Helicobacter pylori

Helicobacter pylori colonises the gastric mucosa of many people, usually without complaints. The bacterium produces urease, neutralises stomach acid locally and causes chronic gastritis. Is looked at with gastric ulcers and chronic gastritis (type B). Straightforward detection by stool antigen test.

How Helicobacter pylori lives in the stomach

Helicobacter pylori is a spiral-shaped bacterium with several flagella. It would not survive long in the acidic stomach contents; it therefore swims purposefully into the mucus layer that covers the stomach wall and is less acidic towards the lining. There it attaches with adhesion proteins to sugar structures on the stomach cells. It is usually acquired in childhood, mainly within the family via saliva or stool. Unless it is specifically eliminated, colonisation generally persists for life.

How Helicobacter pylori affects the stomach lining and the immune system

Many strains inject the protein CagA into the stomach cells through a fine protein channel. CagA alters their signalling pathways, cell shape and division and stimulates them to release the messenger interleukin-8, which attracts neutrophil granulocytes. The toxin VacA forms pores in the cells and slows T cells down. The lining becomes permanently inflamed, yet the defences cannot eliminate the germ: it sits in the mucus layer out of their reach and also promotes regulatory T cells that dampen the immune response. The result is a balance between persistent inflammation and ongoing colonisation.

What happens with long-term Helicobacter pylori colonisation?

What follows depends on where the inflammation sits. If it mainly affects the lower part of the stomach, the restraining hormone somatostatin falls there, gastrin rises and the stomach produces more acid – which favours ulcers in the duodenum. If it affects the body of the stomach, acid-producing cells perish; the lining can shrink and remodel into intestine-like tissue. This explains the raised risk of stomach cancer and of MALT lymphoma; the WHO classifies the germ as carcinogenic. Most people who are colonised, however, never become ill. That absence of the germ goes along with more reflux complaints or asthma has been observed in studies, but is disputed.

The interpretation is given in your report.