Abstract
In Japan, Helicobacter pylori eradication has been approved since 2013 for treatment of H pylori-induced chronic gastritis, in an attempt to reduce the prevalence of gastric cancer, a leading cancer in Japan. H pylori infection affects more than 50% of the world's population. H pylori eradication therapy is generally safe. To our knowledge, no case of newly diagnosed ulcerative colitis occurring immediately after H pylori eradication therapy has previously been reported.A 63-year-old man received a diagnosis of chronic gastritis and H pylori infection. In early March 2014, primary H pylori eradication therapy was initiated; lansoprazole, amoxicillin, and clarithromycin were administered for 1 week. Beginning on the fourth day, he had watery diarrhea twice a day. From the 11th day, bloody stools and watery diarrhea increased to 6 times a day. Colonoscopy, performed on the 40th day after termination of drug therapy, revealed diffuse inflammation in the distal aspect of the colon, with histologic findings consistent with ulcerative colitis. He was admitted to the hospital and was provided with a semivegetarian diet and metronidazole. He noticed a gradual decrease in the amount of blood in his feces then a disappearance of the blood. A fecal occult blood test on the 11th hospital day recorded 337 ng/mL. Fecal occult blood test is not indicated during macroscopic bloody stool but is indicated after disappearance of bloody stool. Therefore, he achieved clinical remission by the 11th hospital day. He was in remission on discharge.New onset of ulcerative colitis should be added to a list of adverse events of H pylori eradication therapy.