Diagnostic accuracy of GenoType^® MTBDR<i>sl</i> VER 2.0 in detecting second-line drug resistance to <i>M. tuberculosis</i>

Setting A tertiary care hospital in North India. Objective To evaluate the GenoType® MTBDRsl VER 2.0 assay for rapid diagnosis of second-line drug resistance to Mycobacterium tuberculosis. Design The MTBDRsl VER 2.0 assay was performed on 431 multidrug-resistant M. tuberculosis clinical isolates and specimens. The results were compared with phenotypic drug susceptibility testing (DST) and DNA sequencing. Molecular characterisation of drug resistance using DNA sequencing was performed for gyrA, gyrB, rrs and eis. Results Of the 415 isolates, respectively 176 (42.4%) and 40 (9.6%) were resistant to levofloxacin (LVX) and kanamycin (KM). The sensitivity and specificity of MTBDRsl VER 2.0 compared with phenotypic DST in detecting LVX resistance were respectively 97.2% (95%CI 93.5-99.1) and 99.1% (95%CI 97-99.9), and for KM resistance they were respectively 92.5% (95%CI 79.6-98.4) and 99.5% (95%CI 98.1-99.9). Conclusion The MTBDRsl VER 2.0 assay showed very high sensitivity and specificity for the detection of second-line drug resistance, suggesting it has potential for the rapid, early detection of such cases.