Helicobacter pylori (H. pylori) is a common bacterium that can infect the stomach lining. Most people with H. pylori have no symptoms, but it can cause gastritis or stomach ulcers. Common symptoms can include upper abdominal pain, nausea, and frequent burping. H. pylori infections are caused by H. pylori germs that get into the stomach lining. The germs appear to be passed from person to person through contact with saliva, vomit or stool. They also may be spread through contaminated surfaces, or tainted food or water. Helicobacter pylori (H. pylori) is a type of bacteria that can cause an infection in your stomach. If you develop an H. pylori infection, you may not have any signs or symptoms. But it can lead. H pylori, a stomach bacteria, causes ulcers and digestive issues. Know its symptoms, causes, and treatment H. pylori (Heliobacter pylori) is a type of bacteria that infects your stomach. It can damage the tissue in your stomach and the first part of your small intestine (the duodenum). In some cases it can also cause painful sores called peptic ulcers in your upper digestive tract. H. pylori infections occur across the world due to exposure to saliva or stool in contaminated water or food. Learn how the bacterium is spread and treated with antibiotics. Helicobacter pylori, previously known as Campylobacter pylori, is a gram-negative bacterium best known for its role in infecting the human stomach, often causing gastric ulcers and sometimes stomach cancer. H. pylori is a common bacteria that may cause pain and increase the risk of ulcers or stomach cancer. Learn about symptoms, complications, and more. Overview What is an H. pylori infection? H. pylori (Helicobacter pylori) is a type of bacteria that infects your stomach. It’s the most common chronic bacterial infection in humans. It affects more than half of the world’s population. But it doesn’t cause illness in most people. If you're concerned about an H. pylori infection, talk with your healthcare professional. Together you can decide whether H. pylori testing might be right for you.