Helicobacter pylori

Helicobacter pylori is a Bactérie which infects the gastric Muqueuse. 80% of the Ulcère S gastro-duodénaux are caused by infections of H. pylori , even if at the majority of human infected, the disease remains asymptomatic.

H. pylori lives exclusively in the human stomach and is the only known organization being able to survive in such an acid environment. It has a helicoid form (from where the name of “ Helicobacter ”) and can be screwed in the stomachic wall in order to colonize it.

History

In 1875, German scientists discovered a helicoid bacterium in human Estomac S. This one could not be cultivated and research relating to it was finally abandoned.

This bacterium was redécouverte in 1982 by two Australian researchers, J. Robin Warren and Barry J. Marshall, which isolated and cultivated organizations starting from human stomachs. In their original publication, Warren and Marshall supported that the majority of the stomachic and gastric ulcers were caused by an infection of this bacterium, and not by the stress or spiced food, as it before was thought. This discovery was worth the to them Nobel Prize of physiology and medicine 2005.

Some think that the medical community spent time before recognizing the role of this bacterium in the gastric ulcers, thinking that no bacterium could survive well a long time in the environment Acide of the stomach. After complementary studies had been carried out, of which that during which Marshall ingurgita a tube test of H. pylori , contracted an ulcer and was looked after with antibiotics (satisfying of this fact 3 of the 4 postulates of Robert Koch), the medical community started to change opinion. In 1994, the National Institutes off Health published a supporting text that the majority of the recurring gastric ulcers were caused by H. pylori , and recommended that antibiotics are included in the treatment.

Before the role of this bacterium is recognized, the stomachic ulcers were usually looked after by drugs which neutralized stomachic acidity, or decreased its production. In spite of the fact that this technique gave good performances, the ulcers very often reappeared. A drug classically used was the bismuth subsalicylate. It functioned rather well, but was finally given up, its mechanism of action being unknown. Nowadays, it seems obvious that the bismuth salt functioned like an antibiotic, and the majority of the ulcers are effectively treated by antibiotics targeting H. pylori .

This bacterium was initially called Campylobacter pyloridis , then C. pylori (after Latin grammatical correction). Finally, after the sequencing of sound DNA had shown that the bacterium did not belong to the kind Campylobacter , it was placed in a new kind: Helicobacter . The name pylori car its origin of Latin “pylorus”, which means “guard of the opening”, and which refers to the circular opening (Pylore) driving of the stomach to the Duodénum.

Whereas H. pylori remains only the Espèce known able to colonize the human stomach, other species of Helicobacter were identified in others Mammifère S, like at some Oiseau X.

Another research team has just shown that Helicobacter pylori was already present in the stomach of approximately half of the Homo sapiens there is 58.000 years in the African stock.

Structure of the bacterium

H. pylori is a bacterium negative Gram of helicoid form, approximately 3 micrometers of length and approximately 0,5 micrometers diameter. It changes 4 to 6 whip. It is known as Microaérophile , i.e. it requires an oxygen contribution, but in proportions lower than those found in the atmosphere. Lastly, still let us announce that it can produce its energy by Méthanogenèse starting from Hydrogène.

Thanks to its helicoid form and with its S Whips, the bacterium slips through the mucous membranes of the stomach and anchors to the epithelial cells thanks to adhésines (fixing proteins). It secretes a Enzyme then called “urease” which transforms urea into Ammoniac and in Carbon dioxide. This ammonia partially will neutralize the gastric acidity (which is amongst other things used to kill the bacteria). Unfortunately, the ammonia is toxic for the epithelial cells, and goes, in.liaison.with other products secreted by H. pylori (Protéase S, Catalase S, Phospholipase S,…) to damage the surface of the epithelial cells, engaging of this fact the formation process of ulcers.

Recent studies tend to show that certain stocks of this bacterium have a particular mechanism of injection of inflammatory agents in the stomachic cells.

Infection and diagnosis

The infection can be symptomatic or asymptomatic (i.e. with or without visible effects). It is estimated besides that 70% of the infections are asymptomatic!

This bacterium was isolated in saddles, Salive and on dental plaques, which leaves suppose that a transmission is possible by ingestion of saddles or gastro-oral way.

It is estimated that approximately 2/3 of the world population are infected by this bacterium! The exact rate of infection varies from one country to another: approximately 25% in the Western countries, and a higher rate in the countries of the Third world. In the latter, it is current to meet infected children, probably because of the bad sanitary arrangements. With the the United States, on the other hand, the people reached are primarily elderly (more than 50% people contaminated beyond 60 years, against approximately 20% at less than 40 years), as well as the most stripped people. The rate of infection is primarily function of the conditions of hygiene, as well as utilization factor of antibiotics. Nevertheless, of resistances against some Antibiotique S appeared at certain stocks of H. pylori . For example, one can find in Great Britain certain stocks resistant to the Métronidazole.

If it is not looked after by an antibiotic catch, it would seem that an infection by H. pylori could persist during all the life of the individual. The human Immune system would thus not be capable of éradiquer this parasite.

It is possible to detect the presence of H. pylori by a simple test Sang uin (detection of Antigène S specific. The test serologic is reliable to detect an infection but it is not it any more to check the success of a treatment anti-helicobacter bus the antibodies remain several months after a possible eradication.), by ingestion of Urée marked with the Carbone ¹³ (if the patient is infected, this urea is metabolized by H. pylori , thus producing of marked CO₂, who is then expelled out of the body via the Poumon S, and can thus be detected by analysis of expired gas), Endoscopie (the objective being to detect the possible presence of urease), or finally by setting in fabric culture presumedly contaminated by the Micro-organism. The Biopsie S realized at the time of the Gastroscopie also make it possible to note possible atrophic lesions on the level of the Antre and Fundus.

Sometimes, Helicobacter pylori can infect the Duodénum in the event of Métaplasie (transformation of part of fabric of the duodenum into gastric fabric).

Pathology related to this infection

Helicobacter pylori causes several more or less serious pathologies according to the individuals. This germ causes:

a nonulcerous Dyspepsia
Of the gastric ulcers and/or duodénaux
Of the generally localized chronic gastrites on the level of the cave but which extend sometimes on the level from the fundus. One speaks then in this case about pangastrite.
a malabsorption of the Vitamin B12
Of the atrophic gastrites involving a hypochlorydrie even a achlorhydrie.
Of the intestinal Métaplasie S which translate a stage pre-cancer patients.
Of cancers (the Cancer of the stomach - Adénocarcinome - and gastric Malt lymphoma)

Treatment of the Infection

This infection is looked after using a trithérapie associating 2 Antibiotique S with a IP (Inhibiteur of the pump with protons) to neutralize the gastric acidity.

There exist several combinations:

Amoxicilline + Clarithromycine + IP
amoxicilline + Métronidazole + IP
métronidazole + Tétracycline + IP
metronidazole + clarithromycine + IP

Studies suggèrent a good effectiveness of the Lévofloxacine and the Rifabutine when those are associated with the Amoxicilline. However these treatments should be used only in third line. These studies remain to be confirmed in France before being applied. A resistance to antibiotics however starts to appear with nearly 20% of failures of eradication.

Salts of Bismuth (heavy metal) can also be used in partnership with a trithérapie. However this last is interdict in France since the Seventies because there are them intoxications with renal disorders as well as indexed encephalopathies. Bismuth continues to be prescribed in many other country successfully.

In 2002 a vaccine test had been tried but this one was abandoned because the side effects were too important. The side effects were related to the Adjuvant used (choleraic Toxine). Moreover the immunization was not sufficiently effective. Only a reduction of the bacterial concentration at summer observed. The researchers try to develop nontoxic additives allowing to stimulate the immunizing response effectively. The immunization of the mucous membranes is very complex. The Vaccin is always under study and should be born in a few years. This one should make it possible to treat the infection like preventing it.

It is also possible to reduce the Infection (in the cases or the various treatments failed), without to eliminate it, by drinking cranberry juice. Several studies showed that molecules (proanthocyanidines with high molecular weight) present in the Canneberge were effective to prevent the adhesion of the Bactérie to the gastric cells. The bacteria are then eliminated naturally when the stomach is emptied.

The cuban doctors treat the cases of gériadis, ulcers or intestinal ignition gastric and/or by ozonées plant oils (natural product due to the embargo), without any counter-indication and with excellent results. Of http://www.ozonotherapie.com/digestion/ulcer.html published show that the hélicobacter can be éradiqué while taking on 10 to 44 days, 3 to 5 times per day the treatment, with a result between 50 and 65% in the 25 days for affections dating between 7 and 11 years. In all the cases, the pain disappeared quickly in a few minutes and in 82% of the cases, it was observed a final eradication. There was no noted negative effect. This product is now associated with plasters or plants, because the hélicobacter becomes resistant to the antibiotics which attack the stomachic and intestinal wall

See too

Random links: