Assessment of the presence of extended-spectrum beta-lactamase-producing Escherichia coli in eggshells and ready-to-eat products.

The principal objective of this study was to assess whether chicken eggshells may be contaminated by ESBL-producing E. coli (ESBLC). Additional analyses were carried out to determine if ESBLEC could be detected in other foodstuffs such as cooked poultry or fresh vegetables. Seventy-two eggshells from different supermarkets and stores as well as 32 salads, 30 samples of cooked poultry and six samples of chicken-based pet food samples were analysed. Characterization of ESBL was performed by PCR and sequencing. Antimicrobial resistance was determined by disk diffusion method. Phylogenetic group was assigned by multiplex-PCR. No ESBLEC was isolated from chicken eggshells, cooked chicken and pet food. One SHV-12-producing E. coli was isolated from a salad sample. This is the first study to analyse chicken eggs in an area where there is a high prevalence of ESBLEC in retail chicken meat.