Neonatal Sepsis from 2014 to 2024: The Resurgence of Gram-Negative Rods

To evaluate the incidence, pathogens, clinical characteristics, and outcomes of neonatal sepsis at a single, level IV, neonatal intensive care unit from 2014 to 2024, and compare results with historical, institutional data.

A retrospective cohort study was undertaken of infants with a documented bloodstream infection from 2014 to 2024. Episodes were documented prospectively, and data were collected retrospectively and assessed via univariate and multiregression analyses. Data were compared between epochs 1 (2004-2013) and 2 (2014-2024) and trends since 1928 analyzed.

In total, 250 episodes of sepsis occurred in 233 infants from 2014 to 2024. Early-onset sepsis (EOS) attributed to gram-negative organisms increased in epoch 2, as did identification of historically uncommon organisms associated with EOS. Escherichia coli(E coli)-related EOS increased between epochs in neonates born late preterm and term (13%-36%; 173% increase) and in very low birth weight infants (58%-64%; 10% increase). Although a lower rate of late-onset sepsis (LOS) was observed in epoch 2, mean gestational age was lower and disease severity greater. Forty percent of LOS episodes were attributed to gram-negative bacteria, with an increase noted from 32% of episodes (2014-2019) to 50% (2020-2024). LOS-related mortality increased in epoch 2 (11%-25%; 127% increase), with overall sepsis-related mortality increasing steadily over 3 decades. Predictors of sepsis-related mortality included lower birth weight, need for pressors, concurrent necrotizing enterocolitis, and thrombocytopenia.

Pathogen distribution for EOS and LOS revealed a sustained increase in gram-negative organisms, predominantly E coli. This trend coupled with decreasing gestational age and increasing baseline illness severity likely contributed to increased sepsis-related mortality.