Acid-fast (Mycobacteria) Smear and Culture With Reflex to Identification

Also known as: Blood Mycobacteria Culture, Culture, Acid-Fast (Sputum, Tissue, Urine, and Gastric Contents), Culture, Blood, Mycobacteria, Mycobacteria Culture (Sputum, Tissue, Urine, and Gastric Contents)

Clinical Use

Order Test

Use

Isolate and identify mycobacteria

Special Instructions

Not provided.

Limitations

Biopsy and body fluid samples have varying efficacy in diagnosing tuberculosis, with sputum and bronchial washing cultures offering higher yields. Some mycobacterial pathogens such as Mycobacterium marinum, Mycobacterium haemophilum, and Mycobacterium genavense require special incubation conditions and media for cultivation, which must be communicated to the laboratory. Sensitivity of gastric aspirate for detecting M. tuberculosis in children is low, while the presence of Mycobacterium smegmatis in genital secretions can produce false positives in urine smears. Mycobacterium avium complex can be isolated from stool samples in patients with AIDS, necessitating ruling out other pathogens for conclusive diagnosis.

Test Details

Methodology

Culture-based

Biomarkers

2 components

Acid Fast SmearAcid Fast Culture

LOINC Codes

Order Codes

94540-2 - Mycobacterial stain + cx Pnl Spec

Result Codes

50941-4 - Mycobacterium Spec Ql Cult
8100-0 - Specimen preparation
11545-1 - Acid fast Stn Spec

Result Turnaround Time

43-56 days

Specimen

Sputum

Volume

5-10 mL

Minimum Volume

2 mL

Container

Sterile container with tight screw-cap seal or green-top (sodium heparin) tube or yellow-top (SPS) tube or Para-Pak® White

Collection Instructions

Collect first morning sputum, not saliva. Collect each of the three separate specimens on separate days.

Storage Instructions

Refrigerate. If sample is to be split for other tests, divide at time of collection so each portion is transported at the appropriate temperature.

Causes for Rejection

Inadequate specimen quantity, swabs from non-superficial exudate sources, use of expired transport media or inappropriate devices, prolonged transport delays, leaking specimens, unlabeled specimens, use of lithium heparin tubes, eSwab devices, paraffin blocks, fixatives, or frozen specimens.