Association of Umbilical Cord Blood P-Selectin and PTX3 Levels with Early-Onset Sepsis in Preterm Infants with Premature Rupture of Membranes

Objective: To investigate the relationship between umbilical cord blood P-selectin and pentraxin 3 (PTX3) levels and early-onset sepsis (EOS) in preterm neonates with premature rupture of membranes (PROM). Methods: A total of 148 preterm neonates with PROM duration > 12 h admitted from September 2024 to September 2025 were included as the experimental group, including 22 with EOS and 126 without EOS. Fifty healthy preterm neonates born to mothers without PROM were enrolled as controls. Umbilical cord blood P-selectin and PTX3 levels were measured by ELISA. Pathogens were identified using an automated bacterial identification system. Pearson correlation analysis and ROC curve analysis were performed. Results: Umbilical cord blood P-selectin and PTX3 levels were higher in the experimental group than in controls (P< 0.05). Among the 22 neonates with EOS, 6 (27.3%) had positive blood cultures, yielding 6 pathogenic strains. Gram-negative bacteria predominated (66.67%), mainly Escherichia coli (33.33%). Compared with the non-sepsis group, the sepsis group had higher CRP, PCT, P-selectin, and PTX3 levels (P< 0.05). P-selectin was positively correlated with PTX3 in neonates with EOS (r=0.639, P< 0.05). The AUCs (95% CI) of P-selectin and PTX3 for evaluating EOS were 0.876 (0.814– 0.937) and 0.883 (0.830– 0.935), respectively. Their combined AUC was 0.911 (0.862– 0.960), with sensitivity of 79.2% and specificity of 96.1%, outperforming CRP and PCT. Conclusion: Gram-negative bacteria were the main pathogens of EOS in preterm neonates with PROM. Umbilical cord blood P-selectin and PTX3 levels showed good value for evaluating EOS in this population.