Study on the diffusion of Salmonella spp. in a finishing herd, from the introduction of animals till the slaughterhouse [swine; Italy]
2006
Curtis, P. De | Magistrali, C. | Cucco, L. | Vischi, O. | Scuota, S. | Zicavo, A. | Pezzotti, G.
Pigs and pork products play an increasing role in epidemiology of Salmonella and its possible transmission to humans. Control at farm is considered a key factor for the prevention of the infection, as required by EU regulations (EC Regulation n. 2160/2003). The aim of the present work was to investigate the transmission routes of Salmonella within a pig finishing herd in Italy. Nine sets of samples were collected during the fattening period (cleaned and disinfected pens, animals at different stages and at slaughter). Salmonella was isolated from disinfected pens, animals (4 out of 5 sets), truck used to transport to the abattoir and after slaughter (cecal content, mesenteric limph nodes and carcasses). Several serovars were isolated; S. typhimurim and S. derby at farm (premises and animals); S. bovismorbificans, S. bredeney, S. blockey, S. hadar and S. corvallis from truck; S. derby, S. hadar, S. bredeney, S. bovismorbificans, S. infantis at slaughter. Antibiotic resistance of the strains was tested according to the Kirby-Bauer method and PFGE was carried out to evaluate the presence of Salmonella clones. PFGE profiling allowed to identify several clones within S. typhimurium and S. derby, while S. bovismorbificans, S. bredeney and S. hadar resulted belonging to one single clone. S. typhimurium strains isolated from the pigs at 30 and 90 days of age belonged to the same clone of the one previously found in the farm. Other isolates (90 days and later) appeared distinct. Salmonella derby strains isolated from live animals and from carcasses clustered in the same PFGE profile. The results show a complex distribution of the strains in the studied farm and a significant role of the indirect transmission within the herd, in particular immediately before slaughtering
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