Group B Streptococcus, also known as Streptococcus agalactiae, colonizes the vaginal and gastrointestinal tracts of up to 45% of healthy women and may infect neonates in utero or during delivery, causing neonatal sepsis in 1-2% of colonized neonates. GBS infection may also occur in nonpregnant (particularly elderly) adults with underlying medical conditions, presenting as urinary tract infection, pneumonia, or soft-tissue infection. [from
NCI]