Rectal experimental infection with H.pylori in mice and rabbits

Abstract

Helicobacter pylori infection in the stomach is etiologically closely associated with chronic active gastritis, peptic ulcer, gastric cancer and gastric mucosa-associated lymphoid tissue lymphoma. In the present study a clinical isolate of H. pylori obtained from dyspeptic patient, was used for experimental infection. An experimental model for H.pylori infection has been established by rectally challenging twenty one animals (mice or rabbits) with a different concentration of bacterial inoculums (1.5×109 ,108, 107, 106, 105, 104, 103 CFU) for three consecutive days. Three animals were inoculated with sterilised brucella broth as control group . All the animals were killed at 2 weeks postinoculation and fragments of stomach, duodenum ileum, colon and rectum were collected and processed for culture and histopathological examination. The present study shows that clinical isolate has been adapted to colonize mice and rabbits. The minimum infectious dose of H.pylori required to colonize mouse models was 106 CFU . while in rabbit models, the minimum infectious dose required to colonize animals was 105 CFU. 1.5×109 CFU was selected to induce infection using rectal infection route in nine experimental animals (mice or rabbits) and follow histopathological alterations at 2, 4, and 8 weeks postinoculation , in addition, bacterial reisolation was achieved at all time points. The result shows infected mice with H.pylori exhibited chronic superficial gastritis. On the other hand infected rabbits exhibited sever chronic gastritis with development of gastric ulcer at 8 weeks postinoculaton .