Early- vs. late-onset culture-confirmed neonatal Escherichia coli infection: a 12-year single-center study (2012–2024)

Early- and late-onset culture-confirmed neonatal Escherichia coli infection may reflect different acquisition pathways and antimicrobial pressure. We described long-term onset-specific trends, clinical profiles, and resistance patterns. This 12-year retrospective single-center study (2012–2024) included neonates (0–28 days) with culture-confirmed neonatal E. coli infection isolated from blood, cerebrospinal fluid, tracheal secretions, urine, or pus. Early-onset disease (EOD) was defined as onset ≤ 72 h and late-onset disease (LOD) as onset 3–28 days. Trends, clinical features, and antimicrobial susceptibility were compared between groups, with adjusted analyses for LOD (vs. EOD). Among 160 neonates, 92 (57.5%) had EOD and 68 (42.5%) had LOD. EOD incidence showed a significant increasing trend (APC = + 7.6%/year; P < 0.001), while LOD incidence declined (APC = − 5.1%/year; P < 0.001). The proportion of EOD increased significantly over the study period (OR 1.157/year; 95% CI 1.056–1.267; P = 0.002). Compared with EOD, LOD occurred in infants with lower birth weight (2616 ± 1024 vs. 3023 ± 821 g; P = 0.015) and showed a distinct clinical spectrum: urinary tract infection was observed only in LOD (16.2% vs. 0%; P < 0.001). ESBL positivity was higher in LOD than EOD (35.3% vs. 18.5%; P = 0.018). LOD also showed higher resistance to key β-lactams, including cefepime (34.3% vs. 13.3%; P = 0.003) and ceftazidime (17.3% vs. 4.8%; P = 0.035), and higher cefotaxime resistance (36.1% vs. 11.3%; P = 0.001). When ESBL-negative isolates were analyzed separately, cephalosporin resistance was minimal (cefotaxime 1.1%; cefepime 1.7%), confirming that β-lactam resistance was predominantly ESBL-driven. These onset-specific differences remained consistent in adjusted analyses. Over 2012–2024, EOD and LOD culture-confirmed neonatal E. coli infections showed distinct clinical profiles and resistance burdens. The higher ESBL burden, with correspondingly higher β-lactam resistance in LOD, supports continued surveillance. not applicable.