Diagnostic Test Directory

Microbiology Laboratory

AFB Culture and Smear

  • Synonyms: TB Culture, Acid Fast Culture
  • LIS Mnemonic: CAFBG


    ACCEPTABLE SPECIMENS INCLUDE: sterile body fluids, tissue, deep wound material, sputum, urine, gastric aspirate, bronchial specimens.

    Stool may only be sent for HIV positive patients.

    For collection of blood or bone marrow, please refer to the "AFB Culture and Smear - Blood and Bone Marrow" procedure.

    Please refer to Nursing Procedure 4:4a "Collection of TB Specimens" for general guidelines

    Please consult with Respiratory Therapy if having trouble obtaining a sputum sample

    Volume Required

    2 mLs (optimally 5 mLs for CSF)

    Minimum Required

    1-2 mLs (optimally 5 mLs for CSF)


    Send to the lab immediately, optimally within 30 minutes of collection. If transport is delayed, the specimen should be refrigerated. Gastric aspirates must be sent to the laboratory immediately or they will be rejected.


    To ensure recovery of any possible acid fast bacteria, specimens should be sent to the lab immediately.

    Unacceptable conditions

    Specimens should not be submitted on swabs. Saliva specimens are not acceptable for this test. 24-hour urine specimens are not acceptable for this test. Urine should not be submitted in preservative-containing tubes. Gastric specimens should not be contaminated with tap water.

Days Performed



Preliminary report in 7 days




Culture; Smear: Screen- fluorescent, Confirmatory- Kinyoun stain