Murine resistance to type III group B streptococci

We examined the role of serum, complement and the reticuloendothelial system in mouse resistance to type III group B streptococci (GBS). Normal serum obtained from 21 day-old mice failed to protect chick embryos against a lethal intravenous (IV) inoculation of GBS-III-SS620/50. Mice that were decomplemented using cobra venom factor remained resistant to intraperitoneal (IP) inoculation of 10(6) colony-forming units (CFU) of GBS-III-22620/50, GBS III-Bell and GBS-III-Minnesota. In contrast, mice prepared with IP oleic acid were killed with 10(4) CFU of GBS-III-SS620/50 IP. However, when mice were injected IV with oleic acid, they remained resistant to IP inoculation of GBS-III-SS620/50. These results suggest that peritoneal macrophages play a role in murine defense against IP infection with GBS-III-SS620/50.