Comparison of Truenat Mycobacterium tuberculosis with line probe assay for the diagnosis of rifampicin resistance and mutation pattern of Mycobacterium tuberculosis

Abstract Background: There is an increasing incidence of multidrug-resistant tuberculosis (TB)/preextensively drug-resistant TB (XDR TB) and XDR TB globally. Therefore, rapid diagnostic tests with good sensitivity and specificity are need of hour. Truenat Mycobacterium tuberculosis (MTB) is one such test which gives results in 1–2 h and can withstand a variety of environmental conditions. Objective: The objective of this study was to compare Truenat MTB with line probe assay (LPA) for the diagnosis of rifampicin resistance and to study the mutation pattern of MTB. Materials and Methods: A comparative record-based study was carried out among 325 patients with multidrug-resistant TB. Sputum samples for pulmonary TB and appropriate site samples for extrapulmonary TB were obtained and tested with Truenat-MTB and LPA. A comparison between results obtained by Truenat-MTB and LPA was done. Based on first-line-LPA and second-line-LPA, gene mutation pattern was studied. Results: Males (69.2%) were more than females (30.8%). 30–49 (34.5%) years of age were most commonly affected. The sensitivity, specificity, positive predictive value, and negative predictive value of Truenat MTB compared to LPA were 82.86%, 93.45%, 60.41%, and 97.83%, respectively. The most common gene mutation observed was katG MUT1 in 59 cases. This was followed by rpoB MUT1 in three cases, rpoB MUT2A in two cases, rpoB MUT2B in four cases, and rpoB MUT3 in 12 cases. gyrA mutation was seen in nine cases among which gyrA MUT3A was seen in one case, gyrA MUT3B in one case, and gyrA MUT3C was seen in four cases. Two cases of rrs MUT1 were seen. Five cases of inhA MUT1 were seen. Conclusion: Truenat has been found to be economical, less time-consuming, giving fast results, and accurate in the diagnosis of DR-TB. The most common gene mutation observed was katG MUT1 in 59 cases.