Is Rapid Molecular Testing Enough In Screening Drug-Resistant Tuberculosis In Community?

BackgroundThe study aimed to compare the sensitivity and specificity of cartridge based nucleic acid amplification test (CBNAAT) for diagnosis of Drug-Resistant tuberculosis (DRTB) with culture sensitivity assays. MethodsPatients with cough symptoms for more than two weeks with any one symptom such as night sweats, fever, and unintentional weight loss were enrolled. Cases where Mycobacterium Tuberculosis was detected on sputum CBNAAT, were included in the study. Demographic variables, clinical features, and chest radiographs were collected. Each sputum sample was divided into three aliquots: smear microscopy, culture, and genotypic drug sensitivity testing (DST). Results of all three diagnostic modalities were compared with CBNAAT. ResultsOut of 236 patients with sputum positive CBNAAT, 49.4 % (117/236) were rifampicin-resistant while 50. 6 % (119/236) were Rifampicin sensitive. The genotypic DST assays carried out on all enrolled patients showed that 76. 3 % (181/236) patients were resistant to one or more first-line or second-line antitubercular (ATT) drugs, while 23.7 % (55/236) patients were sensitive to all ATT drugs. On concordant analysis of CB NAAT with DST assays, we found that among 119 CB NAAT rifampicin sensitive patients, 66 patients were resistant to first-line or second-line antitubercular drugs. ConclusionThis study found that the screening of DRTB with CBNAAT at the community level is suboptimal compared to the gold standard. Although CBNAATs sensitivity in detecting DRTB is significantly higher, the specificity is lower in that population who have received ATT earlier.