title: Characterization of antimicrobial resistance of Escherichia coli recovered from foods of animal and fish origin in Korea.
abstract: Antimicrobial-resistant Escherichia coli is transferred from food-producing animals to humans through the food chain. We investigated the prevalence of antimicrobial resistance and resistance determinants and characterized the integrons of foodborne E. coli in Korea. In  total, 162 E. coli isolates from commercial foods (raw meat, fish, and processed foods) were collected by the National Antimicrobial Resistance Management Program from 2004 to 2006. Susceptibility to 20 antibiotics was tested by disk diffusion, and resistance determinants were detected  using PCR and genomic sequence analysis. The isolates were highly resistant to antibiotics commonly used in livestock farming. Resistance to tetracycline (74.7%) was the most frequently observed, followed by streptomycin (71%) and ampicillin (51.2%). Class 1 integrons were detected in 13 isolates  (8%), and nine of these integrons were located on conjugative plasmids. None of the isolates produced extended-spectrum β -lactamase. One isolate (0.6%) harbored bla(CMY-2), which was located on a conjugative plasmid. Although the qnr gene was not detected, aac(6'9)-Ib-cr  was present in two isolates (1.2%). This is the first report of aac(6'9)-Ib-cr in food isolates. Three or four amino acid substitutions at positions 83 and 87 in gyrA and at positions 80 and/or 84 in parC were found in six isolates, representing high resistance  to ciprofloxacin (MIC ≥ 16 mg/liter). These results suggest that E. coli isolates carrying resistance genes and integrons are present in the Korean food chain.
authors.affiliation: Laboratory of Food Safety and Evaluation, Department of Food Bioscience and Technology, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713, Korea.
authors.forename: Hyon-Ji
authors.initials: HJ
authors.lastname: Koo
authors.forename: Gun-Jo
authors.initials: GJ
authors.lastname: Woo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D007723:Korea; D008460:Meat / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D017747:Seafood / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents