Multiple choice Which of the following is the causative agent for gastric and duodenal ulcers? Yersinia entercolitica Shigella flexneri Helicobacter pylori Campylobacter jejuni Vibrio parahemolyticus Reveal answer Fill a bubble to check yourself C Correct answer Explanation It is a gram-negative, spiral to pleomorphic, prokaryote. H. pylori infection is the main cause of chronic superficial gastritis and it is associated with both gastric and duodenal ulcers.