Group B streptococcal infections


Group B Streptococcus (GBS) – also known as Streptococcus agalactiae – are bacteria which are normal flora of the human gut. They can also colonise the male and female genital tract.  GBS can cause serious disease in neonates and young infants. There are two types of GBS disease in infants:

  • early onset which occurs during the first week of life (less than seven days old)
  • late onset which occurs from the first week of life through to three months of life (seven to 90 days old)

For early-onset disease, GBS most commonly causes:

  • bacteraemia and sepsis
  • pneumonia
  • meningitis

Similar illnesses are associated with late-onset GBS disease. However, meningitis is more common with late-onset GBS disease than with early-onset GBS disease.

GBS infection can also cause a range of diseases in adults. GBS is usually diagnosed by microbiological culture of the affected site.

GBS is spread from mother to child during childbirth if the mother’s genital tract is colonised by the bacteria.  


Further guidance on GBS infections can be found on the Royal College of Obstetricians and Gynaecologists website.

For all infection prevention and control guidance visit the A-Z ​pathogens section of the National Infection and Prevention Control Manual.

Data and surveillance

As seen in Figure 1, the incidence of both early-onset and late-onset GBS has steadily increased since 2013. 

In this section

Streptococcal infections