The organism linked to peptic ulcers and gastritis is which bacterium?

• A. Campylobacter jejuni
• B. Helicobacter pylori
• C. Salmonella Typhimurium
• D. Yersinia enterocolitica

Answer: (B)

The main concept is that a bacterium can cause chronic gastritis and peptic ulcers by living in the stomach and injuring the lining. Helicobacter pylori is uniquely suited to colonize the harsh gastric environment. It produces urease, which converts urea to ammonia, buffering the local acidity and allowing the bacteria to thrive within the mucus layer of the stomach. This colonization triggers inflammation and damages the protective mucous layer and epithelial cells, leading to gastritis and, over time, peptic ulcers. It is the most common cause of peptic ulcers worldwide. The other organisms listed cause various other gastrointestinal infections (acute gastroenteritis, enterocolitis) and are not classically associated with chronic gastric ulcers, making them less likely explanations for this link.