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HelpTest Code LAB3311 Mycobacterium tuberculosis Complex, Molecular Detection, PCR, Varies
Additional Codes
MTBRP
Useful For
Rapid detection of Mycobacterium tuberculosis complex DNA (preferred method)
Detection of M tuberculosis, when used in conjunction with mycobacterial culture
This test should not be used to determine bacteriologic cure or to monitor response to therapy.
This test is not intended for the detection of latent tuberculosis and must not be used as a substitute for tests intended for detection of latent tuberculosis such as the tuberculin skin test or an interferon gamma release assay.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
VariesAdditional Testing Requirements
This test must always be performed in conjunction with mycobacterial culture. If your facility is unable to perform mycobacterial culture, order CTB / Mycobacteria and Nocardia Culture, Varies concurrently with this test.
Shipping Instructions
Specimen must arrive within 7 days of collection; if greater than 7 days of collection, the specimen will be rejected.
Necessary Information
Specimen source is required.
Specimen Required
The high sensitivity of amplification by polymerase chain reaction (PCR) requires the specimen to be processed in an environment in which contamination of the specimen by Mycobacterium tuberculosis DNA is unlikely.
If a single specimen is being shared between mycobacteria culture, acid-fast smear, and/or M tuberculosis PCR, a minimum volume of 2 mL for body fluid, 3 mL for respiratory specimen, or a pea-sized piece of tissue should be obtained. Specimen volumes less than indicated may decrease sensitivity of testing. If insufficient volume is submitted, test or tests will be canceled.
Preferred Specimens: Body fluid, cerebrospinal fluid (CSF), ocular fluid, respiratory (eg, bronchoalveolar lavage [BAL], bronchial washing, sputum), feces, fresh tissue, bone, bone marrow, or urine
Submit a raw clinical sample (not a culture isolate) for testing.
Acceptable Specimens: If no fresh specimen is available, digested respiratory specimens treated with N-acetyl-L-cysteine/sodium hydroxide (NALC/NaOH) are acceptable (eg, BAL, bronchial washing, respiratory fluid, sputum, or tracheal secretion), as are NALC/NaOH-treated gastric washings.
Submit only 1 of the following specimens:
Specimen Type: Body fluid
Sources: Body, bone marrow aspirate, ocular, or CSF
Container/Tube: Sterile container
Specimen Volume: 1 mL
Additional Information: Only fresh, non-NALC/NaOH-digested body fluids are acceptable.
Specimen Type: Gastric washing
Container/Tube: Sterile container
Specimen Volume: 2 mL
Collection Instructions: Neutralize specimen within 4 hours of collection with 20 mg of sodium carbonate per 2 mL of gastric washing.
Specimen Type: Respiratory
Sources: BAL, bronchial washing, or sputum
Container/Tube: Sterile container
Specimen Volume: 1 mL if only PCR ordered or 3 mL if PCR ordered with smear and culture
Specimen Type: Feces
Container/Tube: Sterile container
Specimen Volume: 5 to 10 g
Additional Information: Only fresh, non-NALC/NaOH-digested fecal specimens are acceptable.
Specimen Type: Tissue
Sources: Fresh tissue, bone, or bone marrow biopsy
Container/Tube: Sterile container
Specimen Volume: 5 to 10 mm
Collection Instructions: Keep moist with sterile water or sterile saline
Additional Information: Only fresh, non-NALC/NaOH-digested tissue is acceptable.
Specimen Type: Urine
Container/Tube: Sterile container
Specimen Volume: 1 mL
Collection Instructions: Collect a random urine specimen.
Acceptable
Specimen Type: NALC/NaOH-digested respiratory specimens
Sources: Lavage fluid, bronchial washing, gastric washing, respiratory fluid, sputum, or tracheal secretion
Container/Tube: Sterile container
Specimen Volume: 2 mL
Collection Instructions:
1. Submit digested specimen treated with NALC/NaOH.
2. Clearly indicate on container and order form that specimen is a digested specimen.
Specimen Minimum Volume
Body fluid, nondigested respiratory specimen, urine: 0.5 mL; Fresh tissue or bone: 5 mm; NALC-NaOH-digested specimen, gastric washing: 1 mL; Stool: 5 g
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Refrigerated (preferred) | 7 days | |
| Frozen | 7 days |
Reference Values
Not applicable
Day(s) Performed
Monday through Sunday
CPT Code Information
87556-Mycobacterium tuberculosis, complex, molecular detection, PCR
87015-Mycobacteria culture, concentration (if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| MTBRP | M tuberculosis Complex PCR | 38379-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| SRC62 | MTB Complex PCR, Specimen Source | 31208-2 |
| 56044 | MTB Complex PCR, Result | 38379-4 |
Interpretation
A positive result indicates the presence of Mycobacterium tuberculosis complex DNA. Members of the M tuberculosis complex detected by this assay include M tuberculosis, Mycobacterium bovis, Mycobacterium bovis bacillus Calmette-Guerin, Mycobacterium africanum, Mycobacterium canettii, and Mycobacterium microti. Other species within the M tuberculosis complex (eg, Mycobacterium caprae, Mycobacterium pinnipedii, and Mycobacterium mungi) should, in theory, be detected using the primer and probe sequences in this assay, but they have not been tested. This assay method does not distinguish between the species of the M tuberculosis complex. If an isolate of M tuberculosis complex is already available, species identification can be performed; order TBSP / Mycobacterium tuberculosis Complex Species Identification, PCR, Varies.
A negative result indicates the absence of detectable M tuberculosis complex DNA.
Isoniazid (INH) resistance mediated through a katG variant will be reported when observed but lack of a katG variant does not imply that the isolate is susceptible to INH. There are other genetic loci in addition to katG that can contribute to resistance for this drug.
Method Description
Following specimen digestion and decontamination using N-acetyl cysteine and sodium hydroxide, genomic DNA is extracted using the MagNA Pure (Roche Applied Sciences) extraction platform. The purified genomic DNA is placed on the LightCycler instrument, which amplifies and monitors, by fluorescence, the development of target nucleotide sequences after each polymerase chain reaction (PCR) cycle. A specific target sequence from a portion of the katG gene from Mycobacterium tuberculosis complex is amplified and the resulting segment is detected by melt-curve analysis using sequence-specific fluorescence resonance energy transfer hybridization probes. The LightCycler PCR assay is a closed PCR system that greatly reduces the potential for false-positive results due to specimen cross-contamination as compared with traditional open-system PCR or other amplification methods like transcription-mediated amplification.(Buckwalter SP, Connelly BJ, Louison LK, et al: Description, validation, and review of a decade of experience with a laboratory-developed PCR test for detection of Mycobacterium tuberculosis complex in pulmonary and extrapulmonary specimens. J Clin Tuberc Other Mycobact Dis. 2022 Nov 12;29:100340. doi: 10.1016/j.jctube.2022.100340)
Report Available
1 to 3 daysSpecimen Retention Time
7 daysReject Due To
| Blood Specimen in anaerobe vial or viral transport medium (including but not limited to M4, M5, BD viral transport media, thioglycolate broth) Swabs Tissues in formalin fluid |
Reject |
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| TBT | Concentration, Mycobacteria | No, ( Bill Only) | No |
Testing Algorithm
When this test is ordered, the reflex test may be performed at an additional charge.
For more information see Meningitis/Encephalitis Panel Algorithm.
Method Name
Real-Time Polymerase Chain Reaction (PCR)
Forms
If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.