Nevertheless, cases of HUS provoked by LEE-negative STEC have been reported (Karmali et al., 1985; Paton et al., 1999; Bielaszewska et al., 2009), including a large outbreak in 2011 in Europe caused by an enteroaggregative E. coli that acquired the stx2a gene, and it possessed a combination of virulence genes increasing its virulence (Boisen et al., 2015). This evidence concerns the gene STX2 and hemolytic-uremic syndrome.