Identification of Mutations Associated With Macozinone-Resistant in Mycobacterium Tuberculosis.

Novel anti-tuberculosis drug macozinone (MCZ) is identified as a drug candidate and is currently under clinical development for the treatment of tuberculosis. However, the mutations conferring resistance to MCZ remain inadequately characterized. In this study we investigated resistant mutations to the MCZ through de novo resistance selection in vitro. This was accomplished by passing the Mycobacterium tuberculosis H37Rv on solid agar plates, which were infused with the antibiotic. Through whole genome sequencing and targeted PCR genomic resistance conferring SNPs were catalogued, and the resistant phenotype was analyzed by MABA test. Of MCZ-resistant clones obtained in vitro the mutation of C387S in dprE1 is only observed in high-level resistant clones (MIC > 500 ng/mL) indicating that C387S mutation is directly related to high-level MCZ-resistance. In addition, high-level resistance to MCZ can occur in clone grew on agar plates infused with low concentration MCZ, which means low concentration MCZ induction can produce high-level drug-resistance and it is easy to produce high-level MCZ-resistance. We also found two new mutations (G61A and G248A) in dprE1 for the first time. The MIC of other clones except the clones carrying the C387S mutation was at the same level (20 ng/mL > MIC > 2 ng/mL). Of low-level resistant clones other gene mutations involved in drug efflux or membrane permeability were found (pepQ, Rv0678, arsC, etc.), with highest mutation frequency in Rv0678 (50/64, 78.12%). It suggests that there may be new mechanisms independent of dprE1 mutations.