Helicobacter pylori
Helicobacter pylori
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L 'Helicobacter pylori (Hp) is a spiral shaped bacterium that lives in the stomach and duodenum (the section of intestine immediately below the stomach), causing an inflammation of the gastric mucosa (gastritis).
The gastric juice is composed of concentrated hydrochloric acid and digestive enzymes, which can quickly dissolve even the hardest foods or micro-organisms most resistant. Bacteria, viruses, and the steak dinner yesterday, all are dissolved in this bath of deadly chemicals. For this reason, I always thought that the stomach was sterile, but the discovery of the 'HP by Australian scientists in 1983, changed this belief.
The 'HP has a unique way to adapt to inhospitable environment of the stomach: the stomach is protected by its own gastric juice by a thick layer of mucus covering the gastric mucosa, and HP takes advantage of this protection by living and right multiplying in the mucous layer. Sheltered by the gastric juice, then neutralizes the acid that can reach it through an enzyme that has called "urease". The urease converts urea, abundantly contained in the stomach, in bicarbonate and ammonium, which are strongly alkaline and which neutralize the hydrochloric acid. It then creates a small "cloud" of chemicals that neutralize the acid around to 'Hp and protect him.
The reaction of hydrolysis of 'urea is used in the diagnosis of Hp infection: is the basis of' " Urea Breath Test ", one of the most sensitive and reliable test available today.
Another defense Hp consists in the fact that the natural immune defenses of the organism, can not reach in the gastric mucus. The immune system responds to infection by Hp by sending white blood cells, T lymphocytes "Killer" and other matters of defense, but they can not reach the infection because it does not easily penetrate the mucosal barrier of the stomach. But do not go away either, so the immune factors accumulate more and more: Polymorphonuclear (a type of white blood cells) die and their contents highly destructive (superoxide radicals) is poured on the cells of the gastric mucosa. They are also sent via the blood circulation in more nutrients to boost the white blood cells and takes advantage of Hp, feeding itself of these compounds. In this way, within a few days develops a gastritis which can sometimes progress to peptic ulceration. It is believed that it is not the same Hp to cause gastric mucosal damage, but the immune response to the microorganism.
It is believed that Hp is transmitted by fecal-oral route, following ingestion of food or other material contaminated with fecal material (hand hygiene becomes essential to avoid infection). It 's also possible that the' Hp, rising from the stomach to the mouth as a result of gastro-oesophageal reflux, can also be transmitted through oral contact.
In the Western world, the 'Helicobacter pylori infects about 20% of people under age 40 and about 50% of those over 60 years. It 's rather rare in children.
The methods available to diagnose the presence of H. pylori are essentially four:
Esophagogastroduodenoscopy (EGD)
And 'examination certainly more reliable because it allows direct vision of esophageal and gastric mucosa, the removal of material by biopsy and culture of material taken for H. pylori. However, it is an invasive test and quite expensive.
At first examination the patient is injected with a sedative intravenously, and a local anesthetic is sprayed in the throat. It then introduced a small, flexible tube (roughly the diameter of a little finger), and although most patients have some 'discomfort during the first 5 seconds of the examination, once the tube has passed through the rear wall of the throat, much discomfort fades.
Through the endoscope, the doctor examines the inside of the esophagus, stomach and duodenum, and biopsy specimens taken from sending histology and culture.
After performing the examination, you can not drive the car for the rest of the day. It 'also important to remember that for a successful examination is necessary to suspend any antibiotic therapy from a month earlier, treatment with proton pump inhibitors (omeprazole, lansoprazole, pantoprazole, etc..) From a week earlier and therapy with H2 inhibitors (zantac , Ranidae, ulcex, famodil etc..) by at least 24 hours before.
Search for anti-Helicobacter (blood test)
With a simple blood test, you can search for anti-Helicobacter pylori. This is a fairly quick and economic test, but which nevertheless has important limitations: a positive blood test, it simply indicates that the patient has had over the last 3 years or infection with H. pylori.
You can then tell if the infection is still in place or not. In practice: if the test is negative we have a reasonable certainty that the patient does NOT have an Hp infection, but if the test is positive, we can not tell if the infection is in progress or if there has been in the past.
This test also can not be used to evaluate the efficacy of a therapy against Hp, because the antibodies are reduced slowly and can remain high even after the 'Hp was deleted.
Labeled urea breath test (Urea Breath Test)
Is usually done in the morning, after fasting for at least 6 hours.
It is given a packet of sodium citrate and after 10 minutes, blowing in a separate tube, is collected a first sample of exhaled air. Is then administered to the patient a small tablet of Urea-C13 is collected and a new sample of exhaled air into another test tube after about 30 minutes.
From the amount of CO2 present in the breath after 30 minutes, it goes back to the presence of Hp in the stomach: the Hp in fact, as already seen, splits urea into bicarbonate (and therefore also CO2) and ammonia, and then in the patient with an infection Hp, the CO2 exhaled after half an hour will be higher than that exhaled by a person without infection.
This test is rapid, painless, inexpensive (typically costs about € 50) and very reliable: it detects the presence of Hp in real time and can also be used to check if a possible treatment administered was effective in eradicating the infection Hp
Search for 'fecal antigen of' H. pylori
This search method in the feces, the presence of an antigen of 'Hp, the so-called fecal antigen (HpSA). The presence of the antigen is a sign of ongoing infection and is therefore a most reliable test of the search for antibodies in the blood, however, the false negative (ie, the negativity of the test when instead the 'Hp is present) are superior to those of' Urea Breath Test
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