Home
HelpTest Code TBSP Mycobacterium tuberculosis Complex Species Identification, PCR, Varies
Infectious
Ordering Guidance
This test should be used to identify the species within the Mycobacterium tuberculosis complex from a known M tuberculosis complex isolate.
For identification of M tuberculosis complex from isolate growth, order CTBID / Culture Referred for Identification, Mycobacterium and Nocardia, Varies.
For rapid identification of M tuberculosis complex directly from a specimen, order MTBRP / Mycobacterium tuberculosis Complex, Molecular Detection, PCR, Varies or MTBXS / Mycobacterium tuberculosis Complex, Molecular Detection and Rifampin Resistance, PCR, Sputum.
Shipping Instructions
1. For shipping information see Infectious Specimen Shipping Guidelines.
2. Place specimen in a large infectious container and label as an etiologic agent/infectious substance.
Necessary Information
Specimen source and suspected organism identification are required.
Specimen Required
Specimen Type: Mycobacterium tuberculosis complex isolate growing in pure culture
Supplies: Infectious Container, Large (T146)
Container/Tube: Growth on solid slant media, eg, Middlebrook 7H10, 7H11 and Lowenstein Jensen; growth in broth medium, eg, Mycobacteria Growth Indicator Tube, 7H9 broth BACT/ALERT MP or VersaTREK
Specimen Volume: Isolate with visible growth on solid media; if broth is sent, 3 mL or more of broth culture
Collection Instructions:
1. Bacterial organism must be submitted in pure culture, actively growing. Do not submit mixed cultures.
2. Place specimen in a large infectious container and label as an etiologic agent/infectious substance.
Additional Information: If subculture to Middlebrook agar medium is needed to ensure purity, turnaround time for results may be delayed.
Useful For
Determining the species of a Mycobacterium tuberculosis complex culture isolate
Additional Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| RTBSP | Id, Mtb Speciation, PCR | No, (Bill Only) | Yes |
Testing Algorithm
When this test is ordered, species identification will always be performed at an additional charge.
Special Instructions
Method Name
Real-Time Polymerase Chain Reaction (PCR)
Reporting Name
M tuberculosis species ID, PCRSpecimen Type
VariesSpecimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Refrigerated | |||
Reject Due To
| Agar plate Mixed culture |
Reject |
Clinical Information
This assay provides a species-level identification of microbiologic culture isolates previously identified to be a member of the Mycobacterium tuberculosis complex. Species level identification can be important for patient care or for epidemiologic investigations. For example, the species-level identification of Mycobacterium bovis bacillus Calmette-Guerin (BCG) can assist with identification of disseminated infections following use of the vaccine as an adjuvant during chemotherapy.
Reference Values
Not applicable
Interpretation
This assay can differentiate the most common species within the Mycobacterium tuberculosis complex, which are, M tuberculosis, Mycobacterium bovis, Mycobacterium bovis bacillus Calmette-Guerin (BCG; the vaccine strain), Mycobacterium canettii, Mycobacterium caprae, Mycobacterium microti, and Mycobacterium pinnepedii. This assay cannot distinguish Mycobacterium africanum from Mycobacterium mungi so if that result is obtained, the organism will be reported as M africanum/M mungi.
Cautions
Only isolates of Mycobacterium tuberculosis complex should be submitted and they must be in pure culture. Nontuberculous mycobacteria should not be submitted. Mixed cultures will result in a delay because the M tuberculosis complex organism must be isolated prior to performing the polymerase chain reaction assay.
This assay has not been verified for the direct detection of M tuberculosis complex from clinical specimens. It is intended for use on microbiologic culture isolates already identified as M tuberculosis complex.
Supportive Data
Type strains of Mycobacterium tuberculosis complex members were tested using the species identification polymerase chain reaction (PCR) assay and all were identified correctly. Type strains tested were M tuberculosis ATCC 27294, Mycobacterium bovis ATCC 19210, M bovis BCG ATCC 101472, Mycobacterium africanum ATCC 25240, Mycobacterium microti ATCC 19422, Mycobacterium caprae ATCC BAA 824, Mycobacterium pinnipedii ATCC BAA 688.
In addition, a clinical isolate of Mycobacterium canettii, identified by whole genome sequencing at the New York State Department of Health Wadsworth Center, was tested and confirmed to be M canettii by the M tuberculosis complex species identification PCR assay.
As part of the verification of this assay, 78 M tuberculosis complex isolates with the species identified at a reference laboratory were tested using the species identification PCR assay. All 78 isolates were correctly identified to the species level.
Table. Species reported by reference laboratory
|
LC 480 PCR results |
|
M tuberculosis |
M bovis |
M bovis BCG |
M africanium |
|
M tuberculosis |
53 |
|
|
|
|
|
M bovis |
|
4 |
|
|
|
|
M bovis BCG |
|
|
14 |
|
|
|
M africanium |
|
|
|
7 |
Although the species identification test can be used only for mycobacterial isolates already identified as M tuberculosis complex, 159 other Mycobacterium species isolates were tested to determine whether any nontuberculous mycobacteria would be positive in the test. No nontuberculous mycobacteria were positive in the M tuberculosis complex species identification PCR assay.
Method Description
The method uses real-time polymerase chain reaction on the LightCycler 480 platform with Mycobacterium tuberculosis complex-specific primers coupled with fluorescence resonance energy transfer probes to differentiate the members of the complex to the species level. The probes target specific regions of difference (RD) within the M tuberculosis complex genome. Detection of the presence or absence of these RD allows for differentiation of the species within the M tuberculosis complex.(Halse TA, Escuyer VE, Musser KA. Evaluation of a single tube multiplex real-time PCR for differentiation of members of the Mycobacterium tuberculosis complex in clinical specimens. J Clin Microbiol. 2011;49:2562-2567; Warshauer DM, Salfinger M, Desmond E, and Lin S-Y G. Mycobacterium tuberculosis complex. In: Carroll KC, Pfaller MA, Landry ML, et al, eds. Manual of Clinical Microbiology. 12th edition, ASM Press; 2019:576-594)
The RD's expected for each species within the M tuberculosis complex are shown in the table below. "+" indicates the region is present and "-" indicates the region is absent.
|
Expected RD signature patterns |
RD1 |
RD4 |
RD9 |
RD12 |
RD9-2 |
|
Mycobacterium tuberculosis |
+ |
+ |
+ |
+ |
+ |
|
Mycobacterium bovis |
+ |
- |
- |
- |
+ |
|
Mycobacterium bovis BCG |
- |
- |
- |
- |
+ |
|
Mycobacterium africanum |
+ |
+ |
- |
+ |
+ |
|
Mycobacterium canettii |
+ |
+ |
+ |
- |
+ |
|
Mycobacterium caprae |
+ |
+ |
- |
- |
+ |
|
Mycobacterium microti |
- |
+ |
- |
+ |
+ |
|
Mycobacterium mungi |
+ |
+ |
- |
+ |
+ |
|
Mycobacterium pinnepedii |
+ |
+ |
- |
- |
+ |
Day(s) Performed
Monday through Friday
Report Available
7 to 14 daysSpecimen Retention Time
Subculture: 1 yearPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
87150
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| TBSP | M tuberculosis species ID, PCR | 94576-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| TBSP | M tuberculosis species ID, PCR | 94576-6 |