Forty-eight Escherichia coli strains were chosen due to variable detection of stx or serogroup by PCR. Although all strains were initially determined to be Shiga toxin-producing Escherichia coli (STEC), their genomes revealed 11 isolates carrying stx _1a , stx _1b , stx _2a , and/or stx _2b . Assembled genome sizes varied between 4,667,418 and 5,556,121 bp, with N ₅₀ values between 79,648 and 294,166 bp and G+C contents between 50.