Isolation and molecular characterization of nalidixic acid-resistant extraintestinal pathogenic Escherichia coli from retail chicken products

Antimicrob Agents Chemother. 2003 Jul;47(7):2161-8. doi: 10.1128/AAC.47.7.2161-2168.2003.

Abstract

Fluoroquinolone use in poultry production may select for resistant Escherichia coli that can be transmitted to humans. To define the prevalence and virulence potential of poultry-associated, quinolone-resistant E. coli in the United States, 169 retail chicken products from the Minneapolis-St. Paul area (1999 to 2000) were screened for nalidixic acid (Nal)-resistant E. coli. Sixty-two (37%) products yielded Nal-resistant E. coli. From 55 products that yielded both Nal-resistant and susceptible E. coli, two isolates (one resistant, one susceptible) per sample were further characterized. Twenty-three (21%) of the 110 E. coli isolates (13 resistant, 10 susceptible) satisfied criteria for extraintestinal pathogenic E. coli (ExPEC), i.e., exhibited >or=2 of pap (P fimbriae), sfa/foc (S/F1C fimbriae), afa/dra (Dr binding adhesins), iutA (aerobactin receptor), and kpsMT II (group 2 capsule synthesis). Compared with other isolates, ExPEC isolates more often derived from virulence-associated E. coli phylogenetic groups B2 or D (74% versus 32%; P < 0.001) and exhibited more ExPEC-associated virulence markers (median, 10.0 versus 4.0; P < 0.001). In contrast, the Nal-resistant and -susceptible populations were indistinguishable according to all characteristics analyzed, including pulsed-field gel electrophoresis profiles. These findings indicate that Nal-resistant E. coli is prevalent in retail poultry products and that a substantial minority of such strains represent potential human pathogens. The similarity of the Nal-resistant and -susceptible populations suggests that they derive from the same source population, presumably the avian fecal flora, with Nal resistance emerging by spontaneous mutation as a result of fluoroquinolone exposure.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Anti-Infective Agents / pharmacology*
  • Chickens
  • Cluster Analysis
  • Drug Resistance, Bacterial
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification*
  • Escherichia coli / pathogenicity
  • Escherichia coli Infections / drug therapy
  • Escherichia coli Infections / microbiology
  • Escherichia coli Infections / veterinary*
  • Feces / microbiology
  • Intestines / microbiology
  • Microbial Sensitivity Tests
  • Mutation
  • Nalidixic Acid / pharmacology*
  • O Antigens / genetics
  • Phenotype
  • Phylogeny
  • Poultry Diseases / drug therapy
  • Poultry Diseases / microbiology*
  • Poultry Products / microbiology
  • Random Amplified Polymorphic DNA Technique
  • Virulence
  • Virulence Factors / genetics

Substances

  • Anti-Infective Agents
  • O Antigens
  • Virulence Factors
  • Nalidixic Acid