This is a retrospective chart review study. The proposed study aims to document the risk factors for quinolone resistance in bloodstream isolates of Klebsiella species. Additionally, the adequacy of empiric antibiotic therapy for Klebsiella bloodstream infections will be assessed. This research is important because identification of risk factors may allow earlier initiation of appropriate therapy in patients infected with these bacteria. Additionally, we will identify whether horizontal spread is responsible for this increasing trend.