Prevention of Group B Streptococcal Colonization and Bacteremia in Neonatal Mice with Topical Vaginal Inhibitors

Pregnant Swiss-Webster mice were vaginally inoculated with 105 virulent and avirulent serotype III Streptococcus agalactiae and treated 4 days later with topical vaginal inhibitor solutions. Preparations containing lipoteichoic acid (LTA) or glycerophosphate (GP), the repeating linear backbone of LTA, significantly reduced neonatal colonization and bacteremia by the virulent isolate and colonization by the avirulent strain. Similar results were obtained if bacteria were preincubated with LTA or GP at 37°C for 30 min before vaginal inoculation. Human serum albumin (HSA), a known inhibitor ofbinding of LTA to human fetal epithelial cells, also resulted in reduction in colonization and bacteremia of neonatal mice. However, maternal treatment with a combination of HSA (2%) and GP (1%) completely prevented neonatal colonization and bacteremia without altering the normal aerobic bacterial vaginal flora. These results provide impetus to the development of an alternative means of preventing neonatal group B streptococcal infections in humans without requiring maternal immunization or chemoprophylaxis.