Which organism is associated with peptic ulcers, gastritis and possibly gastric cancer?

• A. Escherichia coli
• B. Staphylococcus aureus
• C. Helicobacter pylori
• D. Salmonella enterica

Answer: (C)

The organism most strongly linked to peptic ulcers, gastritis, and a potential risk for gastric cancer is Helicobacter pylori. This curved, gram-negative bacterium colonizes the stomach lining by producing urease, which converts urea into ammonia and raises the local pH. That buffering allows it to survive the acidic environment and persist in the gastric mucosa, especially the antrum, leading to chronic inflammation (gastritis). Over time, the ongoing mucosal injury from the immune response and bacterial virulence factors promotes ulcer formation and, in some cases, long-term changes that increase the risk of gastric cancer and MALT lymphoma.

Other organisms listed are not classically associated with this triad. Escherichia coli and Salmonella enterica primarily cause acute gastroenteritis or systemic illness rather than chronic gastritis or peptic ulcers, and Staphylococcus aureus is more often linked to skin infections or toxin-mediated food poisoning rather than a persistent gastric infection.