Helicobacter Forums

Dear Dr Marshall
I read a post on another forum where a lady said that she had read in the Harvard Newsletter that there were a lot of false negatives in the detection of H. Pylori and this was partly due to the fact that there were many different strains of H Pylori. I would welcome your thoughts on this, particularly regarding this claim that there are many different strains. If there are so many strains do that standard tests pick up all of them?

Hi,

I can help Prof. Marshall with this question. All H. pylori strains have urease and hence, the chance of false positive using breath test due to different strains is almost zero. Urease is the reason why H. pylori can survive in the stomach. Urease is the enzyme that neutralize the acidic environment. without this enzyme, H. pylori simply cannot survive in the stomach.

however, it is true that there are many many strains of H. pylori. Almost every individual carry a unique strain. But this is not the reason for false positives. other methods such as gene detection or antigen detection is also very very rare for a false positive because of different strains.

re False negatives tests: Regardless of the strains, the serology (IgG) is usually quite sensitive - about 95%. For each country and age group there may be a preferred test. So a serology developed in USA might not be quite so accurate when used in Japan.
There are many strains of H.pylori, and each has about 10% of its genes different, but mostly they are very similar.
BJM