Diagnosis of tuberculosis in patients with pleural effusion in an area of HIV infection and limited diagnostic facilities.

In a prospective study of 118 patients with pleural effusion, tuberculosis (TB) was diagnosed in 112. In 84 patients the diagnosis of TB was made by detection of acid-fast bacilli by stain (auramine, Ziehl-Neelsen) or by culture of mycobacteria (Löwenstein-Jensen medium) in pleural fluid or pleural tissue (obtained by closed biopsy) or by the presence of caseating granulomas in histological sections. In 28 patients the diagnosis of TB was considered probable, based on good response to anti-tuberculous therapy. The highest diagnostic yield was obtained by histology (85%), followed by culture of pleural biopsy (37%) and pleural fluid culture (36%). Pulmonary tuberculosis was found in 8 patients and dissemination of TB to other sites in 25 patients of whom 20 were HIV positive. By logistic regression analysis we identified 2 independent diagnostic markers for TB pleuritis: pleural fluid protein > 50 g/l (Odds ratio 12.1, 95% confidence interval (CI): 1.1-128.3) and adenosine deaminase of > 10 U/l (Odds ratio 11.08, 95% CI: 1.3-96.4). We conclude that conventional facilities of a referral hospital are sufficient to diagnose tuberculous pleuritis as well as disseminated tuberculosis irrespective of HIV infection. However, for regions with overstretched health services and high prevalences of tuberculous pleurisy in patients with pleural effusion we suggest a simplified diagnostic approach based on exclusion of other causes of pleural effusion by simple means and use of these diagnostic markers.