Emergence of Specific gyrA Mutations Associated High-Level Fluoroquinolone-Resistant Mycobacterium tuberculosis among Multidrug-Resistant Tuberculosis Cases in North India

Aim: This study aims to determine the frequency and pattern of gyr A/B mutations in multidrug-resistant (MDR) Mycobacterium tuberculosis (MTB) strains and also to assess the association between different gyr A/B mutations with phenotypic resistance to moxifloxacin (MOX) at clinical breakpoint (CB) drug concentration. Method: A total of 106 clinical MTB isolates carrying gyr A/B mutations were included consecutively. Culture-based MOX susceptibility was tested at CB (1.0 μg/mL) followed by its correlation with gyr A/B mutations using Genotype MTBDR sl assay. The mutations associated with phenotypic resistance were further analyzed on a large dataset of 1,825 MDR tuberculosis (TB) patients. Result: D94G and A90V mutations within gyr A were significantly associated with resistance and susceptible phenotype ( p