E. coli O26 is one of the seven strains of Escherichia coli (E. coli) that is extremely dangerous to humans. The most prevalent strain of Shiga-toxin producing E. coli is O157:H7, which is classified as an 'adulterant' by USDA, meaning that it is tested for, and if its presence is detected, the food is held and/or recalled. The other six strains - O26, O45, O111, O121, O145, and O103 also cause severe illnesses, but have not yet been accepted as adulterants despite great efforts by the food safety community.
Bill Marler, managing partner of the nation's leading law firm representing victims of foodborne illness, Marler Clark, funded a study of the prevalence of the six Shiga toxin-producing strains of E. coli, and then filed a petition with the USDA for their acceptance as adulterants. In late May of 2012, USDA announced that it would begin testing any raw, non-intact beef products or components for contamination with STECs O26, O45, O103, O111, O121, and O145 on June 4, 2012. Any meat samples found to be contaminated with those strains of E. coli are to be legally considered adulterated.