Recommendations for the use of antepartum antibiotics in obstetrics has greatly increased in the past 2 years-i.e. Group B Streptococcus (GBS) prophylaxis, prolongation of preterm premature rupture of membranes (PPROM), and treatment of preterm labor (PTL). Our objective was to determine if antepartum Ampicillin use affects the incidence of and resistance of early onset neonatal sepsis by organisms other than GBS. All cases of blood culture proven neonatal sepsis were prospectively collected from 1/1/91 to 12/31/96. Bacteria type, drug resistance, antepartum antibiotic usage, treatment indication, gestational age, and outcome were evaluated. Early onset neonatal sepsis was defined as < 7 days from birth. 109 cases of sepsis occurred of which 42 were early onset - 15 GBS cases and 27 non-GBS cases. Of the 27 non-GBS cases, 15 mothers received antepartum Ampillicin (for GBS prophylaxis, prolongation of PPROM, PTL treatment and fever) and 13/15 (87%) of the isolates from the neonates were Ampicillin resistant (3 of these died from the sepsis). Of the 12 mothers who did not receive antepartum antibiotics only 2/12 (17%) of the isolates were Ampicillin resistant (p=0.0004). Of these 27 non-GBS septic cases, 21 were gram negative rods and 6 were gram positive cocci. The table reveals that as the incidence of GBS has decreased over the 6-year period, the incidence of non-GBS sepsis has increased, especially E.Coli.

Table 1 No caption available.
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We conclude that at our institution, the use of antepartum Ampicillin appears to be responsible for the increased incidence and resistance of neonatal sepsis from organisms other than GBS.