Some traits of Verotoxin-producing strains of Escherichia coli isolated from cattle

Verotoxin-producing Esherichia coli (VTEC) is one of six pathogenicity groups of Eschericha coli. The reservoir for VTEC is the intestinal tract of domestic animals, primarily ruminants. Investigations in our geographic region have also demonstrated that domestic animals are a significant VTEC reservoir. In spite of this, sporadic diseases in humans caused by these agents are rare, and no epidemics have been registered so far. The question is, therefore, what percentage of VTEC isolated in our region have the characteristics of enterohaemorrhagic E. coli (EHEC) which cause intestinal diseases in humans. The aim of this study was to test the isolated bovine strains for some phenotypic and genotypic traits and to determine the percent of strains that belong to EHEC. A total of 105 VTEC strains isolated from cattle were tested for the presence of verotoxin (vtx) genes by PCR (polymerase chain reaction) method. All of them possessed one or more vtx genes. In accordance with our investigations, only four (3.8%) strains, of a total of 105 VTEC strains belong to groups of EHEC. It may be concluded that the majority of strains isolated from cattle in this part of the world do not have phenotypic traits typical for EHEC. Therefore human VTEC associated diseases in Serbia are rare, despite the fact that domestic animals frequently harbor VTEC.