Analysis of group B streptococcal types associated with disease in human infants and adults.

It is important to resolve existing differences of opinion regarding group B streptococcal type distribution in human disease because of the relevance of type prevalence to future programs of prevention. This report compares data obtained from typing 392 group B streptococci isolated from systemic infections in both infants and adults in the United States from 1972 through 1975. The data showed a substantial predominance of type III among strains isolated from cases of infant meningitis and from "late-onset" septicemia but did not confirm a prior report that type Ia causes most cases of "early-onset" infant septicemia. Type II was the predominant serotype among 11 cerebrospinal fluid isolates from adults. The fact that over one-fourth of the isolates were types other than Ia or III means that future epidemiological studies, including definition of immunological factors, must include all five group B types.