Diversity of pulsed-field gel electrophoresis profiles of Campylobacter jejuni and Campylobacter coli from broiler chickens in France

In 2003 to 2004, 26 free-range broilers flocks excreting Campylobacter were studied for identification of Campylobacter species and genotype diversity. Seventeen flocks were sampled at the end of the indoor rearing period and 9 before departure to the slaughterhouse after access to an open area. Out of 513 isolates, 315 were identified as Campylobacter jejuni and 198 as Campylobacter coli. Pulsed-field gel electrophoresis analysis revealed 35 genotypes for C. jejuni and 43 genotypes for C. coli; 38.4% of the isolates were clustered into 16 genetic groups. This kind of poultry production system is characterized by a large number of Campylobacter coli isolates. Flocks sampled during the indoor phase were predominantly contaminated by C. jejuni, whereas those sampled during warm months were predominantly contaminated by C. coli. The Campylobacter population was genetically highly diverse: multiple genotypes were detected in a single flock. Six flocks were each found to harbor a mixture of genotypes; these isolates were genetically closely related and were grouped into clusters of at least 80% genetic similarity. Isolates with genotypes found in different flocks and strains, but sharing the same genetic clusters, were detected in different farms and at different times in the year. Flocks sampled during the indoor rearing period and when farmers use fresh farm-made litter were associated with a small number of clusters. In conclusion, Campylobacter species were genetically highly diverse. Our findings suggest the presence of genomic rearrangements in Campylobacter colonizing the chick intestine and that some Campylobacter strains are adapted to poultry. In addition, the species diversity in the flocks was affected by season and cloistering measures. Litter and exposure to an open area were likely sources of flock Campylobacter contamination.