Helicobacter pylori is a bacterial pathogen capable of infecting the stomach, increasing the risk of stomach ulcers and subsequently gastric cancers.
On infection, normally by an oral route, H. pylori enters the stomach mucus. Here, urease is secreted to break down the mucus and provide a more hospitable pH for growth. This allows stomach acid (pH 2-3) to reach the gastric epithelium, causing inflammation and ultimately the formation of an ulcer. Needle proteins are used to insert virulence factors into the cells H. pylori has adhered to.
The pain from the formation of ulcers can be decreased by using proton pump inhibitors (such as omeprazole). Antibiotics can also be used, but this is not always effective.
H. pylori can infect asymptomatically. In countries with less developed healthcare systems, these infections are very common (~80% of the population). It is thought H. pylori may provide some protection against gastro-oesophageal reflux disease (GERD), and act as a commensal.