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

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.