Pleural fluid ADA, IgA-ELISA and PCR sensitivities for the diagnosis of pleural tuberculosis.

The diagnosis of pleural tuberculosis (pTB) is difficult, and more sensitive and specific techniques are needed. In the period August 1998 to November 2002, we evaluated 132 patients with a pleural effusion submitted to a thoracentesis and pleural biopsy in a tertiary care hospital in Rio de Janeiro, Brazil. Three tests were performed and compared in the pleural fluid: ADA activity measurement, IgA-ELISA for two combined specific Mycobacterium tuberculosis antigens, and polymerase chain reaction (PCR) for detection of M. tuberculosis DNA. Ninety-five patients (72%) were given a final diagnosis of pTB. Overall histopathologic sensitivity was 77%. The sensitivities of pleural fluid culture and AFB smear were 42% and 1%, respectively. Twenty-one (22%) additional patients had a clinical diagnosis of pTB. Median follow-up time of all TB patients after the completion of antituberculous treatment was 13 months. Sensitivities of ADA, IgA-ELISA and PCR were 91%, 78% and 82%, while specificities were 93%, 96% and 85%, respectively. Only ADA sensitivity was significantly higher than the histopathologic examination (McNemar chi2 test; p = 0.002) and also significantly higher than ELISA (p = 0.049), but not higher than PCR (p = 0.143). We conclude that the routine use of ADA activity measurement in pleural fluid can obviate the need for a pleural biopsy in the initial diagnostic approach to pleural effusions, while IgA-ELISA and PCR techniques, potentially more specific tests, need further refinement to improve their accuracy.

[Relationship between serological diagnosis (ELISA) and severity of pulmonary tuberculosis in children]. / Relação entre o diagnóstico sorológico (ELISA) e a gravidade da tuberculose pulmonar na infância.

Forty eight children from 0 to 13 years old were submitted to the enzyme-linked immunosorbent assay (ELISA) serological test with a view to detect anti PPD IgG antibodies, for diagnosis of pulmonary tuberculosis and to establish the relationship between immune response and radiological gravity of pulmonary tuberculosis (mild, moderate and severe). There were 29 children with pulmonary tuberculosis and 19 children without tuberculosis. The median ELISA optical density were: 0.098 in children with primary complex (mild); 0.092 in children with pneumonic pattern (moderate) and 0.134 in children with miliary tuberculosis (severe). These data show higher positive serological test results in severe forms of pulmonary tuberculosis (p = 0.0007).