ABSTRACT
Pleural tuberculosis [TB] is a diagnostic challenge because of its nonspecific clinical presentation and paucibacillary nature. The inefficiency of conventional laboratory methods and the reliance on pleural biopsy have motivated the evaluation of alternative diagnostic strategies. In this study, our goal was to improve the diagnosis of tuberculous pleural effusion and to determine the most sensitive, specific, and rapid diagnostic methods. We used PCR to detect DNA [IS 6110] specific for M tuberculosis complex and IFN-gamma quantitation on pleural fluid samples and compared them to the results of immunnocytopathology staining and conventional bacteriological methods [Ziehl Neelsen stain and culture using the LJ medium]. The study population included 50 patients presented with pleural effusion at Alexandria Main University Hospital and El Maamora Chest Hospital, between June 2004 to December 2004. In addition 5 cases of malignant pleural effusion were received from Damnhour oncology center - Behira, in the period from January 2004 to December 2004. According to the clinical diagnosis, the patients were distributed into 3 groups; group I; 14 patients with confirmed old tuberculosis patients group II ; 8 patients with Probable pleural tuberculosis and group III; 33 patients with Pleural effusion due to an etiology different from tuberculosis. For each specimen of pleural fluid; Immunocytochemical staining, Ziehl- Neelsen staining, culture on Lowenstein Jensen medium, measurement of IFN-gamma level, and PCR for detection of Mycbacterium tuberculosis DNA [IS 6110] were done. No samples were positive by Ziehl-Neelsen staining or by culture for M.tuberculosis. Only one case was positive for pleural tuberculosis by PCR. IFN-gamma values were significantly higher in the pleural fluid of patients with confirmed tuberculosis than in those with probable pleural tuberculosis. Ten out of 14 patient with confirmed tuberculosis. were reactive to IFN-gamma by ELISA [mean value = 276.2 picogram/ml], while only one case out of 8 cases with probable pleural tuberculosis was reactive [mean value = 2.5 picogram/ml]. As regards the third group with etiology different from tuberculosis, all the cases were not reactive by ELISA for IFN-gamma. PCR, and measurement of IFN-g levels provide the basis for the rapid and efficient diagnosis of pleural TB in different clinical settings