Role of GeneXpert MTB/Rif in detection of tuberculosis from clinical samples: A report from a tertiary care hospital in Mumbai

Abstract

Introduction: Tuberculosis (TB) causes severe morbidity and mortality in millions of people every year, worldwide and India in particular. Hence this study was undertaken to find out the role of the widely used GeneXpertMTB/Rif test in tuberculosis detection. Materials and Methods: A total of 155 samples (pulmonary and extrapulmonary) from patients clinically suspected to have tuberculosis were received for testing by ZN (Ziehl-Neelsen) stain and GeneXpert/MTB Rif. These samples were also processed for histopathology or cytology and mycobacterial culture on request of clinician. The results were studied and compared. Result: Out of the total samples received, lymph node aspirates were 23%,pleural fluid 20%,sputum 19%,pus 10%,tissue 8%,ascitic fluid 8%,cerebrospinal fluid 7%,endometrial tissue 3%,synovial fluid 1% and urine 1%.Nine sputum samples (31%) were positive by GeneXpertMTB/Rif of which two were negative on smear, two positive on culture and there was no culture request for the remaining seven samples.29 (23%) extrapulmonary samples were positive by GeneXpertMTB/Rif out of which there was no culture request for 16 samples. One sample which was negative by GeneXpert MTB/Rif grew Atypical Mycobacteria on culture. Four isolates were detected as rifampicin resistant by GeneXpertMTB/Rif but none of them were sent for Drug Susceptibility Test (DST). Conclusion: GeneXpertMTB/Rif should be used in combination with other tests for diagnosing tuberculosis.