Comparative study of different diagnostic methods for detection of mycobacteria in clinically suspected patients of extrapulmonary tuberculosis at IGIMS, Patna

Background: Tuberculosis is a global problem and incidence of extra pulmonary tuberculosis is increasing day by day. Diagnosis of extra pulmonary tuberculosis is a little bit difficult than pulmonary tuberculosis. Aim and Objective: The aim of this study is to compare different diagnostic methods like ZN staining, LED-FM and GeneXpert assay for detection of Mycobacterium tuberculosis in extrapulmonary tuberculosis (EPTB) cases in respect to their sensitivity, specificity, PPV and NPV respectively. Methodology: This prospective study was carried out in the Department of Microbiology, IGIMS, Patna, Bihar. Samples from 210 suspected extrapulmonary cases were collected and processed for ZN-stain, LED-FM, GeneXpert assay and MGIT culture. Taking the MGIT culture result as Gold standard, result of ZN-stain, LED-FM and GeneXpert were compared.  Result: Out of 210 samples, detection rate of ZN staining, LED-FM, GeneXpert assay and MGIT culture were 10.47%, 14.28 %, 30.47% and 36.66% respectively. The sensitivity, specificity, PPV and NPV of ZN staining and LED-FM were 28.27 %, 100%, 100%, 70.74% and 39.96%, 100%, 100%, 73.88% respectively. The sensitivity, specificity, PPV and NPV of GeneXpert were 59.74%, 86.46%, 71.87% and 78.76% respectively.