What is Helicobacter pylori? Where does it come from? What damage can it cause?

R.

Helicobacter pylori (H. pylori) is a type of bacterium that is found in the human stomach. It was first identified only about 15 years ago. Since that time, much has been learned about this organism.

We know that H. pylori is acquired by fecal-oral spread, meaning that someone who has the organism can pass it to others by direct contact. This frequently occurs in areas with poor hygiene, such as developing countries. In areas with poor sanitation, virtually everyone is infected with H. pylori during childhood. However, in developed nations such as the United States, the chance of harboring these bacteria is about equal to a person's age. Thus, someone who is 50 has about a 50 percent chance of being infected.

H. pylori infection causes no problems in most people. Some patients who have various upper digestive complaints, such as upper abdominal pain, nausea, fullness and bloating (a constellation known as non-ulcer dyspepsia), are found to have H. pylori. However, there is tremendous controversy among medical researchers about whether H. pylori actually plays a role in these patients' symptoms.

Three distinct complications of HP have been definitively identified. First, in people infected early in life (mostly in developing countries), H. pylori can cause an atrophy of the inner lining of the stomach, known as atrophic gastritis. Over many years, atrophic gastritis can lead to stomach cancer. Secondly, H. pylori can induce a type of gastritis that can progress to lymphoma.

The third complication of H. pylori infection is the most common. In these patients, the bacterial infection causes chronic active gastritis and leads to the formation of ulcers in the stomach and upper intestine, or duodenum. H. pylori is the most common cause of ulcers, and eradicating the infection with antibiotics prevents the recurrence of ulcers in 99 percent of such patients.