Mutation Profile Assessment of rpoB, KatG and inhA Genes in Rifampicin and Isoniazid Resistant Mycobacterium tuberculosis in India

Line probe assay (GenoTypeMTBDRplus) is the world health organization (WHO) endorsed molecular technique for rapid screening of rifampicin, isoniazid and multi-drug resistant (MDR) tuberculosis (TB). The aim of this study was to assess the mutation profile of rpoB, KatG, and inhA genes in rifampicin and isoniazid resistant Mycobacterium tuberculosis (M. tb) using the line probe assay (LPA). In this study, acid-fast bacilli (AFB) positive sputum samples were subjected to phenotypic culture, and direct line probe assay (GenoType MTBDRplus ver1/ver2) as per manufacturer’s instructions. Between 2013 to 2015, 878 AFB smear-positive sputum samples of previously treated TB patients were received at Department of Medicine, All India Institute of Medical Sciences, New Delhi. Of these, 168 MDR-TB, 29 RIF resistant/INH sensitive and 52 resistant/RIF sensitive samples were available for mutation analysis. It was observed that mutation of rpoB gene, S315L (MUT3) were more frequent (statistically significant) in MDR-TB (121/168=72 %) patients than RIF resistant/INH sensitive (14/29=48 %). Mutation involving codon 315 (S315T1) were also more frequent in MDR-TB. These results indicate possibility of association of MDR-TB with KatG S315 T1 and rpoB S531L in Indian population. However, additional studies with large number of sample are needed to confirm these observations.