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Evidence summaries

Intrapartum Antibiotics for Known Maternal Group B Streptococcal Colonization

Intrapartum antibiotic prophylaxis for known maternal group B streptococcal colonization appears to reduce early onset group B streptococcus disease in the newborn. Level of evidence: "B"

A Cochrane review [Abstract] 1 included 3 studies with a total of 852 women. The use of intrapartum antibiotic prophylaxis (IAP) compared to no treatment did not significantly reduce the incidence of all cause mortality (RR 0.19, 95% CI 0.01 to 3.82, 1 study, 164 infants), mortality from group B streptococcus (GBS) infection (RR 0.31, 95% CI 0.01 to 7.50, 1 study, 164 infants) or from infections caused by bacteria other than GBS (RR 0.31, 95% CI 0.01 to 7.50, 1 study, 164 infants).

The incidence of early GBS infection was reduced with IAP compared to no treatment (RR 0.17, 95% CI 0.04 to 0.74; RD -0.04, 95% CI -0.07 to -0.01; NNT 25, 95% CI 14 to 100; 3 studies, 488 infants). The incidence of late onset GBS disease (RR 0.36, 95% CI 0.01 to 8.69, 2 studies, 289 infants) or sepsis from organisms other than GBS (RR 1.00, 95% CI 0.15 to 6.79, 2 studies, 289 infants) and puerperal infection (RR 0.16, 95% CI 0.01 to 3.03, 1 study, 121 women) was not significantly different between groups. One trial (352 women) compared intrapartum ampicillin versus penicillin and reported no significant difference in neonatal or maternal outcomes.

American college of obstetricians and gynaecologists (ACOG Committee Opinion) 2 recommends performing universal GBS screening between 36 0/7 and 37 6/7 weeks of gestation. All women whose vaginal-rectal cultures are positive for GBS should receive appropriate intrapartum antibiotic prophylaxis unless a prelabor cesarean birth is performed in the setting of intact membranes. Although a shorter duration of recommended intrapartum antibiotics is less effective than 4 or more hours of prophylaxis, 2 hours of antibiotic exposure has been shown to reduce GBS vaginal colony counts and decrease the frequency of a clinical neonatal sepsis diagnosis.

Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment and blinding).

    References

    • Ohlsson A, Shah VS. Intrapartum antibiotics for known maternal Group B streptococcal colonization. Cochrane Database Syst Rev 2014;(6):CD007467. [PubMed].
    • Prevention of Group B Streptococcal Early-Onset Disease in Newborns: ACOG Committee Opinion, Number 782. Obstet Gynecol 2019;134(1):e19-e40. [PubMed]

Primary/Secondary Keywords