Zoonotic Potential of Escherichia coli Isolates from Retail Chicken Meat Products and Eggs

Chicken products are suspected as a source of extraintestinal pathogenicEscherichia coli (ExPEC), which causes diseases in humans. The zoonotic risk to humans from chicken-sourceE. coli is not fully elucidated. To clarify the zoonotic risk posed by ExPEC in chicken products and to fill existing knowledge gaps regarding ExPEC zoonosis, we evaluated the prevalence of ExPEC on shell eggs and compared virulence-associated phenotypes between ExPEC and non-ExPEC isolates from both chicken meat and eggs. The prevalence of ExPEC among egg-source isolates was low, i.e., 5/108 (4.7%). Based on combined genotypic and phenotypic screening results, multiple human and avian pathotypes were represented among the chicken-source ExPEC isolates, including avian-pathogenicE. coli (APEC), uropathogenicE. coli (UPEC), neonatal meningitisE. coli (NMEC), and sepsis-associatedE. coli (SEPEC), as well as an undefined ExPEC group, which included isolates with fewer virulence factors than the APEC, UPEC, and NMEC isolates. These findings document a substantial prevalence of human-pathogenic ExPEC-associated genes and phenotypes amongE. coli isolates from retail chicken products and identify key virulence traits that could be used for screening.