Mycobacterium tuberculosis Complex Detection and Rifampin Resistance (PCR), Acid-fast Bacillus (AFB) Smear, and AFB Culture (Sputum)
Use
This test is used to detect and identify Mycobacterium tuberculosis complex and an rpoB mutation that is associated with rifampin resistance.
Special Instructions
Specimen processing may include N-acetyl-L-cystine-sodium hydroxide treatment or similar to decontaminate and concentrate samples. Smears should not be performed on blood or when the sample volume is less than 2 mL. Additional charges may apply for identification using real-time PCR, MALDI-TOF, or nucleic acid sequencing. The culture process can also detect Nocardia species and other aerobic Actinomyces.
Limitations
While this test is highly effective for identifying the Mycobacterium tuberculosis complex and rifampin resistance, there are limitations. False negatives may occur if organisms are not present in adequate numbers or if they have been selectively decontaminated. False positives can result if there is contamination during sample collection or processing. The test does not evaluate susceptibility to other antibiotics besides rifampin and is not intended to replace comprehensive culture-based drug susceptibility testing. Negative results do not exclude infection with Mycobacterium tuberculosis or other mycobacterial species.
Methodology
PCR-based (Nested real-time PCR)
Biomarkers
LOINC Codes
- 33634-7
- 50941-4
- 14556-5
- 33634-7
- 8100-0
- 11545-1
Result Turnaround Time
43-56 days
Related Documents
For more information, please review the documents below
Specimen
Sputum
Volume
5 mL
Minimum Volume
3 mL
Container
Sterile container with tight screw-cap seal
Collection Instructions
Determined by submitting institution
Storage Instructions
Refrigerate. If sample is to be split for other tests, specimen should be divided at the time of collection so that each portion is transported at the appropriate temperature.
Causes for Rejection
Quantity not sufficient; inappropriate specimen source (i.e., not sputum); specimen received after leaking out of transport container into the specimen bag; inappropriate transport device; unlabeled specimen container or container with a single patient identifier; name discrepancy between the specimen container label and the computer or the requisition; specimen received after prolonged delay (more than seven days); specimen in a paraffin block; specimen in a fixative; specimen at room temperature received after 72 hours; specimen submitted frozen
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 7 days |