GeneXpert and Acid-Fast Bacilli Smear for Diagnosis of Pulmonary Tuberculosis in a Tertiary Care Center of Rural Nepal

Abstract

Introduction: Mycobacterium tuberculosis is the second most infectious cause of death in adults globally and is major health trouble in Nepal. The diagnosis of pulmonary tuberculosis is mainly carried by acid-fast bacilli smear microscopy, culture on Lowenstein–Jensen media, and GeneXpert MTB/RIF assay. This study aimed to evaluate the GeneXpert MTB/RIF and Acid-Fast Bacilli stain smear used for the diagnosis of pulmonary tuberculosis.

Methods: A cross-sectional study was performed at Karnali Academy of Health Sciences, Jumla, from July 2021 to June 2022. Our study population comprised 390 probable cases of pulmonary tuberculosis from the ages of 2 to 92 years. A total of 390 sputum specimens from suspected presumptive tuberculosis sufferers were tested using the direct smear staining technique of Acid-Fast Bacilli stain smear and GeneXpert for the detection of MTB/RIF. The GeneXpert MTB/RIF technique was compared with the Acid-Fast Bacilli stain smear. Patient’s demographic details, sputum AFB smear, and GeneXpert test results were collected and entered in working Performa. Data were analyzed using SPSS 16.0.

Results: Out of 390 samples 13.84% were positive for Mycobacterium tuberculosis via GeneXpert MTB/RIF assay while 5.12% were positive through AFB microscopy which was statistically significant (p<.0001). When compared with GeneXpert, taking GeneXpert as the gold standard in the rural setup of Nepal the sensitivity of AFB staining was 37.03%, while its specificity was 90.81%.

Conclusions: GeneXpert MTB/RIF is a rapid test that can aid in the timely diagnosis of Mycobacterium tuberculosis, facilitating the timely treatment in the rural area.