This test includes AFB smear, culture, and organism identification from a clinical 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).
This test is typically used when there is low risk of tuberculosis since no direct test for Mycobacterium tuberculosis is performed from the specimen (although it is fully identified if seen). If there is an unknown or higher risk of M. tuberculosis infection, order AFB1.
Typically all days
When appropriate, specimens are processed using a standard digestion/decontamination procedure. An acid fast smear is performed from the processed specimen using a florescent auramine stain. Specimens are cultured on three solid and one liquid media then incubated for 6 weeks. Mycobacteria or partially acid fast organisms are identified to the full extent possible, such as to the species or subspecies level (see AFB4 for further details).
Infectious Disease Laboratory, Mycobacteriology
AFB3, mycobacterial smear, culture and identification
Smear and culture: Reference method, no special licensing required
Identification of AFB: NY State waiver is required.
Negative for acid fast bacilli.
This is a test algorithm. When it is ordered, smear and culture are typically performed. If an organism is recovered, a reflex identification test will be ordered. The identification method used will depend on the organism.