Group B Streptococcus is a type of bacteria that causes illness in people of all ages. Group B strep disease in newborns most commonly causes infection of the blood, pneumonia, and sometimes meningitis. About 25% of pregnant women unknowingly carry group B strep in the rectum or vagina. Group B strep in pregnant women can be prevented. Below you may find medications used to treat or help with Prevention Of Perinatal Group B Streptococcal Disease. More about Prevention of Perinatal Group B Streptococcal Disease