Evaluation of the Efficacy and Safety of Helicobactor Pylori Eradication with Vonoprazan, a Novel Potassium-Competitive Acid Blocker

Background/Aims: Patients with autoimmune gastritis (AIG) are positive for anti-parietal cell antibody (PCA), anti-intrinsic factor antibody, or both have severe atrophic changes in the gastric corpus and have achlorhydria.AIG has been considered relatively rare.However, we found that patients with AIG were included in patients who were introduced to our hospital as they were refractory to the standard 1 st and 2 nd line regimens in Japan.Then, we measured PCA and investigated AIG in consecutive patients who consulted our department.Methods: Subjects were 151 consecutive patients who were diagnosed to have failed in the eradication of H. pylori no less than twice and visited the H. pylori-specific outpatient unit of the hospital of Hamamatsu School of Medicine from June 2015 to September 2016.Failure of eradication in them was diagnosed based on 13 C-UBT.Gastroduodenoscopy was performed to evaluate atrophic changes based on the Kimura-Takemoto classification and the Kyoto classification of gastritis.Gastric mucosal samples were obtained during endoscopy and subjected to culture tests for H. pylori and other bacteria positive for urease activity.We measured serum levels of pepsinogen (PG) I, PG II, gastrin, anti-H.pylori IgG antibody, and PCA in them.When patients had severe atrophic gastritis in the gastric corpus and were positive for PCA, they were diagnosed to have AIG.Results: Of 151 patients, 35 (20.7%) were diagnosed as AIG.The mean age of AIG patients was 66.1 ± 8.9 years, which was significantly higher than that of patients without AIG (56.8 ± 12.6 years) (P < 0.001).Average serum gastrin levels in AIG and non-AIG patients were 2064.7 pg/ml and 359.4 pg/ml (P < 0.001), respectively.Serum PG I, PG II, PG I/PG II ratios in AIG and non-AIGpatients were 9.3 ng/ml vs 57.5 mg/m (p < 0.001), 10.9 ng/ml vs 21.3 ng/ml (p < 0.001), and 1.15 vs 3.22 (p < 0.001) , respectively.In the AIG patients, enlarged folds were not observed and diffuse redness was mild.Culture tests revealed that all patients with AIG were negative for H. pylori but were positive for some urease positive bacterium such as Klebsiella pneumonia, alpha-streptococcus, gamma-streptococcus, Neisseria, Enterococcus, Enterobacter, Corynebacterium, Staphylococcus, etc. Conclusion: Patients with AIG were present at a constant frequency.The endoscopic findings in these cases had severe atrophic gastritis that lacked inflammatory changes.Achlorhydria in AIG might allow some bacterium other than H. pylori from intestinal flora to have habitation in stomach.Some of them are positive for urease-activity and then patients infected with such bacteria are misdiagnosed to be infected with H. pylori refractory to eradication therapy, because such bacteria do not disappear from stomach to be provided from intestinal flora. Sa1182