Serotypes of group B streptococci and their relation to hyaluronidase production and hydrolysis of salicin.

A total of 252 strains of group B streptococci were serotyped and examined for their ability to ferment lactose (lac+), to hydrolyze salicin (sal+), and to produce hyaluronidase (hy+). Of these strains, 67 had been isolated from bacteremia and meningitis in infants less than 2 months old. Eighty-one strains were isolated from bacteremia and meningitis in adults, and 104 strains were from various other infections. Type III was the most common in neonatal disease, especially if isolates from cases of bacteremia in infants less than 10 days of age were not included. Only 6% of the strains were lac+. Sal+/hy+ strains were never type III, but 91% of the strains belonging to the other serotypes were sal+/hy/. Results showed that 81% of the sal+/hy- strains and 95% of the sal-/hy+ strains were type III, and sal-/hy+ strains were more than twice as frequent as sal+/hy- strains in serious neonatal infections, in contrast to the other two disease groups, in which the opposite was found to be the case. These reactions may be used as additional markers in epidemiological studies.