Summary

Group B Streptococcus (GBS, Streptococcus agalactiae) is a gram-positive bacterium carried as normal flora in the vagina and rectum of approximately 20-30% of women. While usually harmless to the mother, GBS is the leading cause of early-onset neonatal sepsis (EONS) in the UK, causing life-threatening infection in newborns including septicaemia, pneumonia, and meningitis. Transmission occurs vertically during labour. The UK uses a risk-based approach (not universal screening) to identify women who should receive intrapartum antibiotic prophylaxis (IAP) with IV benzylpenicillin during labour to reduce neonatal infection.

Key Facts

• Carrier Prevalence: 20-30% of women
• Risk: Leading cause of early-onset neonatal sepsis (<7 days)
• Transmission: During labour/delivery
• UK Approach: Risk-based (not universal screening)
• Prevention: Intrapartum antibiotic prophylaxis (IV benzylpenicillin)
• Timing: IAP ideally >4 hours before delivery

Clinical Pearls

"Risk-Based, NOT Universal": The UK does not routinely screen all pregnant women for GBS. Instead, antibiotics are given based on risk factors or incidental detection.

"≥4 Hours Before Delivery": IAP is most effective when given at least 4 hours before birth. Less than 4 hours still offers some protection.

"Early vs Late Onset": EONS (<7 days) is prevented by IAP. Late-onset (7-90 days) is NOT prevented and is acquired after birth.

"Penicillin is First-Line": IV benzylpenicillin 3g loading, then 1.5g 4-hourly until delivery. Clindamycin if penicillin-allergic.

Maternal

• Usually normal
• Signs of chorioamnionitis if present (fever, uterine tenderness)

Neonatal

• NEWS/NEWTT scoring
• Respiratory rate, work of breathing
• Temperature
• Tone, activity

With IAP

• 80% reduction in EONS
• IAP does NOT prevent late-onset disease

Neonatal EONS

• Mortality: 5-10%
• Survivors of meningitis: 20-30% have long-term disability

Key Guidelines

1. RCOG Green-top Guideline No. 36: Prevention of Early-Onset Neonatal GBS Disease
2. NICE Neonatal Infection Guidelines

Key Evidence

IAP Effectiveness

• Reduces EONS by ~80%
• Does not prevent late-onset disease

Universal vs Risk-Based Screening

• Debate ongoing; UK uses risk-based approach

What is Group B Strep?

Group B Streptococcus (GBS or Group B Strep) is a common bacterium that lives harmlessly in the vagina and bowel of about 1 in 4 women. It usually causes no problems for the mother.

Why Does It Matter in Pregnancy?

Although GBS is harmless to you, it can be passed to your baby during labour. In rare cases, this can cause serious infection in your newborn (sepsis, pneumonia, meningitis).

How is It Managed?

If you have GBS or certain risk factors, you'll be offered antibiotics by drip (IV) during labour. This significantly reduces the risk to your baby.

When Are Antibiotics Given?

• If you've had a baby affected by GBS before
• If GBS was found in your urine in this pregnancy
• If GBS was found on a swab
• If you go into labour before 37 weeks
• If your waters break more than 18 hours before delivery
• If you have a fever during labour

What About My Baby?

Your baby will be monitored closely after birth. If they show any signs of infection, they'll be tested and treated with antibiotics.

Is GBS Testing Routine?

In the UK, routine screening for GBS is not currently offered. Instead, antibiotics are given based on risk factors.