Postnatal penicillin prophylaxis and the incidence of group B streptococcal sepsis in neonates.

We conducted a retrospective chart review of infants, born over a 3-year period, who had positive urine latex agglutination and/or positive blood culture for group B streptococci (GBS). Infants routinely received intramuscular aqueous penicillin for the first half of the study period, and no penicillin was given for the subsequent 18 months. Overall, infants who received penicillin prophylaxis had a decreased incidence of clinical sepsis and positive blood culture for GBS (4.8/1,000 versus 8/1,000 and 1.3/1,000 versus 5.4/1,000, respectively). The incidence of GBS sepsis during the time of penicillin prophylaxis was not different from that in previously reported studies. When analyzed by weight groups, no difference in clinical sepsis or positive blood cultures for GBS was seen in the subset of infants weighing < or = 2,500 g at birth. There were fewer positive blood cultures in the infants who received penicillin and met the criteria for clinical sepsis. Mortality from GBS sepsis was unchanged during these two study periods in all weight groups.