Evaluation of GeneXpert MTB/RIF for the Detection of Mycobacterium Tuberculosis in a Tertiary Care Hospital, Pakistan

Abstract

Objectives: To evaluate the diagnostic concert of GeneXpert MTB/RIF assay for the analysis of pulmonary
tuberculosis and detection of Rifampicin resistance using sputum samples.
Methodology: The retrospective descriptive cross-sectional study was conducted at the department of microbiology.
Federal Government Polyclinic (FGPC), Islamabad, Pakistan, from August 2023 to July 2024. A total of 771 participants,
referred by their physicians as TB suspects, were consecutively enrolled in the study from various wards of FGPC and
other healthcare facilities in Islamabad, Pakistan. Sputum samples were collected from these participants and
examined using light microscopy following Ziehl-Neelsen (ZN) staining. All samples were processed using the
GeneXpert MTB/RIF Assay.
Results: Out of the 771 sputum samples, Mycobacterium tuberculosis was detected in 89 (11.54%) cases using the
GeneXpert MTB/RIF assay. Rifampicin-resistant M. tuberculosis was found in 8 out of these 89 cases (8.98 %). Male
and female ratio of the patients was almost equal. Males were found to be 406 (57.4%) while 365 (42.5%) were
females. The data were expressed as mean, median, and mode, and analyzed using the Statistical Package for Social
Sciences (SPSS) version 25.0. Simple descriptive statistics (frequencies and percentages) were calculated for each
categorical variable. The diagnostic accuracy, i.e., sensitivity, specificity, positive predictive value (PPV), and negative
predictive value (NPV) of the GeneXpert MTB/RIF assay compared to traditional methods was calculated.
Conclusion: The GeneXpert MTB/RIF has higher sensitivity and specificity to conventional ZN smear microscopy. It is
a simple, rapid, and accurate test for detecting Mycobacterium tuberculosis in sputum specimens.
Keywords: GeneXpert MTB/RIF; Pakistan; Pulmonary tuberculosis; Rifampicin resistance.