Trending Eight Years of In Vitro Activity of Ertapenem and Comparators against Escherichia coli from Intra-abdominal Infections in North America-SMART 2002-2009

During 2002 - 2009, 2,885 Escherichia coli intra-abdominal isolates were collected from North America in the Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance program. The incidence of extended-spectrum beta-lactamase producing isolates ranged from 1.7% in 2005 to 7.2% in 2004 and 2006, and was 6.8% in 2009. Susceptibility trends showed that there were only minor fluctuations in susceptibility to ertapenem and imipenem with no significant decrease over time. By contrast, cefepime, cefotaxime, cefoxitin, ceftazidime, ceftriaxone, ciprofloxacin, and levofloxacin exhibited significantly higher minimum inhibitory concentrations against E. coli overall (p<0.05) and (except for cefoxitin) against extended-spectrum beta-lactamase producing isolates. Piperacillin-tazobactam also had significantly diminished activity against E. coli overall, but paradoxically showed significantly increased activity against extended-spectrum beta-lactamase producing isolates. Ertapenem and imipenem susceptibility of E. coli in North America remained consistently high during the period 2002 through 2009, and continuing updates from SMART will be helpful in detecting any changes that occur in the future.