[Pathogenesis, diagnostics and treatment of Helicobacter pylori infection]

Abstract

More than one-half of the world population is infected with Helicobacter pylori. Of those, approx. 500,000 die from gastric carcinoma every year. Ulcer disease, gastricatrophy and the rare MALT lymphoma are other sequelae of H. pylori infection. H. pylori possesses an array of virulence factors that include urease, flagellar motility, adhesins, the vacuolating cytotoxin VacA and the protein CagA. The gene encoding CagA is located on the cag pathogenicity island, comprising 29 genes the majority of which encodes components of a type IV secretion system capable of translocating CagA into epithelial cells where it interferes with cellular signal transduction processes. A number of diagnostic tests for H. pylori infection require gastroendoscopy. These include the biopsy urease test, histology, culture with susceptibility testing, and molecular detection methods such as fluorescent in situ hybridization. Non-invasive tests that do not require endoscopy include the (13)C urea breath test, H. pylori stool antigen ELISA and serology. The latter is unsuitable for treatment follow-up, since antibody titres persist up to a year after successful treatment. When patients have never been treated for H. pylori infection, biopsy urease test and histology are usually sufficient for diagnosis. In patients where endoscopy is not required, H. pylori infection can be reliably detected by (13)C urea breath test, stool antigen ELISA or serology. Patients who have under gone one or more unsuccessful cycles of eradication therapy in most cases harbour H. pylori resistant to one or several antibiotics. In these patients, culture and antibiotic susceptibility testing are indicated. Patients who have never been treated for H. pylori infection usually harbour susceptible strains. In such patients, classic "Italian" or "French" triple therapies may achieve eradication in >90% of cases. In the case of treatment failure, second-line antibiotic treatment regiments (rescue therapy) are used, optimally guided by susceptibility data.