In the study, only one strain (B-59801) carries neither stx2 nor eae genes, and does not belong to the big six serovars.
This strain has a medium HPP resistance and could be safer to use as a surrogate for laboratory safety purposes. In addition, B-59801 also had moderate radiation resistance as noted by Sommers et al. (2015), therefore B-59801 may be used as a surrogate in both HPP and irradiation studies.