October 19, 2025Open Access

Outcomes of carbapenem-resistant Acinetobacter baumannii bloodstream infections in intensive care units and prognostic effect of different antimicrobial regimens

Key Points

Day-28 mortality rate for bloodstream infections was 56.5%, indicating a severe clinical challenge.
Colistin-based therapy improved survival outcomes with an adjusted hazard ratio of 0.56 in critically ill patients.
The study utilized multivariable regression analysis to identify factors influencing mortality risk post-infection.
Highly resistant bacteria like CRAB necessitate effective antimicrobial regimens, with sulbactam showing benefits in pneumonia cases.

Abstract

Abstract Background Carbapenem-resistant Acinetobacter baumannii (CRAB) poses a significant global threat due to limited therapeutic options and high rates of associated mortality. CRAB-related bloodstream infections (BSIs) in intensive care units (ICUs) represent a major clinical challenge. This study aimed to investigate the clinical outcomes of CRAB-BSIs in ICU settings and evaluate the prognostic effect of different antimicrobial regimens. Methods This multicenter, retrospective observational study was conducted at five medical centers in Taiwan and included 393 critically ill patients with CRAB-BSIs between January 2015 and December 2019. Clinical and microbiological outcomes were analyzed. Multivariable regression analysis was used to identify independent prognostic factors for day-28 mortality. Results The most common causes of CRAB-BSIs were pneumonia (42.5%) and catheter-related infections (38.7%). The day-28 mortality rate following BSI onset was 56.5%. A higher sequential organ failure assessment (SOFA) score independently predicted increased day-28 mortality. Colistin-based therapy was associated with improved survival outcomes in the original (adjusted hazard ratio aHR, 0.56; 95% confidence intervals (CI), 0.35–0.88) and time-window bias-adjusted (aHR, 0.59; 95% CI, 0.37–0.94) cohorts. Among patients with pneumonia-related CRAB-BSIs, colistin-based therapy did not significantly improve day-28 survival, whereas sulbactam-based therapy showed survival benefit (aHR, 0.37; 95% CI, 0.15–0.91). Neither carbapenem-based nor tigecycline-based therapies demonstrated a mortality benefit on day 28. Conclusion CRAB-BSIs are associated with high mortality in critically ill patients. In settings where novel antibiotics are not available, colistin-based therapy was associated with improved clinical outcomes. Among patients with pneumonia-related CRAB-BSIs, sulbactam-based therapy was associated with lower mortality.

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