Assessment of rapid methods of pneumococcal antigen detection in routine sputum

Sputum specimens from 480 patients were examined for the presence of pneumococci by Gram film and culture and for pneumococcal antigen by counterimmunoelectrophoresis, coagglutination, and latex agglutination. Ninety six positive specimens were detected. Gram film and culture provided the most reliable techniques in well taken specimens collected early in the illness before antibiotic treatment had started. More than 70% of the specimens examined were submitted after starting antibiotics, however, and in these specimens, methods of antigen detection proved of greater value than either Gram film or culture. Counterimmunoelectrophoresis, coagglutination, and latex agglutination were similar in sensitivity and specificity, but coagglutination and latex agglutination were much easier to perform and to read.