The infection caused by Helicobacter pylori is an important risk factor for gastric and duodenal ulcer. Infection with the bacterium causes a disturbance in the structure and function of cells of the gastric mucosa which may be the beginning of a number of pathological processes, including neoplastic transformation. Infection is associated with the development of chronic inflammation of the gastric epithelial cells of the microorganism caused by adaptation to the environment, defined by the chemical structure and specificity of the bacterial adhesins, the enzymatic activity of H.