Trends in incidence and antimicrobial resistance of early-onset sepsis: population-based surveillance in San Francisco and Atlanta

Abstract

Objective: Although increased use of intrapartum antibiotics caused significant declines in early-onset group B Streptococcus (GBS) infection, the effect on infections caused by other pathogens is not clear. The objective of this study was to determine trends in the incidence of early-onset sepsis caused by organisms other than group B streptococcus in the era of antimicrobial prophylaxis.

Methods: We conducted surveillance for early-onset sepsis as part of the Active Bacterial Core surveillance. A case was defined as isolation of bacteria from blood or cerebrospinal fluid from an infant who was 0 to 6 days of age and born in the surveillance area during 1998 through 2000 (248 184 births).

Results: We identified 408 cases of early-onset infection. GBS caused 166 (40.7%) cases (52 in 1998, 51 in 1999, and 63 in 2000 for incidences 0.62, 0.62, and 0.76 cases per 1000 live births, respectively). Other bacterial pathogens were identified in 242 cases (82 in 1998, 79 in 1999, and 81 in 2000 for incidences 0.99, 0.95, and 0.98 per 1000 live births, respectively) of early-onset sepsis. Escherichia coli caused 70 cases (0.25, 0.28, and 0.31 cases per 1000 live births, respectively, in 1998-2000). The proportion of E coli infections that were resistant to ampicillin increased significantly among preterm infants from 29% (2 of 7) in 1998 to 84% (16 of 18) in 2000 but not in full-term infants: 50% (4 of 8) in 1998 and 25% (1 of 4) in 2000.

Conclusions: Whereas rates of early-onset sepsis caused by GBS and other pathogens were low and did not change significantly during the study period, antibiotic-resistant E coli infections among preterm infants increased. Overall, these trends are reassuring, but careful evaluation of the increase in resistant infections in very young infants is critical in the future.