Stomach Ulcers and Bacterial Infection - New Directions for Research

As recently as 25 years ago, doctors commonly believed that ulcers of the stomach or the duodenum (the part of the small intestine closest to the stomach) were related to stress or diet. The theory was that in some people who were highly stressed, or who ate a lot of spicy foods, the stomach would produce more of the acids normally used to digest food. These acids would irritate the lining of stomach or duodenum, causing a chronic inflammation that if not treated could lead to ulceration or even perforation.

Basing their diagnosis on this hyperacidity theory, doctors usually treated their patients with a "bland" (non-spicy) diet and with antacids. The symptoms would usually subside-but only for a time. Eventually, the disease would recur.

However, two researchers in Australia-J. Robin Warren and Barry J. Marshall-discovered that there was actually a bacterium, later named Helicobacter pylori, present in most people who had ulcers. This was a big surprise, because up to that point no one had believed that bacteria could live in the acid environment of the stomach.

It turns out that H. pylori is capable of producing a substance that neutralizes stomach acid, allowing it to not only live but also grow. Its usual site is the lower part of the stomach, where it causes inflammation of that area or of the duodenum. This inflammation is made worse by increased acid production in the upper part of the stomach (near the esophagus). But a course of antibiotics and acid blockers will usually take care of the problem.

Occasionally, though, H. pylori will also colonize the upper part of the stomach. When it does this, the condition can become much more serious, even progressing to stomach cancer. Although the incidence of stomach cancer has been declining in recent years, it's still the second leading cause of cancer deaths around the world. As a result, the World Health Organization has classified H. pylori as a carcinogen.

Warren and Marshall's discovery, which occurred in 1984, took a long time to be accepted. Eventually, though, researchers began to wonder if other forms of inflammation could also be caused by infection-perhaps from an organism that has yet to be identified.

Chronic inflammation is associated with many different conditions, including ulcerative colitis, rheumatoid arthritis, and multiple sclerosis. It has also been known to lead to cancer. This one discovery could have implications for a wide range of medical conditions-which is probably why Warren and Marshall were awarded the Nobel Prize in Physiology or Medicine in 2005.