This statewide, population-based analysis examined incidence trends of late-onset sepsis (LOS) among infants born at 22 to 31 weeks' gestation in the California Perinatal Quality Care Collaborative from 2010 through 2023. Among 66,441 very preterm infants (VPIs), 6,012 (9.0%) experienced at least one LOS episode. Overall mortality among infants with LOS was 15.4%.
Annual percentage changes (APCs) in LOS incidence were estimated using Poisson regression models, with and without adjustment for gestational age. The investigators reported a biphasic temporal pattern: a decline in LOS incidence during 2010–2017 followed by an increase during 2018–2023.
A total of 6,817 pathogens were identified from positive blood and/or cerebrospinal fluid cultures obtained more than 3 days after birth. Distribution of pathogens was 64.7% gram-positive bacteria, 28.3% gram-negative bacteria, and 7.0% fungi. The most frequently isolated organisms were coagulase-negative staphylococcus (CoNS) (34.5%), Staphylococcus aureus (18.1%), Escherichia coli (10.9%), and Klebsiella species (7.2%).
During 2010–2017 the overall LOS incidence declined from 15.0% to 8.2%. Adjusted analyses reported an adjusted annual percentage change (aAPC) of -5.5% with a 95% confidence interval (CI) from -6.6% to -4.4%. This decline reflects reduced LOS burden across the network during the first period of observation.
From 2018 to 2023, LOS incidence reversed and increased, with an adjusted APC of 2.1% (95% CI, 0.6% to 3.6%). The increase was driven largely by rising rates of non-CoNS gram-positive pathogens (aAPC 5.4%; 95% CI, 3.1% to 7.9%) and gram-negative pathogens (aAPC 5.3%; 95% CI, 2.4% to 8.2%). These pathogen group-specific trends explain the net rise in LOS incidence in the later period.
Organism-level analyses highlighted notable changes in incidence over time. S aureus LOS increased in both time periods: aAPC 4.3% (95% CI, 1.0% to 7.6%) during 2010–2017 and aAPC 7.7% (95% CI, 4.4% to 11.1%) during 2018–2023. Klebsiella species LOS showed a marked increase during 2018–2023 with an aAPC of 9.9% (95% CI, 4.2% to 15.8%). E coli accounted for 10.9% of pathogens overall; the report lists it among the most common isolates but does not provide period-specific aAPCs for E coli in the abstract. Coagulase-negative staphylococcus (CoNS) remained the single most frequent organism (34.5% of isolates), and the recent increases in LOS were described as being driven by non-CoNS gram-positive pathogens rather than CoNS.
Among the VPI cohort, 9.0% developed LOS and mortality among those with LOS was 15.4%, indicating a substantial clinical burden. The changing epidemiology—particularly increases in non-CoNS gram-positive organisms such as S aureus and in gram-negative pathogens such as Klebsiella—suggests that existing prevention strategies may need to be reassessed or augmented to address evolving pathogen patterns. The authors emphasize targeted prevention approaches aligned with current pathogen trends.
The analysis used data from the California Perinatal Quality Care Collaborative covering births from 2010 through 2023. Inclusion criteria were infants born at 22 to 31 weeks' gestation. LOS was defined as a positive blood or cerebrospinal fluid culture obtained more than 3 days after birth. Annual percentage changes were estimated by Poisson regression, and results were reported with and without adjustment for gestational age; adjusted APCs and 95% confidence intervals are reported in the abstract for overall and pathogen-group trends.
In this large, contemporary cohort of very preterm infants, LOS incidence fell from 2010 to 2017 and then rose from 2018 to 2023. The later increase was driven by non-CoNS gram-positive and gram-negative pathogens, with notable rises in S aureus across both periods and in Klebsiella during 2018–2023. The authors conclude that targeted prevention strategies should be directed to the changing pathogen epidemiology of LOS. The abstract does not report specific prevention interventions or detailed subgroup analyses beyond the pathogen-specific APCs.