Assessment of resistance to second line anti-tubercular drugs by line probe assay at a tertiary care hospital

Abstract

Context: Emergence and spread of extensively drug resistance (XDR) tuberculosis (TB) is a challenge in resource-limited settings. Although India accounts for one-fourth burden of multi-drug resistant cases of TB, the prevalence of XDR TB varies widely. Timely detection of resistance to anti-tubercular drugs is important for optimal case management. Aims: Characterization of resistance mutations to second-line anti-tubercular therapy (ATT) using line probe assay (LPA). Materials and Methods: In this cross-sectional, conducted at a Tertiary Care Teaching Hospital in Western Maharashtra, we assessed resistance to second-line antitubercular drugs in 100 consecutive sputum specimens from patients failing first-line ATT as per national guidelines by LPA. Results: Of the 100 specimens studied, a total of 94 assay results were valid. Of these, no resistance was seen in 52 specimens. Resistance to fluoroquinolones (FLQ) was detected in 30% of specimen with a predominance of gyrA gene mutations. A total of 12% isolates were resistant to aminoglycosides with mutations observed in rrs gene. Conclusions: The study demonstrates the utility of LPA as a tool to support the diagnosis of drug-resistant TB in clinical setting.