H. pylori is a spiral bacterium which is implicated in the causation of chronic gastritis, peptic ulcer disease, gastric carcinoma and mucosal associated lymphoid tissue (MALT) lymphoma.
The transmission of H. pylori is not fully understood; however, intrafamilial clustering suggests person-to-person spread and there is an association with lower socio-economic class.
H. pylori binds to the gastric epithelium beneath the protective mucus layer. It produces an enzyme that breaks down the glycoproteins within the mucus. There are also changes in the secretory patterns within the stomach along with toxin-mediated tissue damage. Initial infection causes an acute gastritis which rapidly proceeds to chronic inflammation. Prolonged inflammation results in metaplasia and predisposes to dysplasia and neoplasia.
Most people become colonised by H. pylori during their lifetime; however, only a minority develop symptoms of dyspepsia.
H. pylori causes a mixed acute and chronic inflammatory reaction within the lamina propria and superficial epithelium.
Invasive tests are performed at time of endoscopy and biopsy.
· Rapid urease (CLO) test is performed by mixing the biopsy specimen with a urea solution. The presence of H. pylori is detected as ammonia formation causes a rise in pH changing the colour of indicator solution.
· Biopsy specimens can be cultured on selective media and the sensitivities determined.
· Histological identification can also be performed.
Noninvasive tests can be performed if an endoscopy is not indicated.
· The urea breath test uses ingestion of 13C or 14C labelled urea, if the bacteria is present the urea is broken down releasing labelled carbon dioxide which is detected in the breath. This test can be used to confirm successful eradication, but patients must not be taking proton pump inhibitors or bismuth and must not have had antibiotics in the preceding 4 weeks.
· Serological testing is simple, non-invasive and widely available, but remains positive after clearance or successful eradication.
First line eradication (triple) therapy consists of a proton pump inhibitor, amoxycillin or metronidazole, and clarithromycin for 1 week. Second line (quadruple) therapy is with a proton pump inhibitor, bismuth subcitrate, metronidazole and tetracycline. Compliance with treatment is very important for successful treatment. If symptoms persist or recur a repeat urea breath test should be performed.