group b streptococcus, known as group b strep, is one of many kinds of streptococcus bacteria that infect humans. group b strep can live in a healthy person's body without causing illness. but it can be life-threatening.
people who are at risk for severe group b strep infection include newborns who catch it from their mothers during childbirth and people who have weakened immune systems (as from chronic illness or cancer treatment).
group b strep is treated with antibiotics. testing for group b strep is done during pregnancy. to prevent newborn infection, anyone with group b strep infection is treated in the last weeks of pregnancy or during labour.