Helicobacter Pylori and Ulcers

I was having an interesting discussion with a microbiology student this morning about ulcers. This is how she explained them to me.

We all have helicobactor pylori in our stomachs. It is the bacterium known to cause stomach ulcers. It also causes ulcers in the duodenum. For some reason, people who get one type of ulcer do not get the other.

Getting stomach ulcers is a risk factor for stomach cancer.

It is not yet understood exactly why some people get ulcers and some don't. The mechanism by which they occur is understood as follows:

The helicobactor pylori rely on stomach acid to activate the enzyme 'urease' which they need in order to digest urea. However, to digest the urea they need an acid free environment. To achieve this, they physically burrow into the mucosa, which is the epithelial lining of the stomach. They use their flagella to propel themselves. The mucosa protects the stomach from it's acidic contents. It is the physical damage caused to it by the burrowing helicobactor pylori that allows the acid to get through this protective layer and cause harm to other tissues, thus causing an ulcer.

That is her explanation as I understood it and I'm pretty sure that it's a well accepted one based on her university textbooks, so  I have no reason to question it, but please comment if you know anything further or if I have misunderstood.

Traditionally people have associated ulcers with stress. In the past, doctors have even advised patients with ulcers to avoid stress. The problem with this is that there is no known correlation between stress and either the thickness of the mucosa or the concentration of helicobactor pylori. This means that stress is unlikely to actually be a contributing factor.

Perhaps there is a competitive relationship between Helicobactor pylori and other microbes that inhabit the stomach. That was the first though that occurred to me. Or perhaps the body's ability to regulate the thickness of the mucosa could be impaired somehow, perhaps, for example, through some form of deficiency? Further research will no doubt be required before ulcers can be fully understood and treated.