Pathogenesis of Helicobacter pullorum infections in broilers.

Four groups of 23 one-day-old broiler chickens were each inoculated by gavage with a different Helicobacter pullorum strain isolated from humans or poultry. As a control, a fifth group of eight animals was inoculated with phosphate-buffered saline. Faecal samples were collected weekly and tested for the presence of H. pullorum DNA using PCR. At 1, 8, 15, 22 and 42 days postinoculation, birds were euthanized and samples from the liver and intestinal tract were histologically, immunohistochemically and bacteriologically examined. The samples were also tested for the presence of H. pullorum DNA by PCR. All animals remained clinically healthy throughout the experiment although mild lesions in the caeca were present in animals inoculated with H. pullorum. In all H. pullorum-inoculated groups, DNA of this bacterium was detected in faecal samples until 42 days postinoculation. The main site of colonization was the caecum. Immunohistochemical examination revealed that the bacterium was closely associated with the caecal epithelial cells. It was concluded that H. pullorum may colonize the caecum of broilers and is excreted in their faeces until slaughter age. This implies that chicken meat might constitute a source of infection for human beings.