Research Article - Asian Journal of Biomedical and Pharmaceutical Sciences (2022) Volume 12, Issue 88

Utility of genexpert MTB/RIF in the rapid diagnosis of extra pulmonary tuberculosis

Introduction: The diagnosis of extra pulmonary Tb (EPTB) is a challenge. World Health Organization recommends the use of Genexpert MTB/RIF assay (Cepheid, USA), using a hemi nested real-time PCR to amplify an M. tuberculosis-specific sequence of the rpo B gene for the rapid and simultaneous detection of Mycobacterium tuberculosis complex (MTBC) and resistance to rifampicin from clinical specimen. The purpose of this study is to evaluate the performance of the genexpert MTB/RIF test with conventional Mycobacterial culture in EPTB specimens. Materials and Methods: This prospective study (February to Oct 2017, 11 months) includes data on 287 EPTB specimens that were processed by conventional culture on Lowenstein–Jensen (LJ) medium and the rapid molecular-based genexpert MTB/RIF assay system. Results: Among the 287 EPTB samples tested, the genexpert detected the DNA of MTBC in 51 samples (17.8%). Standard bacteriological assays, including AFB microscopy and culture, were positive in 26 (9.1%) and 35 (12.1%) specimens respectively. Performance of genexpert results was evaluated against. The overall sensitivity and specificity of the Xpert assay were calculated to be 94.6% and 94.4%, respectively. The sensitivity of the Xpert assay with tissue specimens was 84.6% and 80.7% specificity, while there was 86.6% sensitivity and 98.1% specificity with the body fluids. Conclusion: genexpert had high performances than culture for EPTB specimen. It can be a useful tool for early diagnosis of patients with high clinical suspicion of EPTB. The other major advantage of Gene Xpert is that it simultaneously detects Rifampicin resistance within 2 hours.

Author(s): Rangaiahagari Ashok

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