European Journal of Cardiovascular Medicine

Introduction: Only 25% of multidrug-resistant tuberculosis (MDR-TB) cases are currently diagnosed. Line probe assays (LPAs) enable rapid drug-susceptibility testing for rifampicin (RIF) and isoniazid (INH) resistance and Mycobacterium tuberculosis detection. Line probe assays (LPAs) are rapid molecular diagnostics that can detect M. tuberculosis and drug resistance. Although LPAs are more technically complex (designed for reference or regional laboratory settings) and take longer to perform than the Xpert MTB/RIF assay, they have the ability to detect isoniazid (INH) resistance in addition to rifampicin (RIF) resistance unlike Xpert MTB/RIF. Methods: This is a Case-control study was conducted over a period of 1 year where MDR-TB and TB patients were treated. TB patients infected with MDR- M. tuberculosis and non MDRM. tuberculosis strain were considered as cases and controls, respectively. Cases and controls were matched by the date of hospitalization. The data was collected using structured questionnaire with face to face interview. Bivariate and multivariable logistic regression analysis (MLRA) was used to identify determinants associated with MDR-TB. Results: Of the 90 samples tested for smear concentration microscopy, 8.9% were smear negative. For the smear positive samples, the following bacillary loads were observed: 1+ in 28 (31.1%), 2+ in 31 (34.4%) and 3+, 3 (3.3%). 4B, 5B and 10B were observed in just 13 samples while 6B results were observed in 7 (7.9%) samples. To compare the performance of GeneXpert and LPA on smear positive results, 90 samples were used. GeneXpert detected 53 (58.9%) and LPA detected 77 (85.6%) samples as positive. Of 90 samples tested, Culture MGIT detected M. tuberculosis in 60 (66.7%) samples, GeneXpert detected M. tuberculosis in 51 (56.7%), and LPA detected M. tuberculosis in 60 (66.7%). The 90 Culture MGIT positive samples were subjected to the drug susceptibility testing (DST) against Isoniazid, Rifampicin, Streptomycin and Ethambutol. 9 (10%), 11 (12.2%), 15 (16.7%), and 8 (8.9%) samples were found to be resistant to Streptomycin, Isoniazid, Rifampicin and Ethambutol respectively. 3.3% of the samples were resistant to all the four antibiotics and 96.7 of the samples were sensitive to all the antibiotics.  Conclusion: LPA is a robust technique for diagnosis of drug-resistant TB that has provided the basis for rapid and effective control of drug-resistant TB in India. While the reasons for concomitantly negative LPA and culture results of smear-positive sputum samples from MDR-TB suspects may be many, the possible presence of non-tubercular mycobacteria in these samples and the likelihood of inappropriate therapy in these patients cannot be ruled out. Addition of culture to the diagnostic algorithm may enhance the diagnostic yield