Streptococcus agalactiae (also known as Group B streptococcus or GBS) is a member of the gastrointestinal normal flora in some humans and can spread to secondary sites - including the vagina in 10–30% of women.
This is of clinical importance: Streptococcus agalactiae can be transferred to a neonate passing through the birth canal and can cause serious group B streptococcal infection.
In the western world, Streptococcus agalactiae is the major cause of bacterial septicemia of the newborn, which can lead to death or long-term sequelae.
Streptococcus agalactiae (Wikipedia)