STX2 and hemolytic-uremic syndrome: All the above isolates that carry the four LAA modules belong to the phylogroup B1, except the FHI92 strain, which belongs to phylogroup E. Additionally, these strains were associated (p < 0.0001) with Shiga toxin type 2 (Stx2), a toxin that is a risk factor for HUS development8 (Supplementary Table 6).