The aim and objectives of the study: The aim of this study was to investigate Campylobacter spp. prevalence in broiler flocks in Lithuania and to determine aspects related to C. jejuni transmission and survival in broiler meat production chain in Lithuania. To achieve this aim, the objectives were as follows: 1. To investigate the flock prevalence of Campylobacter spp. in broiler flocks in Lithuania. 2. To investigate genetic diversity of C. jejuni in broiler farms in Lithuania and to identify possible persistent strains of C. jejuni. 3. To examine the changes in appearance of C. jejuni genotypes along the broiler meat production chain and to identify potential sources of broiler meat contamination in slaughterhouse. 4. To investigate differences among C. jejuni strain in stress adaptation and the ability to form biofilm and survive at different temperatures relevant to the poultry meat production chain. 5. To investigate relationship between phenotypic and genetic properties of C. jejuni strains isolated at particular point of broiler meat production chain.

There is a lack of data on true Campylobacter spp. prevalence in broiler flocks in Lithuania. Thus, in the present study the prevalence of Campylobacter spp. in broiler flocks from different broiler farms representing about 70% of broiler production was investigated. Such knowledge allowed determining the role of broiler meat as a source for human campylobacteriosis in Lithuania. During this study information on farm management and hygiene procedures has been collected. Also C. jejuni isolates obtained at this study were analyzed genetically to identify variation of this bacterium species at the flock, farm and country levels. Analysis of C. jejuni flock prevalence and genotyping data in combination with farm management data allowed identifying possible interventions reducing the spread of this bacterium from broilers to people at the beginning of broiler meat processing chain, in Lithuania.

Although cross-contamination is considered as the main route of broiler carcass contamination at slaughterhouse with C. jejuni, alternative sources of C. jejuni may have been overlooked. Only limited number of studies focus on sampling of broiler flocks along the entire food chain and not many include the slaughterhouse environment. Therefore, in the present study we have traced the changes of C. jejuni genotypes within one broiler flock from the beginning of rearing to the final product at the slaughterhouse with the aim to evaluate the dynamics and possible sources of carcass contamination with C. jejuni.

Previous studies indicate that not all genotypes of C. jejuni entering the slaughterhouse survive the slaughter processes, as only a few genotypes were found on the meat [20, 28, 35], resulting in the hypothesis that surviving strains may implement a more efficient stress adaptation. Enhanced survival or adaptation properties may cause such C. jejuni isolates to contaminate broiler meat or to survive in the environment. Consequently, to test this hypothesis we compared genotypic and phenotypic properties of different C. jejuni strains collected along the broiler meat chain (broiler cloacae, slaughter house environment, broiler fillets) using a chicken meat juice food model (Birk et al., 2004) as an environment most similar to that C. jejuni experience on broiler meat.

Raktažodžiai: Campylobacter jejuni, broiler meat, genotypes, prevalence