Susceptibility of European Escherichia coli clinical isolates from intra-abdominal infections, extended-spectrum β-lactamase occurrence, resistance distribution, and molecular characterization of ertapenem-resistant isolates (SMART 2008-2009)

A total of 3160 clinical isolates of Escherichia coli from intra-abdominal infections were collected during 2008–2009 from 13 European countries. The frequency of extended-spectrum β-lactamase (ESBL)-producing isolates in Europe was 11%. The most active antibiotics tested were typically imipenem, ertapenem, and amikacin, although the activity of all non-carbapenem antibiotics was lower when tested against ESBL-positive isolates than when tested against ESBL-negative isolates. Ertapenem exhibited 99.3% susceptibility with all isolates, and 96.8% susceptibility with ESBL-positive isolates. With application of the ertapenem CLSI clinical breakpoint for resistance (MIC ≥1 mg/L), only six isolates (0.2%) were ertapenem-resistant, and only three of these were available for molecular characterization. Of those three, only one was ESBL-positive (CTX-M-14), and two were carbapenemase-positive (OXA-48). All three were negative for, VIM, NDM and KPC carbapenemases. Although the level of ertapenem resistance in E. coli is very low, further monitoring of ertapenem susceptibility and molecular characterization of ertapenem-resistant isolates is needed.