Group B streptococcal infections: guidance, data and analysis

The characteristics, diagnosis, treatment, and epidemiology of group B streptococci.

About group B streptococci

Lancefield group B streptococci (GBS), also called Streptococcus agalactiae, form part of the normal bacterial flora of the gut. GBS is also commonly found in the male and female genital tract.

GBS is mainly associated with disease in newborns (neonates) causing meningitis, septicaemia and pneumonia. It also causes septic abortion (loss of pregnancy as a result of infection) and puerperal sepsis (systemic and uterine infection at or following childbirth as a result of bacterial infection).

Infection in newborns may be divided into 2 types:

Early onset disease (EOD)

This occurs in the first week of life. In these cases the source of the infection is usually the mother’s genital flora.

Late onset disease (LOD)

This occurs between the seventh and 90th day of life. In these cases the infant is presumed to have been infected after birth, and infection may have been acquired while in hospital. The exact mode of transmission in late onset disease is unclear although outbreaks in hospitals are known to occur.

GBS infection in older adults is often associated with urinary tract infection (cystitis), or infections of pre-existing wounds or lesions such as diabetic foot ulcers. Deep-seated infections such as endocarditis and arthritis are also reported.


The Antimicrobial resistance and healthcare associated infections reference laboratory (AMRHAI), and the Staphylococcus and Streptococcus reference service provide reference and microbiology services related to GBS.

SMI B 58: detection of carriage of group B streptococci describes the processing of specimens from pregnant women to determine GBS carriage.

Treatment and prevention

The standard treatment of choice is usually antibiotic with penicillin, cephalosporin or vancomycin. These antibiotics are also used for prevention of early-onset infection in the neonate when prescribed appropriately to the mother in labour.

See the group B streptococcal disease, early-onset (Green-top guideline No. 36) guidelines by the Royal College of Obstetricians and Gynaecologists (RCOG). This guideline provides guidance for obstetricians, midwives and neonatologists on the prevention of early-onset neonatal group B streptococcal (EOGBS) disease.

Outbreaks of GBS infection in adult and paediatric wards can occur. Clusters in healthcare (hospital and community) settings should be investigated to prevent further transmission.


Pyogenic and non-pyogenic streptococcal bacteraemia: annual data from voluntary surveillance

For reports from 2012 and earlier, see the HPR archive.

Updates to this page

Published 1 April 2013
Last updated 18 December 2023 + show all updates
  1. Updated diagnosis section: AMRHAI now provides services related to group B streptococci.

  2. Updated with the potential for outbreaks.

  3. Updated treatment section to reflect current national guidance.

  4. Added position statement on enriched culture medium test for group B streptococcus infection.

  5. First published.

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