Enlargement of Gastric Hyperplastic Polyps Arising from Helicobacter heilmannii sensu strico-infected Mucosa after the Successful Eradication of Helicobacter pylori and the Long-Term Use of a Proton Pump Inhibitor

Helicobacter pylori eradication is effective for the regression of gastric hyperplastic polyps (GHPs). We report a case which demonstrated an enlargement of GHPs after H. pylori eradication. The patient, who received long-term proton-pump inhibitor (PPI) therapy, lived with a dog, a natural host of Helicobacter heilmanii sensu stricto. Gastric colonization with Helicobacter heilmannii s.s. was observed after H. pylori eradication, thus suggesting the involvement of non-H. pylori Helicobacter species (NHPHs) infection for the enlargement of GHPs, in addition to the proliferative effects of PPI use on the gastric epithelium. Screening for NHPHs may be necessary in dog lovers to avoid paradoxical responses to H. pylori eradication.