Use of the "RAM" susceptibility testing method for rapid detection of clarithromycin resistance in the Mycobacterium avium complex

Victor Flauta, Gerard Osterhout, Brandon Ellis, Michael Grayson, Myron Sasser, Sam Cohen, Melissa Sander, Kim Dionne, Karen Carroll, Nicole Parrish

Research output: Contribution to journalArticlepeer-review

Abstract

Standard susceptibility testing of the Mycobacterium avium complex (MAC) can require 7 to 14 days from initial isolation. We evaluated a high-performance liquid chromatography-based susceptibility test for rapid determination of clarithromycin (CLR) resistance in MAC. This method can be completed in 72 h of incubation. A total of 110 MAC strains were tested using the following concentrations of CLR: 4, 16, and 64 μg/mL, for a total of 330 tests. Microbroth dilution was used as the reference method. Rapid analysis of mycolic acid ("RAM") concordance with the reference method for CLR susceptibility was 98% (254/258) and 100% for CLR resistance (72/72). The 4 discordant results occurred with 2 strains, which demonstrated intermediate resistance with an MIC of 16 μg/mL. This study demonstrates that "RAM"-based susceptibility testing for determination of CLR resistance in MAC is both rapid and accurate, providing a significant reduction in turn-around-time from 7 to 14 days to 72 h of incubation.

Original languageEnglish (US)
Pages (from-to)47-51
Number of pages5
JournalDiagnostic Microbiology and Infectious Disease
Volume67
Issue number1
DOIs
StatePublished - May 1 2010

Keywords

  • Mycobacterium avium complex
  • RAM
  • Susceptibility testing

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases

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