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HelpTest Code TB2LN Susceptibility, Mycobacterium tuberculosis Complex, Second Line, Varies
Infectious
Useful For
Determination of Mycobacterium tuberculosis complex minimal inhibitory concentrations to second-line antimicrobial agents
Additional Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| STV2 | Susceptibility, Mtb Cx, 2nd Line | No, (Bill Only) | Yes |
Testing Algorithm
When this test is ordered, the additional test will always be performed at an additional charge.
Special Instructions
Reporting Name
Susceptibility, Mtb Complex, 2 LineSpecimen Type
VariesAdditional Testing Requirements
If organism identification is not provided, CTB / Mycobacteria and Nocardia Culture, Varies or CTBID / Culture Referred for Identification, Mycobacterium and Nocardia, Varies must also be ordered and will be charged separately.
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: Organism
Supplies: Infectious Container, Large (T146)
Container/Tube: Middlebrook 7H10 agar slant
Specimen Volume: Isolate
Collection Instructions: Organism must be in pure culture, actively growing.
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Refrigerated | |||
Reject Due To
| Agar plate | Reject |
Clinical Information
The Clinical and Laboratory Standards Institute (CLSI) provides a consensus protocol for the methods, antimycobacterial agents, and concentrations of each agent to be tested to permit standardized interpretation of Mycobacterium tuberculosis complex susceptibility testing results. CLSI guidelines suggest that additional agents should be tested when an isolate of M tuberculosis complex is resistant to rifampin, is monoresistant to the critical concentration of isoniazid and the physician intends to use a fluoroquinolone for therapy or is resistant to any combination of two first-line agents.
This test uses a broth microdilution minimal inhibitory concentration (MIC) method for susceptibility testing of M tuberculosis complex against antimycobacterial agents. Agents tested are amikacin, ethionamide, kanamycin, moxifloxacin, ofloxacin, p-aminosalicylic acid, rifabutin, and streptomycin.
Reference Values
Interpretive criteria and reporting guidelines are followed using the Clinical Laboratory Standards Institute (CLSI) M24S document.
Interpretation
Results are reported as minimal inhibitory concentrations in mcg/mL.
This test is used as an alternative to TB1LN / Antimicrobial Susceptibility, Mycobacterium tuberculosis Complex, First Line, Varies for ethambutol, isoniazid and rifampin when reagents are not available to perform the TB1LN test. Ethambutol, isoniazid, and rifampin are not routinely reported with this test.
Method Description
This test utilizes the Sensititre MycoTB broth microtiter dilution plate (Trek/ThermoFisher). Antimicrobials are tested according to CLSI M24 guidelines.(Thermo Scientific Sensititre MIC Susceptibility Plates for Mycobacterium tuberculosis. Product Insert. 011-MYCOTB-CID9502. Revision Date: 09/07/2016; Brown-Elliott, BA, Cirillo DM, Musser KA, Rowlinson M-C. Susceptibility Test Methods: Mycobacteria, Nocardia, and Other Actinomycetes. In: Carroll KC, Pfaller MA, eds. Manual of Clinical Microbiology, 13th Edition. ASM Press, 2023)
Day(s) Performed
Monday through Sunday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
87186-Susceptibility, Mtb Cx, 2nd Line
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| TB2LN | Susceptibility, Mtb Complex, 2 Line | 29579-0 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| TB2LN | Susceptibility, Mtb Complex, 2 Line | 29579-0 |
Method Name
Minimum Inhibitory Concentration (MIC) by Microtiter Broth Dilution Method
Secondary ID
34550Specimen Minimum Volume
See Specimen Required