COMPARISON OF GENEXPERT MTB/RIF AND FIRST-LINE LINE PROBE ASSAY FOR DETECTION OF MYCOBACTERIUM TUBERCULOSIS AND RIFAMPICIN RESISTANCE FROM CLINICALLY SUSPECTED CASES OF PULMONARY AND EXTRAPULMONARY TUBERCULOSIS

Background: Molecular methods like GeneXpertMTB/RIF and FL-LPA, endorsed by WHO for diagnosing drug-resistant tuberculosis. AIM: Evaluation of diagnostic performance of GeneXpertMTB/RIF and FL-LPA in comparison with liquid culture, the “gold standard” for diagnosing pulmonary and extrapulmonary tuberculosis. Methods: In total 2912 pulmonary and 2522 extrapulmonary samples were subjected to GeneXpert MTB/RIF upfront, of which 388 were AFB smear positive, processed for direct LPA. A total 2524 pulmonary samples and 2522 extrapulmonary samples were subjected to liquid culture, of which samples flagged out as culture positive were put for FL-LPA. Results: Concordance was 100% in GeneXpertMTB/RIF and FL-LPA for AFB smear positive pulmonary samples. The sensitivity and specificity of GeneXpert MTB/RIF for pulmonary samples was found 91.39% and 94.49%, PPV and NPV were 82.07% & 97.55%. For extrapulmonary samples, sensitivity & specificity were 78.48% & 93.20%. PPV& NPV were 68.11% & 95.90%. The sensitivity of FL-LPAfor pulmonary samples was 98.35%, PPV was 100%, for extrapulmonary samples sensitivity was 97.64%, PPV was 100%. Rifampicin resistance detection by GeneXpert MTB/RIF in 24.52% of total samples. In FL-LPA, MDR-TB, Mono-rifampicin resistance was seen in 22.62% & 1.85% cases, respectively. Conclusion: The study reinforces reliability on GeneXpert MTB/RIF and LPA as rapid diagnostic tools in drug resistance detection. GeneXpert with its rapid turnaround time and ease of use is especially valuable in primary and peripheral settings, while LPAoffers early and detailed drug resistance.