Abstract 1216 Poster Session II, Sunday, 5/2 (poster 5)

Background: Efforts to prevent early-onset group B streptococcal (GBS) infections involve increased use of intrapartum antibiotics. The applicability of GBS strategies to infections caused by other organisms is not clear.

Methods: Multicenter surveillance during 1995-6 for culture confirmed early-onset sepsis in an aggregate of 52,406 births; matched case-control study of risk factors for GBS and sepsis due to other organisms.

Results: Early-onset disease (all organisms) occurred in 188 infants (3.5 cases per 1000 live births). GBS (1.4 cases per 1000 births) and Escherichia coli (0.6 cases per 1000 births) caused most infections. GBS sepsis occurred less frequently among preterm neonates compared to other organisms causing infection (GBS: 16% preterm; Other: 60%; p <0.001). Compared with gestation-matched controls without sepsis, GBS disease was associated with intrapartum fever (matched odds ratio [mOR] 4.1, CI 1.2-13.4) and frequent vaginal exams (mOR 2.9, CI 1.1-8.0). The vast majority of early-onset GBS case-mothers had received prenatal care. An obstetric risk factor--preterm delivery, intrapartum fever, or membrane rupture≥18 hours-was evident in 49% of GBS cases and 79% of other sepsis. Intrapartum antibiotics had an adjusted efficacy of 68.2% (95% CI, 23.4%-86.8%;p=0.011) against any early-onset sepsis. Ampicillin-resistance was found in 68% (22 of 32) of E. coli isolates; no deaths occurred among 10 susceptible E. coli infections while 9 (41%) ampicillin resistant E. coli infections were fatal (p=0.05). Most (90.9%) infants who developed ampicillin resistant E. coli infections were preterm, and 59% of these infants were born to mothers who had received intrapartum antibiotics.

Conclusions: Either prenatal GBS screening or a risk-based strategy could potentially prevent a large portion of GBS cases. Sepsis caused by other organisms is more often a disease of prematurity. Intrapartum antibiotics appear efficacious against early-onset sepsis. However, the severity of ampicillin resistant E. coli sepsis and its occurrence following maternal antibiotics suggest caution regarding use of ampicillin instead of penicillin for GBS prophylaxis.

This study was funded by the Office of Minority and Women's Health, NCID, CDC.