Bacterium Gram negative, Helicobacter pylori lives only in thestomach human. Very widespread, it is estimated that 50% of the world’s population is infected, with a predominance in developing countries. It is estimated that in France, 20 to 50% of adults are infected. It is spread by mouth or through stool and transmission requires proximity. This is why the contamination generally occurs in the family environment (contact with the saliva, sharing of cutlery …), especially from parents to young children.
Spiral in shape, it has two to six flagella allowing it to move around the mucus. In addition, it has the particularity of secreting a enzyme, urease, which allows it to protect itself from the acidity ofstomach by releasingammonia (increase in pH). The activity of this urease is conditioned by the presence of a nickel carrier specific to the bacteria.
Identification and demonstration ofHelicobacter pylori
It was inconceivable for scientists to imagine that a bacterium could live in an environment acid (pH of the stomach on an empty stomach is between 1.5 and 5). However in 1982, two Australian researchers John Robin Warren and Barry Marshall took an unlisted bacterium from the stomach wall of patients withgastric ulcer, put it in culture and can thus identify it. They then put forward the hypothesis concerning his responsibility in pathologies gastric bypass and in 2005 obtained the Nobel Prize in medicine for this discovery.
Since then, the involvement ofHelicobacter pylori in diseases of the stomach has been widely accepted and it is the first bacterial infection associated with the development of a Cancer.
Pathologies associated with Helicobacter pylori
Infection with Helicobacter pylori can cause inflammatory lesions in the mucous of the stomach. This gastritis can tend to become chronic and persist throughout life if left untreated. It can progress (5% of cases) to a gastric ulcer considered until then as a pathology linked to stress. It is now established that the majority of ulcers in the stomach or duodenum are caused by this bacteria and the treatment consists of the establishment of antibiotics.
A few infected people (1 to 3%) could develop a cancerous pathology (carcinoma of the stomach) in the very long term.
How to detect and treat Helicobacter pylori?
A fibroscopy allows a small sample to be taken from the stomach. A rapid test on the fragment taken can be easily carried out to demonstrate the presence of the specific enzyme: urease. Other methods exist such as serology or a respiratory test (demonstration of the bacterium in L’air expired).
Treatment consists of antibiotic therapy for one to two weeks which is usually effective for eradication. Nevertheless, surveillance is carried out in France, in particular by the GEFH (French study group for Helicobacter) with regard to the possible antibiotic resistance.
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