Identification of Streptococcus pneumoniae by the Phadebact coagglutination test

The Phadebact Pneumococcus Test is a coagglutination slide test for the serological identification of Streptococcus pneumoniae. Of 200 alpha-hemolytic streptococcal isolates, coagglutination test results agreed with those of optochin susceptibility and bile solubility in 189 cases, 105 of which were identified as S. pneumoniae by all three methods. The Phadebact test was 100% (113 of 113) sensitive and 98% (85 of 87) specific and was more sensitive than counterimmunoelectrophoresis in detecting the presence of pneumococcal antigen in cerebrospinal fluid. In fluids seeded with known amounts of pneumococcal antigen, it consistently detected lower levels than did counterimmunoelectrophoresis. The test provides a rapid and simple method for the definitive identification of S. pneumoniae.