In 1982, Australian researchers Barry Marshall and Robin Warren discovered spiral-shaped bacteria in the stomach, later named Helicobacter pylori (H. pylori) After closely studying H. pylori's effect on the stomach, they proposed that the bacteria were the underlying cause of gastritis and peptic ulcers.

Marshall and Warren came to this conclusion because in their studies all patients with duodenal ulcers and 80% of patients with stomach ulcers had the bacteria. The 20% of patients with stomach ulcers who did not have H.pylori were those who had taken NSAIDs such as aspirin and ibuprofen, which are a common cause of stomach ulcers.

Although their findings seem conclusive, Marshall and Warren's theory was hotly debated and remained in dispute. The debate continued even after Marshall and a colleague performed an experiment in which they infected themselves with H. pylori and developed gastritis.

Evidence linking H. pylori to ulcers mounted over the next 10 years as numerous studies from around the world confirmed its presence in most people with ulcers. Moreover, researchers from North America and Europe proved that using antibiotics to eliminate H. pylori healed ulcers and prevented recurrence in about 90% of cases.

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What is H. pylori

H. pylori is a spiral-shaped bacterium found in the stomach. Research shows that the bacteria (along with acid secretion) damage the stomach and duodenal tissue, causing inflammation and ulcers. Scientists believe this damage occurs because of H. pylori's shape and characteristics.

H. pylori survives in the stomach because it produces the enzyme urease. Urease generates substances that neutralize the stomach's acid- enabling the bacteria to survive. Because of their spiral-shape and the way they move, the bacteria can penetrate the stomach's protective mucous lining. The body's immune system responds by releasing white blood cells (neutrophils) to attack the H. pylori bacteria. The bacteria can produce substances that weaken the stomach's protective mucous and make the stomach cells more susceptible to the damaging effects of acid and pepsin.

The bacteria can also attach to stomach cells further weakening the stomach's defensive mechanisms and producing local inflammation. For reasons not completely understood, H. pylori can also stimulate the stomach to produce more acid.

Excess stromach acid and other irritating factors can cause inflammation of the upper end of the duodenum, the duodenal bulb. In some people, over long periods of time, this inflammation results in production of stomach-like cells called duodenal gastric metaplasia. H. pylori then attacks these cells causing further tissue damage and inflammation which may result in an ulcer.

Within weeks of infection with H. pylori, most people develop gastritis- an inflammation of the stomach lining. However, most people will never have symptoms or problems related to the infection. Scientists do not yet know what is different in those people who develop H. pylori-related symptoms or ulcers.

Studies show that H. pylori infection in North America varies with age, ethic group and socioeconomic status. The bacteria are more common in older adults, those of Asian, African and Hispanic descent, and those from lower socioeconomic groups. The organism appears to spread through the fecal-oral route (when infected stool comes into contact with hands, food, or water). Most individuals seem to be infected during childhood and their infection lasts a lifetime.

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Testing for H. pylori

Confirming the presence of H. pylori is important once the doctor has diagnosed an ulcer because elimination of the bacteria is likely to cure ulcer disease. Blood, breath, and stomach tissue tests may be performed to detect the presence of H. pylori.

Blood tests
Blood tests such as the enzyme-linked immunosorbent assay (ELISA) and quick office-based tests identify and measure H. pylori antibodies. The body produces antibodies against H. pylori in an attempt to fight the bacteria. The advantages of blood tests are their low cost and availability to doctors. The disadvantage is the possibility of false positive results in patients previously treated for ulcers since the levels of H. pylori antibodies fall slowly.

Breath tests
Breath tests measure carbon dioxide in exhaled breath. Patients are given a substance called urea with carbon to drink. Bacteria break down this urea and the carbon is absorbed into the blood stream and lungs and exhaled in the breath. Analysing the levels of carbon in the collected breath determine whether H. pylori bacteria are present or absent. Urea breath tests are 90-99% accurate for diagnosing the bacteria and are particularly suitable to follow-up treatment to see if bacteria have been eradicated.

Tissue tests
If the doctor performs and endoscopy, tissue samples of the stomach can be obtained. The doctor may then perform one of several tests on the tissue. A rapid urease test detects the bacteria's enzyme urease. Histology involves visualizing the bacteria under the microscope. Culture involves specially processing the tissue and watching for growth of H. pylori organisms.

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Treating H. pylori

The discovery of the link between ulcers and H. pylori has resulted in a new treatment option. Now, in addition to treatment aimed at decreasing the production of stomach acid, doctors may prescribe antibiotics for patients with H. pylori. This treatment is a dramatic medical advance because eliminating H. pylori means the ulcer may now heal and most likely will not come back.

The most effective therapy is a 2 week, triple therapy. The regimen eradicates the bacteria and reduces the risk of ulcer recurrence in 90% of people with duodenal ulcers. People with stomach ulcers that are not associated with NSAIDs also benefit from bacterial eradication. While triple therapy is effective, it is sometimes difficult to follow because the patient must take three different medications four times each day for 2 weeks.

In addition, the treatment commonly causes side effects such as yeast infection in women, stomach upset, nausea, vomiting, bad taste, loose or dark bowel movements, and dizziness. The 2 -week, triple therapy combines two antibiotics, tetracycline and metronidazole with bismuth subsalicylate (Pepto-Bismol®). Some doctors may add an acid-suppressing drug to relieve ulcer pain and promote ulcer healing. In some cases tetracycline may be substituted for amoxicillin.

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