Which bacterium is strongly associated with stomach ulcers and chronic gastritis?

Helicobacter pylori is strongly associated with stomach ulcers and chronic gastritis.

H. pylori is a spiral-shaped, flagellated bacterium adapted to living in the acidic environment of the human stomach. It produces urease, an enzyme that helps neutralize stomach acid around the cell, allowing colonization of the stomach lining.

The bacterium was identified as a major cause of peptic ulcer disease by Australian physicians Barry Marshall and Robin Warren. Their work overturned the older belief that ulcers were caused mainly by stress, spicy food, or excess acid, and earned them the 2005 Nobel Prize in Physiology or Medicine.

H. pylori infection can also increase the risk of gastric cancer and mucosa-associated lymphoid tissue lymphoma. Antibiotics combined with acid-suppressing medicine are commonly used for eradication. It is distinct from Campylobacter, another curved bacterium that more often causes intestinal infection.