Also for the O26 strains, although PLS regression revealed that serogroup O26 strains in HUS group 2 containing stx2 were separated from strains that contained stx1, no core gene variants were found to be significantly over- or underrepresented in either of these two groups (Table 2, Table S10 in File S2). This evidence concerns the gene STX2 and hemolytic-uremic syndrome.