The villain in most peptic ulcers: Helicobacter pylori

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Until now, the traditional treatment for peptic ulcer disease involved minimizing and suppressing acid secretion with drugs.

Despite the fact that gastric cancer appears to occur more frequently in some populations with higher rates of H.pylori infection, the panel found no conclusive evidence that treating the infection reduces cancer risk.

Using a combination of antibiotics to eradicate a stomach bacterium may finally offer a cure to the 25 million Americans who at some time in their lives develop peptic ulcer disease.

According to a 14-member independent panel recently convened by the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institutes of Health (NIH) Office of Medical Applications of Research, ulcer patients who test positive for Helicobacter pylori (H. pylori) infection should be treated for at least two weeks with a combination of bismuth and antimicrobial drugs. Antimicrobial drugs kill microorganisms such as H. pylori, a bacterium said to infect 80 percent of patients with stomach ulcers. Dual and triple combinations of bismuth and antimicrobial drugs successfully cure H. pylori infection and reduce the rate of ulcer recurrence in up to 90 percent of ulcer patients, Said the panel.

Of the several drug combinations presented during the 2 1/2-day conference, the panel said that triple therapies, consisting of bismuth plus the antibiotics metronidazole and tetracycline, were the most effective. In some cases, resistance to metronidazole may require a substitution of amoxicillin.

The panel also identified several effective dual therapies, one of which combines amoxicillin with omeprazole, a proton-pump inhibitor. Mild side effects occur with each drug combination, but they do not normally prevent patients from completing their treatment. The panel added that standard acid-suppressing drugs should be added to the antimicrobial regimen to relieve ulcer symptoms.

Until now, the traditional treatment for peptic ulcer disease involved minimizing and suppressing acid secretion with drugs called H-2 blockers, which interfere with the release of histamine and thus reduce acid production in the stomach. The most commonly used H-2 blockers are ranitidine and cimetidine. Although H-2 blockers successfully heal ulcers, if the patient stops taking these drugs, he or she has a 50 to 80 percent chance of the ulcer recurring.

But since the 1982 isolation of H. pylori by Australian researchers Barry Marshall and Robin Warren, many have believed that the spiral organism plays a significant causal role in peptic ulcer disease, and there has been growing interest in using antibiotics to treat ulcers.

Peptic ulcer disease, estimated to affect 4.5 million people each year in the United States, is a chronic inflammation of the stomach lining or of the duodenum. Although peptic ulcer disease causes death in only a few people, it is responsible for substantial human suffering and staggering economic costs. Every year four million people report missing approximately six days from work because of their ulcers. Now the panel believes that their recommended treatments not only will alter the way doctors treat ulcers but also will lower health care costs and reduce human suffering.

Research indicates that H. pylori infects approximately six in ten people in the United States by age 60, while the infection rate in developing countries is eight in ten people by age 5. Although uncertainty remains about how the infection is spread, person-to-person contact appears to be a significant means of transmitting the bacterium. Whether or not H. pylori infection can be transmitted through contaminated food and water, and how often, requires further study.

To prevent the development of bacterial resistance to antimicrobials, the panel stressed that an accurate diagnosis should be made before a patient starts any antimicrobial treatment. The panel cited several invasive and noninvasive tests that are useful in diagnosing H. pylori infection.

Endoscopic biopsy and cell culture are invasive tests that provide visualization and details about the status of the gastric and duodenal lining. Sensitivity and specificity of these procedures range from 85 to 100 percent.

However, the panel said that excellent diagnostic sensitivities and specificities are also produced with noninvasive tests. These include blood tests to measure the urease-secreting properties of H. pylori.

Although a number of highly accurate diagnostic tests are available, the panel said that some now used only in research studies will soon be available for commercial use. Despite these diagnostic tools, the panel noted that there are no readily available, inexpensive, or accurate noninvasive methods to monitor eradication of H. pylori. Without such tools, routine monitoring for relapse, reinfection, or treatment failure cannot be recommended.

The panel also found an association between H. pylori infection and gastric cancer. Gastric cancer considered a slow and insidious disease; the incidence of gastric cancer increases with age, and the disease occurs more frequently in blacks and Hispanics than whites. Despite the fact that gastric cancer appears to occur more frequently in some populations with higher rates of H. pylori infection, the panel found no conclusive evidence that treating the infection reduces cancer risk. They contend that there are factors other than H. pylori infection, such as geography, socioeconomic status, and ethnicity, that cause the development of gastric cancer.

Finally, the experts called for future research to determine the mechanisms and natural history of H. pylori infection, whether H. pylori eradication prevents gastric cancer, and to analyze the comprehensive cost and impact of treating versus not treating all patients who are infected with H. pylori.

PHOTO: A colony of Helicobicter Pylori Bacterium (magnified 10,000 times)

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