STX2 and hemolytic-uremic syndrome: Another example of hetero-pathogenic strains was STEC/ExPEC isolates of the O80:H2 serotype, which carried the combination of Shiga toxin stx2a and stx2b genes and numerous virulence genes of the ExPEC pathotype and caused not only severe forms of HUS but also posed a threat of bacteremia [52,53].