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HelpTest ID: TB1LN Antimicrobial Susceptibility, Mycobacterium tuberculosis Complex, First Line, Varies
Infectious
Test Down Notes
This test is temporarily unavailable. For additional details, see test update here
Ordering Guidance
This test includes testing for the drugs isoniazid, rifampin and ethambutol. If testing for pyrazinamide is needed, order TBPZA / Susceptibility, Mycobacterium tuberculosis Complex, Pyrazinamide, Varies on the same order number as this test.
Additional Testing Requirements
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 unless identification of organism is provided.
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
Rapid, qualitative susceptibility testing of Mycobacterium tuberculosis complex isolates growing in pure culture
Affirming the initial choice of chemotherapy for M tuberculosis complex infections
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 at an additional charge.
If resistance to a first line antimicrobial agent is detected, reflex testing of second line agents will be performed at an additional charge.
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
Primary treatment regimens for Mycobacterium tuberculosis complex often include isoniazid, rifampin, ethambutol, and pyrazinamide. Susceptibility testing of each M tuberculosis complex isolate against these first-line antimycobacterial agents is a key component of patient management.
In vitro susceptibility testing methods are available to assess the susceptibility of M tuberculosis complex isolates to selected antimycobacterial agents. The Clinical Laboratory Standards Institute (CLSI) provides consensus protocols for the methods, antimycobacterial agents, and critical concentrations of each agent to be tested in order to permit standardized interpretation of M tuberculosis complex susceptibility testing results. Current recommendations indicate that laboratories should use a rapid broth method in order to obtain M tuberculosis susceptibility data as quickly as possible to help guide patient management.
This test uses an FDA-cleared commercial system for rapid broth susceptibility testing of M tuberculosis complex and assesses resistance to the antimycobacterial drugs isoniazid, rifampin and ethambutol at the critical concentrations.
Pyrazinamide rapid broth susceptibility testing must be ordered separately (TBPZA / Susceptibility, Mycobacterium tuberculosis Complex, Pyrazinamide, Varies).
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 (0.1 mcg/mL) but not exhibiting resistance to high levels (0.4 mcg/mL) 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. Blumberg HM, Burman WJ, Chaisson RE, et al: American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America: treatment of tuberculosis. Am J Respir Crit Care Med 2003;167(4):603-662
2. Inderlied CB, Pfyffer GE: Susceptibility test methods: Mycobacteria. In Manual of Clinical Microbiology. Eighth edition. Edited by PR Murray, EJ Baron, JH Jorgensen, et al. ASM Press, 2003, pp 1149-1177
3. LaBombardi VJ: Comparison of the ESP and BACTEC Systems for testing susceptibilities of Mycobacterium tuberculosis complex isolates to pyrazinamide. J Clin Microbiol 2002;40:2238-2239
4. CLSI. Susceptibility Testing of Mycobacteria, Nocardia species, and Other Aerobic Actinomycetes. Third edition. CLSI standard M24. Clinical and Laboratory Standards Institute; 2018
5. CLSI. Performance Standards for Susceptibility Testing of Mycobacteria, Nocardia species, and Other Aerobic Actinomycetes. First edition. CLSI supplement M62. Clinical and Laboratory Standards Institute; 2018
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