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.

引言：新生儿败血症（neonatal sepsis）与显著的病死率及致残率密切相关。中低收入国家承受着不成比例的疾病负担，但在高收入国家中，28周以下早产儿仍有高达20%的概率发生晚发型败血症（late-onset sepsis, LOS）。了解特定医疗机构的本土数据对于指导临床诊疗至关重要。

方法：本研究在珀斯国王爱德华纪念医院（King Edward Memorial Hospital, KEMH）开展一项回顾性队列研究，纳入2012年1月至2022年6月期间入院的新生儿。数据从常规电子数据库中提取，明确败血症的发病率与病原学特征，并分析败血症与新生儿临床结局的关联。

结果：研究期间共纳入23395名入院新生儿，中位胎龄37周，出生体重2800g。350名新生儿共发生370例败血症事件：其中102例为早发型败血症（early-onset sepsis, EOS），发病率为1.6例/1000活产儿，主要致病菌为无乳链球菌（S. agalactiae，35例，占34.3%）与大肠埃希菌（E. coli，27例，占26.5%）；268例为晚发型败血症（LOS），发病率为0.9例/1000住院日，主要致病菌为凝固酶阴性葡萄球菌（Coagulase-negative staphylococci, CONS，156例，占57.6%）与大肠埃希菌（30例，占11.1%）。2012年至2022年，LOS的发病率呈显著下降趋势（p=0.002）。

早发型败血症患儿的脑损伤发生率（25.7% vs 4.1%；p=0.002）与病死率（18.8% vs 1.6%；p<0.001）均显著高于非败血症患儿。晚发型败血症患儿的住院时长（中位95天 vs 15天；p<0.001）、病死率（15.3% vs 1.6%；p=0.018）、坏死性小肠结肠炎（necrotising enterocolitis, NEC，7.4% vs 0.5%；p<0.001）及慢性肺疾病（chronic lung disease, CLD，58.1% vs 5.9%；p=0.005）均显著升高。与未发生感染的28周以下早产儿相比，患败血症的该类患儿神经发育障碍的发生风险显著升高（43.2% vs 30.9%，p=0.027）。

结论：尽管本研究观察到LOS发病率有所下降，但败血症仍与更高的病死率相关，且存活患儿的住院时长更长，脑损伤、坏死性小肠结肠炎、慢性肺疾病及神经发育障碍的发生风险也显著增加。