Detection of genes encoding for virulence and adherence factors in Escherichia coli isolated in slaughtered Sarda breed sheep.

In order to investigate the pathogenic profile of Escherichia coli hosted in "Sarda" sheep, autochthonous race present in Sardinia, thirty-seven E. coli strains collected from different sources (fleeces, carcass swabs and gut mucosa) of pre-chill slaughtered sheep (ewes and lambs) were serotyped using pheno- and genotypic methods. Furthermore, the presence of genes encoding for virulence factors and mediating for localized mucosal adherence factors was investigated, and pulsed-field gel electrophoresis (PFGE) characterization was performed. Twenty-one (56.8%) of the isolates belonged to O91 serogroup and sixteen (43.2%) belonged to nine different serotypes (O5:H11, O8:H14, O26:H2, O38:H26, O116:H9, O116:H11, O132:H34, O149:H?, O161:H-). Of these non-O91 strains, five (13.5%) were able to produce verocytotoxin (VT) and were ascribed to VTEC pathogroup, eleven (29.7%) were attributed to the Enteropathogenic E. coli (EPEC) pathogroup; the other strains (n.21) cannot be ascribed to a pathogenic group. However, various associated virulence genes were observed in all isolated strains. Macrorestriction analysis highlighted a large heterogeneity of the E. coli strains. The results confirm the role of sheep as reservoir of pathogenic E. coli serotypes potentially able to colonize and to damage the intestinal mucosa.