CDC/AAP/Group B Streptococcal Infections

To the Editor. In the March 1997 issue of Pediatrics, the Committee on Infectious Diseases and the Committee of Fetus and Newborn published guidelines for the prevention of group B streptococcal infection.1 Their suggested approach to the infant born to a mother who has received intrapartum antibiotics differs according to how many doses of antibiotics the mother has received before the infant was delivered: if the mother has received two or more doses, no evaluation or therapy is recommended.In the May 1996 supplement to the Morbidity and Mortality Weekly Report, similar guidelines were published.2 They include an almost identical algorithm for the management of a neonate born to a mother who received intrapartum antibiotics; however, they suggest basing the decision of whether to evaluate or treat such an infant on the duration of antibiotic prophylaxis before delivery: if the antibiotics were given more than 4 hours before delivery, no evaluation or therapy is recommended.From the text of the AAP guidelines, I believe the authors assume that after 4 hours a second dose of antibiotics will be administered, so the point is moot. However, our obstetricians more frequently order ampicillin every 6 hours than ampicillin or penicillin every 4 hours. Even if antibiotics are ordered every 4 hours, it is not hard to imagine that if the delivery were just about 4 hours after the first dose, the second one might not be given exactly on time in the confusion of the moment.For those of us in primary care distant from academic centers, it is especially helpful if published guidelines are precise, and if different authorities agree with each other. I would appreciate clarification of whether the more important factor to consider is how long the antibiotics have been circulating, or how many doses the mother has received.In Reply. Dr Fenster has pointed out a small difference between the Centers for Disease Control and Prevention consensus guidelines1-1 and the recent Academy guidelines for prevention of group B streptococcal infections.1-2 As Dr Fenster appropriately pointed out, this is a small point because penicillin or ampicillin should be administered every 4 hours for intrapartum prophylaxis. Optimal concentrations of penicillin or ampicillin are achieved after 2 to 4 hours in amniotic fluid.1-3 The studies demonstrating increased effectiveness after 4 hours (or two doses) of antibiotic administration to the mother could not distinguish between time and number of doses administered. The Committee on Infectious Diseases and the Committee on the Fetus and Newborn believe that obtaining information about the number of doses that women had received would likely be simpler than trying to determine the exact time that the antimicrobial agent administration was completed in the mother and calculating the time to delivery. If the penicillin or ampicillin is administered at 4-hour intervals and two doses had been administered then, at least 4 hours should have elapsed and the antibiotic concentrations in amniotic fluid should be sufficient to prevent transmission of group B streptococci to the newborn.We hope that this helps clarify the issue for Dr Fenster and other practitioners and that they encourage their obstetrician colleagues to follow the Centers for Disease Control and Prevention guidelines (which have been endorsed by the Advisory College on Obstetrics and Gynecology) to administer penicillin or ampicillin at 4-hour intervals for intrapartum prophylaxis.