Establishment of a small animal model for human Helicobacter pylori infection using germ-free mouse.

OBJECTIVE

To understand why oral inoculation of Helicobacter pylori resulted in continuous colonization of the stomach in germ-free athymic mice, but only temporary colonization in mice that were not germ-free.

METHODS

We inoculated germ-free and "not-germ-free" euthymic mice with H. pylori and studied the resulting colonization of the stomach, comparing it against the germ-free athymic mouse model. In addition, we investigated Lactobacillus in the above-described three mouse groups.

RESULTS

H. pylori were detected in all germ-free athymic mice and all germ-free euthymic mice continuously. However, in all euthymic mice that were not germ-free, H. pylori was detected only temporarily after inoculation. Lactobacilli were detected only in the not-germ-free mouse group. The number of H. pylori in the germ-free euthymic mice was significantly lower than in the germ-free athymic mice during the period of this study after inoculation.

CONCLUSIONS

We therefore suggest that the growth of H. pylori may be suppressed by the immunological system and eradicated by Lactobacilli previously inhabiting the stomach.