Examinations of Campylobacter transmission routes in broiler flocks on selected poultry farms in Switzerland

On 15 farms, broiler flocks, other farm animals, and the environment were examined during consecutive rearing periods for Campylobacter (C.). Of the 5154 samples, 311 (6%) from 14 farms were Campylobacter positive by culture, Amongst them, 228 tested positive for C. jejuni and 92 for C. coli. Positive samples originated from broilers, the broiler houses, cattle, pigs, bantams, laying hens, a horse, and a mouse. Genotyping using flagellin gene typing (flaA-RFLP), macrorestriction profiling with PFGE, and AFLP analysis allowed the following conclusions: (1) On eight farms, matching genotypes were isolated from broiler flocks and other farm animals (cattle, pigs, or laying hens); (2) indications of persistent contamination of the broiler house were evident on four farms where matching genotypes were detected in consecutive broiler flocks, but not concurrently in other samples; (3) especially on farms with extensive outdoor flocks, multiple genotypes were found within a rearing period; (4) some genotypes proofed to be identical across different farms. These results emphasize the importance of other farm animals on poultry farms as reservoirs and risk factors for broiler flock colonization with Campylobacter and retrieve the role of personnel moving between different farm areas as potential vectors. However, certain other niches or vectors may not be excluded on some farms.