Population structure and uropathogenic potential of extended-spectrum cephalosporin-resistant Escherichia coli from retail chicken meat

BMC Microbiol. 2021 Mar 29;21(1):94. doi: 10.1186/s12866-021-02160-y.


Background: Food-producing animals and their products are considered a source for human acquisition of antimicrobial resistant (AMR) bacteria, and poultry are suggested to be a reservoir for Escherichia coli resistant to extended-spectrum cephalosporins (ESC), a group of antimicrobials used to treat community-onset urinary tract infections in humans. However, the zoonotic potential of ESC-resistant E. coli from poultry and their role as extraintestinal pathogens, including uropathogens, have been debated. The aim of this study was to characterize ESC-resistant E. coli isolated from domestically produced retail chicken meat regarding their population genetic structure, the presence of virulence-associated geno- and phenotypes as well as their carriage of antimicrobial resistance genes, in order to evaluate their uropathogenic potential.

Results: A collection of 141 ESC-resistant E. coli isolates from retail chicken in the Norwegian monitoring program for antimicrobial resistance in bacteria from food, feed and animals (NORM-VET) in 2012, 2014 and 2016 (n = 141) were whole genome sequenced and analyzed. The 141 isolates, all containing the beta-lactamase encoding gene blaCMY-2, were genetically diverse, grouping into 19 different sequence types (STs), and temporal variations in the distribution of STs were observed. Generally, a limited number of virulence-associated genes were identified in the isolates. Eighteen isolates were selected for further analysis of uropathogen-associated virulence traits including expression of type 1 fimbriae, motility, ability to form biofilm, serum resistance, adhesion- and invasion of eukaryotic cells and colicin production. These isolates demonstrated a high diversity in virulence-associated phenotypes suggesting that the uropathogenicity of ESC-resistant E. coli from chicken meat is correspondingly highly variable. For some isolates, there was a discrepancy between the presence of virulence-associated genes and corresponding expected phenotype, suggesting that mutations or regulatory mechanisms could influence their pathogenic potential.

Conclusion: Our results indicate that the ESC-resistant E. coli from chicken meat have a low uropathogenic potential to humans, which is important knowledge for improvement of future risk assessments of AMR in the food chains.

Keywords: AMR; Antimicrobial resistance; E. coli; Foodborne; Norway; Phenotype; Poultry; UTI; Urinary tract infection; Virulence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cephalosporin Resistance* / genetics
  • Chickens
  • Escherichia coli / classification*
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Escherichia coli / pathogenicity
  • Genetic Variation
  • Humans
  • Meat / microbiology*
  • Urinary Tract Infections / microbiology