Enzyme-linked immunosorbent assay for detection of Streptococcus pneumoniae antigen.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Streptococcus pneumoniae polysaccharide antigen in cerebrospinal fluid and serum. Sensitivity and specificity were determined for purified antigen preparations. Specificity was also evaluated in the rabbit meningitis model, and the sensitivity was compared to counterimmunoelectrophoresis, using the infected rabbits' cerebrospinal fluid and serum. The ELISA was a specific technique for detecting S. pneumoniae antigen. ELISA was 25 times more sensitive than counterimmunoelectrophoresis for purified antigen and resulted in an increased positivity of the cerebrospinal fluid and serum from infected rabbits. ELISA should prove very useful in the diagnosis of pneumococcal infections.