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AFB Culture and Smear
Test CodeAFB CULTURE AND SMEAR(O)
Alias/See Also
Acid Fast Bacillus
Mycobacteriology
Mycobacteriology
Includes
AFB Culture AFB Smear
AFB Susceptibility (Only if AFB culture is positive)
AFB Susceptibility (Only if AFB culture is positive)
Preferred Specimen
Sputum, Bronchial specimens, Body Fluids, Tissues in saline, Urine
Minimum Volume
5-10 mls
Instructions
Early morning sputum preferred.
Specimen every 8 hours is optimal
Transport Temperature
RT < 2 hours
Specimen Stability
Refrigerated < 24 hours
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
No Swabs
No Specimens wrapped in gauze
No Specimens wrapped in gauze
Methodology
Acid fast smear.
Confirmation or identification to the complex or species level by Genprobe Accuprobe, and/or biochemical testing.
Setup Schedule
Mon - Fri
Report Available
Acid-Fast stain results are reported within 24 hours of specimen receipt by the testing laboratory.
Acid-Fast culture results are reported upon growth of any Acid-Fast Bacillus or are negative after 60 days, whichever comes first.
If an Acid-Fast culture is positive the organism(s) will be identified, and susceptibility testing will be performed on isolates when clinically appropriate in a timely manner.
Acid-Fast culture results are reported upon growth of any Acid-Fast Bacillus or are negative after 60 days, whichever comes first.
If an Acid-Fast culture is positive the organism(s) will be identified, and susceptibility testing will be performed on isolates when clinically appropriate in a timely manner.
Limitations
Low volume can lead to false negatives or delay of positive cultures.
Reference Range
Culture Negative
Comments:
Acid-fast organisms are slow-growing and the full scope of testing may take greater than 60 days.
AFB Culture & Smear is routinely added to all bronchial specimens and respiratory tissues.
Collection of three sputum specimens at 8-24 hour intervals and including at least one first morning specimen is recommended for acid-fast smears and culture in patients with clinical and chest x-ray findings compatible with tuberculosis. If MTB is suspected, then this should be the first test ordered. (after infectious disease approval has been received)
Routine AFB Culture & Smear (send out test) should be ordered and collected either simultaneously or next time sputum is available after the MTB PCR is collected. Mycobacterial cultures are a more sensitive method than molecular testing for the diagnosis of tuberculosis and are still considered the gold standard due to the sensitivity of culture, the need for susceptibility testing, genotyping or to ascertain the presence of viable organisms in patients currently being treated.
Comments:
Acid-fast organisms are slow-growing and the full scope of testing may take greater than 60 days.
AFB Culture & Smear is routinely added to all bronchial specimens and respiratory tissues.
Collection of three sputum specimens at 8-24 hour intervals and including at least one first morning specimen is recommended for acid-fast smears and culture in patients with clinical and chest x-ray findings compatible with tuberculosis. If MTB is suspected, then this should be the first test ordered. (after infectious disease approval has been received)
Routine AFB Culture & Smear (send out test) should be ordered and collected either simultaneously or next time sputum is available after the MTB PCR is collected. Mycobacterial cultures are a more sensitive method than molecular testing for the diagnosis of tuberculosis and are still considered the gold standard due to the sensitivity of culture, the need for susceptibility testing, genotyping or to ascertain the presence of viable organisms in patients currently being treated.
Performing Laboratory
Test performed by VA Connecticut Laboratory.
Last Updated: October 10, 2025
