INTERPRETATION OF GENEXPERT RESULTS AND THEIR ASSOCIATION WITH SPUTUM SMEAR STATUS IN SUSPECTED PULMONARY TUBERCULOSIS PATIENTS

Sadia Sarwar; Hashir Masood; Samra Zulfiqar; Muhammad Aqib Nadeem; Noor ul Ain; Hamda Raza; Kainat Saleem; Misbah Saeed; Tayyaba Anmol; Sidra; Ali Haider; Muhammad Abdullah Butt

Authors

Sadia Sarwar
Hashir Masood
Samra Zulfiqar
Muhammad Aqib Nadeem
Noor ul Ain
Hamda Raza
Kainat Saleem
Misbah Saeed
Tayyaba Anmol
Sidra
Ali Haider
Muhammad Abdullah Butt

Keywords:

Tuberculosis, Mycobacterium tuberculosis, GeneXpert MTB/RIF, Ziehl-Neelsen staining, sputum smear microscopy, pulmonary tuberculosis, smear-negative TB.

Abstract

Background: Tuberculosis (TB) remains a major public health problem, particularly in high-burden countries such as Pakistan. Ziehl-Neelsen (ZN) sputum smear microscopy is widely used because of its low cost and simplicity, but its sensitivity is limited, especially in patients with low bacterial loads. GeneXpert MTB/RIF is a rapid molecular method that can detect Mycobacterium tuberculosis and rifampicin resistance with greater sensitivity. This study was conducted to determine the relationship between GeneXpert MTB/RIF results and sputum smear microscopy among suspected pulmonary TB patients.

Methods: A cross-sectional analytical study was conducted at the GeneXpert Laboratory of DHQ South City Hospital, Okara, Pakistan, from 1^st September to 1^st December 2025. A total of 187 sputum samples from patients suspected of pulmonary TB were selected through non-probability convenience sampling. Each sample was tested using both ZN smear microscopy and GeneXpert MTB/RIF. Demographic and laboratory data were recorded and analyzed using SPSS version 26. The Chi-square test was used to assess the association between GeneXpert and smear microscopy results, with p < 0.05 considered statistically significant.

Results: Among the 187 participants, 114 (61.0%) were male and 73 (39.0%) were female, with a mean age of 49.49 years. ZN smear microscopy detected TB in 35 (18.7%) patients, whereas GeneXpert detected M. tuberculosis in 60 (32.1%) patients. All 35 smear-positive samples were also GeneXpert-positive, while 25 (41.7%) of the GeneXpert-positive cases were smear-negative. GeneXpert therefore detected approximately 71% more cases than smear microscopy. A statistically significant association was observed between GeneXpert and smear microscopy results (p < 0.001).

Conclusion: GeneXpert MTB/RIF demonstrated a higher detection rate than ZN smear microscopy and identified a substantial proportion of smear-negative cases. The findings indicate that a negative sputum smear does not exclude pulmonary TB. GeneXpert should therefore be considered an important diagnostic method for suspected TB, particularly where rapid and sensitive detection is required.