Helicobacter pylori is a widespread microorganism that infects half of the world’s population. Its prevalence is very high in developing countries and is relatively low in the developed countries. According to World Gastroenterology Organization, infection prevalence in adults in Eastern Europe and Asia is 70-80%.
Recent studies have shown the key role of bacterium Helicobacter pylori in the pathogenesis of stomach and duodenal ulcers. H.pylori is detected almost in 100% of adult patients with duodenal ulcer, approximately in 80% of patients with peptic ulcer, in 92% of patients with gastric cancer and in 92% of patients with active chronic gastritis. Research has demonstrated that elimination of helicobacter leads to disappearance of gastritis and significantly reduces the incidence of duodenal ulcer recurrence.
Helicobacteriosis is a chronic infection with long and often asymptomatic course. Its symptoms do not differ from clinical manifestations of gastro-duodenitis (usually there is a constant pain in epigastrium). H.pylori is often present in patients with no clinical manifestations of disease.
H.pylori strains are extremely heterogeneous and divided into two groups - strains expressing both antigens VacA and CagA (type I) and strains that express only VacA (type II). Strains of the first group dominate in the patients with peptic ulcer disease and gastric cancer. CagA protein penetrates the epithelial cells of the mucous membrane, causes abnormal mitotic divisions, and induces chromosome instability. When humans are infected with CagA-positive strains of H.pylori, CagA-specific antibodies are produced. Antibodies to CagA protein are found in 80-100% of patients with duodenal ulcer and in 94% of patients with gastric cancer. Therefore, the presence of antibodies to CagA protein is an informative marker in the diagnosis of duodenal ulcer and gastric cancer.
Among strains of H.pylori type II (CagA negative) the prevalence of severe gastric and duodenal ulcers, particularly peptic ulcer disease and cancer, is lower.
H.pylori infection can be diagnosed both with invasive and non-invasive diagnostic methods. Invasive methods include the study of biopsied material of gastrointestinal mucosa with histological and culture methods, or with rapid urease test. However, heterogeneous distribution of H.pylori in tissues often leads to false-negative results. Non-invasive diagnostic methods include serologic study of patient sera for the presence of specific antibodies to H.pylori and respiratory urease test using isotope labeled urea. Enzymatic immunoassays for detection of specific antibodies of IgG/IgA/IgM classes is a minimally invasive, rapid, highly sensitive, and informative method for diagnostics of H.pylori-infection.
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