KRT32 and infection: Within the ECOR strains, only of 15% encode hha2 and 4% hha3. The presence of hha2 and hha3, rather than being linked to a pathotype (i.e., EAEC), is a marker of a set of pathogenic isolates that includes clones causing some of the most severe E. coli-mediated infections (i.e., EAEC O104:H4 or the worldwide distributed ExPEC ST131 clone).