Inflammatory large bowel disease in immunodeficient rats naturally and experimentally infected with Helicobacter bilis

Proliferative and ulcerative typhlitis, colitis, and proctitis were found i ncidentally in a breeding colony of male athymic nude (Cr:NIH-rnu) rats. Wi thin the crypts of the large intestine, modified Steiner's silver stain rev ealed spiral organisms that were identified by culture, polymerase chain re action, and sequencing to be Helicobacter bills. The large bowel disease wa s reproduced in H. bilis-free male athymic nude rats that were injected int raperitoneally with a culture of H. bilis from the affected colony. The org anism was isolated from the feces and cecum of the experimentally infected rats. H. bilis should be considered a potential pathogen in immunocompromis ed rats. The infection in immunocompromised rats may serve as an animal mod el for inflammatory large bowel disease.