Carbapenem resistance and mortality in pediatric Acinetobacter bloodstream infections: determinants from a 12-year tertiary-care cohort study.

UNLABELLED: Carbapenem-resistant (CR) Acinetobacter spp. bloodstream infections (BSIs) are difficult to treat in children, yet pediatric data on factors associated with resistance and mortality remain limited. We aimed to identify factors associated with carbapenem resistance and 30-day mortality in pediatric Acinetobacter BSIs. We retrospectively analyzed children with monomicrobial Acinetobacter BSIs at a tertiary-care university hospital between January 2014 and September 2025. Factors associated with carbapenem resistance were assessed using co-primary logistic regression analyses in the full cohort and within A. baumannii; 30-day mortality was assessed using Cox regression. Among 128 episodes, median age was 2.0 years (IQR 0.76-8.01), 60.2% (77/128) were male and 90.6% (116/128) had comorbidities. Carbapenem resistance was identified in 54/128 episodes (42.2%), all caused by A. baumannii (54/87, 62.1%). Increasing age, longer hospitalization before BSI onset, mechanical ventilation (MV), and prior meropenem exposure were associated with resistance in both co-primary models. Adjusted ORs for MV were 23.77 (95% CI, 7.54-74.92) in the full cohort and 23.20 (95% CI, 5.39-99.95) within A. baumannii. Overall 30-day mortality was 13.3% (17/128) and was higher in CR than carbapenem-susceptible episodes (22.2% versus 6.8%; p = 0.011). Exploratory comparisons across CR A. baumannii treatment categories were inconclusive (exact p = 0.256). Thrombocytopenia (aHR, 6.12; 95% CI, 2.13-17.61) and carbapenem resistance (aHR, 3.01; 95% CI, 1.04-8.71) were associated with mortality in the primary Cox model.

CONCLUSION: Thrombocytopenia and carbapenem resistance were associated with 30-day all-cause mortality in the primary adjusted analysis; the resistance association was not statistically significant in A. baumannii-restricted and first-episode-only sensitivity analyses.

WHAT IS KNOWN: • Acinetobacter BSIs mainly affect medically complex hospitalized children. • Pediatric evidence on factors associated with carbapenem resistance and mortality remains scarce.

WHAT IS NEW: • Increasing age, longer hospitalization before BSI onset, mechanical ventilation, and prior meropenem exposure were associated with carbapenem resistance in both the full Acinetobacter cohort and within A. baumannii. • Carbapenem resistance was associated with 30-day mortality in the primary model, but this finding was not consistently supported in sensitivity analyses; thrombocytopenia remained associated with mortality.