O-Antigen Diversification Masks Identification of Highly Pathogenic Shiga Toxin-Producing Escherichia coli O104:H4-Like Strains

Our data suggest that the high-virulence ensemble of the STEC O104:H4 outbreak strain remains a global threat because genomically similar strains cause disease worldwide but that the horizontal acquisition of O-antigen gene clusters has diversified the O-antigens of strains belonging to ST678. Thus, the identification of these highly pathogenic strains is masked by diverse and rare O-antigens, thereby confounding the interpretation of their potential risk.