FRIDAY, Aug. 1 (HealthDay News) -- Four hours of intrapartum penicillin G prophylaxis may not be necessary in women positive for group B streptococci, according to research published in the August issue of Obstetrics & Gynecology.
Emma L. Barber, of the Yale University School of Medicine in New Haven, Conn., and colleagues analyzed data from 98 laboring group B streptococci (GBS)-positive women who were given 5 million units of intravenous penicillin G, then 2.5 million units every four hours until delivery. Umbilical cord blood samples, collected after delivery, were assessed for penicillin G levels.
The researchers found that fetal serum penicillin levels peak within an hour of maternal administration, and fetuses exposed to less than four hours had higher penicillin levels than those exposed to more than four. Penicillin levels in every sample were 10- to 179-fold above the minimal inhibitory concentration (MIC) for the organism.
"Providers may believe that four hours of prophylaxis are necessary to achieve adequate levels in the fetal bloodstream to prevent GBS transmission and therefore, may choose not to begin penicillin G dosing during precipitous labor. Likewise, providers may attempt to prolong labor to reach the four-hour recommendation. Our data indicate that fetal serum levels far exceed the MIC at durations well under one hour, suggesting that antibiotic prophylaxis should be pursued even in the most precipitous of deliveries and that it is unnecessary to prolong labor to achieve adequate levels in fetal serum. Likewise, prolonging labor beyond one hour will not achieve higher penicillin levels in fetal serum," the authors write.
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