Helicobacter pylori Infection

Helicobacter pylori (HELL-ih-ko-bak-ter pie-LOR-eye), also called H. pylori, is a bacterium that can cause inflammation of the stomach and is associated with the development of peptic ulcers * and some types of stomach cancer.

What Is Helicobacter pylori Infection?

* responds to the presence of H. pylori. This can cause inflammation * of the lining of the stomach, a condition called gastritis (gah-STRY-tis). Some people go on to develop peptic ulcers. A peptic ulcer is a painful open sore that forms in the stomach or the duodenum. H. pylori infection is also associated with an increase in the likelihood of developing certain stomach cancers.

Common sites of ulcers in the human stomach. The need for ulcer surgery has diminished due to the discovery that Helicobacter pylori, an infectious bacterium, plays a major role in causing ulcers.

Common sites of ulcers in the human stomach. The need for ulcer surgery has diminished due to the discovery that Helicobacter pylori, an infectious bacterium, plays a major role in causing ulcers.
Illustration by Electronic Illustrators Group. © 2016 Cengage Learning®.

How Common Is H. pylori Infection?

In the United States, about 10 percent of children under the age of 12 are infected with H. pylori. This number increases with age until about half of all Americans over the age of 60 years have the infection. The infection is much more common among African Americans, Hispanics, and Native Americans than among non-Hispanic Caucasians. The rate of infection is much higher in the developing world. Even though infection with H. pylori is associated with peptic ulcer, most people who are infected with the bacterium never experience any symptoms or develop a peptic ulcer.

Is H. pylori Infection Contagious?

H. pylori infection appears to be contagious, but as of 2016, it was not known how it spreads. Researchers suspected that the infection can be spread when an infected person passes the bacterium in feces (FEE-seez), or bowel movements. When another person is exposed to the infected feces, whether by changing a diaper, cleaning a bathroom, or doing someone's laundry, that person could become infected with the bacterium. Mouth-to-mouth contact may also contribute to the spread of H. pylori infection. Some research has found H. pylori bacteria in saliva, leading researchers to suggest that kissing is one way that the bacteria spread. In addition, coming into contact with food, water, or vomited material that contains H. pylori bacteria may put a person at risk of infection.

In 1982 (John) Robin Warren (b. 1937), a biologist, and Barry J. Marshall (b. 1951), a physician, were the first researchers to discover a link between stomach inflammation (gastritis), peptic ulcers, and a bacterium later known as Helicobacter pylori.

Originally, Warren and Marshall were unsuccessful in growing the bacterium Warren had found in stomach samples until cultures containing the bacterium were accidentally left to grow for an unusually long time because of a vacation break. It turned out that the H. pylori bacterium just took longer to grow than many other bacteria.

Warren and Marshall were able to show a connection between infection with H. pylori and peptic ulcers. For their work, they were awarded the Nobel Prize in Physiology or Medicine in 2005.

What Are the Signs and Symptoms of H. pylori Infection?

H. pylori infection can cause a variety of symptoms, but the most common one is abdominal pain. About 90 percent of people with peptic ulcer disease are also infected with H. pylori. A person with peptic ulcer disease may feel a gnawing or burning pain below the ribs and above the navel. Abdominal pain from an ulcer usually occurs when the stomach is empty, typically several hours after eating or in the morning or evening hours. Eating food, drinking milk, or taking antacids may make the pain subside for a short time. Nonetheless, the vast majority of people infected with H. pylori have no symptoms.

Other symptoms of peptic ulcer disease are:

Symptoms of stomach cancer are similar to those of peptic ulcer disease. As of 2016, researchers did not fully understand the relationship between H. pylori, gastric inflammation, and peptic ulcers. For example, about 90 percent of people who have peptic ulcers are infected with H. pylori, but the vast majority of those infected do not develop an ulcer. About 10 percent of people with ulcers do not have H. pylori infections. Also, antibiotic treatment to rid the body of H. pylori does not, by itself, cure most ulcers.

How Is H. pylori Infection Diagnosed?

If a person has lasting abdominal pain or other symptoms of peptic ulcer disease, there are several methods a doctor can use to make a diagnosis. One of the most common ways to check for ulcers is with endoscopy (en-DOS-ko-pee). For this procedure, a person is given medication to relax and numb the throat. Then a doctor gently inserts an endoscope (a thin, flexible tube with a camera and light on the end) down the throat, through the esophagus, and into the stomach and intestines. The camera on the end of the endoscope allows the doctor to view the digestive system and take pictures of it. In addition, the doctor can perform a biopsy, removing a small amount of tissue for study. The biopsied tissue can be sent to a laboratory for further testing and to check for evidence of H. pylori infection.

A person's blood can also be checked for the presence of antibodies * to H. pylori, indicating infection.

How Is H. pylori Infection Treated?

People who are infected with H. pylori are treated for 10 to 14 days with what is called triple therapy. This approach consists of a combination of two or three antibiotic medicines that kill H. pylori bacteria and a drug that reduces acid production in the stomach. Two classes of drugs reduce acid production: histamine antagonists * and proton pump inhibitors. Patients may also take an antacid that temporarily helps coat the inside of the stomach. After treatment has been completed, tests should be done to check that the H. pylori infection has been eliminated. Reinfection is possible.

Although many people who are infected with H. pylori never have symptoms and never develop peptic ulcers, if left untreated ulcers can lead to serious problems. In some cases, the ulcer can make a hole all the way through the stomach or duodenum wall. In other cases, the ulcer or acid breaks a blood vessel and causes serious internal bleeding. It is important to get medical help promptly for the following symptoms, which may signal a peptic ulcer or other serious problem:

Are There Complications of H. pylori Infection?

A person who has untreated H. pylori infection has an increased risk of developing stomach cancer later in life. Long-term loss of blood from the gastrointestinal tract due to ulcers can cause anemia * . Severe untreated ulcers can lead to a perforation, or a hole, when the sore erodes all the way through the lining of the stomach or intestine. Perforations can cause sudden severe bleeding and spread of infection into the abdominal cavity, which can be fatal.

Antiulcer drugs

Antiulcer drugs
Table by Lumina Datamatics Ltd. © 2016 Cengage Learning®.

Can H. pylori Infection Be Prevented?

As of 2016, H. pylori infection could not be prevented. Researchers did not fully understand how H. pylori spreads or why some infected people develop ulcers and others do not. As a general precaution, people should wash their hands thoroughly after going to the bathroom and before eating. They should eat food that has been properly cooked and drink water from a clean, safe source. As of 2016, there was no vaccine against H. pylori infection.

See also Intestinal Infections • Peptic Ulcer • Stomach Cancer


Books and Articles

Charisius, Hanno. “When Scientists Experiment on Themselves: H. pylori and Ulcers.” Scientific American, July 5, 2014. http://blogs.scientificamerican.com/guest-blog/when-scientists-experiment-on-themselves-h-pylori-and-ulcers (accessed June 9, 2016).

Koeppel, Max, et al. “Helicobacter pylori Infection Causes Characteristic DNA Damage Patterns in Human Cells.” Cell Reports 11, no. 11 (2015): 1703–1713. http://www.cell.com/cell-reports/abstract/S2211-1247(15)00566-5?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2211124715005665%3Fshowall%3Dtrue (accessed July 16, 2015).


National Cancer Institute. “Helicobacter pylori and Cancer.” National Institutes of Health. http://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/h-pylori-fact-sheet (accessed June 9, 2016).

National Institute of Diabetes and Digestive and Kidney Diseases. “Peptic Ulcer Disease.” National Institutes of Health. (accessed July 16, 2015).


Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30333. Toll-free: 800-311-3435. Website: http://www.cdc.gov (accessed July 16, 2015).

Helicobacter Foundation. 35 Stirling Highway, Crawley, WA 6009, Australia. Telephone: 61-86-488-6000. Website: http://www.helico.com (accessed July 16, 2015).

NHMRC Helicobacter Research Laboratory. Room 1.11, L Block QEII Medical Centre, Nedlands, WA 6009 Australia. Telephone: 61-89-346-4815. Website: http://www.hpylori.com.au (accessed July 16, 2015).

* ulcers are open sores on the skin or the lining of a hollow body organ, such as the stomach or intestine. They may or may not be painful.

* immune system (im-YOON SIStem) is the system of the body composed of specialized cells and the substances they produce that helps protect the body against disease-causing germs.

* inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that often involves swelling, pain, redness, and warmth.

* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.

* antagonist (an-TAG-oh-nist) a chemical that acts within the body to reduce or oppose the effects of another chemical.

* anemia (uh-NEE-me-uh) is a blood condition in which there is decreased hemoglobin in the blood and, usually, fewer than normal numbers of red blood cells.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)