Detection of virulence‐associated genes characteristic of intestinal Escherichia coli pathotypes, including the enterohemorrhagic/enteroaggregative O104:H4, in bovines from Germany and Spain

Abstract Cattle are reservoirs of enterohemorrhagic Escherichia coli; however, their role in the epidemiology of other pathogenic E. coli remains undefined. A new set of quantitative real‐time PCR assays for the direct detection and quantification of nine virulence‐associated genes (VAGs) characteristic of the most important human E. coli pathotypes and four serotype‐related genes ( wzx O104 , fli C H4 , rbf O157 , fli C H7 ) that can be used as a surveillance tool for detection of pathogenic strains was developed. A total of 970 cattle fecal samples were collected in slaughterhouses in Germany and Spain, pooled into 134 samples and analyzed with this tool. stx 1, eae and inv A were more prevalent in Spanish samples whereas bfp A, stx 2, ehx A, elt , est and the rbf O157 / fli C H7 combination were observed in similar proportions in both countries. Genes characteristic of the hybrid O104:H4 strain of the 2011 German outbreak ( stx 2/ agg R/ wzx O104 / fli C H4 ) were simultaneously detected in six fecal pools from one German abattoir located near the outbreak epicenter. Although no isolate harboring the full stx 2/ agg R/ wzx O104 / fli C H4 combination was cultured, sequencing of the agg R positive PCR products revealed 100% homology to the agg R from the outbreak strain. Concomitant detection by this direct approach of VAGs from a novel human pathogenic E. coli strain in cattle samples implies that the E. coli gene pool in these animals can be implicated in de novo formation of such highly‐virulent strains. The application of this set of qPCRs in surveillance studies could be an efficient early‐warning tool for the emergence of zoonotic E. coli in livestock.