Posted: February 26th, 2011 - 10:07am
Source: EFSA Journal 2011;9(2):2017 [85 pp.]

Abstract
A European Union-wide baseline survey on Campylobacter in broiler batches and on Campylobacter and Salmonella on broiler carcasses was carried out in 2008. In the Salmonella sub-survey a total of 10,035 broiler batches were sampled from 561 slaughterhouses in 26 European Union Member States and two countries not belonging to the European Union. From each randomly selected batch one carcass was collected after chilling and the neck skin together with the breast skin was examined for the presence of Salmonella. Multivariable regression analysis showed that the risk for Salmonella-contaminated carcasses increased with the slaughter capacity of the slaughterhouse and with processing of the carcass later during the day. The risk for contamination of carcasses with Salmonella varied significantly between countries and between slaughterhouses within a country, even when other associated factors were accounted for. The Salmonella serovar distribution varied among Member States, many of them having a specific distribution pattern of their own and no specific serovar was predominant in all countries in the survey. The most commonly reported serovars were S. Infantis, S. Enteritidis and S. Typhimurium. Many of the reported serovars seem to have become well-established in broiler production.
Summary
A European Union-wide baseline survey on Campylobacter in broiler batches and on Campylobacter and Salmonella on broiler carcasses was carried out in 2008. In the Salmonella subsurvey, a total of 10,035 broiler batches were sampled from 561 slaughterhouses in 26 European Union Member States, plus Norway and Switzerland. From each randomly selected batch, one carcass was collected after chilling and the neck skin together with the breast skin was examined for the presence of Salmonella and Campylobacter. The results of the analysis of Salmonella prevalence have already been published by the European Food Safety Authority on 17 March 2010 in the Part A report. The Part B report on the Campylobacter subsurvey was published by the European Food Safety Authority on 5 August 2010. The present Part B report on the Salmonella subsurvey provides the results from analyses of the associations of eight-batch or slaughterhouse level factors and Salmonella contamination of carcasses. The investigated prevalence was the observed prevalence, meaning that the prevalence estimates did not account for imperfect test characteristics.
Multivariable regression analysis showed that the risk for Salmonella-contaminated carcasses increased with the slaughter capacity of the slaughterhouse and with processing of the carcass later during the day. The risks for contamination of carcasses with Salmonella varied significantly between countries and between slaughterhouses within a country, even when other associated factors were accounted for. The results showed that for the country group having a lower Salmonella prevalence other factors were associated with Salmonella contamination of broiler carcasses. Specifically, for the group of countries with prevalence below the European Union median[1] , the only factor indicating an association with Salmonella-contaminated carcasses was the type of chilling used for the carcasses, as the risk of Salmonella contamination of carcasses appeared to be lower if broiler carcasses were chilled by a mixed-chilling method. This factor was not significant in the analysis based on the overall dataset nor in the analysis of the subset of group of countries with prevalence above the European Union median. For this latter group of countries the associated factors were consistent with the results based on the overall European Union level dataset.
Factors that were included in the analysis, but which were not significantly associated with Salmonella contamination of carcasses were flock production type, thinning of flocks, age of broilers, quarter of sampling during the year, time between sampling and testing, the carcass chilling method used and Campylobacter contamination results on the broiler carcass. For some of the factors tested, the power of the analyses was low due to too few samples in some specific categories. Moreover, the analyses showed that 46% of the unexplained variance in the Salmonella contamination results might have been attributable to slaughterhouse-specific factors for which no data were gathered during the survey.
The Salmonella serovar distribution varied among Member States, many of them having a specific distribution pattern of their own and no specific serovar was predominant in all countries in the survey. The most commonly reported serovars were S. Infantis, S. Enteritidis and S. Typhimurium. Although there was a concentration of most S. Infantis isolates in one Member State it was the most widely-distributed serovar and reported by 15 countries. This indicates that the presence of S. Infantis is not a local phenomenon. S. Enteritidis was present in 14 countries and the dominant serovar in five countries confirming its role as the most important serovar found in broilers in Europe. S. Typhimurium was less frequently reported compared to S. Kentucky but was more spread across Europe. S. Agona and S. Mbandaka were also widely distributed, although at a lower prevalence. The serovar distribution in broiler carcasses tended generally to be the same and in similar proportions as the distribution observed in the broiler flocks baseline survey, even though the latter survey had been conducted two years earlier. This suggested that many of the serovars have become well-established in the broiler production. The descriptive analysis of the serovar distribution also supported the notion that broiler meat contributes to human Salmonella infection.
Based on the prevalence of Salmonella-contaminated broiler carcasses, a simulation exercise was performed to investigate the Member State-specific probability of meeting the Salmonella process hygiene criteria in poultry meat as laid down by Regulation (EC) No 2073/2005. The outcome of this simulation exercise was rather uncertain for about one third of the Member States. Of the remaining group of countries, five Member States and Norway and Switzerland would meet those Salmonella microbiological process hygiene criteria in poultry meat.
It is recommended that Member States consider the factors found to be associated with Salmonella-contaminated broiler carcasses at European Union level in this survey, when they are designing and implementing national Salmonella control programmes for broiler meat. Member States are specifically encouraged to verify the food business operators’ own controls for Salmonella in their slaughterhouses in order to prevent subsequent contamination of broiler carcasses and to improve the protection of public health. Further national studies identifying more closely the factors that put broiler carcasses at risk of becoming contaminated with Salmonella in a country are recommended, taking into account the national Salmonella prevalence and the characteristics of the national broiler production, including slaughter procedures.