SP5 and hemolytic-uremic syndrome: In E.coli O157:H7, Shiga toxins Stx1 and Stx2 are encoded on two lambda-like prophages, Sp5 and Sp15, respectively.67,110 The toxins are produced upon prophage induction, which leads to severe diseases, including hemorrhagic colitis and life-threatening hemolytic uremic syndrome (HUS).111,112 In S. dysenteriae serotype 1, Stx is also associated with lambdoid phage genes, though it is expressed from the bacterial chromosome and not encoded by the active prophage.113 Stx is one of the main virulence factors of S. dysenteriae, being responsible for the disease severity.114,115