Identification of Novel Mutations Associated with Bedaquiline Resistance in Mycobacterium Marinum

Abstract

Because infections caused by nontuberculous mycobacteria (NTM) are rapidly increasing globally, a need exists for developing novel antibiotics and discovering the mechanism of resistance. This research was aimed at understanding the mechanism of bedaquiline resistance in the model NTM species Mycobacterium marinum ( M. marinum ). The Mycobacterium marinum M strain was subjected to mutant selection with different concentrations of BDQ. After three rounds of evolution, 58 BDQ-resistant mutants were isolated and subjected to WGS. The results were confirmed through PCR and Sanger sequencing. We identified seven genetic mutations among these mutants. The highest drug resistance (6–10× MIC) was associated with a mutation in AtpB, the primary biochemical target of BDQ in Mtb. Numerous mutations and insertions mapped to the gene MMAR_1007 (46/58), which encodes the homolog of Rv0678 (MmpR) in Mtb. More than 93% of mutants (54/58) contained a single mutation (G563A) in MMAR_4049 , which encodes the integral membrane protein YrbE3A-1. Both target-based and efflux-based actions contribute to BDQ resistance in M. marinum. Our findings may aid in developing novel potent anti-NTM (BDQ-based) drug regimens and diagnostic assays for the detection of BDQ-resistant M. marinum .