<prompt> Peptic ulcer is caused byH. pyloriCampylobacter jejuniPneumocystis cariniiCrypto sporidium  <response>: A. i.e. H. pylori 594 - Basic pathology 8thPEPTIC ULCER - two conditions are key for the development of peptic ulcers1. H. pylori infectioni 70 - 90 persons with duodenal ulcerii 70 persons with gastric ulcers2. Mucosal exposure to gastric acid and pepsin NSAIDs are the major cause of peptic ulcer disease in persons who do not have H. pylori infection 