Characterization of Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolated from Fresh Produce and Agricultural Environments in Korea

• Published in: Journal of food protection 2020-07, Vol.83 (7), p.1115-1124
• Main Authors: Cha, Min-Hyeok, Ryu, Jae-Gee, Chi, Young-Min, Woo, Gun-Jo
• Format: Article
• Language: English
• Subjects: Acids; Agricultural practices; Agricultural production; Agriculture; Anti-Bacterial Agents - pharmacology; Antigens; Antimicrobial agents; Antimicrobial resistance; beta-Lactamases - genetics; Cephalosporins; Chinese cabbage; Contamination; Deoxyribonucleic acid; DNA; Drug resistance; E coli; Epidemiology; Escherichia coli; Escherichia coli - genetics; Escherichia coli Infections; Farms; Food safety; Gene transfer; Genes; Homology; Horizontal transfer; Humans; Laboratories; Lactose; Livestock; Phylogenetics; Plasmids; Republic of Korea; Resistance factors; Strains (organisms); Stream water; Toxins; Virulence; Water analysis; Water sampling
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/JFP-19-483

This study was conducted to characterize Escherichia coli strains and evaluate the spread of antimicrobial resistance among these strains from fresh produce and farm environments in Korea. We then conducted phenotypic and genetic studies on antimicrobial-resistant isolates. We determined the genetic epidemiological characteristics of isolates that produced extended-spectrum β-lactamase (ESBL) and confirmed plasmid transfer in isolates that carried blaCTX-M-type genes. E. coli strains were isolated from 8 samples of fresh produce and 152 samples from the farm environment collected from May 2014 to June 2016. Cephalosporin resistance was the most prevalent (61.8%) type of resistance among the isolates. Five ESBL-producing strains with high genetic homology with E. coli of human or livestock origin were identified. Lateral transfer of plasmids harboring blaCTX-M-type genes to transconjugants was successful. Two isolates from Chinese cabbage and from water samples collected from a nearby stream harbored the ISEcp1-blaCTX-M-55-orf477 operon and were confirmed as sequence type 1196 and the same type of plasmid replicon, suggesting that cross-contamination was highly likely. A high-risk clone of sequence type 69 (clonal complex 69) isolates was also recovered from the farm environment. This study provides genetic evidence that antimicrobial resistance factors in E. coli from farm environments originate in the clinic or in livestock, highlighting the fact that good agricultural practices in farming are important to inhibit the spread of antimicrobial resistance to bacteria on fresh produce.