AFB Culture - Mycobacteria - TB Culture - Tuberculosis - Atypical Mycobacteria


AFB smear (concentrated)


Sputum: Three specimens collected 8-24 hours apart and include at least one first morning specimen is recommended.

Urine: Early morning void on 3 consecutive days is recommended.

Gastric: Collect before the patient eats in a sterile, plastic container with a leak proof lid. Gastric Aspirates must be buffered with aliquots of liquid bicarbonate buffer provided to each core laboratory by the Microbiology Department within 30 minutes.

Induced sputum: Induced sputum collection should only be performed under close medical supervision and using strict infection control procedures. Patients requiring induced sputum collection should be referred to a pulmonary clinic.

Specimen Collection Requirements


First morning Sputum, Urine, Gastric Fluid, Stool, Tissue or Body Fluid

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Refrigerate samples after collection (2-8°C). Deliver gastric specimens immediately to lab (samples must be buffered within 30 minutes of collection).

For stool specimens, see Specimen Collection-Transport Guide for Stool Orders.

Submit tissue and body fluid in sterile container. Submit specimens in sterile cup in individual sealed bag at 2-8°C. Tissue and swabs should remain moist; submit in 2 mL sterile saline, ground tissue is preferred.

For Blood and Bone Marrow, refer to Culture, Blood for Acid Fast Bacilli

Preferred Volume

Body Fluids: As large a volume as possible

Bronchoscopy specimens: 3.0 mL

CSF: 2.0-3.0 mL

Sputum: 3.0 mL

Urine: 40.0 Ml

For Blood and Bone Marrow, refer to CULTURE, BLOOD FOR ACID FAST BACILLI

Minimum Volume

1.0 mL


Refrigerated (2-8°C)

Rejection Criteria

24 hour urine, 24 hour sputum, specimens treated with formalin


Ambient: 24 hours; Refrigerated: 1 week; Frozen: 1 week

MTB PCR stable for 7 days refrigerated

Refer to M TUBERCULOSIS PCR (XPERT) for PCR testing information

Testing Information


MTB PCR will automatically be reflexed on new ACID FAST smear positive AFB cultures, sputum and bronchial samples only on patients 18 years and older. MTB PCR may also be ordered on smear negative cultures.

Legacy Lab requires that a Culture AFB be ordered with any MTB PCR test for diagnostic purposes.


7 days/week


Smear: 24 hours; Positive: as soon as detected; Negative Preliminary: 1 week; Final Negative: 42 days


Culture, PCR if needed

Reference Values

Reference Values

Culture negative for acid-fast bacilli

Critical Values

Positive smears for acid-fast bacilli from respiratory specimens or smears positive for AFB on blood cultures.

MTB PCR positive.


MTB PCR will be reflexed from new ACID FAST smear positive sputum and bronchial specimens. To add the MTB PCR to ACID FAST smear negative sputum and bronchial specimens, contact Microbiology at 503-413-2258.

Cepheid MTB PCR is only available on sputum and bronchial sources. This assay has not been FDA authorized for use in specimens from pediatric patients (patients less than 18 years old).

Additional charge for concentration CPT 87015 and stain CPT 87206. If positive then possible CPT 87556, 87149 for identification

CPT Codes

87116, 87206, 87015 (87556, 87149 if applicable)

Last Updated: Thursday, January 5, 2017 03:41:55 AM