Safepork 2015 Con ference 117 Epidemiology of infection / control and mitigation option of foodborne pathogens and zoonotic diseases in the pork production chain. Is the Salmonella contaminaton of swine carcasses at slaughter related to the Salmonella load in caecum? Magistrali, C.F.*; Cucco, L.; De Luca, S.; Massacci, F.R.; Maresca, C.; Medici, L.; Paniccià, M.; Scoccia, E.; Stafolani, M.; Pezzotti, G. Abstract The aim of this study was to examine the relatonship between the load of Salmonella spp. in caeca and the carcass contaminaton in an Italian slaughterhouse. The sampling scheme was designed to be representatve of the pigs slaughtered in a day and to estmate a 12% prevalence of pigs highly contaminated by Salmonella spp. (HCP, cecal load ≥3log). Environmental swabs were taken before slaughter. Cecal contents and carcass swabs were collected from the same pig. Salmonella MPN were estmated according to ISO6579- 2:2012/A1 and ISO7218:2007/E. The overall Salmonella prevalence were 34.64% and 7.19% for ceca and carcasses respectvely, with S. Derby and S. 4,[5],12:i:- being the prevalent serotypes. The HCP prevalence was 11.44%. 7/59 environmental swabs tested positve; when the same serotype was isolated from the environment and from carcasses, the samples were excluded from further analysis. Statstcal analysis was performed to investgate the relatonship between Salmonella spp. loads in the cecum and contaminaton of the carcass of the same pig and the prevalence of HCP and the contaminaton of carcasses on the same day. For this purpose, the days were classifed as “high prevalence days” depending on the proporton of caeca resulted positve (≥36%) and as “high load” days depending on the prevalence of HCP (≥10%). A correlaton between the contaminaton of carcasses and the cecal Salmonella loads of the same animal was found (Spearman’s correlaton coefcient: 0.2254; p-value=0.0001). No correlaton was found between the contaminaton of carcasses and the categorizaton of the day of sampling as “high prevalence day”. Conversely, a correlaton was found between the contaminaton of carcasses and the “high load” category of the sampling day (Wilcoxon test, p=0.0011). Notably, not the prevalence of pigs carrying Salmonella spp. but the prevalence of highly contaminated pigs was shown to be related to the contaminaton of carcasses. Introducton Salmonellosis is stll one of the most important foodborne diseases in the EU. Even though the layer hen reservoir remains the most important source of human salmonellosis in the EU, in some Countries, including Italy, pork is considered the frst contributor to the infecton (Pires, 2011). The risk of Salmonella infecton in man is not only associated to its presence on carcasses, but also to the bacterium load, since high levels of Salmonella can increase the consumer’s exposure. However, most data on the Salmonella prevalence in the pig producton chain are only qualitatve, and this can impair quanttatve risk assessment (EFSA, 2008). At the slaughterhouse, the source of contaminaton of carcasses can be from the same animal, from other pigs, or from the environment, a process known as cross-contaminaton. Salmonella can contaminate the environment either in a persistent way, being present as a ‘house fora’ of the slaughter plant, or in a transient way, by cross contaminaton from animals slaughtered on the same day (Smid, 2014). In this complex scenario, the intestnal content and the faeces of carrier pigs are, directly or indirectly, the predominant source of Salmonella for carcasses (van Hoeck, 2011). Our hypothesis was that there was a positve associaton between the Salmonella load in the intestnal content and the contaminaton of carcasses at slaughter. This associaton was studied on individuals, correlatng the amount of Salmonella in caecum and the Salmonella load of the carcass of the same pig. Then, to unveil the role of intestnal load in cross-contaminaton, the correlaton between the prevalence of highly contaminated pigs and the contaminaton of carcasses on the same working day was investgated.