Helicobacter pylori (H. pylori) infection is a bacterial infection that causes stomach inflammation (gastritis), peptic ulcer disease, and certain types of stomach cancer.
Infection with Helicobacter pylori is the most common cause of gastritis and peptic ulcer disease worldwide. Infection is very common and increases with age. By age 60, about 50% of people are infected. However, recent studies show fewer young people are becoming infected with H. pylori. Infection is most common among blacks, Hispanics, and Asians.
H. pylori can be found in stool, saliva, and plaque on the teeth. H. pylori can be transmitted from person to person, especially if people who are infected do not thoroughly wash their hands after a bowel movement. Because people may also spread the bacteria through kissing or other close contact, infections tend to cluster in families and among people who live in nursing homes and other supervised facilities.
H. pylori bacteria grow in the protective mucus layer of the stomach lining, where they are less exposed to the highly acidic juices produced by the stomach. Additionally, H. pylori produce ammonia, which helps protect it from stomach acid and enables it to disrupt and penetrate the mucus layer.
Virtually all people who have H. pylori infection have gastritis, which may affect the entire stomach or only the lower part (antrum). Infection can sometimes lead to erosive gastritis and perhaps even a stomach (gastric) ulcer.
H. pylori contributes to ulcer formation by increasing acid production, interfering with the stomach's normal defenses against stomach acid, and producing toxins.
Long-term infection with H. pylori increases the risk of stomach cancer.
Most people with gastritis resulting from H. pylori infection do not develop symptoms, but people who do develop symptoms have those typical of gastritis, including indigestion and pain or discomfort in the upper abdomen.
Ulcers caused by H. pylori infection cause symptoms similar to ulcers caused by other disorders, including pain in the upper abdomen.
H. pylori can be detected with tests that use breath or stool samples.
Sometimes doctors use a flexible viewing tube (endoscope) to do an upper endoscopy to obtain a sample (biopsy) of the stomach lining. The sample can be tested for H. pylori by several methods.
The likelihood that a peptic ulcer caused by H. pylori infection will recur during the course of 1 year is greater than 50% in people who have not been treated with antibiotics. This percentage decreases to less than 10% in people who have been treated with antibiotics. In addition, treatment of H. pylori infection may heal ulcers that have resisted previous treatment.
H. pylori infection must be treated with antibiotics. The most popular treatments for H. pylori infection include a proton pump inhibitor (see Table: Drugs Used to Treat Peptic Ulcer Disease) to reduce acid production, two antibiotics, and sometimes also bismuth subsalicylate.
Doctors typically confirm that treatment was successful by repeating breath or stool tests about 4 weeks after treatment was finished.