Burak Kizilcay, Yusuf Emre Ozdemir
In ICU-onset gram-negative bloodstream infections, carbapenem resistance, catheter-related source, older age, and previous cerebrovascular event were associated with increased 30-day mortality, while appropriate empirical therapy was associated with improved survival. These findings support risk-based empirical treatment decisions guided by patient characteristics, infection source, invasive support exposure, and the anticipated likelihood of resistant pathogens.
BACKGROUND: ICU-onset gram-negative bloodstream infections carry high mortality, rising antimicrobial resistance, and empirical treatment challenges.
AIMS: To evaluate resistance phenotypes, empirical therapy appropriateness, infection source, and invasive ICU exposures in these infections.
METHODS: This single-centre retrospective cohort included adults with gram-negative bloodstream infection occurring ≥ 48 h after ICU admission between January 2021 and December 2025. Clinical characteristics, pathogen distribution, carbapenem and colistin resistance, empirical therapy appropriateness, and factors associated with 30-day mortality were analysed.
RESULTS: Overall, 352 patients were included; mean age was 70.3 ± 15.9 years and 58.5% were male. The most common sources were pneumonia (33.5%), urinary tract infection (25.3%), and catheter-related bloodstream infection (14.5%). The leading pathogens were Klebsiella spp. (26.7%), Acinetobacter baumannii (21.0%), and Pseudomonas aeruginosa (21.0%). Carbapenem and colistin resistance were detected in 50.8% and 33.8% of isolates, respectively. Carbapenem resistance was independently associated with longer pre-bacteraemia ICU stay, primary bacteraemia, and mechanical ventilation, whereas colistin resistance was associated with age ≥ 65 years. Thirty-day mortality was 57.9%. Older age (OR 1.017; p = 0.046), catheter-related source (OR 3.388; p = 0.002), previous cerebrovascular event (OR 2.061; p = 0.030), and carbapenem resistance (OR 1.872; p = 0.043) were independently associated with mortality, whereas appropriate empirical therapy was protective (OR 0.404; p = 0.003).
CONCLUSION: In ICU-onset gram-negative bloodstream infections, carbapenem resistance, catheter-related source, older age, and previous cerebrovascular event were associated with increased 30-day mortality, while appropriate empirical therapy was associated with improved survival. These findings support risk-based empirical treatment decisions guided by patient characteristics, infection source, invasive support exposure, and the anticipated likelihood of resistant pathogens.