Abstract:
Background: Tuberculous pleural effusion (TPE) is a common cause of lymphocytic pleural effusion. Definite diagnosis, confirmed by microbiologic identification of M. tuberculosis from pleural fluid or pleural tissue, has low sensitivity and time consuming. Xpert MTB/RIF is a new easily performed molecular diagnostic test of tuberculosis and rifampicin resistance. However, its efficacy in diagnosis of TPE has not been evaluated. Methods: Patients with undiagnosed exudative lymphocytic pleural effusion were enrolled and underwent thoracentesis and pleural biopsy. In addition to standard tests to make final diagnosis of pleural effusion, AFB staining, mycobacterial culture and Xpert MTB/RIF assays were done from pleural fluid, pleural biopsy specimen and sputum samples. Results: There were 27 TPE and 25 non-TB cases. Xpert MTB/RIF of pleural fluid and pleural tissue specimens were positive in 6 (22%) and 20 patients (74%), respectively. Sputum samples were positive in 4 of 25 collectable samples of TPE cases (15%). The overall sensitivity of Xpert MTB/RIF from pleural fluid and pleural tissue samples was 81.5 %, and specificity was 100%. Histology of the pleural tissues showed granulomatous pleuritis in 24 patients (88.8%). Combination of pleural tissue histology and Xpert MTB/RIF test of pleural fluid and pleural tissue revealed 100% sensitivity. 2 patients were detected rifampicin resistance by Xpert MTB/RIF. Conclusions: Xpert MTB/RIF test have good sensitivity and specificity for diagnosis of tuberculous pleural effusion. Additional diagnostic yield on histology results was documented.