HETEROGENEITY OF TYPE III GROUP B STREPTOCOCCI IN MOUSE PROTECTION TESTS

Seven strains of group B streptococci (GBS) type III isolated from neonatally-infected infants were tested for mouse-virulence. The LD50 varied between 105 and 107 colony-forming units. Two antisera raised in rabbits against the type III reference strain D136C could only protect mice against 5 of the 7 GBS isolates.