title: In vitro activities of various beta-lactam antimicrobial agents against clinical isolates of Escherichia coli and Klebsiella spp. resistant to oxyimino cephalosporins.
abstract: Broth microdilution testing was used to study the activity of several beta-lactam antimicrobial agents, including piperacillin-tazobactam and cefepime, against 108 clinically derived Escherichia coli and Klebsiella sp. strains resistant to oxyimino cephalosporins (i.e., putative extended-spectrum beta-lactamase producers). On the basis of the percentage of susceptible strains, imipenem (100%), cefotetan (> or = 92%), and piperacillin-tazobactam (> or = 86%) were the most active agents. Cefepime activity (52 to 64% susceptible) was comparable to that of cefotaxime (40 to 63% susceptible) and aztreonam (20 to 63% susceptible). Among all beta-lactams tested, imipenem and cefotetan demonstrated the highest and most consistent level of activity and were the least affected by challenges with increased sizes of inocula of these resistant organisms.
authors.affiliation: Division of Laboratory Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: B D
authors.initials: BD
authors.lastname: Jett
authors.forename: D J
authors.initials: DJ
authors.lastname: Ritchie
authors.forename: R
authors.initials: R
authors.lastname: Reichley
authors.forename: T C
authors.initials: TC
authors.lastname: Bailey
authors.forename: D F
authors.initials: DF
authors.lastname: Sahm
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018550:Cephalosporin Resistance; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology; D004927:Escherichia coli Infections / Q000382:microbiology; D006801:Humans; D007709:Klebsiella / Q000187:drug effects* / Q000201:enzymology; D007710:Klebsiella Infections / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000096:biosynthesis; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases