High diversity of Clostridium difficile genotypes isolated from a single poultry farm producing replacement laying hens.

Clostridium difficile is well established as a pathogen of horses, calves, and pigs, but little is known about its prevalence in poultry. In this study, chicken fecal samples were collected on four occasions from two populations being raised as layer replacements. Samples were examined by an enrichment culture method, and 38 of 61 (62.3%) were culture positive. The rate of colonization seemed to be age dependent: 100% of fecal samples from 2-week- old birds were culture positive, and the colonization rate decreased to 71.4% in 14-week- old birds, and to 40.9% in 18-week- old birds. Unlike in other domestic animal hosts, the diversity of PCR ribotypes found on a single farm was high, and 44 isolated strains belonged to 12 PCR ribotypes. Furthermore, the prevalence of variant strains having changed toxin genes for toxins A and B and possessing an additional toxin, binary toxin, was low. The majority of strains were toxinotype 0, although two were nontoxinogenic and three were binary toxin-positive toxinotype IV. Toxinotype V strains, which are often associated with food animals, were not found.