Antimicrobial prevention of early-onset group B streptococcal sepsis: Estimates of risk reduction based on a critical literature review

Objective. To identify interventions that reduce the attack rate for early-onset group B streptococcal (GBS) sepsis in neonates. Study Design. Literature review and reanalysis of published data. Results. The rate of early-onset GBS sepsis in highrisk neonates can be reduced by administration of antibiotics. Treatment during pregnancy (antepartum prophylaxis) fails to reduce maternal GBS colonization at delivery. With the administration of intravenous ampicillin, the risk of early-onset infection in infants born to women with preterm premature rupture of membranes is reduced by 56% and the risk of GBS infection is reduced by 36%; addition of gentamicin may increase the efficacy of ampicillin. Treatment of women with chorioamnionitis with ampicillin and gentamicin during labor reduces the likelihood of neonatal sepsis by 82% and reduces the likelihood of GBS infection by 86%. Universal administration of penicillin to neonates shortly after birth (postpartum prophylaxis) reduces the early-onset GBS attack rate by 68% but is associated with a 40% increase in overall mortality and therefore is contraindicated. Intrapartum prophylaxis, alone or combined with postnatal prophylaxis for the infants, reduces the early-onset GBS attack rate by 80% or 95%, respectively. Conclusions. Women with chorioamnionitis or preterm premature rupture of membranes and their infants should be treated with intravenous ampicillin and gentamicin. Intrapartum antimicrobial prophylaxis may be appropriate for other women whose infants are at increased but less extreme risk, and supplemental postpartum prophylaxis may be indicated for some of their infants. Selection of appropriate candidates and prophylaxis strategies requires careful consideration of costs and benefits for each patient.