Evaluation of GenoType® MTBDRplus assay for rapid detection of drug susceptibility testing of multi-drug resistance tuberculosis in Northern India.

BACKGROUND: The problem of multi-drug resistance tuberculosis (MDR-TB) is growing in several hotspots throughout the world. Rapid and accurate diagnosis of MDR-TB is crucial to facilitate early treatment and to reduce its spread in the community. The aim of the present study was to evaluate the new, novel GenoType® MTBDRplus assay for rapid detection of drug susceptibility testing (DST) of MDR-TB cases in Northern India.

MATERIALS AND METHODS: A total of 550 specimens were collected from highly suspected drug resistant from pulmonary and extra-pulmonary TB cases. All the specimens were processed by Ziehl- Neelsen staining, culture, differentiation by the GenoType® CM assay, first line DST using BacT/ALERT 3D system and GenoType® MTBDRplus assay. The concordance of the GenoType® MTBDRplus assay was calculated in comparison with conventional DST results.

RESULTS: Overall the sensitivity for detection of rifampicin, isoniazid and MDR-TB resistance by GenoType® MTBDRplus assay was 98.0%, 98.4% and 98.2% respectively. Out of 55 MDR-TB strains, 45 (81.8%), 52 (94.5%) and 17 (30.9%) strains showed mutation in rpoB, katG and inhA genes respectively (P < 0.05). The most prominent mutations in rpoB, katG and inhA genes were; 37 (67.3%) in S531L, 52 (94.5%) in S315T1 and 11 (20%) in C15T regions respectively (P < 0.05).

CONCLUSIONS: Our study demonstrated a high concordance between the GenoType® MTBDRplus assay resistance patterns and those were observed by conventional DST with good sensitivity, specificity with short turnaround times and to control new cases of MDR-TB in countries with a high prevalence of MDR-TB.