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HelpTest ID: TB1LN Antimicrobial Susceptibility, Mycobacterium tuberculosis Complex, First Line, Varies
Infectious
Test Down Notes
Effective August 08, 2024:  This test is temporarily unavailable due to reagent supply. The downtime is expected to be >30 days. Order TB2LN as an alternative. See test notification here.
Ordering Guidance
If testing for the first-line agent pyrazinamide is desired, order TBPZA / Susceptibility, Mycobacterium tuberculosis Complex, Pyrazinamide, Varies.
Additional 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. See Infectious Specimen Shipping Guidelines in Special Instructions.
2. Place specimen in a large infectious container (T146) 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.
Forms
If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.
Useful For
Susceptibility testing of Mycobacterium tuberculosis complex isolates growing in pure culture.
Additional Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| STV1 | Susceptibility, Mtb Complex, Broth | No, (Bill Only) | Yes |
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| TB2LN | Susceptibility, Mtb Complex, 2 Line | Yes | No |
Testing Algorithm
When this test is ordered, the additional test will always be performed and charged separately.
If resistance to a first line antimicrobial agent is detected, reflex testing of second line agents will be performed and charged.
Special Instructions
Method Name
Broth Dilution at Critical Drug Concentrations
Reporting Name
Susceptibility, Mtb Complex, 1 LineSpecimen Type
VariesSpecimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Refrigerated | |||
Clinical Information
Initial treatment regimens for Mycobacterium tuberculosis complex often include isoniazid, rifampin, ethambutol, and pyrazinamide. Susceptibility testing of M tuberculosis complex isolates against these antimycobacterial agents is a key component of patient management.
The Clinical Laboratory Standards Institute (CLSI) provides consensus protocols for the methods, antimycobacterial agents, and critical concentrations of each agent to be tested to permit standardized interpretation of M tuberculosis complex susceptibility test results.
This test uses an US Food and Drug Administration cleared commercial system for rapid broth susceptibility testing of M tuberculosis complex and assesses resistance to antimycobacterial drugs at the CLSI-recommended critical concentrations.
Reference Values
Results are reported as susceptible or resistant.
Interpretation
Mycobacterium tuberculosis complex isolates are reported as susceptible or resistant to the aforementioned drugs at the critical concentrations.
Some experts believe that patients infected with strains exhibiting resistance to low levels of isoniazid but not exhibiting resistance to high levels may benefit from continuing therapy with this agent. A specialist in the treatment of tuberculosis should be consulted concerning the appropriate therapeutic regimen and dosages.
Clinical Reference
1. Nahid P, Mase SR, Migliori GB, et al. Treatment of Drug-Resistant Tuberculosis. An Official ATS/CDC/ERS/IDSA Clinical Practice Guideline [published correction appears in Am J Respir Crit Care Med. 2020 Feb 15;201(4):500-501
2. Clinical and Laboratory Standards Institute (CLSI). Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. 3rd ed. CLSI standard M24. CLSI; 2018
3. Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. 2nd ed. CLSI supplement M24S. CLSI; 2023
Day(s) Performed
Monday through Sunday
Report Available
10 to 21 daysTest 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
87188 x 3-Antimicrobial Susceptibility, Mycobacterium tuberculosis Complex, Broth Method
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| TB1LN | Susceptibility, Mtb Complex, 1 Line | 29579-0 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| TB1LN | Susceptibility, Mtb Complex, 1 Line | 29579-0 |
mml-mycobacteria