Diagnostic accuracy of BAL Gene Xpert compared to BAL AFB staining in Sputum negative Pulmonary Tuberculosis Suspects

Abstract

Tuberculosis has stood the test of time over the millennia and still wreaks havoc on human life all over the world. We have studied the role of bronchoscopy in smear negative PTB suspects and have compared the results of BAL Gene Xpert with BAL AFB staining among the study population. We have also determined the microbiological profile in cases who are MTB negative. We retrospectively reviewed the respiratory samples (sputum and BAL) of 82 sputum negative PTB suspects from july 2018 – july 2019 for ZN stain and Gene Xpert. 25 cases were detected by Gene Xpert additionally to the 11 cases detected by BAL afb staining alone. Out of the 36 cases detected on gene Xpert 3(8%) were RIF resistant. These 5 samples which were positive on BAL AFB and negative on Gene Xpert, are suspected to be NON TB mycobacteria. Out of the remaining 41 samples, non TB culture results showed 8 Acinetobacter, 10 pseudomonas, 12 klebsiella, 2 e.coli, 2 candida, 7 no growth on culture. According to our study, the bronchoscopic samples when subjected to Gene Xpert detect a higher number of cases which would go undetected otherwise compared to BAL AFB staining. Hence, bronchoscopy must be performed on such smear negative suspects and Gene Xpert could replace smear microscopy as initial diagnostic testing. It also helps in detecting first line drug resistance in addition.