STX2 and infection: While there were similar proportions of O157 strains with Stx2a+ associated with human infections in England and Wales compared with Scotland, in Scotland >80 % of the Stx2a+ strains were associated with sub-lineage Ic (PT21/28) as opposed to England and Wales where Stx2a+ strains were associated with various sub-lineages and alternative PTs (e.g. PT8, PT54) [5].