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Test Code 0292581 Acid-Fast Smear for Mycobacterium

Important Note

Must be ordered in conjunction with Mycobacteria (AFB) Culture, 0292623.

Additional Codes

Mayo Test ID

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Detection of acid-fast bacilli in clinical specimens

Testing Algorithm

When this test is ordered, the reflex tests may be performed and charged.


See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Method Name

Auramine-Rhodamine Stain

Reporting Name

Acid Fast Smear For Mycobacterium

Specimen Type


Advisory Information

MTBRP / Mycobacterium tuberculosis Complex, Molecular Detection, PCR is the preferred test for rapid, direct detection of Mycobacterium tuberculosis from clinical specimens.

Necessary Information

Specimen source is required.

Specimen Required

Submit only 1 of the following specimens:


Specimen Type: Body fluid

Container/Tube: Sterile container

Specimen Volume: 1 mL


Specimen Type: Bone marrow

Container/Tube: SPS/Isolator System or green top (lithium heparin)

Specimen Volume: Entire collection


Specimen Type: Gastric washing

Container/Tube: Sterile container

Specimen Volume: 10 mL

Collection Instructions: Neutralize specimen within 4 hours of collection with 100 mg of sodium carbonate per 5 to 10 mL of gastric wash.


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 from source with sterile swab.

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.

Specimen Minimum Volume

Varies; If mycobacterial culture is also requested, then 1.5 mL for body fluid, 3 mL for respiratory specimen, or a pea-sized piece of fresh tissue. If smear only is requested, then 0.5 mL for body fluid, 3 mL for respiratory specimen, or a pea-sized piece of fresh tissue.

Specimen Stability Information

Specimen Type Temperature Time
Varies Refrigerated (preferred) 7 days
  Ambient  7 days

Reject Due To








Blood or serum


Reference Values

Negative (reported as positive or negative)


Patients whose sputum specimens are identified as acid-fast positive should be considered potentially infected with Mycobacterium tuberculosis, pending definitive diagnosis by molecular methods or mycobacterial culture.

Day(s) and Time(s) Performed

Monday through Sunday; Continuously

Analytic Time

1 day

Specimen Retention Time

3-7 days

Test Classification

This test uses a standard method. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


87176-Tissue processing (if appropriate)

87015-Mycobacteria culture, concentration (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SAFB Acid Fast Smear For Mycobacterium 676-7


Result ID Test Result Name Result LOINC Value
SAFB Acid Fast Smear For Mycobacterium 676-7

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
TBT Mycobacteria Culture, Conc No, (Bill Only) No
TISSR Tissue Processing No, (Bill Only) No


If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.