(A) AccI restriction analysis of plasmid DNA from Escherichia coli transconjugants that contained a single plasmid carrying blaCTX-M representing 5 Ohio dairy herds. Lanes: 1, Fisher exACTGene 1kb Plus DNA ladder; 2, Roche Applied Science DNA molecular weight marker II (DIG labeled); 3, 5-5; 4, 6-17; 5, 7-23; 6, 17-9; 7, 17-29; 8, 19-1; 9, 19-2; 10, 19-7; 11, 19-10; 12, 19-14; 13, 19-18; 14, negative-control CMY-2 plasmid DNA; 15, Roche Applied Science DNA molecular weight marker II (DIG labeled); 16, Fisher exACTGene 1kb Plus DNA ladder (lanes 3 to 13 are identified as herd number-isolate number). (B) Southern blot hybridization using CTX-M probe of AccI restriction analysis of plasmid DNA from a subset of Escherichia coli transconjugants that contained a single plasmid carrying blaCTX-M representing 5 Ohio dairy herds. Lanes: 1, Fisher exACTGene 1kb Plus DNA ladder; 2, Roche Applied Science DNA molecular weight marker II (DIG labeled); 3, 5-5; 4, 6-17; 5, 7-23; 6, 17-9; 7, 17-29; 8, 19-1; 9, 19-2; 10, 19-7; 11, 19-10; 12, 19-14; 13, 19-18; 14, negative-control CMY-2 plasmid DNA; 15, Roche Applied Science DNA molecular weight marker II (DIG labeled); 16, Fisher exACTGene 1kb Plus DNA ladder (lanes 3 to 13 are identified as herd number-isolate number).