NEONATAL AMOXICILLIN CONCENTRATION AFTER INTRAPARTUM CHEMOPROPHYLAXIS

Amoxicillin is effective against S. agalactiae (MIC 50 = 0.03 mg/l). N eonatal prophylaxis of GBS infection had already been studied but very few data are available regarding pharmacokinetic of these antibiotics . In this study, 58 pregnant women with GBS colonisation and/or with e pidemiologic risk factors received intrapartum antibiotic infusion at the begining of the labor (1g amoxicillin every 6 hours until the deli very). At delivery, cord blood and gastric fluid were taken in delay f rom 0.5 to 6 hours after the begining of the infusion. Dosages were do ne in triplicate with a microbiological method using Bacillus subtilis ATCC 6633 as test strain. In cord blood amoxicillin appeared as early as the first half hour. Concentration were from 5 to 7 mg/l between 1 hour and 4 hours after the begining of the infusion, and from 3 to 4 mg/l after 4 hours. In gastric fluid, concentrations obtained were ove r 1 mg/l after 1.5 hour and over 3 mg/l after 2.5 hours with good effi ciency even after the sixth hour. The protocol using a slow intrapartu m amoxicillin infusion (1g) gave concentrations in gastric fluid and c ord blood over S. agalactiae MIC.