Prevalence and antimicrobial susceptibility data for extended-spectrum β-lactamase- and AmpC-producing Enterobacteriaceae from the MYSTIC Program in Europe and the United States (1997-2004)

This article presents prevalence and susceptibility data from the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program in Europe (1997-2004) and the United States (1999-2004) for Enterobacteriaceae producing extended-spectrum β-lactamase (ESBL) and/or AmpC β-lactamases. For ESBL-producing isolates, the prevalence of Escherichia coli and Klebsiella spp. in Europe and Enterobacter spp. in the United States increased over time. For AmpC-producing isolates, the prevalence of Enterobacter spp. and Citrobacter spp. decreased over time in Europe and the United States, respectively. Compared with other antimicrobial agents, meropenem and imipenem had greatest activity against ESBL-producing E. coli and Klebsiella spp. in both Europe (96.9-100.0%) and the United States (100.0%). Such activity was also found for AmpC-producing Enterobacteriaceae in Europe (50.0-100.0%), and Enterobacter spp. and Citrobacter spp. from the United States (100.0% for both). The continued efficacy of carbapenems such as meropenem confirms that these remain first-line agents for treatment of nosocomial infections caused by Enterobacteriaceae-producing ESBL or AmpC β-lactamases.