Evaluation of real-time PCR of patient pleural effusion for diagnosis of tuberculosis

For this cross-sectional study, 150 consecutive patients with pleural effusion diagnosed by chest radiography, who were referred for diagnostic thoracocentesis and pleural biopsy and met eligibility criteria, had a pleural fluid specimen submitted for real-time PCR testing. Overall, 98 patients had pleural TB and 52 had pleural effusion secondary to other disease. TB diagnosis was obtained using acid-fast bacilli (AFB) smear or culture for mycobacteria and/or histopathologic examination in 94 cases and by clinical findings in 4 cases. Sensitivity, specificity, positive and negative predictive values of PCR testing for pleural TB diagnosis were 42.8% (95% CI 38.4 - 44.8), 94.2% (95% CI 85.8 - 98.0), 93.3% (95% CI 83.6 - 97.7), and 48.5% (95% CI 44.2 - 50.4), respectively. The real-time PCR test improved TB detection from 30.6% to 42.9% when compared to AFB smear and culture methods performed on pleural fluid specimens, although the best sensitivity was achieved by combining the results of culture and histopathology of pleural tissue specimens.The real-time PCR test of pleural fluid specimens is a useful and non-invasive additional assay for fast diagnosis of pleural TB.Diagnosis of pleural tuberculosis (TB) remains a challenge due to its nonspecific clinical presentation and paucibacillary nature. Conventional methods, such as direct testing for acid-fast bacilli (AFB) and culture of pleural fluid, lack sensitivity (less than 5% and 40%, respectively) [1-3]. Despite improved detection rates with new methods, high pleural fluid levels of adenosine deaminase (ADA) may be found in other diseases, especially empyema and parapneumonic effusions, and there is no established cut-off value for measurement of interferon-gamma in pleural fluid [4,5].Therefore, a definitive diagnosis of pleural TB still depends on demonstration of M. tuberculosis or caseous granulomas in pleural biopsy, an invasive method with possible complications requiring specialized medical care that is no