Helicobacter-pylori associated duodenal ulcer

**Definition:** Helicobacter pylori (H. pylori) is a gram-negative bacillus that is found in the mucous layer overlying gastric epithelium, within epithelial cells and attached to mucous cells, leading to inflammation. In the case of duodenal ulcers, H. pylori is believed to infect the gastric antrum or ectopic gastric mucosa in the duodenum. This is associated with increased acid production and duodenal ulceration.