Excretion patterns of <i>Campylobacter jejuni</i> by dairy cows

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