Group B Strep tests for pregnant women

SUZANNE CALLANDER looks at the different testing methods that can identify Group B Streptococcus carriage in pregnant women and highlights the latest testing technology developments.

Group B streptococcus (GBS) is a Gram positive bacterium found as part of the normal gut flora in 20-30% of people. It ‘colonises’ the vagina in roughly 22% of women. Carrying the bacterium is not associated with any health risks or symptoms. However, it is one of the leading causes of infectious neonatal morbidity and mortality. The bacteria can be passed from mother to baby in the birth canal from the colonised vaginal and gastrointestinal tracts in healthy women. Colbourne et al¹ estimates that approximately 14% of all women in the UK are carriers.

Most babies are unaffected by GBS colonisation. However, a small number may develop a clinical infection, known as early-onset GBS infection. Typically, this happens within the first 12 hours of life, with the baby becoming symptomatic between birth and seven days of life. In its 2012 report, the UK National Screening Committee estimated that one in 2,000 babies born in the UK and Ireland develop early onset GBS infection. Consequently, around 340 of the 680,000 babies born in the UK each year are likely to develop early-onset GBS infection.