false negative on breath test

[cartz]

Hello,

I was diagnosed with h.pylori via a blood test and was treated with HP7 treatment in Nov 2011. I had a breath test in late February to confirm eradication which returned a negative result.

As my symptoms were still a problem I decided to have a DNA sequencing stool test in March to see if there were other parasites (the Metametrix GI Profile).

The stool test came back positive for h.pylori.

What is the likely reason for my negative breath test? I had not taken any medication since the HP7 treatment. Could it be my system or the strain of h.pylori that the breath test isn't working for? Or is it hit and miss? If I had another breath test would you expect that to be positive or still negative?

I need to go back and see my doctor to arrange the next treatment phase. Should I have another breath test before treatment to see if it picks up the h.pylori? What course of treatment do you recommend now (I am in Tasmania, Australia).

Thanks,

cartz.

[Helico_expert]

it is interesting to know that your stool test came back positive for H. pylori DNA. I do suggest you go for another breath test before any more treatment. Breath test will only fail if
1. you took PPI and your acid is too high to make the breath test work.
2. your bacteria load is too low to make breath test positive.

do you know how negative is your breath test result in February? perhaps it is a borderline negative.

DNA test generally has higher false positives than breath test.

[cartz]

Thanks.

I had not taken a PPI for over 2 months before I took the last breath test.

I will arrange for another breath test with my doctor this week.

I don't understand how a DNA stool test can show up a false positive. If there is h.pylori DNA present then surely that means there is h.pylori present. The test come up with a high amount of h.pylori DNA.

I will find out how negative the test was.

[Helico_expert]

it depends how they detect H. pylori using stool test. my personal opinion is, DNA testing may be too sensitive, any DNA that is similar to H. pylori will be scored as positive.

[cartz]

I went back to the doctor and she felt another breath test was unnecessary due to the stool test result. The stool test was not the standard stool test done in Australia. It was sent to the Metamatrix labs in the US for a complete DNA stool profile. Personally I am comfortable with this as if DNA was prone to false positives then the legal system would be in a mess. The stool test can be found at http://www.metametrix.com/test-menu/pro ... gi-effects

However, I am a little concerned about the prescription my doctor has written and have posted in the Treatments part of the forum with a question on that.

One other thing, perhaps the reason for the negative on the breath test is that I am eating an extremely low fibre diet to control my symptoms. As it helps so much with my symptoms it seems logical that it would keep numbers of h.pylori down and hence the breath test may not pick them up. As soon as I start adding fibre my symptoms go crazy.

[barjammar]

Re value of stool test (? using DNA) and urea breath test (UBT): I can't see the type of test used for the Metametrix panel of pathogens. PCR/DNA on stool is problematic but maybe they have a very good validated test. Stool antigen is the usual test and that is close to the accuracy of the UBT. As backup, ask to have a serology for H.pylori. In cured patients it returns negative or is on the way to returning to a low value. This is useful if past tests showed it to be very high. The rule I use is that if there are two conflicting tests (in your case UBT and stool test), repeat the tests or use another accurate test to adjudicate. Its a waste of time and effort to treat non-existent H.pylori, and it delays the investigation and treatment of something else causing the symptoms (sometimes). But not everyone has a complete symptom cure after H.pylori eradication. Acid reflux, irritable bowel (whatever that is??!) etc. can still be present.