Clinical and laboratory characteristics according to the onset of neonatal sepsis: a retrospective cohort study

Aims: Neonatal sepsis remains a major cause of neonatal morbidity and mortality despite advances in neonatal intensive care. Although early-onset sepsis (EOS) and late-onset sepsis (LOS) differ in their pathophysiology and clinical presentation, comparative data including neonates who experience both EOS and LOS remain limited. This study aimed to compare the clinical and laboratory characteristics of neonates with EOS, LOS, and combined EOS+LOS. Methods: This retrospective cohort study included 289 neonates with sepsis admitted to a tertiary neonatal intensive care unit between January 2020 and January 2022. Patients were classified into three groups: EOS (n = 207), LOS (n = 32), and EOS+LOS (n = 50). Demographic characteristics, clinical findings, microbiological results, and laboratory parameters were compared among the groups. Results: Neonates with EOS+LOS had significantly lower gestational age, birth weight, Apgar scores, platelet count, and plateletcrit, but longer hospitalization, higher prematurity rates, and higher mean platelet volume than the other groups (all p <0.05). Compared with the LOS and EOS+LOS groups, neonates with EOS had significantly higher white blood cell count, hemoglobin, hematocrit, red cell distribution width, absolute neutrophil count, nucleated red blood cell count, neutrophil-to-lymphocyte ratio, and C-reactive protein levels (all p <0.05). Absolute lymphocyte count was significantly higher in the LOS group. Conclusion: Clinical and laboratory characteristics differ according to the onset of neonatal sepsis. Routinely available hematological parameters may complement clinical assessment and support the early evaluation of neonatal sepsis. Larger prospective multicenter studies are needed to validate these findings.