Trends and Interhospital Variability of NICU Bloodstream Infections in Korea

Health care-associated bloodstream infections (BSIs), particularly central line-associated BSIs (CLABSIs), remain an important cause of morbidity among neonates admitted to neonatal intensive care units (NICUs). Long-term Korean national data describing the trends and interhospital variability in NICU-associated infections remain limited.

To evaluate national trends, interhospital variability, and microbiological characteristics of NICU-associated BSIs in Korea using nationwide surveillance data.

This nationwide cohort study analyzed data from the NICU module of the Korean National Healthcare-Associated Infections Surveillance System, including NICUs that participated between July 2019 and June 2024. Surveillance definitions were based on modified Centers for Disease Control and Prevention criteria. Data were analyzed from October 2025 to June 2026.

Outcomes of interest were annual BSI and CLABSI rates per 1000 patient-days and 1000 central line-days, respectively, and device utilization ratios (DURs). Temporal trends were assessed using mixed-effects negative binomial regression models with hospital-level random intercepts, adjusting for birth weight category, NICU bed capacity, and nurse staffing grade.

Between July 2019 and June 2024, 74 to 82 NICUs were included annually, contributing a total of 2 178 107 patient-days and 585 582 central line-days of surveillance, with annual NICU admissions ranging from 24 607 to 30 260 neonates. Overall, 948 BSIs were identified, including 836 CLABSIs (88.2%). The pooled mean BSI rate declined from 0.56 (95% CI, 0.49-0.63) to 0.35 (95% CI, 0.29-0.41) per 1000 patient-days, and the CLABSI rate declined from 1.78 (95% CI, 1.56-2.03) to 1.16 (95% CI, 0.98-1.38) per 1000 central line-days. After adjustment, the adjusted rate ratio per surveillance year was 0.91 (95% CI, 0.86-0.96) for BSI, 0.92 (95% CI, 0.87-0.97) for CLABSI, and 0.95 (95% CI, 0.93-0.98) for DUR. Despite overall improvement, substantial interhospital variability in both BSI and CLABSI rates persisted. Gram-positive cocci predominated, followed by gram-negative bacilli and fungi.

In this nationwide surveillance cohort study of NICUs, BSIs and CLABSIs rates declined significantly over 5 years, while substantial interhospital variability persisted. Although institutional-level risk adjustment was applied, the absence of patient-level clinical variables limits individual hospital comparisons, underscoring the need for refined risk adjustment and targeted quality improvement strategies.