Risk Factors for and Outcomes of Bacteremia Caused by Extended-Spectrum ß-Lactamase– Producing Escherichia coli and Klebsiella Species at a Canadian Tertiary Care Hospital

Background: Antimicrobial resistance due to production of extended-spectrum ß-lactamases by Escherichia coli and Klebsiella species (ESBL-EK) is concerning. Previous studies have shown that bacteremia due to ESBL-producing organisms is associated with increases in length of stay and/or mortality rate. Rates of infection by ESBL-EK vary worldwide, and regional differences in the prevalence of risk factors are likely. Few Canadian studies assessing risk factors for ESBL-EK infections or the outcomes of empiric therapy have been published. Objectives:To determine risk factors for and patient outcomes associated with ESBL-EK bacteremia. The appropriateness of empiric antibiotic therapy and the effect of inappropriate empiric therapy on these outcomes were also examined. Methods: In a retrospective, 1:1 case–control study conducted in a tertiary care hospital between 2005 and 2010, data for 40 patients wit