Which bacterium is the primary cause of peptic ulcers?

Which bacterium is the primary cause of peptic ulcers? Helicobacter pylori is the primary bacterial cause of peptic ulcer disease.

H. pylori is a Gram-negative, spiral-shaped bacterium adapted to the stomach. Its multiple flagella help it move through the stomach’s mucus layer, while urease produces ammonia that locally reduces acidity. This allows the organism to persist near the stomach lining, where it can cause chronic inflammation called gastritis.

That inflammation weakens the protective mucosal barrier, allowing stomach acid and the digestive enzyme pepsin to damage tissue and form gastric or duodenal ulcers. H. pylori infection does not always produce symptoms, and many infected people never develop an ulcer. Another major cause of ulcers is long-term or excessive use of nonsteroidal anti-inflammatory drugs, including aspirin and ibuprofen.

Robin Warren and Barry Marshall identified the bacterium’s role in gastritis and ulcers in the early 1980s, overturning the older belief that stress or excess acid alone explained most ulcers. Their work earned the 2005 Nobel Prize in Physiology or Medicine. H. pylori-associated ulcers are treated with combinations of antibiotics and acid-suppressing medicines to eradicate the infection and allow healing.