Chemoprophylaxis for group B streptococcus transmission in neonates.

GBS causes infection in 1.35-5.4 neonates per 1000 live births. Early-onset GBS infection in neonates develops rapidly and has a high mortality rate. Preventing the transmission of GBS to neonates is of considerable value to avert neonatal morbidity and mortality. Although some controversy exists regarding who should receive chemoprophylaxis and when, AAP guidelines suggest that all pregnant women be screened between 26 and 28 weeks' gestation for GBS colonization by obtaining swabs form vagina and anorectal areas and culturing them or testing by rapid antigen test. According to the latest guidelines from the CDC, any pregnant woman who tests positive for GBS and who has one or more risk factors should be given intrapartum penicillin 5 million units i.v. as the first dose and then 2.5 million units q6h until delivery. Ampicillin, in a dosage of 2 g as the first dose and then 1 g every 4-6 hours may be used as an alternative. Patients who are allergic to penicillin can be given either erythromycin 500 mg i.v. q6h or clindamycin 600 mg i.v. q8h. The chemoprophylaxis is primarily effective for early-onset GBS infection; for late-onset infection, aggressive treatment of the neonate should be initiated promptly with ampicillin and gentamicin. Although many studies have been published that establish the efficacy of ampicillin for intrapartum GBS prophylaxis, there is a need for large-scale studies to show the efficacy of both erythromycin and clindamycin. Various vaccines are under development for maternal administration to prevent the transmission of GBS to neonates. When one is available, it will be an added weapon against GBS.