<prompt> Characteristic of H. Pylori isDoesnt affect normal duodenal mucosaImpoant cause for gastric ulcerProtozoaAntibiotics not useful  <response>: Normal duodenum cannot harbour H pylori, duodenum with gastric metaplasia can very well get infected by H pylori which explains why it is involved in duodenal ulcer. It is a gram-negative spiral like flagellated organism, it is most common cause of duodenal ulcer 95, triple regime including clarithromycin - metronidazole - omeprazole is used for its treatment Reference SRB edition :5 page : 819, 820 