The use of real-time polymerase chain reaction and an adenosine deaminase assay for diagnosing pleural tuberculosis

The diagnosis of pleural tuberculosis remains a challenge, because the most widely used conventional diagnostic tools are unable to rapidly detect Mycobacterium tuberculosis in pleural fluid with sufficient sensitivity. Objectives The aim of this study was to evaluate the usefulness of an adenosine deaminase assay and real-time polymerase chain reaction (qPCR) in diagnosing pleural tuberculosis. Methods One hundred and five consecutive pleural fluid specimens collected between August 2008 and March 2009 were assessed. Among the 105 specimens, 50 (48%) were unconfirmed tuberculosis cases, 21 (20%) were confirmed tuberculosis cases and 34 (32%) were non-tuberculosis cases (controls). Real-time PCR was performed using the Light Cycler Mycobacterium detection kit according to the manufacturer‘s instructions (Roche Diagnostics). An adenosine deaminase assay was carried out using a commercial colorimetric assay kit as a user-defined method on a Beckman DxC 600 Synchron analyser. Results The sensitivity of the qPCR was 67% and specificity was 100%. The sensitivity of the adenosine deaminase assay was 80% and specificity was 94%. Conclusion The findings show that the adenosine deaminase assay had higher sensitivity than qPCR. Real-time PCR had 100% specificity, thus a combination of the two methods may be useful for the diagnosis of pleural tuberculosis.