Characterization of Extraintestinal Pathogenic Escherichia coli from Human Clinical and Poultry Samples

Extraintestinal Pathogenic Escherichia coli (ExPEC) are leading causes of adult bacteremia, neonatal meningitis, pneumonia, and the vast majority of urinary tract infections. ExPEC are present in food, mostly in poultry products. Despite the high burden of ExPEC on human health, their source and impact on food safety are largely unknown. Food-isolated ExPEC carry an abundance of virulence and antibiotic resistance genes and are suggested to have zoonotic potential. Here, ExPEC were characterized for sanitizer tolerance, biofilm formation, antibiotic susceptibility, and adherence to Caco-2 cells (a human intestinal epithelial-derived cell line). The ExPEC used were isolated from poultry meat and from archived collections of poultry and human clinical samples. Overall, low frequency of sanitizer tolerance (2.4%) and biofilm formation (6%) were observed under the test conditions used. The frequency of antibiotic susceptibility was significantly higher (p < 0.05) among human clinical ExPEC (55%) compared to poultry-isolated ExPEC (27.9%). Overall, 62.8% of poultry ExPEC showed adherence to human intestinal epithelia at a level comparable to that of the control enteric pathogen E. coli O157:H7. In summary, the results of this work suggest that the human gastrointestinal tract could serve as a reservoir of high-risk poultry ExPEC if consumed, and, hence, it is a potential source of extraintestinal infections.