Lab Test Dictionary

AFB Smear & Culture (Clinical Specimen Only ( NAAT) (AFB1) (Special Request Only)

Methodology

The specimen is screened for M. tuberculosis complex with a nucleic acid amplification test (TB NAAT). A smear for AFB is performed and the specimen is cultured on solid and liquid media (see AFB7 for more details). Mycobacteria or partially acid-fast organisms are identified to the full extent possible, such as to the species or subspecies level (AFB4).

Synonyms

AFB; Acid Fast Bacili; Mycobacteria; Mycobacterial; MTB; TB; NAAT

Specimen Type

See Collection Instructions

Performing Lab

National Jewish Health (NJH) Mycobacteriology

Epic ID

LAB080027

Lab Test Days

24 Hours-8 Weeks

Standard TAT

Monday-Saturday

Collection Information

Specimen Required

5-10 mL Sputum or Lower respiratory track (bronchoalveolar lavage, bronchial lavage, etc.) or 2-4 mL Body fluids (pericardial, synovial, pleural, etc.) or CSF, 1-2 g Fresh tissue, 10 mL Gastric lavage or wash or 5-10 mL Urine in a sterile container. For Fresh tissue, submerge in sterile non-bacteriostatic saline in a sterile container. For Gastric lavage/wash, Neutralize specimen within 4 hours of collection with 100 mg of sodium carbonate.

Processing Information - Lab Use Only

Specimen Stability

Room Temp: Unacceptable (72 Hours for Fresh Tissue or Gastric lavage/wash); Refrigerated: 7 Days (Unacceptable for Fresh Tissue or Gastric lavage/wash); Frozen: Unacceptable

Rejection Criteria

Sample collected in wax containers are not acceptable. Wax containers may produce false-positive smear results; Swabs are not recommended for the isolation of mycobacteria, since they provide limited material and the hydrophobicity of the mycobacterial cell envelop often compromises a transfer from the swabs onto solid media or into broth media; Swabs, stool, and blood cannot be used in the TB NAAT assay; Specimen received in the lab 14 days post-collection.

Processing Instructions

Complete a NJH Mycobacteriology requisition form and submit with specimen Monday-Friday, no weekends or holidays. For Fresh tissue, submerge in sterile non-bacteriostatic saline in a sterile container. For Gastric lavage/wash, Neutralize specimen within 4 hours of collection with 100 mg of sodium carbonate.

Comments

This is the same test as Quest test code 4554 AFB Smear and Culture unless requested for Cystic Fibrosis protocol. Do not duplicate tests. The Centers for Disease Control and Prevention (CDC) recommends that NAAT should be performed on at least one respiratory specimen from each patient with signs and symptoms of pulmonary TB for whom a diagnosis of TB is being considered but has not yet been established, and for whom the test result would alter case management or TB control activities. Smear is not performed for urine, stool, or blood specimens. TB NAAT is not performed on swabs, stool, or blood specimens.

CPT Codes

87556, 87798 (x2), 87206, 87015, 87116, 87798 (x9), 87798 (x7) 87556, 87153 (x2)

Revised

5/29/24