COMPARATIVE STUDY OF GENEXPERT WITH ZN STAINING IN SPUTUM SAMPLES OF SUSPECTED PULMONARY TUBERCULOSIS

*Dr. Abdul Hashim K. P. and Dr. Muhammed Anas Ayoob

ABSTRACT

Background: Tuberculosis remains one of the deadliest communicable diseases. There are number of tests available for the diagnosis of tuberculosis but conventional microscopy has low sensitivity and culture although gold standard, takes longer time for positivity. Gene-Xpert is real-time PCR based rapid molecular assay for diagnosing TB. By early detection of tuberculosis, GeneXpert can prevent the spread of TB. Aim: The aim of this study was to find the effectiveness of GeneXpert in detecting the MTB in sputum samples of suspected pulmonary tuberculosis patients and to compared with ZN staining (AFB smear microscopy). Materials and Methods: We retrospectively reviewed the sputum samples of suspected pulmonary tuberculosis 98 patients for 2 years. The sensitivity, specificity, PPV and NPV of GeneXpert and ZN microscopy were calculated using Mycobacterium tuberculosis culture as gold standard. Results: A total of 98 patient samples were evaluated in final analysis. Of these, 66 sputum samples were negative by all three methods used. 21sputum samples were ZN staining positive & 31 samples (31.6%) were GeneXpert TB positive. Out of 77 ZN staining negatives samples, 10 were positive in GeneXpert. The overall sensitivity, specificity, PPV and NPV of GeneXpert were 96.8%, 100%, 100%, & 98.5% respectively. Conclusion: GeneXpert is more accurate and reliable than sputum smear microscopy. GeneXpert can be a useful tool for early diagnosis of patients with high clinical suspicion of pulmonary tuberculosis.

Keywords: Pulmonary TB, Gene Xpert, Rapid diagnosis.