Comparison of slide coagglutination test and countercurrent immunoelectrophoresis for detection of group B streptococcal antigen in cerebrospinal fluid from infants with meningitis.

The usefulness of Phadebact streptococcus reagents for the detection of group B streptococcal antigen in cerebrospinal fluid was evaluated in 54 infants with meningitis and in 22 normal infants. Antigens was detected by slide coagglutination in 19 (82.6%) and by countercurrent immunoelectrophoresis in 20 (87.0%) of 23 cerebrospinal fluid specimens from infants with group B streptococcal meningitis at admission. After initiation of antimicrobial therapy, antigen could be detected in 11 of 19 (by slide coagglutination) and 7 of 18 (by countercurrent immunoelectrophoresis) cerebrospinal fluids. False-positive reactions were noted by slide coagglutination in one infant with S. bovis meningitis and one with group B streptococcal bacteremia without meningitis; none occurred with countercurrent immunoelectrophoresis. The commercial availiability, simplicity, sensitivity (82.6%), and specificity (96.4%) of the Phadebact slide coaggluatination test for detecting group B streptococcal antigen in cerebrospinal fluid suggest that it may be useful for the early and rapid diagnosis of group B streptococcal meningitis.