Laboratory Services

Acid-Fast Smear for Mycobacterium, Varies

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Updated Test Information:

Test Description
Acid-Fast Smear for Mycobacterium, Varies
Synonym(s)

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
SAFB
General Information

Useful for:



  • Detection of acid-fast bacilli in clinical specimens

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

Specimen Type

  • Body fluid

  • Bone marrow

  • Gastric washing

  • Respiratory

    • Bronchoalveolar lavage fluid

    • Bronchial washing

    • Sputum



  • Stool

  • Tissue

  • Urine

  • Wounds

Specimen Collection / Processing Instructions

Submit only 1 of the following specimens:



  • Specimen Type: Body fluid

    • Container/Tube: Sterile container



  • 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

    • Sources:

      • Wound

      • Tissue

      • Body fluid

      • 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



    • Container/Tube: Culture transport swab (noncharcoal) Culturette

    • Specimen Volume: Adequate specimen

    • Collection Instructions:

      • Before collecting specimen, wipe away any excessive amount of secretion and discharge, if appropriate

      • Obtain secretions or fluid from source with sterile swab

      • Only collect a swab if unable to collect a tissue or fluid

      • If smear and culture are requested or both a bacterial culture and mycobacterial culture are requested, collect a second swab to maximize test sensitivity.





Required Information

Specimen source is required

Stability

  • Refrigerated (preferred):7 days

  • Ambient: 7 days

Unacceptable Specimen Conditions

  • Blood

  • Serum

Limitations

Artifacts may exhibit nonspecific fluorescence and be confused with organisms.

Methodology

Auramine-Rhodamine Stain

Estimated TAT

1 day

Testing Schedule

Monday through Sunday

Retention

3-7 days

CPT Code(s)

87206

Additional Information
Minimum Sample Volume

Varies; If mycobacterial culture is also requested, then 1.5 mL for body fluid, 3 mL for respiratory specimen, or a peasized 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.

Reference Range

Negative

Performing Lab

Mayo

LOINC Code(s)

676-7