Performance comparison of GenoTypeMTBDRsl Version 1 and Version 2 for rapid detection of resistance to fluoroquinolones and injectable drugs among multidrug-resistant Mycobacterium tuberculosis in a low MDR-TB setting

Abstract

Aims and objectives: Fluoroquinolones (FQs) are potent antibiotics against multidrug-resistant Mycobacterium tuberculosis (MDR-TB) and resistance to FQs is associated with higher patient mortality. Rapid and accurate drug susceptibility testing (DST) against FQs and injectable drugs is essential for successful treatment of MDR-TB. FQ resistance mutation detection is equivalent to culture-based DST for predicting MDR-TB treatment outcome. This study compared performance of GenoTypeMTBDRsl Version 1 and Version 2 for detection of resistance to FQs and injectable drugs among MDR-TB strains in Kuwait, a country with low incidence of MDR-TB. Methods: MDR-TB strains (n=93) cultured from 74 pulmonary and 19 extra-pulmonary specimens from 93 patients were analyzed by GenoTypeMTBDRsl Version 1 and Version 2 for FQ and injectable drug resistance-associated mutation detection. Repeat isolates from 22 patients, 50 pansusceptible isolates and M. tuberculosis H37Rv (as control) were also tested. Results were confirmed by PCR-sequencing of gyrA, gyrB, rrs, embB and eis genes. Fingerprinting of isolates was done by spoligotyping. Results: Among 93 MDR-TB strains, GenoTypeMTBDRsl Version 1 with/without PCR-sequencing identified 10 isolates with gyrA mutation (A90V, n=2; D94G, n=4; D94A, n=2; D94N, n=1; D94Y, n=1), seven isolates with rrs mutation (A1401G) and 51 isolates with an embB mutation. GenoTypeMTBDRsl Version 2 with/without PCR-sequencing confirmed Version 1 results for gyrA/rrs genes and additionally identified two isolates with gyrB mutation (T500N, n=1; N538D, n=1) and one isolate with eis mutation (-10 G/A). Repeat isolates yielded expected results. No mutation was detected in 50 pansusceptible isolates. Spoligotyping identified 10 Shared International Types among 12 isolates with gyrA/B mutation. Conclusions: Our data show that GenoTypeMTBDRsl Version 2 is superior to Version 1 as it identified two additional isolates with gyrB mutations. Improved detection of FQ resistance by GenoTypeMTBDRsl Version 2 will help in proper management of MDR-TB patients in low MDR-TB settings. Supported by KURS grant MI01/18.