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Neonatal Group B Streptococcal Disease Prevention

RCOG Green-top Guideline No. 36 Prevention of Early-onset Group B Streptococcal Disease. Last reviewed Sep 2017.

Background Information

Purpose: to prevent early-onset neonatal group B streptococcal disease (<7 days of age).

Causative agent: group B beta-haemolytic streptococcus infection (Streptococcus agalactiae)

GBS colonisation (carries) is present in the bowel flora of 20-40% of adults.

 

GBS is the most common cause of severe early-onset infection in the newborn (<7 days of age).

Risk factors for baby with early-onset GBS disease:
  • Previous baby with GBS disease (50% chance in this pregnancy)
  • Maternal GBS carriage during pregnancy (e.g. in urine, vagina, rectum)
  • Preterm birth
  • Prolonged rupture of membranes
  • Suspected maternal intrapartum infection (e.g. chorioamnionitis)
  • Maternal pyrexia

Guidelines

Universal GBS screening should NOT be offered to all women (maternal request is not an indication for screening).

There are 2 main ways to detect GBS carrier status in a pregnancy:
 
Test Test details Indication Subsequent action
Bacteriological testing Timing: 35-37 weeks of gestation or 3-5 weeks prior anticipated delivery date

Method: separate vaginal and rectal swabs for culture		 Previous pregnancy with:
  • GBS carriage
  • GBS neonatal disease

NB these are the ONLY indications for bacteriological testing		 If there is previous GBS carriage or neonatal disease, the women should be offered either:
  • Bacteriological testing and only offer IAPIntrapartum antibiotic prophylaxis if +ve, or
  • Offer IAPIntrapartum antibiotic prophylaxis without bacteriological testing
Urine culture n/a Routine or symptomatic urine cultures
  • GBS UTIUrinary tract infection should be treated during pregnancy
  • IAPIntrapartum antibiotic prophylaxis is still required even if successful treatment
 

The mainstay of early-onset GBS disease is maternal IAP (intrapartum antibiotic prophylaxis).
 

These are the only indications for GBS IAP as per RCOG:
  • Preterm labour (intact / ruptured membrane) - IAP should be offered regardless of GBS status
    • NB PPROMPreterm prelabour rupture of membrane on its own is not an indication for IAP (erythromycin is given instead)
 
  • Previous GBS disease (offer the option of IAP immediately or bacteriological testing and IAP if +ve)
    • GBS carriage in the previous pregnancy
    • Previous GBS neonatal disease
 
  • GBS carriage in current pregnancy (+ve recto-vaginal swab or GBS bacteriuria at any point in this pregnancy)
  • Intrapartum pyrexia (>38ºC)
 

If a GBS +ve pregnant woman is undergoing a planned C-section with intact membranes and no signs of labour → GBS IAP is NOT required.

1st line IAP: intrapartum IV benzylpenicillin (3g ASAP after onset of labour and 1.5g 4-hourly until delivery)

Penicillin allergy:
  • No severe allergy → cephalosporin
  • Severe allergy (e.g. anaphylaxis) → vancomycin
 

Women should be counselled that IAP reduces, but does NOT eliminate early-onset GBS disease (~80% effective).

Offer immediate induction of labour or Caesarean birth in those with +ve GBS status AND
  • Pre-labour rupture of membranes at term, OR
  • Pre-term pre-labour rupture of membranes (P-PROM)

References

Author: Adams Lau
Reviewer:
Last edited: 03/07/25