Two hundred and fifty samples (100 fecal samples, 100 carcasses sponge swabs and 50 Environmental samples) were collected from feedlot cattle at Kafer EL-Sheikh abattoir for molecular characterization of rectal carriage of Escherichia coli O157:H7 and Salmonella spp. and its effects on the carcasses contamination. In fecal samples, the prevalence of Escherichia coli O157:H7 and Salmonella spp. were 5% and 3% respectively, while carcass contaminations with the same microbes were 1% and 0% respectively. In environmental samples, water samples have no Escherichia coli O157:H7 and 4% S. Enteritidis. There were isolates of E. coli non-O157 (O125:H21, O44:H18 and O103:H7) either from fecal, and carcasses sponge swab samples, which have great public health importance. Both E. coli O157 and E. coli non-O157 have Shiga toxin producing genes. Salmonella serotype isolates were S. Montevideo and S. Enteritidis. These results indicated that more hygienic measure needed in meat processing plants to prevent meat contamination with these pathogens and other pathogenic microorganisms.
Key words: : Molecular, Rectal carriage, E coli O157: H7, Salmonella spp., feedlot, carcasses contamination