STX1A and hemolytic-uremic syndrome: Of these, five contained stx2 alone, and as described by Friedrich et al. [31], stx2 is clinically and epidemiologically the most important Shiga-toxin type, and the probability of HUS development in infections from strains harbouring stx2 is higher than that from strains containing either stx1 or both stx1 and stx2.