Detection of Pneumococcal Capsular polysaccharide antigens by latex agglutination, counterimmunoelectrophoresis, and radioimmunoassay in middle ear exudates in acute otitis media.

The presence of pneumococcal antigen in middle ear exudates during acute otitis media was studied by latex agglutination and counterimmunoelectrophoresis. The positive antigen findings were confirmed by radioimmunoassay. Latex agglutination gave a positive result in 63% and counterimmunoelectrophoresis in 76% of samples that grew Streptococcus pneumoniae. The methods were complementary; the antigen was detected by one or both of the methods in 88% of these samples. Pneumococcal antigen was further detected in 15% of samples that grew other otitis pathogens and in 33% of samples in which no pathogenic bacteria were recovered by culture. The distribution of pneumococcal serotypes found by immunochemical methods only corresponded to that found by culture.