Group B Strep Test

Group B Strep Test

Group B Streptococcus is the commonest cause of life-threatening infection in newborn babies.  Most GBS infections can be prevented by giving all women with GBS intravenous antibiotics at the onset of labour, as well as to those delivering prematurely or with a history of GBS.  This recommended use of antibiotics reduces the likelihood of GBS infection developing in a baby born to a woman carrying GBS at the time of delivery from around 1 in 300 to less than 1 in 6000.  Oral antibiotics given have not been shown to be effective at preventing GBS infection in babies, but intravenous antibiotics in labour are highly effective.  There are always small but possibly serious risks associated with taking antibiotics, and management and treatment need to be fully discussed.

Detecting a GBS carrier
Testing for GBS infection is not generally available in the NHS but is routinely undertaken at MUMS.  The method for testing is an enriched culture medium (ECM) specifically designed for the isolation of GBS in swabs.  Two swabs (lower vaginal and rectal) need to be cultured at 35-37 weeks’ gestation to best predict colonisation with GBS around the time of delivery.

The facts concerning GBS
GBS is the most common cause of bacterial infection in newborn babies in the UK.  Around 1 in 1000 babies in the UK develop a GBS infection i.e. about 700 babies a year.

Babies are usually exposed to GBS shortly before or during birth.  It is not understood why some babies are susceptible to the bacteria and develop infection, whilst others do not.  What is clear, however, is that most GBS infections in newborn babies can be prevented by giving women in higher risk circumstances intravenous antibiotics from the onset of labour until the baby is born.