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Mycobacterium avium Complex Susceptibility−Broth Dilution

Test Number 182832
Test number copied
CPT 87186
Synonyms
  • AFB Susceptibility Testing
  • M avium Complex Susceptibility Testing
  • MAC Susceptibility Testing

Test Details

Methodology

Sensititre® broth microdilution (MIC)

Result Turnaround Time

21 - 30 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Information

Related Documents

Test Includes

Susceptibility testing for amikacin, ciprofloxacin, clarithromycin, doxycycline, moxifloxacin, rifabutin, rifampin, streptomycin and trimethoprim/sulfamethoxazole. MIC values will be reported with CLSI interpretive comments, if available.

Use

Determine the susceptibility of Mycobacterium avium complex isolates to a profile of antimycobacterial agents. Testing is recommended for isolates from patients with previous macrolide therapy, patients who relapse while on macrolide therapy, or patients with initial isolates from blood, tissue, or clinically relevant respiratory specimens. Repeat susceptibility is recommended after 3 months (disseminated disease) or 6 months (chronic pulmonary disease) if the cultures are still positive or if there is no clinical improvement.

First line drugs for M. avium complex treatment includes clarithromycin and amikacin (IV or inhaled). Clarithromycin is the most appropriate class drug for the macrolides due to technical challenges with azithromycin. Second line drugs include moxifloxacin and linezolid, however, the in vivo effectiveness of these drugs for treatment of M. avium complex is unproven. These are the only drugs with CLSI interpretations for M. avium complex. Note that while ethambutol can be used as part of the treatment regimen for M. avium complex, studies have shown that MIC values do not correlate with clinical outcomes. For this reason, ethambutol is not reported for M. avium complex isolates.

Limitations

Susceptibilities cannot be reported if the organism fails to grow in the test medium. Susceptibilities cannot be performed on mixed cultures.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Custom Additional Information

Failure to take all drugs in a multidrug regimen can lead to a shift toward resistant organisms and treatment failure. Nontuberculous mycobacteria, particularly strains of the M avium complex, are resistant to those drugs used for therapy of M tuberculosis.2 Clarithromycin (and azithromycin) are the only agents for which CLSI interpretive guidelines are established. Treatment of MAC for most patients with nodular/bronchiectatic disease includes a three-times-weekly regiment of clarithromycin or azithromycin, rifampin, and ethambutol. For patients with MAC lung disease or severe nodular/bronchiectatic disease, a daily regime of clarithromycin or azithromycin, rifampin or rifabutin, and ethambutol with consideration of three-times-weekly amikacin or streptomycin early in therapy is recommended. Treatment should occur until the patient is culture negative for one year.3 Treatment of disseminated MAC disease should include clarithromycin or azithromycin and ethambutol with or without rifabutin until the symptoms have resolved and cell-mediated immune function has returned.

Specimen Requirements

Specimen

Mycobacterium avium complex isolated from a primary clinical specimen, on a submitted AFB conventional solid medium, or an AFB broth medium

Volume

Pure culture isolate on an AFB conventional solid medium or a minimum of 1 mL of AFB broth medium

Container

Conventional or broth medium, tightly sealed, in etiologic agent packaging

Storage Instructions

Maintain media at room temperature.

Causes for Rejection

Specimen received in leaking or in broken transport tube or vial; specimen received in expired transport medium; mixed culture; unlabeled culture or name discrepancy between specimen and request label

References

Clinical Laboratory Standards Institute (CLSI). Performance Standards for Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. 1st ed. CLSI supplement M62. Wayne, PA: CLSI; 2018.
Clinical Laboratory Standards Institute (CLSI). Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes. 3rd ed. CLSI standard M24. Wayne, PA: CLSI; 2018.
Griffith DE, Aksamit T, Brown-Elliott BA, et al. An official ATS/IDSA statement: Diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases. Am J Respir Crit Care Med. 2007 Feb 15;175(4):367-416.17277290
Woods GL, Lin SYG, Brown BA, Desmond EP. Susceptibility Test Methods: Mycobacteria, Nocardia and Other Actinomycetes. Manual of Clinical Microbiology, 12th ed. 2018; 78:1398-1419.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
182832 MAC Susceptibility Broth 29576-6 182831 Organism ID 40699-1
182832 MAC Susceptibility Broth 29576-6 998535 Amikacin 5-Dec
182832 MAC Susceptibility Broth 29576-6 998536 Ciprofloxacin 185-9
182832 MAC Susceptibility Broth 29576-6 998528 Clarithromycin 189-1
182832 MAC Susceptibility Broth 29576-6 998244 Clofazimine 16623-1
182832 MAC Susceptibility Broth 29576-6 998710 Doxycycline 225-3
182832 MAC Susceptibility Broth 29576-6 998530 Linezolid 29254-0
182832 MAC Susceptibility Broth 29576-6 998756 Minocycline 335-0
182832 MAC Susceptibility Broth 29576-6 998531 Moxifloxacin 31037-5
182832 MAC Susceptibility Broth 29576-6 998238 Rifabutin 16100-0
182832 MAC Susceptibility Broth 29576-6 998532 Rifampin 428-3
182832 MAC Susceptibility Broth 29576-6 998533 Streptomycin 460-6
182832 MAC Susceptibility Broth 29576-6 998715 Trimethoprim/Sulfa 516-5
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code182831
Result Code NameOrganism ID
UofM
Result LOINC40699-1
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998535
Result Code NameAmikacin
UofM
Result LOINC5-Dec
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998536
Result Code NameCiprofloxacin
UofM
Result LOINC185-9
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998528
Result Code NameClarithromycin
UofM
Result LOINC189-1
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998244
Result Code NameClofazimine
UofM
Result LOINC16623-1
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998710
Result Code NameDoxycycline
UofM
Result LOINC225-3
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998530
Result Code NameLinezolid
UofM
Result LOINC29254-0
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998756
Result Code NameMinocycline
UofM
Result LOINC335-0
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998531
Result Code NameMoxifloxacin
UofM
Result LOINC31037-5
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998238
Result Code NameRifabutin
UofM
Result LOINC16100-0
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998532
Result Code NameRifampin
UofM
Result LOINC428-3
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998533
Result Code NameStreptomycin
UofM
Result LOINC460-6
Order Code182832
Order Code NameMAC Susceptibility Broth
Order Loinc29576-6
Result Code998715
Result Code NameTrimethoprim/Sulfa
UofM
Result LOINC516-5
Reflex Table for Organism ID
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 000000 Antimicrobial Susceptibility 000000 Antimicrobial Susceptibility N/A
Reflex 1
Order Code000000
Order NameAntimicrobial Susceptibility
Result Code000000
Result NameAntimicrobial Susceptibility
UofM
Result LOINCN/A