Evaluation of GeneXpert as a new diagnostic tool for detection of pulmonary tuberculosis

Background Over the past decade, genotyping of Tuberculosis strains has become an increasingly valuable tool in tuberculosis (TB) control. Molecular epidemiology has helped to identify unsuspected transmission, determine likely locations of transmission, and measure the extent of transmission. Often traditional contact investigations focus on persons in the household and workplace. The Xpert Mycobacterium tuberculosis (MTB)/rifampin (Rif) assay is a rapid test that identifies both the presence of MTB and resistance to Rif in a single test. This can enable early and appropriate treatment initiation as well as accelerate the implementation of multi drug resistant (MDR)-TB control measures, and ultimately reducing TB case incidence. Patients and methods This descriptive study was carried out in Mansoura Chest Hospital from May 2015 to June 2016. A total of 165 subjects suspected to have active TB were included in the present study. Sputum samples of each case were divided into three methods of research: staining with Ziehl–Neelsen for acid-fast bacilli, GeneXpert (GX) MTB Rif assay, and culture. Results GX test has 97.6% sensitivity, 81% specificity, 84.5% positive predictive value, 97% negative predictive value, and 89.7% accuracy. Sensitivity, specificity, positive predictive value, and negative predictive value of GX MTB/Rif were 100, 89.3, 72, and 100%, respectively.