Salmonella is one of the major causes of food borne disease in the European Union (EU). Some of the human cases are related to pork products. An EU baseline survey to assess the Salmonella pork prevalence was performed. Mesenteric lymph nodes were cultured and Salmonella sp. isolates were serotyped. Data concerning the animal and the slaughterhouse was also collected. The aim of the present study was to search for potential risk factors to the presence of Salmonella sp. in pigs lymph nodes in Portugal and to search for differences in the risk profile between groups of serotypes. The data was analysed using a Bayesian approach to incorporate the hierarchical structure of the data (samples nested in slaughterhouses). Two models were analysed: a binomial (presence/absence of Salmonella sp.) and categorical model (absence of Salmonella sp., serotype Typhimurium or serotype 1,4,[5],12:i:-, other serotypes). A total number of 659 samples were tested, belonging to 36 slaughterhouses. Around 23.7% of the samples were positive for Salmonella sp.. In the binomial model a significant association was found for region of the slaughterhouse - Lisbon and Tagus Valley Region with lower risk compared to the Centre Region (OR=0.36). In the categorical model a significant association for category Typhimurium or 1,4,[5],12:i:- was found for the variable hour when the sample was taken - afternoon with lower risk compared to morning (OR=0.20). The association found for the slaughterhouse region should be a matter of furthers studies to evaluate the hygiene practices in the slaughterhouses of that region
