Title: Smear Negative Pulmonary Tuberculosis: Clinico-radiological profile and diagnostic role of bronchoscopy with BAL studies in Indian population

Background: Early diagnosis of pulmonary tuberculosis in smear negative pulmonary TB suspects is critical for early initiation of therapy. Aim: To study the clinico-radiological profile of smear negative Pulmonary TB suspects and evaluation with Bronchoscopy and BAL fluid studies including GenXpert and MGIT culture. Materials and Methods: Retrospective analysis of 71 smear negative Pulmonary TB suspects was done. Demographic profile, clinical, radiological, bronchoscopic findings and results of BAL studies including GeneXpert and MGIT culture at 6 weeks recorded. Diagnostic yield of BAL Gene Xpert was evaluated using BAL MGIT culture as gold standard. Statistical analysis was done with SPSS ver 20. Results: The median age of presentation was 32yrs. HRCT was showing mediastinal lymphadenopathy in significant number of patients with microbiologically confirmed TB. There was no statistically significant difference in clinical and other radiologic findings among TB and non TB patients. Bronchoscopy revealed discharge from bronchus (60%), unhealthy mucosa (15%), endobronchial growth (8%). BAL fluid Gene Xpert detected MTB in 31% of total patients and of them, 17% showed Rifampicin resistance. MGIT culture at 6 weeks was positive for 22%. Sensitivity, specificity, PPV and NPV for Gene Xpert were 92%, 95%, 95% and 92% respectively. Conclusion: Bronchoalveolar lavage GeneXpert has a superior diagnostic yield (with high sensitivity and positive predictive value) to detect Mycobacterium tuberculosis in smear-negative Pulmonary TB.