H. pylori infection occurs when a type of bacteria called Helicobacter pylori (H. pylori) infects your stomach. This usually happens during childhood. A common cause of peptic ulcers, H. pylori infection may be present in more than half the people in the world.
Most people don't realize they have H. pylori infection, because they never get sick from it. If you develop signs and symptoms of a peptic ulcer, your doctor will probably test you for H. pylori infection, because it can be treated with antibiotics.