1. Academic Validation
  2. In Vitro Activity of Bedaquiline against Nontuberculous Mycobacteria in China

In Vitro Activity of Bedaquiline against Nontuberculous Mycobacteria in China

  • Antimicrob Agents Chemother. 2017 Apr 24;61(5):e02627-16. doi: 10.1128/AAC.02627-16.
Yu Pang 1 Huiwen Zheng 2 Yaoju Tan 3 Yuanyuan Song 2 Yanlin Zhao 4
Affiliations

Affiliations

  • 1 National Clinical Laboratory on Tuberculosis, Beijing Key Laboratory on Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Institute, Beijing, China [email protected] [email protected].
  • 2 National Center for Tuberculosis Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
  • 3 Department of Clinical Laboratory, Guangzhou Chest Hospital, Guangdong Province, Guangzhou, China.
  • 4 National Center for Tuberculosis Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China [email protected] [email protected].
Abstract

The main goal of our study was to evaluate the in vitro bedaquiline susceptibility of six prevalent species of pathogenic nontuberculous mycobacteria (NTM) in China. In addition, we investigated the potential molecular mechanisms contributing to bedaquiline resistance in the different NTM species. Among slowly growing mycobacteria (SGM), bedaquiline exhibited the highest activity against Mycobacterium avium; the MIC50 and MIC90 values were 0.03 and 16 mg/liter, respectively. Among rapidly growing mycobacteria (RGM), Mycobacterium abscessus subsp. abscessus (M. abscessus) and Mycobacterium abscessus subsp. massiliense (M. massiliense) seemed more susceptible to bedaquiline than Mycobacterium fortuitum, with MIC50 and MIC90 values of 0.13 and >16 mg/liter, respectively, for both species. On the basis of bimodal distributions of bedaquiline MICs, we proposed the following epidemiological cutoff (ECOFF) values: 1.0 mg/liter for SGM and 2.0 mg/liter for RGM. Among M. avium, Mycobacterium intracellulare, Mycobacterium kansasii, M. abscessus, M. massiliense, and M. fortuitum isolates, 14 (29.8%), 41 (27.2%), 33 (39.3%), 44 (20.2%), 42 (25.8%), and 7 (31.8%), respectively, were resistant to bedaquiline. No significant differences in the proportions of bedaquiline resistance among these species were observed (P > 0.05). Genetic mutations were observed in 74 isolates (10.8%), with all nucleotide substitutions being synonymous. In conclusion, our data demonstrate that bedaquiline shows moderate in vitro activity against NTM species. Using the proposed ECOFF values, we could distinguish between bedaquiline-resistant and -susceptible strains with the broth dilution method. In addition, no nonsynonymous mutations in the atpE gene that conferred bedaquiline resistance in all six NTM species were identified.

Keywords

ECOFF; bedaquiline; nontuberculous mycobacteria.

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