Single-Dose Penicillin Prophylaxis against Neonatal Group B Streptococcal Infections: A Controlled Trial in 18,738 Newborn Infants

Neonatal Group B streptococcal infections may not respond to antimicrobial therapy and have been associated with case fatality rates of 50 per cent or greater. We evaluated the effect on colonization and disease rates of a single intramuscular dose of aqueous penicillin G given at birth in a prospectively controlled study of 18,738 neonates during a 25-month period. The colonization rate in the mothers was 26.6 per cent, with 50 per cent concordance in the untreated infants and 12.2 per cent in the penicillin-treated infants (P<0.001). There was a significant decrease in the incidence of disease caused by all penicillin-susceptible organisms in the penicillin group (0.64 vs. 2.26 cases per thousand live births, P=0.005). Disease caused by penicillin-resistant pathogens was increased in the penicillin-treated group during the first year of the study but was unaffected during the second year. Routine administration of parenteral penicillin at birth cannot be recommended until the effect on the incidence of disease caused by penicillin-resistant pathogens is fully defined. (N Engl J Med. 1980; 303:769–75.) DURING the past decade the Group B streptococcus has been the pathogen most frequently isolated from cultures in sick neonates in the United States. Prompt institution of antimicrobial therapy may not be curative, and mortality rates of 50 per cent or greater have been reported for the fulminant, early-onset syndrome.¹ Consequently, attention has focused on prevention. Until immunoprophylaxis is proved to be safe and effective, chemoprophylaxis of mother or infant has been considered the most practical approach to this problem. Oral administration of ampicillin to carriers of Group B streptococcus who are in the third trimester of pregnancy fails to.