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25475 Mycobacterium tuberculosis Complex, Molecular Detection, PCR (MTBRP)

Mycobacterium tuberculosis Complex, Molecular Detection, PCR (MTBRP)
Test Code: MTBRPSO
Synonyms/Keywords
Acid-Fast Bacilli, AFB, Bacillus-Acid Fast, MTB, ​​Mycobacterium tuberculosis, TB, Tuberculosis, Mycobacterium tuberculosis, Tubercle Bacilli: Mycobacterium tuberculosis,
Test Components
Mycobacterium tuberculosis complex DNA unique sequence within the katG gene.​​
Useful For
​Rapid detection of Mycobacterium tuberculosis complex DNA, preferred method. Detection of Mycobacterium tuberculosis, when used in conjunction with mycobacterium culture.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​No ​Body fluid (body, bone marrow, aspirate, ocular, or CSF) ​Sterile container ​1.0 mL ​0.5 mL
​No ​Gastric washing ​Sterile container ​2.0 mL 1.0 mL
​No ​Respiratory (BAL, bronchial washing, or sputum) ​Sterile container ​3.0 mL ​0.5 mL
​No ​Stool ​Sterile container 10 grams ​5 grams
​No ​Tissue (fresh tissue, bone, or bone marrow biopsy) ​Sterile container ​10 mm ​5 mm
​No ​Urine ​Sterile container ​1.0 mL ​0.5 mL
​No​NALC/NaOH-digested respiratory specimens (lavage fluid, bronchial washing, gastric washing, respiratory fluid, sputum, or tracheal secretion)​Sterile container​2.0 mL​1.0 mL
Collection Processing Instructions

This test should always be performed in conjunction with mycobacterial culture.

​Body fluid: Only fresh, non-NALC/NaOH-digested body fluid is acceptable.

Gastric washing: Neutralize specimen within 4 hours of collection with 20 mg of sodium carbonate per 2 mL of gastric washing.

Stool: Only fresh, non-NALC/NaOH-digested stool is acceptable. 

Tissue: Only fresh - keep moist with sterile water or saline, non-NALC/NaOH-digested tissue is acceptable.

Urine: Collect a random urine specimen.

NALC/NaOH-digested respiratory: Submit digested specimen treated with NALC/NaOH. Clearly indicate on the container and order form that specimen is a digested specimen.

Specimen Stability Information
Specimen Type Temperature Time
Varies​ ​ ​ ​Refrigerate (preferred) ​7 days
​Frozen ​7 days
Rejection Criteria
Blood specimen in anaerobe vial or viral transport medium (including but not limited to M4, M5, BD viral transport media, thioglycolate broth)
​Swab tissues in formalin fluid
Interference

​This rapid PCR assay detects Mycobacterium tuberculosis complex nucleic acid and, therefore, does not distinguish between viable, disease-related organisms and nucleic acid persisting from prior infection. Test results should be correlated with patient symptoms and clinical presentation before a definitive diagnosis is made.

A negative result does not rule out the presence of M tuberculosis complex or active disease because the organism may be present at levels below the limit of detection for this assay.

This test has not been studied for use with specimens from patients being treated with antituberculous agents and, therefore, should not be used to determine bacteriologic cure or to monitor response to therapy. It is not known how long the PCR assay can remain positive following treatment for M tuberculosis.

The sensitivity of this test with stool specimens is 80% and testing of additional stool specimens should be considered if the result from the first specimen is negative.

Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories ​Monday through Sunday ​1-3 days ​Real-Time Polymerase Chain Reaction (PCR)
Reference Lab
Test Information

Each year, Mycobacterium tuberculosis accounts for approximately 1.4 million deaths and is responsible for 9 million newly diagnosed cases of tuberculosis worldwide. M tuberculosis is spread from person-to-person via respiratory transmission, and has the potential to become resistant to many or all of the antibiotics currently used if antimycobacterial treatment is not promptly initiated. Therefore, rapid and accurate detection of M tuberculosis in patient specimens is of clinical and public health importance.

Conventional culture methods can generally detect M tuberculosis in 2 to 3 weeks, although up to 8 weeks of incubation may be required in some instances. Developed at Mayo Clinic, this rapid PCR assay detects M tuberculosis complex DNA directly from respiratory specimens and other specimens without waiting for growth in culture and, therefore, the results are available the same day the specimen is received in the laboratory. A mycobacterial culture should always be performed in addition to the PCR assay. The PCR assay is rapid but the culture has increased sensitivity over the PCR assay. The PCR assay targets a unique sequence within the katG gene, which is present in members of the M tuberculosis complex. In addition, the assay can detect genotypic resistance to isoniazid mediated by mutations in the katG target, when present.

Reference Range Information
​See Report
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, M bovis, M bovis bacillus Calmette-Guerin (BCG), M africanum, M canettii, and M microti. Other species within the M tuberculosis complex (eg, M caprae, M pinnipedii, and M 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.

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.

Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
87556​ ​1 ​M. tuberculosis Complex PCR
​87015 ​1 ​Mycobacteria Culture, Conc ​If needed (Reflex)
Synonyms/Keywords
Acid-Fast Bacilli, AFB, Bacillus-Acid Fast, MTB, ​​Mycobacterium tuberculosis, TB, Tuberculosis, Mycobacterium tuberculosis, Tubercle Bacilli: Mycobacterium tuberculosis,
Test Components
Mycobacterium tuberculosis complex DNA unique sequence within the katG gene.​​
Ordering Applications
Ordering Application Description
​Clinical Order Manager ​M. Tuberculosis, PCR
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​No ​Body fluid (body, bone marrow, aspirate, ocular, or CSF) ​Sterile container ​1.0 mL ​0.5 mL
​No ​Gastric washing ​Sterile container ​2.0 mL 1.0 mL
​No ​Respiratory (BAL, bronchial washing, or sputum) ​Sterile container ​3.0 mL ​0.5 mL
​No ​Stool ​Sterile container 10 grams ​5 grams
​No ​Tissue (fresh tissue, bone, or bone marrow biopsy) ​Sterile container ​10 mm ​5 mm
​No ​Urine ​Sterile container ​1.0 mL ​0.5 mL
​No​NALC/NaOH-digested respiratory specimens (lavage fluid, bronchial washing, gastric washing, respiratory fluid, sputum, or tracheal secretion)​Sterile container​2.0 mL​1.0 mL
Collection Processing

This test should always be performed in conjunction with mycobacterial culture.

​Body fluid: Only fresh, non-NALC/NaOH-digested body fluid is acceptable.

Gastric washing: Neutralize specimen within 4 hours of collection with 20 mg of sodium carbonate per 2 mL of gastric washing.

Stool: Only fresh, non-NALC/NaOH-digested stool is acceptable. 

Tissue: Only fresh - keep moist with sterile water or saline, non-NALC/NaOH-digested tissue is acceptable.

Urine: Collect a random urine specimen.

NALC/NaOH-digested respiratory: Submit digested specimen treated with NALC/NaOH. Clearly indicate on the container and order form that specimen is a digested specimen.

Specimen Stability Information
Specimen Type Temperature Time
Varies​ ​ ​ ​Refrigerate (preferred) ​7 days
​Frozen ​7 days
Rejection Criteria
Blood specimen in anaerobe vial or viral transport medium (including but not limited to M4, M5, BD viral transport media, thioglycolate broth)
​Swab tissues in formalin fluid
Interference

​This rapid PCR assay detects Mycobacterium tuberculosis complex nucleic acid and, therefore, does not distinguish between viable, disease-related organisms and nucleic acid persisting from prior infection. Test results should be correlated with patient symptoms and clinical presentation before a definitive diagnosis is made.

A negative result does not rule out the presence of M tuberculosis complex or active disease because the organism may be present at levels below the limit of detection for this assay.

This test has not been studied for use with specimens from patients being treated with antituberculous agents and, therefore, should not be used to determine bacteriologic cure or to monitor response to therapy. It is not known how long the PCR assay can remain positive following treatment for M tuberculosis.

The sensitivity of this test with stool specimens is 80% and testing of additional stool specimens should be considered if the result from the first specimen is negative.

Useful For
​Rapid detection of Mycobacterium tuberculosis complex DNA, preferred method. Detection of Mycobacterium tuberculosis, when used in conjunction with mycobacterium culture.
Test Components
Mycobacterium tuberculosis complex DNA unique sequence within the katG gene.​​
Reference Range Information
​See Report
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, M bovis, M bovis bacillus Calmette-Guerin (BCG), M africanum, M canettii, and M microti. Other species within the M tuberculosis complex (eg, M caprae, M pinnipedii, and M 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.

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.

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories ​Monday through Sunday ​1-3 days ​Real-Time Polymerase Chain Reaction (PCR)
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
87556​ ​1 ​M. tuberculosis Complex PCR
​87015 ​1 ​Mycobacteria Culture, Conc ​If needed (Reflex)
For most current information refer to the Marshfield Laboratory online reference manual.