Immunodiagnoses of community-acquired pneumonia in childhood.

A diagnosis of bacterial pneumonia requires isolation of the pathogen from blood, lung or tracheal aspirate; however, cultures of blood and pleural fluid samples are usually insensitive. Thus, in the majority of patients the etiology is rarely determined. A total of 840 pleural fluid effusion samples from children with clinical and laboratory diagnoses of acute bacterial pneumonia were evaluated by Dot-ELISA. This method was standardized in order to detect polysaccharide capsular bacterial antigen in pleural fluid samples previously treated with 0.1 M EDTA and dotted on nitrocellulose membrane strips. Pneumococcal omniserum and H. influenzae type b antiserum diluted 1:200 were employed for detection of S. pneumoniae and H. influenzae type b antigens, respectively. Dot-ELISA showed relative indices of 0.913 for sensitivity and 0.552 for specificity, and a total positivity of 75.6 per cent, being 53.21 per cent for S. pneumoniae and of 22.38 per cent for H. influenzae.