Helicobacter pylori

Helicobacter pylori is a Eubacterium that infects the mucus lining of the human stomach. Many peptic ulcers and some types of gastritis are caused by H. pylori infection, although most humans who are infected will never develop symptoms. This bacterium lives in the human stomach exclusively and is the only known organism that can thrive in that highly acidic environment. It is helix-shaped (hence the name helicobacter) and can literally screw itself into the stomach lining to colonize.

Infection and diagnosis

Infection may be symptomatic or asymptomatic (without visible ill effects). It is estimated that up to 70% of infection is asymptomatic.

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The bacteria have been isolated from feces, saliva and dental plaque of infected patients, which suggests gastro-oral or faecal-oral as possible transmission routes.

Related Topics:
Feces - Saliva - Plaque

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It is estimated that about 2/3 of the world population are infected by the bacterium. Actual infection rates vary from nation to nation - the West (Western Europe, North America, Australasia) having rates around 25% and the Third World much higher. In the latter it is common, probably due to poor sanitary conditions, to find infections in children. In the United States, infection is primarily in the older generations (about 50% for those over the age of 60 compared with 20% under 40 years) and the poorest.

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This is largely attributed to higher hygiene standards and more widespread use of antibiotics. However antibiotic resistance is appearing in H. pylori. There are already metronidazole resistant strains present in the UK population.

Related Topics:
Antibiotic resistance - Metronidazole - UK

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In the absence of antibiotic based treatments, H. pylori infection apparently persists for life; the human immune system is not able to eradicate it.

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One can test for H. pylori infection with blood antibody or stool antigen tests, or with the carbon urea breath test (in which the patient drinks 14C- or 13C-labelled urea, which the bacterium metabolizes producing labelled carbon dioxide that can be detected in the breath), or endoscopy to provide a biopsy sample for testing for the presence of urease ('rapid urease test'), histology or microbial culture.

Related Topics:
Blood - Antibody - Antigen - Carbon urea breath test - ¹⁴C - ¹³C - Urea - Carbon dioxide - Endoscopy - Histology

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