Test Catalog

Test Id : MMLSG

Antimicrobial Susceptibility, Acid-Fast Bacilli, Slowly Growing, Varies

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

Determination of resistance of slowly growing mycobacteria to 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
RSLG Susceptibility Slow Grower 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, susceptibility for slow growers will be performed at an additional charge. Antimicrobials are tested and reported using the Clinical and Laboratory Standards Institute (CLSI) guidelines.(1, 2)

 

Antimicrobials tested for Mycobacterium avium complex (MAC): amikacin, clarithromycin, clofazimine, linezolid, and moxifloxacin. Per the CLSI standards set in document M24 for susceptibility testing of M avium complex, Minimum inhibitory concentration (MIC) data for ethambutol, rifampin, and rifabutin have shown poor correlation with clinical response.(1,2) Therefore, although these drugs are in the recommended Infectious Diseases Society of America (IDSA) treatment regimen for MAC, breakpoints for these agents that separate susceptible from resistant strains cannot be determined.(3,4) Reporting of MICs for these drugs is not recommended for use in patient care. Synergy testing for nontuberculous mycobacteria has also not been standardized and its value is unclear at this time. For these reasons, ethambutol, rifampin, rifabutin and combinations of these drugs will not be tested or reported. M avium complex isolates will not be forwarded to other institutions for susceptibility testing of rifampin, rifabutin, ethambutol or synergy testing since this practice is not recommended by the CLSI nor the IDSA.(5,6) An Infectious Diseases expert with experience in difficult or refractory MAC cases should be consulted since in vitro MIC values are not useful for these drugs.

 

Antimicrobials tested for all other slowly growing Mycobacterium species: amikacin, clarithromycin, clofazimine, ciprofloxacin, doxycycline, linezolid, minocycline, moxifloxacin, rifabutin, rifampin, and trimethoprim /sulfamethoxazole. Interpretive criteria are provided according to the CLSI standards.(1,2)

 

Clofazimine interpretive criterion is not available.

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

Microtiter Broth Dilution

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

Susc, AFB, Slowly Growing

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

Acid-Fast Bacilli (AFB)

AFB (Acid-Fast Bacilli)

Antibiotic Susceptibility

Bacillus, Acid-Fast

MIC (Minimum Inhibitory Concentration)

Minimum Inhibitory Concentration (MIC)

Mycobacteria Antimicrobial Susceptibility (MIC) (Minimum Inhibitory Concentration)

Mycobacterium marinum Susceptibility Testing

Mycobacterium kansasii Susceptibility Testing

Mycobacterium avium complex Susceptibility Testing

Slow Growing Mycobacteria to Antimicrobial Agents

Susceptibility Testing

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

When this test is ordered, susceptibility for slow growers will be performed at an additional charge. Antimicrobials are tested and reported using the Clinical and Laboratory Standards Institute (CLSI) guidelines.(1, 2)

 

Antimicrobials tested for Mycobacterium avium complex (MAC): amikacin, clarithromycin, clofazimine, linezolid, and moxifloxacin. Per the CLSI standards set in document M24 for susceptibility testing of M avium complex, Minimum inhibitory concentration (MIC) data for ethambutol, rifampin, and rifabutin have shown poor correlation with clinical response.(1,2) Therefore, although these drugs are in the recommended Infectious Diseases Society of America (IDSA) treatment regimen for MAC, breakpoints for these agents that separate susceptible from resistant strains cannot be determined.(3,4) Reporting of MICs for these drugs is not recommended for use in patient care. Synergy testing for nontuberculous mycobacteria has also not been standardized and its value is unclear at this time. For these reasons, ethambutol, rifampin, rifabutin and combinations of these drugs will not be tested or reported. M avium complex isolates will not be forwarded to other institutions for susceptibility testing of rifampin, rifabutin, ethambutol or synergy testing since this practice is not recommended by the CLSI nor the IDSA.(5,6) An Infectious Diseases expert with experience in difficult or refractory MAC cases should be consulted since in vitro MIC values are not useful for these drugs.

 

Antimicrobials tested for all other slowly growing Mycobacterium species: amikacin, clarithromycin, clofazimine, ciprofloxacin, doxycycline, linezolid, minocycline, moxifloxacin, rifabutin, rifampin, and trimethoprim /sulfamethoxazole. Interpretive criteria are provided according to the CLSI standards.(1,2)

 

Clofazimine interpretive criterion is not available.

Specimen Type
Describes the specimen type validated for testing

Varies

Ordering Guidance

For Mycobacterium tuberculosis complex, see TB1LN / Antimicrobial Susceptibility, Mycobacterium tuberculosis Complex, First Line, Varies and TBPZA / Susceptibility, Mycobacterium tuberculosis Complex, Pyrazinamide, 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

2. Place specimen in a large infectious container (T146) and label as an etiologic agent/infectious substance.

Necessary Information

Specimen source and organism identification are required.

ORDER QUESTIONS AND ANSWERS

Question ID Description Answers
Q00M0071 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 or other appropriate media

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

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

See Specimen Required

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

Agar plate Reject

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 resistance of slowly growing mycobacteria to 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, susceptibility for slow growers will be performed at an additional charge. Antimicrobials are tested and reported using the Clinical and Laboratory Standards Institute (CLSI) guidelines.(1, 2)

 

Antimicrobials tested for Mycobacterium avium complex (MAC): amikacin, clarithromycin, clofazimine, linezolid, and moxifloxacin. Per the CLSI standards set in document M24 for susceptibility testing of M avium complex, Minimum inhibitory concentration (MIC) data for ethambutol, rifampin, and rifabutin have shown poor correlation with clinical response.(1,2) Therefore, although these drugs are in the recommended Infectious Diseases Society of America (IDSA) treatment regimen for MAC, breakpoints for these agents that separate susceptible from resistant strains cannot be determined.(3,4) Reporting of MICs for these drugs is not recommended for use in patient care. Synergy testing for nontuberculous mycobacteria has also not been standardized and its value is unclear at this time. For these reasons, ethambutol, rifampin, rifabutin and combinations of these drugs will not be tested or reported. M avium complex isolates will not be forwarded to other institutions for susceptibility testing of rifampin, rifabutin, ethambutol or synergy testing since this practice is not recommended by the CLSI nor the IDSA.(5,6) An Infectious Diseases expert with experience in difficult or refractory MAC cases should be consulted since in vitro MIC values are not useful for these drugs.

 

Antimicrobials tested for all other slowly growing Mycobacterium species: amikacin, clarithromycin, clofazimine, ciprofloxacin, doxycycline, linezolid, minocycline, moxifloxacin, rifabutin, rifampin, and trimethoprim /sulfamethoxazole. Interpretive criteria are provided according to the CLSI standards.(1,2)

 

Clofazimine interpretive criterion is not available.

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

The slowly growing nontuberculous mycobacteria are associated with a variety of infections including pulmonary, extra-pulmonary, and disseminated disease.

 

Slowly growing mycobacteria differ from the rapidly growing mycobacteria and Mycobacterium tuberculosis complex by their growth rates, metabolic properties, and antimicrobial susceptibility profiles. The antimicrobial susceptibility profile of an organism within this group varies depending on the species and is performed according to the Clinical and Laboratory Standards Institute (CLSI) guideline for slowly growing mycobacteria.(1,2)

 

The antimicrobials listed below are included on the routine panel. Those marked with an "X" are routinely reported.

Organism

Antimicrobial agent

 

Amikacin

Clarithromycin

Clofazimine

Ciprofloxacin

Doxycycline

Linezolid

Minocycline

Moxifloxacin

Rifabutin

Rifampin

Streptomycin

Trimethoprim-sulfamethoxazole

Mycobacterium avium complex

X

X

X

 

 

X

 

X

 

 

 

 

Other slowly growing nontuberculous Mycobacterium species

X

X

X

X

X

X

X

X

X

X

 

X

 

 

The extremely fastidious slowly growing mycobacteria (Mycobacterium genavense and Mycobacterium haemophilum) will not be tested. Mycobacterium malmoense can be difficult to grow in the test medium so some isolates may not be amenable to testing.

 

Mycobacterium xenopi requires incubation at a higher temperature and may require extended incubation times.

 

Mycobacterium gordonae is frequently encountered in the environment and in clinical laboratories but is almost always considered nonpathogenic; therefore, antimicrobial susceptibility testing for M gordonae is performed by specific request only.

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.

Interpretive criteria for Mycobacterium avium-intracellulare complex

Antimicrobial agent

Minimum inhibitory concentration (MIC, mcg/mL) for each interpretation

 

S

I

R

Clarithromycin

< or =8

16

> or =32

Linezolid

< or =8

16

> or =32

Moxifloxacin

< or =1

2

> or =4

Amikacin (IV)

< or =16

32

> or =64

Amikacin (liposomal, inhaled)

< or =64

-

> or =128

 

Interpretative criteria for Mycobacterium kansasii and other slowly growing mycobacteria

Antimicrobial agent

MIC (mcg/mL) for each interpretation

 

S

I

R

Amikacin

< or =16

32

> or =64

Ciprofloxacin

< or =1

2

> or =4

Clarithromycin

< or =8

16

> or =32

Doxycycline

< or =1

2-4

> or =8

Linezolid

< or =8

16

> or =32

Minocycline

< or =1

2-4

> or =8

Moxifloxacin

< or =1

2

> or =4

Rifabutin

< or =2

-

> or =4

Rifampin

< or =1

-

> or =2

Trimethoprim/
Sulfamethoxazole

< or =2/38

-

> or =4/76

 

Interpretation
Provides information to assist in interpretation of the test results

Results are reported as the minimum inhibitory concentration in micrograms/mL.

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

No significant cautionary statements

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

1. CLSI: Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. 3rd ed. CLSI standard M24. Clinical and Laboratory Standards Institute; 2018

2. CLSI: Performance Standards for Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. CLSI supplement M62. Clinical and Laboratory Standards Institute; 2018

3. Daley CL, Iaccarino JM, Lange C, et al: Treatment of nontuberculous mycobacterial pulmonary disease: an official ATS/ERS/ESCMID/IDSA clinical practice guideline. Eur Respir J. 2020 Jul 7;56(1):2000535. doi: 10.1183/13993003.00535-2020

4. Daley CL, Iaccarino JM, Lange C, et al: Treatment of Nontuberculous Mycobacterial Pulmonary Disease: An Official ATS/ERS/ESCMID/IDSA Clinical Practice Guideline. Clin Infect Dis. 2020 Aug 14;71(4):e1-e36. doi: 10.1093/cid/ciaa241

5. Griffith DE, Winthrop KL: You gotta make me see, what does it mean to have an MIC? Chest. 2021 Feb;159(2):462-464. doi: 10.1016/j.chest.2020.11.007

6. Schon T, Chryssanthou E: Minimum inhibitory concentration distributions for Mycobacterium avium complex-towards evidence-based susceptibility breakpoints. Int J Infect Dis. 2017 Feb;55:122-124. doi: 10.1016/j.ijid.2016.12.027

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

The method employed in this assay is microtiter broth dilution using the commercially available SLOMYCO2 plate from Trek Diagnostics. Antimicrobials included in the assay are tested according to Clinical and Laboratory Standards Institute (CLSI) guidelines.(CLSI. Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. 3rd ed. CLSI standard M24. CLSI; 2018; CLSI. Performance Standards for Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. CLSI supplement M62. CLSI; 2018)

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.

Varies

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.

12 to 35 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

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
MMLSG Susc, AFB, Slowly Growing 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.
MMLSG Susc, AFB, Slowly Growing 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