Mutations in Rv0678, Rv2535c, and Rv1979c Confer Resistance to Bedaquiline in Clinical Isolates of Mycobacterium Tuberculosis.

Introduction: Reduced bedaquiline (BDQ) sensitivity to antimycobacterial drugs has been linked to mutations in the Rv0678, pepQ, and Rv1979c genes of Mycobacterium tuberculosis (MTB). Resistance-causing mutations in MTB strains under treatment may have an impact on novel BDQ-based medication regimens intended to reduce treatment time. Due to this, we investigated the genetic basis of BDQ resistance in Turkish TB patients with MTB clinical isolates. Furthermore, mutations in the genes linked to efflux pumps were examined as a backup resistance mechanism.

Methods: We scrutinized 100 MTB clinical isolates from TB patients using convenience sampling. Eighty MDR and twenty pan-drug susceptible MTB strains were among these isolates. Sequencing was performed on all strains, and genomic analyses were performed to find mutations in BDQ resistance-associated genes, including Rv0678 and pepQ(Rv2535c), which correspond to a putative Xaa-Pro aminopeptidase, and Rv1979c. Of the 74 isolates with PepQ (Rv2535c) mutations, four isolates (2.96%) exhibited MGIT-BDQ susceptibility.

Results: Twenty-one (19.11%) of the ninety-one isolates carrying mutations, including Rv1979c, were MGIT-BDQ-sensitive. Nonetheless, out of the 39 isolates with Rv0678 mutations, four (2.96%) were sensitive to MGIT-BDQ. It was found that resistance-associated variants (RAVs) in Rv0678, pepQ, and Rv1979c are often linked to BDQ resistance.

Conclusion: In order to include variations in efflux pump genes in genome-based diagnostics for drug-resistant MTB, further evidence about their involvement in resistance is needed.