Early detection of resistance to second-line anti-tuberculosis drugs is important for the management of multidrug-resistant (MDR)-TB. The Genotype® MTBDRsl VERSION 2.0 (VER 2.0) line probe assay has been redesigned for molecular detection of resistance-conferring mutations of fluoroquinolones (FLQ) (gyrA and gyrB genes) and second-line injectable drugs (SLID) (rrs and eis genes). The study evaluated the diagnostic performance of MTBDRsl VER 2.0 for the detection of second-line drug resistance compared with phenotypic drug susceptibility testing (DST), using the Bactec™ MGIT 960 system on Mycobacterium tuberculosis complex isolates from South Africa. A total of 268 repository isolates collected between 2012 and 2014, with rifampicin -mono-resistant (RR) or MDR based on DST were selected. MTBDRsl VER 2.0 testing was performed on these isolates and results analysed. The MTBDRsl VER 2.0 sensitivity and specificity indices for culture isolates were; FLQ 100% (95% CI, 95.8-100%) ; 98.9% (95% CI, 96.1-99.9%) and SLID 89.2% (95% CI, 79.1-95.6%); 98.5% (95% CI, 95.7-99.7%). The sensitivity and specificity observed for individual SLID were: amikacin 93.8% (95% CI, 79.2-99.2%); 98.5% (95% CI, 95.5-99.7%), kanamycin 89.2% (95% CI, 79.1-95.6%); 98.5% (95% CI, 95.5-99.7%) and capreomycin 86.2% (95% CI, 68.3-96.1%) ; 95.9% (95% CI, 92.2-98.2%). An inter-operator reproducibility of 100% and an overall inter-laboratory performance of 93 % – 96% were found. The overall improvement in sensitivity and specificity with excellent reproducibility makes the Genotype® MTBDRsl VER 2.0 a highly suitable tool for rapid screening of clinical isolates for second-line drug resistance for use in high burden TB/HIV settings.
Evaluation of the Genotype® MTBDRsl® VER 2.0 assay for second-line drug resistance detection of Mycobacterium tuberculosis isolates in South Africa.