Helicobacter pylori

Today’s post is about a type of bacteria known as Helicobacter pylori (H. pylori).  It can be ingested in childhood and reside in the stomach. In industrialised countries, about 20-50% of people will have this bacteria, and some of these people (not all) will get stomach inflammation and or peptic ulcers because of it. How is this bacteria able to survive in the stomach, and why do only some people develop further health conditions because of it?

The stomach is supposed to be this fantastic immunological barrier against all the potentially disease-causing things  you accidentally ingest, and protect the rest of the body due to its highly acidic pH. H. pylori have evolved in a certain way to overcome this. H. pylori have multiple flagella (like a tail), they can use to gain motility. This means that can move away from areas of the stomach that are REALLY acidic and go where it is less acidic, for example to the mucosa. They also have a protein called urease that allows them to hydrolyse its own urea, which increases its pH, which helps it survive in an acidic environment. H. pylori have a high mutation rate, combined with a cooperative system of sharing the DNA that is working well for some H. pylori, around with the rest of them. This enables more of the H. pylori population to have the tools necessary to live happily in the acidic stomach environment.

So why do some people get peptic ulcer disease, gastritis, or carcinomas because of H. pylori, whilst others don’t even know it is in their stomach? If some kind of damage occurs in the stomach (such as loss of blood flow, hyperacidity, consumption of alcohol or aspirin etc), this allows the H. pylori to overcome the normal defensive processes in place of the stomach walls, damage that first epithelial layer and cause an ulcer.

Treatment of peptic ulcers often involves a proton pump inhibitor (PPI), however this just reduces acidity by inhibiting gastric acid secretion. To actually cure the problem, there needs to be eradication of the H. pylori and therefore peptic ulcers, caused by H. pylori, need to be treated with antibiotics.

When you think about having bacteria in your stomach, causing ulcers and things, it doesn’t sound good, but there is something about H. pylori which is useful for us! By having that bacteria in your stomach, it protects you against invasion from other diseases. Because it is already populating that location, other pathogens are not able to.


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