Antibiotic exposure for suspected early-onset sepsis in late-preterm and full-term newborns in Quebec: a 11-year single-center cohort study.

BACKGROUND: Antibiotic exposure during the first postnatal week is common among late-preterm and term newborns and represents an important target for neonatal antimicrobial stewardship. We aimed to quantify antibiotic exposure, assess temporal trends, and determine the incidence and mortality of culture-proven early-onset sepsis (CP-EOS) in a Canadian tertiary care center. METHODS: This retrospective cohort study included all inborn neonates ≥34 weeks' gestation born at a Canadian tertiary care center between 2013 and 2023. Data were extracted from electronic medical records and institutional microbiology and pharmacy databases. Primary outcomes were antibiotic exposure during the first postnatal week and treatment duration. Secondary outcomes included the incidence and mortality of CP-EOS. Antibiotic exposure indicators were calculated using standardized international benchmarking metrics. RESULTS: Among 34,668 late-preterm and term newborns born during the study period, 1,824 (5.3%; 95% CI, 4.5%-6.0%) received intravenous antibiotics during the first postnatal week for suspected early-onset sepsis (EOS). The median (IQR) antibiotic duration was 3 (3-4) days overall, 9 (5-14) days among neonates with CP-EOS, and 3 (3-5) days among those without proven EOS. Overall antibiotic exposure corresponded to 238 (IQR, 218-259) antibiotic days per 1,000 livebirths. CP-EOS incidence was 0.55 per 1,000 livebirths (95% CI, 0.24-0.83). Overall, for each confirmed EOS case, 96 newborns received antibiotics, and 433 antibiotic days were administered. CONCLUSIONS: Antibiotic exposure substantially exceeded the burden of CP-EOS. Standardized benchmarking indicators may help guide neonatal antimicrobial stewardship efforts.