Helicopacter pylori

AL-KALAMOON UNIVERSITYNUTRITION DEPARTMENT

DR.LOUAY LABBAN

• INTRODUCTION — Helicobacter pylori, also known as H. pylori, is a bacterium that is commonly found in the stomach. It is present in approximately one-half of the world's population.

• The vast majority of people infected with H. pylori infection have no symptoms and will never develop problems

Helicobacter pylori

• is a gram negative, microaerophilic, curved bacillus. It is motile, has flagellae and has a special affinity for human gastric mucosa.

• Since its initial discovery it has been implicated in the pathogenesis of a number of gastroduodenal disorders including acute and chronic gastritis, gastric and duodenal ulceration, gastric cancer and gastric MALT lymphoma

• Up to 50% of the population in developed countries such as Australia will have evidence of H. pylori infection by the age of 50 years. The organism is present in up to 92% of patients with active chronic gastritis, 88-100% with duodenal ulceration, 58-100% with gastric ulceration and 46-94% with gastric cancer. In duodenal ulcer disease eradication of the organism has been shown to markedly reduce ulcer recurrence rates and possibly change the natural history of the disease.

• However, H. pylori is capable of causing a number of gastrointestinal disorders, including ulcers, and, much less commonly, stomach cancer. It is not clear why some people get these conditions and others do not.

• In the United States and other developed countries, infection is unusual during childhood but becomes more common during adulthood. However, in developing countries, most children are infected with H. pylori before age 10.

• RISK FACTORS — H. pylori is probably spread by consuming food or water contaminated with fecal matter. Children living in developing countries may become infected after swimming in contaminated pools, streams, or rivers, by drinking contaminated water, or by eating uncooked vegetables.

• H. pylori causes changes to the stomach and duodenum (the first part of the small intestine, show figure 1). The bacteria invades the protective tissue that lines the stomach. This leads to the release of certain enzymes and toxins. These enzymes and toxins may directly or indirectly injure the cells of the stomach or duodenum.

• As a result of these changes, the stomach and duodenum are more vulnerable to damage from digestive juices, such as stomach acid. This results in chronic inflammation in the walls of the stomach (gastritis) or duodenum (duodenitis).

• SYMPTOMS — Most individuals with chronic gastritis or duodenitis have no symptoms. However, some people develop more serious problems, including stomach or duodenal ulcers. Ulcers can cause a variety of symptoms or no symptoms at all.

• Common complaints include pain or discomfort (usually in the upper abdomen), bloating, feeling full after eating a small amount of food, lack of appetite, nausea, vomiting, and dark or tar-colored stools. Ulcers that bleed can cause a low blood count and fatigue.

• Less commonly, chronic gastritis causes abnormal changes in the stomach lining, which can lead to certain forms of cancer. It is uncommon to develop cancer as a result of H. pylori infection.

• Nevertheless, because so many people in the world are infected with H. pylori, it is considered to be an important cause of stomach cancer. People who live in countries in which infection occurs at an early age are at greatest risk of stomach cancer.

• DIAGNOSIS — There are several ways to diagnose H. pylori. The most commonly used tests include one or more of the following:

• Blood tests — Blood tests can detect specific antibodies (proteins) that the body's immune system develops in response to the H. pylori bacterium.

• Breath tests — Breath tests (known as urea breath tests) require that the patient drink a specialized solution containing a substance (13C [carbon]- or 14C-labeled urea) that is broken down by the H. pylori bacterium. The breakdown products can be detected in a person's breath.

• Stool tests — Tests are available that detect H. pylori proteins in stool.

• Endoscopy — Testing may include endoscopy of the upper gastrointestinal tract to confirm certain gastrointestinal conditions, such as peptic ulcer, as well as infection with H. pylori. However, endoscopy is not required for the diagnosis of H. pylori.

• During an endoscopy, a flexible tube is inserted through the mouth into the esophagus, stomach, and upper region of the small intestine.

• The tube contains a light and camera, which can be used to examine the various areas. Small tissue samples (biopsy samples) can be taken from the stomach, which are then tested for H. pylori.

WHO SHOULD BE TESTED?

• Patients with symptoms — Diagnostic testing for H. pylori infection is recommended for people with active gastric or duodenal ulcers and those with a past history of ulcers.

• Although H. pylori infection is the most common cause of ulcers, not all patients with ulcers have H. pylori. Certain medications (eg, aspirin, ibuprofen (Motrin®, Advil®), naproxen (Aleve®)) can also cause peptic ulcers. Thus, testing for H. pylori is recommended.

• Patients without symptoms — H. pylori testing is usually not recommended for people who have no symptoms and no past history of peptic ulcer disease.

• However, it may be considered for selected people, such as those with a family history or concern about stomach cancer, particularly individuals of Chinese, Korean, or Japanese descent; these groups have a higher incidence of stomach cancer.

• Nonulcer (functional) dyspepsia — Because H. pylori infection is so common, researchers have tried to determine if other illnesses could be caused or worsened by the infection. One example of this is a condition known as nonulcer (functional) dyspepsia

• It is generally reserved for patients who require endoscopy for other reasons (eg, evaluation of stomach pain, follow up of peptic ulcer disease, or for the diagnosis or follow up of stomach cancer).

• Functional dyspepsia causes recurrent or persistent pain or discomfort in the upper abdomen. It has no identifiable cause.

• In general, studies suggest that few, if any, patients with functional dyspepsia benefit from treatment of H. pylori infection. Most patients with functional dyspepsia are tested for H. pylori before treatment is recommended.

• Methods of detection of H. pylori• The organism is usually present in the gastric

antrum and lives beneath the mucus layer. One of its special characteristics is its ability to produce urease, an enzyme that is not normally found in the human stomach.

• Various methods have been developed for detecting H. pylori, including :

• using endoscopic biopsy samples where the

• organism can be detected – on histological examination – culture – the polymerase chain reaction – a positive rapid urease test performed on the

sample

• serological tests for H. pylori antibodies performed on blood or less commonly saliva

• 13C or 14C urea breath tests

Serological tests for H. pylori

These are non invasive laboratory tests for antibody against H. pylori. Various methods exist, including : Elisa

• complement fixation • latex agglutination.

• Tests for IgG antibodies are the most sensitive as once infected with the organism an IgG response is seen in 95%, an IgA response in 68-80% and IgM response in only 14% of infected patients. The majority of tests are performed on blood and the sensitivity of salivary antibody tests is low, probably as the majority of salivary antibodies are IgA rather than IgG. It is important that serological tests are locally validated.