DEVELOPMENT OF A TOOL FOR SALMONELLA PORK MEAT CONTAMINATION MODELLING IN BELGIUM

1. DEVELOPMENT OF A TOOL FOR SALMONELLA PORK MEAT CONTAMINATION MODELLING IN BELGIUM Delhalle L., Farnir F., Daube G. Laboratoire de Microbiologie – Département des Sciences des Denrées Alimentaires Faculté de Médecine Vétérinaire – Université de Liège – Sart Tilman, B43bis – 4000 Liège Introduction An original database including microbiological results from monitoring plans of zoonotic agents in the pork chain was created from data of the Federal Food Agency and private societies in Belgium. The aim of this study is to obtain descriptive statistics on contamination by Salmonella, germs indicators of general hygiene (aerobic mesophilic total germs with 30°C) or indicators of faecal contamination (Escherichia coli) from the slaughterhouse to the consumer portion. The data base allows the realization of detailed statistics like the comparison of different companies for the prevalence of Salmonella and the calculation of logistic regressions in order to determine an association between a risk factor and the presence of Salmonella. A lot of information could be obtained from this data base. Thanks to the data collected on the pork chain from the slaughterhouse to the consumer portion, this work will allow to establish a risk analysis model of the pork chain in Belgium. Material and methods A large number of samples have been collected (n=36.450): 15.350 for Salmonella, 15.073 for E. coli and 6.027 for aerobic mesophilic total germs. Some laboratories results have to be taken with caution. The majority of the companies are using accredited and validated analytical methods, but not all. Therefore it was privileged to use only the results from the Federal Food Agency and from the private firms which used validated methods for calculations. A rigorous and critical selection of the results of the analyses is an essential stage to produce reliable results. Companies with results of extremes prevalence were selected in order to show the variability of the contamination in the pork meat production in Belgium from the slaughterhouse to the consumer portion (Figure 1). From this selection, logistics regressions were calculated to determine risk factors of contamination (Table 1). Figure 1: Prevalence of Salmonella along the pork meat production chain Table 1: Results of the logistics regressions Discussion and conclusions This study shows clearly the variability between some societies for the prevalence of Salmonella along the pork meat production in Belgium. The efforts must be brought especially on the companies with high rates of prevalence for Salmonella in order to decrease the total prevalence in Belgium. First logistic regressions were carried out with co-variables like the seasons, the aerobic colony and the E. coli counts. A significant logistic regression was found for E. coli for each stage and for the season only for cutting and minced meat plant. Tests of the association of Salmonella with the total germs did not appear significant. E. coli is a germ found in the intestines of the pig, a high level on meat indicates that there was a problem of faecal contamination at the beginning of the production, for example during the evisceration of white offals in the slaughterhouse. In this study, E. coli is clearly associated with Salmonella at all the stages (Odds Ratio =1.3-1.4). But OR can double for the societies with a high prevalence in Salmonella. The control of Salmonella can require various elements : both the prevention of live pig carriage, the reduction of industrial cross-contamination and the limitation of the bacterial multiplication in slaughterhouses, cutting plants and retail. Present tool is an essential element for a future quantitative risk assessment in Belgium. References Berends, B. R., F. Van Knapen, et al. (1998). "Salmonella spp. on pork at cutting plants and at the retail level and the influence of particular risk factors." Int J Food Microbiol 44(3): 207-17. Ghafir, Y., B. China, et al. (2005). "Belgian surveillance plans to assess changes in Salmonella prevalence in meat at different production stages." J Food Prot 68(11): 2269-77. Korsak, N., B. Jacob, et al. (2003). "Salmonella contamination of pigs and pork in an integrated pig production system." J Food Prot 66(7): 1126-33. Acknowledgements This study has been carried out with the financial support of the Belgian Federal Public Service of Health, Food Chain Safety, and Environment research programme (R-04/003-Metzoon) ‘Development of a methodology for quantitative assessment of zoonotic risks in Belgium applied to the ‘Salmonella in pork’ model’.