Impact of Gene Xpert in resource limited settings to meet End TB strategy

Abstract

Objective: To extensively analyze the diagnostic accuracy of Gene Xpert MTB/RIF assay in cases of both pulmonary and extra pulmonary TB, versus the standard conventional methods like Ziehl Neelsen smear microscopy.

Methodology: This study was conducted from Augus, 2023 to March 2024 at Microbiology Laboratory MTI- GKMC/BKMC, Swabi. Samples received both from pulmonary and/or extra-pulmonary sites, were subjected to formation of smear followed by microscopy on Ziehl Neelsen staining, and further subjection to Gene Xpert analysis.

Results: Out of the total 863 samples, 78 were detected positive on Gene Xpert, with an overall positivity of 9.03%, whereas the overall positivity on microscopy was lower i.e. 8.45%. Overall Rifampicin resistance as seen on Gene Xpert analysis was 1.28%, as only one pus sample out of a total of 78 pulmonary and extra pulmonary samples, was detected to be Rifampicin resistant. Diagnostic performance of Gene Xpert MTB/RIF in comparison with Microscopy was calculated using the following 2X2 table, taking Gene Xpert as a standard which showed a sensitivity of 93.58% and specificity of 100%, a positive predictive value was calculated to be 100%, a negative predictive value of 99.36% with an accuracy of 99.42%.

Conclusion: Gene Xpert MTB/RIF assay has proven to be a highly sensitive user-friendly technique for diagnosing TB and resistance against rifampicin simultaneously for both pulmonary and extra pulmonary TB.