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Assessing Romaine lettuce “Forward Processing” for potential impacts on EHEC growth, antimicrobial susceptibility, and infectivity


Fresh-cut Romaine lettuce has been implicated in multiple outbreaks of enterohemorrhagic Escherichia coli (EHEC) O157:H7, including recently in 2016, 2017, 2018, 2019, and 2020, with nearly all implicated products traced back to ranches in the Salinas Valley in California. Whole genome sequencing showed that the EHEC strains in several of the outbreaks in different years constituted a cluster which was closely related to strains isolated from cattle fecal samples in the same area.