Characterization of the risk to human health of pathogenic Escherichia coli isolates from chicken carcasses

The purpose of this study was to evaluate the risk for human health associated with pathogenic Escherichia coli isolated from airsacculitis and cellulitis in chickens, by comparing the genotypic and phenotypic profiles of avian E. coli isolates and E. coli strains isolated from sick humans during the same period and in the same geographical area as the avian isolates. A total of 96 isolates and 46 isolates from lesions of cellulitis and airsacculitis, respectively, were obtained. Isolates from the backs of some of the affected and healthy birds and 91 intestinal and extraintestinal isolates from humans with diarrhea, urinary tract infections, or septicemia were examined. The frequency of antimicrobial resistance was in general higher in the avian than in the human isolates. VT1-VT2-Eae and VT2-Eae, pathotypes associated with hemolytic and uremic syndrome and bloody diarrhea in humans, were the most frequently encountered pathotypes in human intestinal isolates but were not recovered from the avian isolates. Aero-Pap-TSH and Aero-TSH were the most frequently encountered pathotypes in avian isolates but were rarely observed in human isolates. No avian isolate was of serogroup O157, whereas many human isolates belonged to this O group. O78 and O2 were the most frequently observed O groups in avian isolates but were rarely found in human isolates. Only two avian isolates demonstrated possible relatedness to human isolates based on pulsed-field gel electrophoresis profiles, but they belonged to different pathotypes. Our results suggest that avian isolates recovered from cellulitis and air sacullitis possess very few of the attributes required to cause diseases in humans. It is also concluded that isolates from cellulitis and airsacculitis do not represent a greater hazard than isolates from the back of healthy birds.