The primary objective is to assess for independent predictors of in-hospital mortality (up to 28 days) in patients with Acinetobacter bloodstream infection. Secondary Objectives include the following: To determine the impact of inactive empiric antimicrobial therapy, defined as receipt of empiric antimicrobial therapy with no in vitro activity against the offending isolate for at least 24hrs, on the outcome (end points defined below) of patients with Acinetobacter bloodstream infection. To determine the impact of carbapenem resistance and pan-drug resistance (defined as resistance to all antimicrobials except colistin and/or tigecycline if these agents were tested) on the outcome of patients with Acinetobacter bloodstream infection. To assess the efficacy of varying definitive therapies on the outcome of patients with Acinetobacter bloodstream infection. To characterize the molecular epidemiology of Acinetobacter on a global level, as determined by pulsed-field gel electrophoresis (PFGE) and other techniques, and to assess whether patient outcomes are clonally related and to characterize the mechanisms of resistance in Acinetobacter on a global scale.