STX2 and hemolytic-uremic syndrome: While it has been reported that subtypes Stx2a and Stx2c are more frequently associated with HUS than other Stx2 subtypes, Stx2b, Stx2d, and Stx2e strains have also been isolated from the stools of patients with HUS; therefore, it is important for diagnostic assays to be able to identify these Shiga toxin subtypes as well (10, 24, 38, 39).