DNA Testing of Stool for Bacterial and Parasitic Markers – Unanswered Questions

The latest lab test being marketed heavily is a DNA Stool test for bacterial and parasites. While the theory of testing for pathogens using their DNA signatures sounds real good, is it necessarily ready for use, especially as a way of determining treatment protocols?  I for one am not sold on the idea yet.

A couple of issues come up that I haven’t heard adequate answers for.  Here are my main problems with this test:

  • If we find the DNA for a bug, yet it was dead before we ingested it, does this warrant treatment?  Obviously no but how do the labs determine if it is alive or not. An answer I heard was that they deal with it but how?  I’d be interested in knowing.
  • If our body already is dealing with a bacterial or parasitic pathogen and the DNA is picked up, do we deal with it or not?  Remember, overuse of antibiotics or other medications may lead to the development of resistant strains.
  • How accurate and specific is the test? I have not been convinced that it is that accurate as the DNA of pathogenic bacteria is often times very similar to non-pathogenic ones.
  • Quantification of bacteria and parasites is another issue. Does the lab have anyway of saying that the bacteria level is high, low, normal or not. There is a claim that there is a developed reference range but how? What if the infection level is high but not much DNA sloughs off?  What if a lot of DNA from a particular bug is found but there isn’t a high level of infection?

These issues do happen according to the literature I have reviewed so are we ready for the clinical use of this test or do we need more research? My feeling is that more research is needed before we abandon the gold-standard of stool testing, which is culturing. Why drop a very well respected and time-tested methodology for something that has not been shown to actually be superior?  This is akin to trying Nexium® because it has a 3% better efficacy than Prilosec® but is 10 times more expensive.

Another issue I have is that when we treat for a bacteria or parasite, the treatment often times kills more than just the specified “enemy”. When we use antibiotics or even natural treatments, we run the risk, and often times do, kill both beneficial and pathogenic species. Caution is the concept to remember here. The beneficial bacteria are extremely important in a healthy immune response, detoxification of xenobiotics, creation of nutients from food and more.

The use of genetic testing is a sexy concept but some labs seem to be way ahead of the practicality curve here. Just because a test is new and is accompanied by hot marketing doesn’t mean it’s time to abandon what works.

I would be real interested in hearing from the experts who claim DNA stool testing is the best and how they would respond to my concerns.

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