What are the recommended antibiotic prophylaxis protocols for GBS in women with risk factors during labor?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 22 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

Offer intrapartum antibiotic prophylaxis to women in labour who have risk factors for group B streptococcus (GBS) infection, including those with GBS colonisation, bacteriuria, or infection during the current pregnancy; those with previous GBS colonisation, bacteriuria, or infection without a recent negative test; those with a previous baby affected by invasive GBS infection; and those with a clinical diagnosis of chorioamnionitis.

Administer the first dose of antibiotics as soon as possible after labour starts or when infection is suspected, and continue until the birth of the baby.

For women without penicillin allergy, use intravenous benzylpenicillin.

For women with a non-severe penicillin allergy, use a cephalosporin with activity against GBS (e.g., cefotaxime), noting this is off-label use and should be used with caution.

For women with a severe penicillin allergy, consider vancomycin or an alternative antibiotic active against GBS based on sensitivity testing or local susceptibility data; in cases of chorioamnionitis, combine vancomycin with gentamicin and metronidazole.

If gentamicin is used during labour, administer it once daily and consider therapeutic drug monitoring for gentamicin or vancomycin.

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