Approximately one of every 100 to 200 babies whose mothers carry GBS develop signs and symptoms of GBS disease. Sepsis, pneumonia, and meningitis are the most common problems. Meningitis is more common with late-onset GBS disease. Late-onset disease is very rare. GBS disease is diagnosed when the bacterium is grown from cultures of sterile body fluids, such as blood or spinal fluid.
Cultures take a few days to complete.
GBS carriage can be detected during pregnancy by taking a swab of both the vagina and rectum for special culture. Women who carry GBS should not be given oral antibiotics before labor because antibiotic treatment at this time does not prevent GBS disease in newborns. An exception to this is when GBS is identified in urine during pregnancy. GBS in the urine should be treated at the time it is diagnosed. Most GBS disease in newborns can be prevented by giving certain pregnant women antibiotics through the vein during labor.