Mortality outcomes and their predictors in patients with carbapenem-resistant Acinetobacter baumannii bacteraemia: a prospective cohort study from South India

Abstract Background Carbapenem-resistant Acinetobacter baumannii (CRAB) bloodstream infections (BSIs) are associated with high mortality, yet predictors of early mortality remain inadequately studied. Methods We conducted a prospective observational study of patients with CRAB-BSI from July 2021 to December 2023. Patients ≥18 y of age with CRAB bacteraemia were included. Clinical, microbiological and treatment data were collected. Multivariable logistic regression was performed to identify independent predictors of 7-d mortality. Results A total of 154 patients were included. The 7- and 30-d mortality rates were 57.1% and 76.6%, respectively. Common BSI sources included hospital-acquired pneumonia (51.3%) and vascular catheters (29.2%). Only 37% received appropriate empirical therapy. On multivariable analysis, type 2 diabetes mellitus (adjusted odds ratio [aOR] 2.35, p=0.031), inotrope requirement at BSI onset (aOR 3.11 [95% confidence interval 1.28 to 7.56], p=0.013) and higher tigecycline minimum inhibitory concentration in Vitek-2 (aOR 2.50, p=0.040) were independent predictors of early mortality. Vascular catheter–related BSI (aOR 0.25, p=0.003) was associated with lower early mortality. The association between appropriate targeted therapy (aOR 0.21, p=0.001) and mortality was interpreted cautiously because of potential survivor bias. Conclusions Early mortality in patients with CRAB-BSI is linked to host factors, severity of illness and antimicrobial resistance. Catheter-associated BSI, likely reflecting the feasibility of source control, was associated with improved outcomes. Appropriate targeted therapy was also associated with survival, which should be interpreted cautiously because of potential survivor bias.