What is the most infectious strain of E. coli?

E. coli 0157:H7 is recognized as the most infectious and pathogenic strain among the options listed. This strain is commonly associated with severe foodborne outbreaks and has been linked to multiple instances of hemolytic uremic syndrome (HUS), which can lead to serious health complications, especially in young children and the elderly.

E. coli 0157:H7 produces Shiga toxin, which can cause severe gastrointestinal illness and potentially life-threatening outcomes. Its infectious nature stems from the low infectious dose required to cause illness, allowing a small amount of contaminated food or water to lead to infection. The public health awareness surrounding this strain also highlights its prevalence in contaminated beef, unpasteurized dairy, and contaminated vegetables, prompting strict food safety regulations.

Other strains listed, while pathogenic, do not have the same level of association with severe outbreaks and serious health consequences as E. coli 0157:H7, making this strain particularly significant in food safety discussions and educational materials focused on food handler certification.