Impact of Inadequate Initial Antimicrobial Therapy on Mortality in Infections Due to Extended-Spectrum β-Lactamase–Producing Enterobacteriaceae

Abstract
Since the initial emergence of extended-spectrum β-lactamase–producing Escherichia coli and Klebsiella species (ESBL-EK) in the 1980s, their prevalence has increased steadily.1,2 Infections with ESBL-EK have been associated with increased morbidity, mortality, hospital length of stay, and hospital cost.3 These infections are particularly problematic because choices for antimicrobial therapy, both empirical and definitive, may be severely restricted given that these organisms are often resistant to multiple antibiotics and antibiotic classes.4,5