Test Catalog

Test Id : TB2LN

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Susceptibility, Mycobacterium tuberculosis Complex, Second Line, Varies

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Overview

Test Catalog

Useful For
Suggests clinical disorders or settings where the test may be helpful

Determination of Mycobacterium tuberculosis complex minimal inhibitory concentrations to second-line antimicrobial agents

Additional Tests
Lists tests that are always performed, at an additional charge, with the initial tests.

Test Id Reporting Name Available Separately Always Performed
STV2 Susceptibility, Mtb Cx, 2nd Line No, (Bill Only) Yes

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the additional test will always be performed at an additional charge.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Minimum Inhibitory Concentration (MIC) by Microtiter Broth Dilution Method

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Susceptibility, Mtb Complex, 2 Line

Aliases
Lists additional common names for a test, as an aid in searching

Acid-Fast Bacilli (AFB)

AFB (Acid-Fast Bacilli)

Antibiotic Susceptibility

Antimicrobial Susceptibility, Mycobacterium tuberculosis

Bacillus, Acid-Fast

MTB (Mycobacterium tuberculosis)

Mycobacteria Antimicrobial Susceptibility (MIC) (Minimum Inhibitory Concentration)

Mycobacterium tuberculosis (MTB)

Susceptibility Testing

Susceptibility, Mycobacterium tuberculosis

TB (Tuberculosis)

Tubercle Bacilli: Mycobacterium tuberculosis

Tuberculosis (TB)

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the additional test will always be performed at an additional charge.

Specimen Type
Describes the specimen type validated for testing

Varies

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. 

 

ORDER QUESTIONS AND ANSWERS

Question ID Description Answers
Q00M0073 Specimen source (Required) and Organism Identification (Required unless concurrent identification test is ordered)

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

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. 

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Other Agar plate

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)
Refrigerated

Useful For
Suggests clinical disorders or settings where the test may be helpful

Determination of Mycobacterium tuberculosis complex minimal inhibitory concentrations to second-line antimicrobial agents

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the additional test will always be performed at an additional charge.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

The Clinical and Laboratory Standards Institute (CLSI) provides a consensus protocol for the methods, antimycobacterial agents, and critical concentrations of each agent to be tested in order to permit standardized interpretation of Mycobacterium tuberculosis complex susceptibility testing results. CLSI guidelines suggest that second-line 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 2 first-line agents.

 

This test uses a broth microdilution method for susceptibility testing of M tuberculosis complex against second-line agents. Agents tested are amikacin, ethionamide, kanamycin, moxifloxacin, ofloxacin, p-aminosalicylic acid, rifabutin, and streptomycin. In contrast to other M tuberculosis complex susceptibility methods which test 1 or 2 critical concentrations of a drug, this method examines a range of drug concentrations and produces a minimal inhibitory concentration result.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Results are reported as minimal inhibitory concentration (MIC) values with units of mcg/mL and tentative interpretations of susceptible or resistant are provided.

Interpretation
Provides information to assist in interpretation of the test results

Results are reported as minimal inhibitory concentrations (MIC) in mcg/mL and tentative interpretations of susceptible or resistant are provided.

 

Agent

MIC range tested

(mcg/mL)

MIC tentative interpretations (mcg/mL)*

Susceptible

Resistant

Amikacin

0.12-16

< or =4.0

>4.0

Cycloserine

2-256

< or =32.0

>32.0

Ethionamide

0.3-40

< or =5.0

>5 .0

Kanamycin

0.6-40

< or =5.0

>5.0

Moxifloxacin

0.06-8

< or =2.0

>2.0

Ofloxacin

0.25-32

< or =2.0

>2.0

Para-aminosalicylic acid

0.5-64

< or =2.0

>2.0 

Rifabutin

0.12-16

< or =0.5

>0.5

Streptomycin

0.25-32

< or =2.0

>2.0

Isoniazid**

0.03-4

< or =0.12

>0.12

Ethambutol**

0.5-32

< or=42

>48

Rifampin**

0.12-16

< or=1

>1

*Laboratory-derived tentative interpretations based on MIC breakpoints established relative to the indirect agar proportion method; consensus breakpoint interpretations are not available at this time.(1)

**This test is used as an alternative to TB1LN / Antimicrobial Susceptibility, Mycobacterium tuberculosis Complex, First Line, Varies when reagents are not available to perform the TB1LN test. These agents are not routinely reported with this test.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Consensus guidelines for interpretive criteria using this method are not available at this time. Breakpoints were established by Mayo Clinic by comparison to the critical concentration for each drug and are considered tentative until consensus guidelines are established.

 

In vitro susceptibility does not guarantee clinical response. Therefore, the decision to treat with a particular agent should not be based solely on the antimicrobial susceptibility testing result.

 

Drug susceptibility testing should be performed on pure culture isolates of Mycobacterium tuberculosis complex.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Hall L, Jude KP, Clark SL, et al: Evaluation of the Sensititre MycoTB plate for susceptibility testing of the Mycobacterium tuberculosis complex against first- and second-line agents. J Clin Microbiol 2012;50:3732-3734

2. Centers for Disease Control and Prevention. Treatment of Tuberculosis, American Thoracic Society, CDC, and Infectious Diseases Society of America. MMWR 2003;52(No. RR-11):1-79

3. Woods GL, Lin S-Y G, Desmond EP: Susceptibility test methods: Mycobacteria, Nocardia and other Actinomycetes. In Manual of Clinical Microbiology. 10th edition. Edited by J Versalovic, KC Carroll, G Funke, et al: Washington, DC, ASM Press, 2011, pp 1215-1238

4. CLSI. Performance Standards for Susceptibility Testing of Mycobacteria, Nocardia species, and Other Aerobic Actinomycetes.First editionCLSI supplement M62. Clinical and Laboratory Standards Institute; 2018

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

This test utilizes the MycoTB broth microtiter dilution plate (Trek Diagnostic Systems, Inc.). Antimicrobials included in the assay are tested according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The plate contains lyophilized antimicrobials which are rehydrated prior to testing. A standardized suspension of the Mycobacterium tuberculosis isolate is added to the plate wells and the plate is incubated at 36 degrees C in 5% to 10% carbon dioxide for up to 14 days. The first drug-containing well with no visible growth is determined to be the endpoint.(CLSI. Susceptibility Testing of Mycobacteria, Nocardiae, and Other Actinomycetes; Approved Standard. Third edition. CLSI standard M24.CLSI, 2018; Hall L, Jude KP, Clark SL, et al: Evaluation of the Sensititre MycoTB plate for susceptibility testing of the Mycobacterium tuberculosis complex against first- and second-line agents. J Clin Microbiol 2012;50:3732-3734; Thermo Scientific Sensititre MIC Susceptibility Plates for Mycobacterium tuberculosis. Product Insert. 011 - MYCOTB - CID9502. Revision Date: 09/07/2016)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

21 to 30 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 year

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

87186-Susceptibility, Mtb Cx, 2nd Line

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
TB2LN Susceptibility, Mtb Complex, 2 Line 29579-0
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
TB2LN Susceptibility, Mtb Complex, 2 Line 29579-0

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
Test Changes - Method 2022-11-30