title: Evaluation of eight different cephalosporins for detection of cephalosporin resistance in Salmonella enterica and Escherichia coli.
abstract: This study evaluates the efficacy of eight different cephalosporins for detection of cephalosporin resistance mediated by extended spectrum beta-lactamases (ESBL) and plasmidic AmpC beta-lactamases in Salmonella and Escherichia coli. A total of 138 E. coli and 86 Salmonella isolates with known beta-lactamase genes were tested for susceptibility toward cefoperazone, cefotaxime, cefpodoxime, cefquinome, ceftazidime, ceftiofur, ceftriaxone, and cefuroxime using minimum inhibitory concentration determinations and disc diffusion. The collection consisted of 84 ampicillin-susceptible, 57 ampicillin-resistant but cephalosporin-susceptible, 56 ESBL isolates and 19 isolates with plasmidic AmpC, as well as 10 ampC hyper-producing E. coli. The minimum inhibitory concentration distributions and zone inhibitions varied with the tested compound. Ampicillin-resistant isolates showed reduced susceptibility to the cephalosporins compared to ampicillin-susceptible isolates. Cefoperazone, cefquinome, and cefuroxime were not useful in detecting isolates with ESBL or plasmidic AmpC. The best substances for detection were cefotaxime, cefpodoxime, and ceftriaxone, whereas ceftazidime and ceftiofur were not as efficient. Ceftriaxone may be the recommended substance for monitoring because of some ability in separating ampC hyper-producing E. coli from ESBL and plasmidic AmpC isolates.
authors.affiliation: WHO Collaborating Centre for Antimicrobial Resistance in Food borne Pathogens and EU Community Reference Laboratory for Antimicrobial Resistance, National Food Institute, Technical University of Denmark, Copenhagen, Denmark. fmaa@food.dtu.dk
authors.forename: Frank M
authors.initials: FM
authors.lastname: Aarestrup
authors.forename: Henrik
authors.initials: H
authors.lastname: Hasman
authors.forename: Kees
authors.initials: K
authors.lastname: Veldman
authors.forename: Dik
authors.initials: D
authors.lastname: Mevius
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018550:Cephalosporin Resistance / Q000187:drug effects / Q000235:genetics; D002511:Cephalosporins / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D019779:Salmonella enterica / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D012486:Salmonella typhimurium / Q000187:drug effects; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases