Bugs in the stomach

helicobacter from Wikipedia

Helicobacter pylori’s unconventional role in health and disease.:
[Via PLoS Pathogens]
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Helicobacter pylori’s unconventional role in health and disease.

PLoS Pathog. 2009 Oct;5(10):e1000544

Authors: Dorer MS, Talarico S, Salama NR

The discovery of a bacterium, Helicobacter pylori, that is resident in the human stomach and causes chronic disease (peptic ulcer and gastric cancer) was radical on many levels. Whereas the mouth and the colon were both known to host a large number of microorganisms, collectively referred to as the microbiome, the stomach was thought to be a virtual Sahara desert for microbes because of its high acidity. We now know that H. pylori is one of many species of bacteria that live in the stomach, although H. pylori seems to dominate this community. H. pylori does not behave as a classical bacterial pathogen: disease is not solely mediated by production of toxins, although certain H. pylori genes, including those that encode exotoxins, increase the risk of disease development. Instead, disease seems to result from a complex interaction between the bacterium, the host, and the environment. Furthermore, H. pylori was the first bacterium observed to behave as a carcinogen. The innate and adaptive immune defenses of the host, combined with factors in the environment of the stomach, apparently drive a continuously high rate of genomic variation in H. pylori. Studies of this genetic diversity in strains isolated from various locations across the globe show that H. pylori has coevolved with humans throughout our history. This long association has given rise not only to disease, but also to possible protective effects, particularly with respect to diseases of the esophagus. Given this complex relationship with human health, eradication of H. pylori in nonsymptomatic individuals may not be the best course of action. The story of H. pylori teaches us to look more deeply at our resident microbiome and the complexity of its interactions, both in this complex population and within our own tissues, to gain a better understanding of health and disease.


We are used to thinking about bacteria on our skin, in our mouths or in our intestines. However the ability for bacteria to not only live in the acid of our stomachs but to also cause disease was a huge paradigm shift for researchers.

Helicobacter pylori is just such an organism. The researchers (Marshall and Warren) that demonstrated that this organism was responsible for stomach ulcers not only one the Nobel prize but also took part in one the the great examples of self-experimentation in modern history.

In order to demonstrate that Helicobacter was responsible, Marshall drank a beaker of the bacteria. He became very ill within a few days and the presence of the bacteria was found in his stomach. A course of antibiotics not only reduced his gastritis but also removed the bacteria.

This story is one of the great examples of how researchers can go against conventional wisdom. They went up against dogma that people had learned for almost a century. They were originally ignored. They did very good, basic work, published in peer-reviewed journals, changed everyone’s minds and won the Nobel Prize.

Whenever anyone tries to say that there is a conspiracy of researchers preventing the truth from coming out, all I do is think of Marshall and Warren. If you have the data, if you are right, you will overcome any conventional wisdom. That is how science works,

And you could probably win the Nobel Prize and have your career set for life. Wouldn’t you think that some young hotshot out there would try to do just that?

But the key is that they have to have the data. Simply being contrarian will not work.

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