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. 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. 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. In the past 40 years, enormous progress has been achieved in the clinical and basic research on H. pylori infection. However, challenges in preventing and treating H. pylori infection exist. H pylori symptoms can include bloating, loss of appetite, stomach burning, nausea, burping, excess gas, vomiting, and dark or bloody stools. Diagnosis and treatment help prevent gastritis, ulcers, and long-term complications. 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. 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. Helicobacter pylori (H. pylori) is a type of bacteria that infects your stomach. It can cause sores and inflammation in the lining of your stomach or the upper part of your small intestine (the. 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. 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.