Question about False Negative Test Results

[lawc30]

Hello all,
I have been here before when I was battling c. diff. last fall. I am well now and am even able to eat salads and Mexican with only a little heart burn! That is an answer to much prayer!

I am writing now for my grandmother. On August 11, she had a heart attack for which she was in the hospital for 15 days. She began having some pain under her rib cage that the doctors ascribed to a UTI and placed her on heavy antibiotics. She had some constipation, asked for a laxative and then began having D. This has continued for about 6 weeks now. One doctor was all but 100% sure that she had c. diff. and sent her home with Flagyl. My grandmother was unable to produce a stool sample while at the doctor's office, and the doctor sent the kit home with her. She took a dose of Flagyl before giving the sample, and the lab came up negative for c. diff.

Is it possible for one dose of Flagyl to give a false negative in anyone's experience? I know that my doctor was furious with me if I took a dose of Vancomycin when I feared a relapse before giving a sample because he said it could mess up the test. I didn't know if that early on with one dose of Flagyl could have the same effect.

My grandmother finished the round of Flagyl anyway. She is still having terrible D. and now blood as well, but she says the cramping has ceased and the terrible smell is gone, so she thinks it helped some. I am concerned that she may indeed have c. diff. and may not get proper treatment because of a false test result.

Thanks,
Laura

[ClDif]

Hi Laura,

yes, the flagyl could have influenced the test result, but even without that, the ELISA testing that is mostly done for c diff only has a sensitivity of 30 - 60%, depending on the type, so false negatives are very common with c diff. It is genereally recommended to hand in 3 stool samples for c diff rather than one, preferably from 3 different BMs. Making sure the sample gets examined within 4 hrs after collection also greatly maximises chances for an objective result. Also, make sure the lab tests for both toxin A and B.

Will your grandmother's doctors continue treatment without a positive sample? It might be a good idea to switch her to vancomycin which seems to work better for many people and hardly has any side effects... It is very expensive though, so your grandmother might want to double check with her insurance if it would be covered without a positive stool test. But at her age, I really wouldn't take any chances...

[feelinghopeful]

You're probably going to get swamped with answers from people who got false negatives even without having taken antibiotics first. Out of I don't know how many tests (9, 10? I have so lost count of everything at this point) I had over the course of close to 1.5 years I only had 3 or 4 positives, I think 3 but am being conservative. It's one of the frustrating and frightening things about trying to get treated properly. You have to use your gut feeling and don't give up if you really believe C-Diff is the culprit. My life would be miserable still if I hadn't persevered. I'm knocking on wood every time I even allude to having been cured. I guess it takes time to stop feeling that the anvil is always waiting to drop.

[lawc30]

Hi,
Thank you for the info. I also only had one positive test result over a course of 7 months, but was still having symptoms. My doctor was willing to treat me anyway because he understood more about it. He was an ID doctor. My grandmother's doctor seems to know nothing about it. He insists that a false negative is not possible or likely, and I am pretty sure that he has taken her off the Flagyl now. He is giving her another test, but she still has the flagyl in her system, and my gut tells me it will be negative as well. The doctor is planning on Vancomycin if it does come up positive.

Thanks for the advice about the stool samples...giving 3 and what to make sure they are testing for.

I am thankful that she is going to a GI doctor, but her appointment isn't until a week from today. That means another week of untreated c. diff. if it is indeed what she has.

Thanks again!
Laura

[cindym]

LAW- Given the age of your Grandmother there is no time to put up with ignorant doctors. Call around and find an experienced GI in your area that has dealt with cdiff. Older people are at higher risk of more severe fatal cases of cdiff as their immune systems are not as strong and they are more fragile. If a doctor will not take your word for it that "IT IS BACK" then move on. As a sufferer for more than 7 years I learned that lesson a long time ago to stop the constant near fatal hospitalizations. After a couple of relapses you KNOW when it is back and really a test is secondary. A good doctor should not allow an elderly person with cdiff history to have continual diarrhea just because of a negative test as they happen in many cases through lab error. I would demand she be put on meds!

[PJV1963]

This is a learn as you go process.My Mom's GP was afraid to start her on anything until the cultures came back, but, as so many have said,you KNOW when there is a relapse,if by nothing else, the smell!
Thankfully,her GI team is very experienced in treating C.Diff and they feel she is not as far gone as she was the last time. So far, the cultures have come back neg, but they are treating her as before.Flagyl made her worse,so back on Vanco and IV steroids.They are not going to mega dose her this time, in hopes that she will have an easier time tapering down than before.
It's funny, so many people are aware of MRSA and C.Diff is by far a more difficult bug to treat.Just does not have the same awareness that MRSA does. When people ask what Mom has, I simplify it and say it is the "new MRSA". That they understand,say C.Diff. and the majority of people have no idea what it is. Most have no idea what it is and only those who are affected by it know what it is.

[cindym]

Steroids I was told by infectious disease doctor was like giving fertilizer to the cdiff bacteria. I would question that treatment! I was told not to take steroids or anything similar unless it was forced.