Within-flock variations of Campylobacter loads in caeca and on carcasses from broilers

The proportions of broiler caeca and carcass rinse samples positive for Campylobacter spp. within broiler flocks were determined. Twenty intact caeca per flock from 27 flocks were analyzed individually. Rinse samples were obtained from 5 to 25 carcasses from 27 other flocks. In total, 540 caecum samples and 445 carcass rinse samples were analyzed. The proportion of positive caeca within flocks ranged from 10 to 100%, and the proportion of positive carcasses ranged from 85 to 100%. The highest and lowest numbers of Campylobacter spp. found in positive caecum samples were 8.6 and 1.7 log cfu/g caecal contents, respectively. The number of Campylobacter spp. in the caeca from individual broilers within a flock varied by up to 6.3 log cfu/g caecal contents. The highest number found on one carcass was 4.2 log cfu/ml carcass rinse sample, and the within-flock variation in Campylobacter spp. was up to 3.2 log cfu/ml rinse sample. There was thus great variation in the load of Campylobacter spp. in individual caecum and carcass samples obtained from each positive broiler flock. This large variation in the numbers of Campylobacter spp. carried by individual birds should be considered when only one or a few samples are collected from a flock and the results are used for risk assessments.