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
Scope
Purpose: to prevent early-onset neonatal group B streptococcal disease (<7 days of age).
Causes
Causative agent: group B beta-haemolytic streptococcus infection (Streptococcus agalactiae)
GBS colonisation (carriers) is present in the bowel & lower genital tract 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
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
Investigation and Diagnosis
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:
NB these are the ONLY indications for bacteriological testing |
If there is previous GBS carriage or neonatal disease, the woman should be offered either:
|
| Urine culture | n/a | Routine or symptomatic urine cultures |
|
GBS Prophylaxis
The mainstay of early-onset GBS disease is maternal IAP (intrapartum antibiotic prophylaxis)
Indications for IAP
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 PPROM 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.
Vertical transmission of GBS and subsequent neonatal infection are highly unlikely in the absence of labor or ruptured membranes. Standard perioperative antibiotic prophylaxis for cesarean section should still be administered to reduce maternal postoperative infection risk, but this is not intended for GBS prophylaxis.
IAP Regimen
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).
Induction of Labour or Caesarean Birth
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)