Predictors of mortality and therapeutic efficacy in carbapenem-resistant Acinetobacter baumannii bacteremia

Summary Objectives: Bacteremia caused by carbapenem-resistant Acinetobacter baumannii (CRAB) is associated with high morbidity and mortality. The primary objective was to identify clinical and therapeutic factors associated with 14- and 30-day mortality following infection onset. Methods: This was a prospective, observational, multicenter study conducted across 52 Italian centers. Over an 18-month period, adult hospitalized patients with CRAB bacteremia were enrolled. Results: Among 398 patients with CRAB bacteremia, sources were mainly CVC-related or primary, with 14- and 30-day mortality rates of 22% and 27% respectively. Cox regression analysis identified male sex (p=0.006), and chronic kidney disease (p=0.016) as independent predictors of 14-day mortality, while colistin-containing regimen (p=0.014), and cefiderocol-containing-regimen (p<0.001) were associated with 14-day survival; male sex (p=0.027), septic shock (p=0.018), previous colonization by A. baumannii (p<0.001), and tigecycline-containing regimen (p=0.021) were independent predictors of 30-day mortality, while cefiderocol-containing-regimen (p<0.001) was associated with 30-day survival. Propensity score matching revealed that cefiderocol was significantly associated with 14-day survival and clinical success. The combination of cefiderocol plus Fosfomycin was also significantly associated with clinical success. Conclusion: Our findings highlight key clinical and therapeutic determinants of mortality and survival in patients with CRAB bacteraemia, providing valuable insights for improving the management of this challenging infection.