Phenotypic and genotypic characteristics of non-O157 Shiga toxin-producing Escherichia coli (STEC) from Swiss cattle

The strains belonged to 29 serovirotypes (association between serotypes and virulence factors). O103:H2 stx1eae-ɛ ehxA, O116:H- stx2, and ONT:H- stx2c were the most common accounting for 29% of the strains. Only one strain (2.4%) of serovirotype O145:H- stx1stx2eae-γ1ehxA showed a pattern of highly virulent human strains. This is the first study providing characterization data of bovine non-O157 STEC in Switzerland, and underlining the importance of the determination of virulence factors (including intimin types) in addition to serotypes to assess the potential pathogenicity of these strains for humans.