culture, and appropriate identification. NAAT is a molecular test used to detect M. tuberculosis complex and rifampin resistance from a specimen. The AFB smear is a direct fluorescent stain from the specimen and can be used to quickly establish the presence of mycobacteria. The AFB culture is the inoculation of a clinical specimen onto multiple media types followed by monitoring for six weeks. Growth of any AFB (i.e. mycobacteria) or partially acid fast organisms (e.g. aerobic actinomycetes) is identified. Identification will occur to the greatest extent possible, which is usually to the species level but can be to the subspecies level for some organisms (e.g. Mycobacterium abscessus subsp. abscessus) .