OBJECTIVETo establish a stable and reliable model of Helicobacter pylori infection in Mongolian gerbil and to observe pathological changes in gastric mucosa from the infected animals.

METHODSMongolian gerbils were randomly divided into six groups infected with H.pylori strain NCTC11637 (n=6, group N), six groups infected with H.pylori clinical strain Y06 (n=6, group Y) and six groups as negative control (n=4, group C). H.pylori suspensions at the concentrations of 2 X 10(8)CFU/ml and 2 X 10(9) CFU/ml of strain NCTC11637 and strain Y06 were prepared with Brucella broth from Columbia agar containing sheet blood. The animals in one group N and in one group Y were orally challenged once with 0.5 ml of 2 X 10(8) CFU/ml H.pylori suspension. The animals in another group N and in another group Y were orally challenged with 0.5 ml of 2 X 10(9) CFU/ml H.pylori suspension for three times at the intervals of 24 hours, respectively. The animals were killed after 2nd, 4th and 6th week of the last infection and the gastric mucosal samples were taken for urease test, bacterial isolation, routine pathological and H.pylori histochemical examinations.

RESULTSInfection rates of the animals in group N and group Y at the 2nd, 4th and 6th week after one challenge were 0%, 0%, 66.7% and 0%, 16.7%, 16.7%, respectively. Infection rates of the animals in groups N and Y at the 2nd, 4th and 6th week after three challenges were 66.7%, 100%, 100% and 66.7%, 66.7%, 100%, respectively. In animals with positive bacterial isolation H.pylori was found to colonized on the surface of gastric mucosal cells and in the gastric pits, and the lamina propria of gastric mucosal was infiltrated with chronic inflammatory cells.

CONCLUSIONBy using H.pylori suspension at high concentration of 1 X 10(9) CFU for multiple times, the orally challenged Mongolian gerbils can be prepared as a stable and reliable H.pylori infection model. H.pylori can colonize in gastric mucosa of the infected animals, and mild inflammation reactions can be seen.