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Helicobacter Pylori

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Medical Author:

Dennis Lee, MD

Dennis Lee, MD

Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

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Medical Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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What is Helicobacter pylori?

Helicobacter pylori (H. pylori) is a bacterium that causes chronic inflammation of the inner lining of the stomach (gastritis) in humans. This bacterium also is the most common cause of ulcers worldwide. H. pylori infection is most likely acquired by ingesting contaminated food and water and through person to person contact. In the United States, 30% of the adult population is infected. (50% of infected persons are infected by the age of 60.) The infection is more common in crowded living conditions with poor sanitation. In countries with poor sanitation, 90% of the adult population can be infected. Infected individuals usually carry the infection indefinitely unless they are treated with medications to eradicate the bacterium. One out of every six patients with H. pylori infection will develop ulcers of the duodenum or stomach. H. pylori also is associated with stomach cancer and a rare type of lymphocytic tumor of the stomach called MALT lymphoma.

How is H. pylori infection diagnosed?

Accurate and simple tests for the detection of H. pylori infection are available. They include blood antibody tests, urea breath tests, stool antigen tests, and endoscopic biopsies.

Blood tests for the presence of antibodies to H. pylori can be performed easily and rapidly. However, blood antibodies can persist for years after complete eradication of H. pylori with antibiotics. Therefore, blood antibody tests may be good for diagnosing infection, but they are not good for determining if antibiotics have successfully eradicated the bacterium.

The urea breath test (UBT) is a safe, easy, and accurate test for the presence of H. pylori in the stomach. The breath test relies on the ability of H. pylori to break down the naturally occurring chemical, urea, into carbon dioxide which is absorbed from the stomach and eliminated from the body in the breath. Ten to 20 minutes after swallowing a capsule containing a minute amount of radioactive urea, a breath sample is collected and analyzed for radioactive carbon dioxide. The presence of radioactive carbon dioxide in the breath (a positive test) means that there is active infection. The test becomes negative (there is no radioactive carbon dioxide in the breath) shortly after eradication of the bacterium from the stomach with antibiotics. Despite the fact that individuals having the breath test are exposed to a minute amount of radioactivity, the breath test has been modified so that it also may be performed with urea that is not radioactive.

Endoscopy is an accurate test for diagnosing H. pylori as well as the inflammation and ulcers that it causes. For endoscopy, the doctor inserts a flexible viewing tube (endoscope) through the mouth, down the esophagus, and into the stomach and duodenum. During endoscopy, small tissue samples (biopsies) from the stomach lining can be removed. A biopsy specimen is placed on a special slide containing urea (e.g., CLO test slides). If the urea is broken down by H. pylori in the biopsy, there is a change in color around the biopsy on the slide. This means that there is an infection with H. pylori in the stomach.

The most recently-developed test for H. pylori is a test in which the presence of the bacterium can be diagnosed with a sample of stool. The test uses an antibody to H. pylori to determine if H. pylori is present in the stool. If it is, it means that H. pylori is infecting the stomach. Like the urea breath test, in addition to diagnosing infection with H. pylori, the stool test can be used to determine if eradication has been effective shortly after treatment.