Excretion patterns of Campylobacter jejuni by dairy cows

Excretion of the human bacterial pathogen Campylobacter jejuni by naturally infected dairy cows was investigated by monitoring 18 and 17 cows on two different commercial farms fortnightly for up to 12 months. C. jejuni was enumerated in the collected faeces by a most probable number technique and genotyped by enterobacterial repetitive intergenic consensus (ERIC) sequences. On both farms, C. jejuni excretion was highly variable among the studied cows, with excretion patterns ranging from chronic to sporadic. Chronic excretion of C. jejuni was associated with long-term predominance of a given genotype, co-excretion of a few genotypes, or succession over time of dominant genotypes. Sporadic excretion was with re-excretion of the same C. jejuni genotype when there was less than 1.5 months between C. jejuni-positive samples. Overall, the results showed the complexity of C. jejuni excretion pattern by dairy cows with an animal and farm specificity.