Helicobacter pylori is a spiral-shaped bacterium discovered in 1982 by Australian scientist Barry Marshall and his colleague Robin Warren. Since then, much research has been conducted to understand its role in gastrointestinal diseases, the results of which have revealed a complex and interesting picture. H. pylori is a gram-negative bacterium, which means that it has a cell wall composed mainly of lipopolysaccharides. This gives it greater resistance to stomach acids than other bacteria. Its spiral shape allows it to perforate the mucous layer of the stomach using specific enzymes called mucinases, and colonise the surface of the gastric mucosa. Its adhesion to stomach cells is favoured by the presence of adhesins, i.e. proteins that are able to bind the bacterium to specific proteins on the surface of enterocytes in a fairly stable manner, making it a persistent host in the gastric environment. This bacterium has been associated with several gastrointestinal diseases, including gastritis, peptic ulcers, gastric cancer and MALToma. H. pylori infection is one of the main causes of gastritis, an inflammation of the stomach that can lead to symptoms such as abdominal pain, nausea and vomiting. This bacterium is implicated in the development of peptic ulcers, which are open lesions that occur in the stomach lining. These ulcers can cause severe pain and bleeding. In addition, H. pylori has been recognised as a risk factor for the development of gastric cancer and MALToma, a rare type of lymphoma associated with the bacterium. To determine whether an individual is infected with H. pylori, various diagnostic methods are available, including the urea breath test. The urea breath test is based on the ability of H. pylori to convert urea into carbon dioxide. The patient is made to drink a solution containing Carbon13 or Carbon14-labelled urea, which, when it reaches the stomach, if the bacterium is present, will be converted into labelled CO2, which will be detected on exhalation by a specific machine. Other methods include the search for antibodies against H. pylori, which can be detected by a blood test. A gastric biopsy during a gastroscopy can also confirm infection. If the bacterium is diagnosed, treatment is generally indicated to reduce the risk of complications. Therapy to eradicate the infection involves a combination of antibiotics (usually amoxicillin and clarithromycin to which a third antibiotic, metronidazole, may be added in specific cases) and proton pump inhibitors such as omeprazole to reduce gastric acidity.