Comparative Genetic Characterization of Pathogenic Escherichia coli Isolated from Patients and Swine Suffering from Diarrhea in Korea

SIMPLE SUMMARY: The objective of this study was to compare the virulence and antimicrobial resistance characteristics of the most prevalent Escherichia coli strains causing diarrhea in both swine and humans. Results show that the swine strains exhibited a considerably higher level of resistance compared to those from human patients, particularly against fluoroquinolones. Moreover, five sequence types (ST 100, ST 1, ST 10, ST 641, and ST 88) were identified in both swine and human isolates. Furthermore, it was confirmed that both swine and human isolates possessed comparable virulence traits and shared similar phylogenetical relationships. These results suggest that cross contamination and the transmission of antimicrobial resistance may occur between swine and humans. ABSTRACT: The aim of this study was to compare the virulence factors and antimicrobial resistance of the most common pathogenic Escherichia coli strains in swine and patients with diarrhea in Korea. We examined virulence genes and antimicrobial susceptibility in 85 and 61 E. coli strains isolated from swine and patients with diarrhea, respectively. The most prevalent pathogen in swine was enterotoxigenic E. coli (ETEC) (47.1%), followed by Shiga toxin-producing E. coli (STEC) (32.9%). Similarly, the majority of the patient isolates (50.8%) were proven to be STEC, the most common pathotype, followed by ETEC (23.0%). We found that swine isolates had significantly higher resistance than patient isolates, especially to fluoroquinolones (ciprofloxacin: 37.5% and 16.1%; norfloxacin: 29.7% and 16.1%, respectively). Additionally, sequence type (ST) 100 (swine: 21; patients: 4), ST 1 (swine: 21, patients: 2), ST 10 (swine: 8; patients: 6), ST 641 (swine: 3, patients: 2), and ST 88 (swine: 2, patients: 11) were detected in both swine and humans. In addition, we confirmed that isolates from swine and patients had similar virulence traits and were phylogenetically similar. According to these findings, swine and humans are susceptible to cross infection and the transfer of antimicrobial resistance.