Transmission of Helicobacter pylori from challenged to nonchallenged nude mice kept in a single cage.

To determine the transmission route of Helicobacter pylori, one nude mouse was challenged by H. pylori, and then raised with nonchallenged nude mice in a single cage in a sterilized environment with and without exposure to their feces. After coraising for two and four weeks, all mice were killed to determine H. pylori in the stomach, saliva, and feces and to assess gastritis grade. Natural transmission of H. pylori occurred in 50% (2/4) and 70% (7/10) of mice after two weeks and four weeks of coraising when they were exposed to their feces. H. pylori was detected not only in the stomach but also in saliva and feces by PCR of all challenged and transmitted mice. However, no transmission occurred in mice not exposed to feces of a challenged mouse, while sharing food and water in a single cage. These findings suggest that the fecal-oral transmission route is important, at least in the animal model. Serum levels of anti-H. pylori urease IgG of the H. pylori-transmitted mice increased after coraising, and gastritis was observed in the stomach of both challenged and transmitted mice. We conclude that H. pylori bacteria are transmitted through the fecal-oral route from challenged to nonchallenged nude mice, resulting in gastritis.