Which bacteria are linked to chronic gastritis and peptic ulcers?

The bacterium linked to chronic gastritis and peptic ulcers is Helicobacter pylori.12

This bacterium is a major factor in the development of both conditions. It survives in the highly acidic environment of the stomach by converting urea into carbon dioxide and ammonia, a process that creates a more neutral local environment but ultimately causes the mucosal lining to break down. Once the lining is weakened, it becomes susceptible to the corrosive effects of gastric acid, which can lead to the formation of an ulcer.213

H. pylori infection is considered one of the two primary causes of peptic ulcers, alongside the long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs). It is estimated that up to 90 percent of individuals with duodenal ulcers and 70 percent of those with gastric ulcers are infected with this bacterium. Treatment for H. pylori-induced ulcers typically involves a combination of antibiotics and acid-suppressing medications, such as proton pump inhibitors.132