The Prevalence And Biological Property Of Salmonella And E.Coli0157:H7during Processing In Chinese Cattle Slaughtering Plants

E. coli O157:H7and Salmonella are asymptomatically carried by cattle but associated with thecontamination of meat products and do harm to public health and food safety. China is the4th-largest beef-producing nation, but little is known of the prevalence of foodborne pathogensinasmuch as a short beef industry and the habit of consumption. This study was carried out toinvestigate the prevalence of E. coli O157:H7and Salmonella on slaughtered cattle and to evaluatethe different stages during processing. According to the detection of the virulence gene and theantibiotic resistance of the isolated strains, the epidemiological data of these strains was clarified.In this study, the main results are as follows:A total of510samples were collected from four plants by excising or surface swabbing atseven processing points. All of the samples were analyzed with a modified IMS method later.Overall, the prevalence of Salmonella spp. on feces, hide, post-dehiding, post-evisceration,post-washing, chilled carcasses, raw meat was20.0%，17.1%，1.4%，2.9%，2.9%，2.5%and3.8%,respectively. For the E. coli O157, the prevalence at feces, hide and chilled carcasses was1.4%，1.4%，1.3%respectively. A sharp decreasing was found when the process hide removal was appliedbut no significant reduction was found in the following in-plant processing points. The plant A has ahigh prevalence of the Salmonella and which demonstrate a significant difference to different areasin China.Stx2, eae, rfbEo157, flicH7and hlyA were deteced from all of the seven isolated strains in thedetection of the virulence gene of the isolated E.coli O157:H7strains. This resault indicate arelatively high threaten to the public health. The gene invA was deteced from all the salmonella.To research the antibiotic resistance of salmonella,58isolates of Salmonella from beef cattlewere tested by16antimicrobials.3.4%of the isolates were medium sensitivity to the ampicillin,cefalotin and streptomycin;1.7%of the isolates were medium sensitivity to the cefatriaxone,gentamycin and kanamycin;6.9%of the isolates were medium sensitivity to the tetracycline. Theepidemiological data demonstrate a relative low antibiotic resistance of salmonella duringprocessing.