We established an automated screening method to characterize adhesion of
Escherichia coli to intestinal porcine epithelial cells (IPEC-J2) and their
probiotic activity against infection by enteropathogenic E. coli (EPEC). 104
intestinal E. coli isolates from domestic pigs were tested by PCR for the
occurrence of virulence-associated genes, genes coding for resistances to
antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion
rates and probiotic activity were examined for correlation with the presence
of these genes. Finally, data were compared with those from 93 E. coli
isolates from wild boars. Isolates from domestic pigs carried a broad variety
of all tested genes and showed great diversity in gene patterns. Adhesions
varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial
cell after 2 or 6 hours respectively. Most isolates from domestic pigs and
wild boars showed low adherence, with no correlation between
adhesion/probiotic activity and E. coli genes or gene clusters. The gene
sfa/foc, encoding for a subunit of F1C fimbriae did show a positive
correlative association with adherence and probiotic activity; however E. coli
isolates from wild boars with the sfa/foc gene showed less adhesion and
probiotic activity than E. coli with the sfa/foc gene isolated from domestic
pigs after 6 hour incubation. In conclusion, screening porcine E. coli for
virulence associated genes genes, adhesion to intestinal epithelial cells, and
probiotic activity revealed a single important adhesion factor, several
probiotic candidates, and showed important differences between E. coli of
domestic pigs and wild boars