Discordant Streptococcus agalactiae (Group B streptococcus) gestational infection in monochorionic/diamniotic and dichorionic/diamniotic twins.

Infection due to Streptococcus agalactiae or Group B streptococcus may be acquired during parturition or gestation. Discordant twin gestational Group B streptococcus infections are rarely reported. We describe two cases of fatal discordant gestational Group B streptococcus infection in both a monochorionic/diamniotic pregnancy and in a dichorionic/diamniotic pregnancy. In both instances, cultures, examination of the placentae, and autopsy findings demonstrated infection by Group B streptococcus in only the presenting fetus. Despite the ubiquity of this organism, this is the first documented case of discordant gestational Group B streptococcus infection in monochorionic/diamniotic twins and only the third case documented in dichorionic/diamniotic twins.