Test Directory

Acid-Fast Smear for Mycobacterium, Varies

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Updated Test Information:

Test Description
Acid-Fast Smear for Mycobacterium, Varies

Acid-Fast Bacilli (AFB), Acid-Fast Smear for Mycobacterium, AFB (Acid-Fast Bacilli), Bacillus, Acid-Fast, MTB (Mycobacterium tuberculosis), Mycobacterium tuberculosis (MTB), Smear, Acid-Fast Bacilli (AFB), TB (Tuberculosis), Tubercle Bacilli: Mycobacterium tuberculosis, Tuberculosis (TB)

Test ID
General Information

Useful For: Detection of acid-fast bacilli in clinical specimens

Specimen Type


Specimen Requirements

Sterile Container

Specimen Collection / Processing Instructions

Submit only 1 of the following specimens:

Specimen Type: Bone marrow
Container/Tube: SPS/Isolator System or green top (lithium heparin)
Specimen Volume: Entire collection

Specimen Type: Respiratory
Sources: Bronchoalveolar lavage fluid, bronchial washing, sputum
Container/Tube: Sterile container
Specimen Volume: 4 mL
Collection Instructions: Collect 3 respiratory specimens for acid-fast smears and culture in patients with clinical and chest X-ray findings compatible with tuberculosis. These 3 specimens should be collected at 8- to 24-hour intervals (24 hours when possible) and should include at least 1 first-morning specimen.

Specimen Type: Stool
Supplies: Stool Collection Kit, Random (T635)
Container/Tube: Sterile container
Specimen Volume: 5-10 g

Specimen Type: Tissue
Container/Tube: Sterile container
Specimen Volume: 5-10 mm
Collection Instructions: Collect a fresh tissue specimen.

Specimen Type: Urine
Container/Tube: Sterile container
Specimen Volume: 2 mL
Collection Instructions: Collect a random urine specimen.

Specimen Type: Swab
Additional Information: Fresh tissue or body fluid is the preferred specimen type instead of a swab specimen. Recovery of mycobacteria and aerobic actinomycetes from swabs is variable.
Sources: Wound, tissue, or body fluid
Container/Tube: Culture transport swab (noncharcoal) Culturette
Specimen Volume: Adequate specimen
Collection Instructions: 1. Before collecting specimen, wipe away any excessive amount of secretion and discharge, if appropriate. 2. Obtain secretions or fluid (>=1 mL) from source. Only collect a swab if unable to collect a tissue or fluid. 3. If smear and culture are requested or both a bacterial culture and mycobacterial culture are requested, collect a second swab to maximize test sensitivity.


Refrigerated (preferred) 7 days
Ambient 7 days

Unacceptable Specimen Conditions

Blood or serum


Artifacts may exhibit nonspecific fluorescence and be confused with organisms.


Auramine-Rhodamine Stain

CPT Code(s)


Minimum Sample Volume

1.5 mL for body fluid, 3 mL for respiratory specimen, or a pea-sized piece of fresh tissue

Reference Range

Negative (reported as positive or negative)

Performing Lab


LOINC Code(s)