Streptococcus agalactiae Group B streptococci Colonies of Streptococcus agalactiae cultivated on Columbia agar with 5% sheep blood. Cultivation 24 hours in an aerobic atmosphere enriched with 5% carbon dioxide. Colonies are surroundend by a zone of beta-hemolysis.
Streptococcus agalactiae 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: S. agalactiae can be transferred to a neonate passing through the birth canal and can cause serious group B streptococcal infection. In the western world, S. agalactiae is the major cause of bacterial septicemia of the newborn, which can lead to death or long-term sequelae.