Supplementary Material for: Epidemiology and outcomes of neonatal sepsis – experience from a tertiary Australian NICU

Introduction: Neonatal sepsis is associated with significant mortality and morbidity. Low-middle-income countries are disproportionately affected, but late-onset sepsis (LOS) still occurs in up to 20% of infants <28 weeks in high-income countries. Understanding site-specific data is vital to guide management. Methods: A retrospective cohort study was conducted at King Edward Memorial Hospital (KEMH), Perth. Infants admitted between January 2012 and June 2022 were included. Data were extracted from routine electronic databases. Incidence and aetiology of sepsis were determined and the association of sepsis with neonatal outcomes analysed. Results: During the study period, 23,395 newborns were admitted with a median gestation of 37 weeks and birth weight 2800g. There were 370 sepsis episodes in 350 infants; 102 were early-onset sepsis (EOS) (1.6 per 1000 live births), predominantly S. agalactiae (35, 34.3%) and E. coli (27, 26.5%); 268 were LOS (0.9 per 1000 inpatient days), predominantly Coagulase-negative staphylococci (CONS) (156, 57.6%) and E. coli (30, 11.1%). The incidence of LOS declined from 2012 to 2022 (p=0.002). Infants with EOS had increased brain injury (25.7% vs 4.1%; p=0.002) and mortality (18.8% vs 1.6%; p<0.001). Those with LOS had increased hospital stay (median 95 vs 15 days; p<0.001), mortality (15.3% vs 1.6%; p=0.018), necrotising enterocolitis (NEC) (7.4% vs 0.5%; p<0.001) and chronic lung disease (CLD) (58.1% vs 5.9%; p=0.005). Infants <28 weeks with sepsis were at increased risk of neurodevelopmental impairment compared to those without infection (43.2% vs 30.9%, p=0.027). Conclusions: While we observed a reduction in LOS incidence, sepsis remains associated with higher mortality, and in survivors with longer hospital stay and increased risk of brain injury, NEC, CLD and neurodevelopmental impairment.