In vitro efficacy of six cephalosporins tested against Enterobacteriaceae isolated at 38 North American medical centres participating in the SENTRY Antimicrobial Surveillance Program, 1997-1998

The SENTRY Antimicrobial Surveillance Program is an ongoing international c ollaboration that monitors the predominant bacterial and fungal pathogens a nd antimicrobial susceptibility patterns associated with community-acquired and nosocomial infections. SENTRY data on the current cephalosporin suscep tibility patterns (1997-98) of North American isolates of clinically import ant Enterobacteriaceae were analyzed. Susceptibility to a selection of ceph alosporins was assessed at a central laboratory using reference broth micro dilution methods and interpretive criteria specified by the National Commit tee for Clinical Laboratory Standards. The third- and fourth-generation cep halosporins tested demonstrated excellent activity against Escherichia coli and Klebsiella pneumoniae, whereas some of the older agents maintained goo d efficacy. Extended spectrum p-lactamases were detected in all regions of the United States and Canada (1.8-10.7%). Cefepime was the most active agen t tested against pathogens with the potential for enzyme-mediated resistanc e due to Amp C. The third-generation agents maintained acceptable efficacy against Serratia marcescens, but were less effective against Citrobacter an d Enterobacter species. The older cephalosporins were generally inadequate against these pathogens, in contrast to cefepime, which was the widest spec trum cephalosporin overall. Some significant regional variations in spectru m were detected. (C) 2000 Elsevier Science B.V. and International Society o f Chemotherapy. All rights reserved.