Diagnostic Utility of Fluorescent Microscopy vis-a-vis GeneXpert MTB/RIF in Extra Pulmonary Tuberculosis: A Retrospective Analysis

• Main Authors: Dinesh Verma, Ghanshyam Soni, Rashmi Sharma, Praveen Kumar
• Format: Article
• Language: English
• Published: JCDR Research and Publications Pvt. Ltd. 2019-10-01
• Series: National Journal of Laboratory Medicine
• Subjects: mycobacterium tuberculosis; sensitivity; specificity
• Online Access: http://www.njlm.net/articles/PDF/2373/42589_PD(SHU)_V.1_V.2(PoG_SL)_CE[Ra1]_F(SHU)_PF1(AG_SHU)_PFA(SHU)_PB(AG_SHU)_PN(SHU).pdf

Introduction: Tuberculosis (TB) kills more people in India and Southeast Asia than any other infectious disease. In developing countries like India, the percentage of Extra Pulmonary Tuberculosis (EPTB) is between 15-20% which has increased to more than 50% among HIV co-infected patients. Aim: To evaluate the frequency of EPTB and diagnostic efficacy of GeneXpert MTB/RIF in comparison to fluorescent microscopy. Materials and Methods: A retrospective analysis of EPTB cases was done during April 2018-January 2019 and a total of 239 cases were enrolled. Pus, CSF, Pleural fluid, Ascitic fluid was screened for TB by GeneXpert MTB/RIF and fluorescent microscopy and data was statistically analysed. Results: Out of the 239 EPTB cases, 101 were pus, 16 were CSF, 105 were pleural fluid and 17 were ascitic fluid. Overall, 14.64% (35/239) cases were found positive for TB by GeneXpert MTB/RIF while 20% (7/35) cases were found to be RIF resistant. Among 35, 23.7% (24/101) pus cases were positive while 10.4% (11/105) pleural fluid cases were found positive for TB nucleic acid. None of CSF and Ascitic fluid sample were found positive for TB. Among these 35 GeneXpert cases 16 cases, were confirmed positive by fluorescent microscopy. Considering GeneXpert as a standard, fluorescent microscopy was found to be 45.7% (95% CI, 28.83% to 63.35%) sensitive and 100% specific (98.21% to 100.00%). Conclusion: Present study showed 14.64% (35/239) cases positive for TB bacilli in EPTB while 20% (7/35) were found to be resistant for RIF. Lower sensitivity of microscopy may be intended to paucity of bacilli in these extra pulmonary sites.