Fluoroquinolone resistance and mutational profile of gyrA gene in pulmonary MDR tuberculosis patients

Abstract Background In recent year’s high proportion of flouroquinolone (FQs) resistance in Mycobacterium tuberculosis isolates has been observed. The multidrug resistant TB is a serious risk for its transition to XDR-TB. Methods A total of 562 samples were included in the study from patients with pulmonary TB which had been on anti-tuberculosis therapy. MTBDRsl assay was performed for molecular detection of mutations. Sequence analysis was performed for characterization and mutational profiling of FQ resistant isolates. Results FQs resistance was observed in 104 (18.5%) samples and most of them were previously treated and treatment failure cases. A total of 102 isolates had mutations in gyr A gene, D94G and A90V being the most prevalent while gyr B gene mutations were observed in only two isolates. Some substitutions in amino acid D, A and T were also determined by sequence analysis in hybridization pattern of both co-existence cases which appeared with both wild type and mutant probe and with missing wild type probe as well. Conclusion The findings suggest that the genotypic studies for FQs resistance should be carried out at time of initial diagnosis, before starting treatment, to rule out all type of mutations for potential use in the treatment and to control its resistance.