Definition and Epidemiology:
• H. pylori is a gram-negative and flagellated (motile) bacterium.
• It is thought that H. pylori is transmitted by fecal-oral and/or oral-oral routes.
• Human is the only known reservoir for H. pylori.
• Although its frequency increases with age, the most important determinant of its frequency is socio-economic conditions.
pathogenesis
• H. pylori can only colonize on gastric-type mucosa. H. pylori can be found on gastric metaplasia in regions other than the stomach (duodenum, etc.).
• It is colonized with various enzymes (urease, etc.) and antigens (adhesin, flagella, etc.); Cag-A can cause ulcers and cancer with toxins such as VagA.
• Not all strains of H. pylori have the same pathogenic characteristics. Different pathogenic features in bacterial strains and immunological factors of the host determine the clinical outcome in the spectrum of carrier and disease.
• H. pylori is the most important cause of chronic gastritis and peptic (duodenal) ulcer.
• Almost all individuals colonized with H. pylori have histologically chronic active gastritis in the stomach. However, most of these patients are asymptomatic.
• Only 10% to 1% of individuals infected with H. pylori develop peptic ulcers.
• It has been suggested that H. pylori may also be associated with some extraintestinal pathologies.
The most important of these are chronic immune thrombocytopenic purpura and chronic urticaria.
Diagnosis
• Methods used in the diagnosis of H. pylori infection are divided into two main groups as invasive and non-invasive, according to the need for endoscopy.
• Invasive tests are based on urease activity (rapid urease test=CLO), histological examination, culture, direct smear or PCR examination of gastric mucosa samples taken during endoscopy.
• Non-invasive tests to diagnose H. pylori without the need for endoscopy; urea breath test, serological methods, urine antigen and stool test.
• Urea breath (breathing) test
It is the process of making the patient drink a urea solution with a marked carbon atom and then detecting this carbon atom in carbon dioxide in the expiratory air (the presence of urease is shown indirectly).
It is the most suitable test especially for the control of eradication.
It has the highest accuracy rate (sensitivity + specificity) among all tests.
PPI and antibiotic treatments may cause false negatives in urease-related tests.
• Serology
It is a method of investigating specific antibodies against H. pylori in serum.
Although the bacterium is eradicated, serology may be positive for a long time, so it cannot be used to control eradication.
It can be used in community surveys.
• Culture ;H. pylori is the most specific test, but its sensitivity is low because the bacteria are difficult to grow. It also allows detection of antibiotic resistance.
