What does c diff antigen positive mean

Q: How long does C. diff antigen stay positive?

Up to 50% of patients have positive C diff PCR for as long as six weeks after the completion of therapy. Therefore, signs and symptoms rather than repeat testing should be used to assess whether a patient has responded to therapy for C. diff.

Q: Is C. diff antigen contagious?

Is C. diff contagious? Yes, but most healthy adults who come in contact with C. diff wont get sick.

Q: What does positive C. difficile GDH antigen mean?

If the result is GDH positive a second test is performed to look for toxins that are produced when C. diff is causing an infection. If the second stage of testing shows you do not have the toxins present, this means you do not have a C. diff infection, but you carry the C. diff bacteria in your bowels.

Q: What happens when you test positive for C. diff?

If your results were positive, it means your symptoms are likely being caused by C. diff bacteria. If you are diagnosed with a C. diff infection and are currently taking antibiotics, you will probably need to stop taking them.

Specimens will be rejected from patients who were administered laxatives in the previous 48 hours. Specimens less than 7 days from a negative result or 14 days from a positive result will be rejected. Rejection criteria do not apply to outpatient specimens.

Table of Contents Show

What is it used for?
Why do I need C. diff testing?
What happens during C. diff testing?
Will I need to do anything to prepare for the test?
Are there any risks to testing?
What do the results mean?
Is there anything else I need to know about C .diff testing?
Related Health Topics
Related Medical Tests
How long does C. diff antigen stay positive?
Is C. diff antigen contagious?
What does positive C. difficile GDH antigen mean?
What happens when you test positive for C. diff?

4 hours (upon receipt in laboratory)

This is a cascading test, where a positive PCR for C. difficile toxin genes is followed with antigen testing for toxins A and B to establish gene expression consistent with active C. difficile disease.

There are three typical outcomes of testing:
1) PCR negative: C. difficile not detected, no further testing performed.
2) PCR positive, toxin antigen negative: Most consistent with C. difficile colonization rather than infection, although infection is possible.
3) PCR positive, toxin antigen positive: Consistent with active C. difficile infection.

It is generally recommended that C. difficile toxin screen be performed only for patients with > 3 liquid stools within a 24 hour period. Since C. difficile colonization rather than infection may exist, only unformed stool specimens from patients with signs and symptoms of C. difficile infection should be tested. The significance of Clostridium difficile and C. difficile toxin detection in infants (<1 year old) is uncertain because of the high rate of asymptomatic C. difficile carriage in this age group.

Once a patient is diagnosed with C. difficile infection, therapeutic response should be based on clinical signs and symptoms; a "test of cure" should not be done since patients may remain colonized with toxin producing strains following recovery.

PCR for C. difficile toxin via Cepheid C. difficile/Epi AND Rapid Membrane Enzyme Immunoassay for the simultaneous Detection of Clostridium difficile Glutamate Dehydrogenase Antigen and Toxins A and B; C. Diff Quick Chek Complete (Alere). The C. difficile GDH result is not reported as it is redundant to C. difficile PCR.

C. diff testing checks for signs of a C. diff infection, a serious, sometimes life-threatening disease of the digestive tract. C. diff, also known as C. difficile, stands for Clostridium difficile. It is a type of bacteria found in your digestive tract.

There are many types of bacteria that live in your digestive system. Most are "healthy" or "good" bacteria, but some are harmful or "bad." The good bacteria help with digestion and control the growth of bad bacteria. Sometimes, the balance of good and bad bacteria gets upset. This is most often caused by some types of antibiotics, which can kill both good and bad bacteria.

C. diff is not normally harmful. But when the bacteria in the digestive system get out of balance, C. diff bacteria can grow out of control. When C. diff gets overgrown, it makes toxins that are released into the digestive tract. This condition is known as a C. diff infection. A C. diff infection causes symptoms that range from mild diarrhea to life-threatening inflammation of the large intestine. It is especially dangerous to people with weakened immune systems.

C. diff infections are most often caused by the use of certain antibiotics. But C. diff can also be contagious. C. diff bacteria are passed into stool. The bacteria can spread from person to person when a someone with an infection doesn't thoroughly wash their hands after a bowel movement. They may then spread the bacteria to food and other surfaces they touch. If you come in contact with a contaminated surface and then touch your mouth, you may get the infection.

Other names: C. difficile, Clostridium difficile, Glutamate dehydrogenase test GDH Clostridioides difficile, C. difficile toxin test

What is it used for?

C. diff testing is most often used to find out if diarrhea is being caused by C. diff bacteria.

Why do I need C. diff testing?

You may need C. diff testing if you have any of the following symptoms, especially if you've recently taken antibiotics.

Watery diarrhea three or more times a day, lasting for more than four days
Abdominal pain
Nausea and vomiting
Loss of appetite
Blood or mucus in the stool
Weight loss

You are more likely to need C. diff testing if you have these symptoms, along with certain risk factors. You are at higher risk for getting a C. diff infection if you:

Are aged 65 or older
Live in a nursing home or health care facility
Are a patient in a hospital
Have inflammatory bowel disease or other disorder of the digestive system
Recently had gastrointestinal surgery
Are getting chemotherapy for cancer
Have a weakened immune system
Had a previous C. diff infection

What happens during C. diff testing?

You will need to provide a sample of your stool. Testing may include tests for the C. diff toxins, bacteria, and/or genes that make the toxins. But all tests can be performed on the same sample. Your provider will give you specific instructions on how to collect and send in your sample. Your instructions may include the following:

Put on a pair of rubber or latex gloves.
Collect and store the stool in a special container given to you by your health care provider or a lab.
If you have diarrhea, you can tape a large plastic bag to the toilet seat. It may be easier to collect your stool this way. You will then put the bag into the container.
Make sure no urine, toilet water, or toilet paper mixes in with the sample.
Seal and label the container.
Remove the gloves, and wash your hands.
Return the container to your health care provider as soon as possible. C. diff toxins may be harder to find when stool is not tested quickly enough. If you are unable to get to your provider right away, you should refrigerate your sample until you are ready deliver it.

Will I need to do anything to prepare for the test?

You don't need any special preparations for C. diff testing.

Are there any risks to testing?

There is no known risk to having C. diff testing.

What do the results mean?

If your results were negative, it probably means your symptoms are not being caused by C. diff bacteria, or that there was a problem with testing your sample. Your health care provider may retest you for C. diff and/or order more tests to help make a diagnosis.

If your results were positive, it means your symptoms are likely being caused by C. diff bacteria. If you are diagnosed with a C. diff infection and are currently taking antibiotics, you will probably need to stop taking them. Other treatments for a C. diff infection may include:

Taking a different type of antibiotics. Your provider may prescribe antibiotics that target C. diff bacteria.
Taking probiotics, a type of supplement. Probiotics are considered "good bacteria." They are helpful to your digestive system.

If C. diff infections keep returning after you've been treated, your provider may recommend a fecal microbiota transplantation (FMT). It's also known as stool transplantation. In this procedure, stool from a healthy donor is transplanted into your colon. Research has shown that FMT is very successful in treating recurrent C. diff infections. It has not been approved by the Food and Drug Administration (FDA). So it is still considered experimental. You can talk with your provider about whether this is an option for you.

If you have questions about your results and/or treatment, talk to your health care provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about C .diff testing?

Clostridium difficile has been renamed Clostridioides Clostridioides difficile. But the older name is still frequently used. The change does not affect the commonly used abbreviations, C. diff and C. difficile.

References

Familydoctor.org [Internet]. Leawood (KS): American Academy of Family Physicians; c2019. Clostridium difficile (C. diff) Infection; [updated 2017 Oct 6; cited 2019 Jul 6]; [about 2 screens]. Available from: https://familydoctor.org/condition/clostridium-difficile-c-diff-infection
Harvard Health Publishing: Harvard Health Medical School [Internet]. Boston: Harvard University; c2010-2019. Can gut bacteria improve your health?; 2016 Oct [cited 2019 Jul 16]; [about 3 screens]. Available from: https://www.health.harvard.edu/staying-healthy/can-gut-bacteria-improve-your-health
Harvard Health Publishing: Harvard Medical School [Internet]. Boston: Harvard University; 2010-2020. Stool transplants are now standard of care for recurrent C. difficile infections; 2019 May 9 [cited 2020 Aug 3]; [about 3 screens]. Available from: https://www.health.harvard.edu/blog/stool-transplants-are-now-standard-of-care-for-recurrent-c-difficile-infections-2019050916576
Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Clostridial Toxin Assay; p. 155.
Johns Hopkins Medicine [Internet]. Baltimore: The Johns Hopkins University; c2020. Fecal Transplantation (Bacteriotherapy); [cited 2020 Aug 3]; [about 3 screens]. Available from: https://www.hopkinsmedicine.org/gastroenterology_hepatology/clinical_services/advanced_endoscopy/fecal_transplantation.html
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Clostridium difficile and C. diff Toxin Testing; [updated 2019 Jun 7; cited 2019 Jul 6]; [about 2 screens]. Available from: https://labtestsonline.org/tests/clostridium-difficile-and-c-diff-toxin-testing
Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2019. C. difficile infection: Diagnosis and treatment; 2019 Jun 26 [cited 2019 Jul 6]; [about 4 screens]. Available from: https://www.mayoclinic.org/diseases-conditions/c-difficile/diagnosis-treatment/drc-20351697
Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2019. C. difficile infection: Symptoms and causes; 2019 Jun 26 [cited 2019 Jul 6]; [about 3 screens]. Available from: https://www.mayoclinic.org/diseases-conditions/c-difficile/symptoms-causes/syc-20351691
National Institute of Diabetes and Digestive and Kidney Diseases [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Your Digestive System and How it Works; 2017 Dec [cited 2019 Jul 6]; [about 3 screens]. Available from: https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works
Saint Luke's [Internet]. Kansas City (MO): Saint Luke's; What Is C. diff?; [cited 2019 Jul 6]; [about 2 screens]. Available from: https://www.saintlukeskc.org/health-library/what-c-diff
UF Health: University of Florida Health [Internet]. Gainesville (FL): University of Florida Health; c2019. Stool C difficile toxin: Overview; [updated 2019 Jul 5; cited 2019 Jul 6]; [about 2 screens]. Available from: https://ufhealth.org/stool-c-difficile-toxin
University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Clostridium Difficile Toxin (Stool); [cited 2019 Jul 6]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=clostridium_difficile_toxin_stool
UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2019. Health Information: Clostridium Difficile Toxins: How It Is Done; [updated 2018 Jun 25; cited 2019 Jul 6]; [about 5 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/clostridium-difficile-toxins/abq4854.html#abq4858
UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2019. Health Information: Clostridium Difficile Toxins: Test Overview; [updated 2018 Jun 25; cited 2019 Jul 6]; [about 2 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/clostridium-difficile-toxins/abq4854.html#abq4855
Zhang YJ, Li S, Gan RY, Zhou T, Xu DP, Li HB. Impacts of gut bacteria on human health and diseases. Int J Mol Sci. [Internet]. 2015 Apr 2 [cited 2019 Jul 16];16(4):7493-519. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425030

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The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.

How long does C. diff antigen stay positive?

Up to 50% of patients have positive C diff PCR for as long as six weeks after the completion of therapy. Therefore, signs and symptoms rather than repeat testing should be used to assess whether a patient has responded to therapy for C. diff.

Is C. diff antigen contagious?

Is C. diff contagious? Yes, but most healthy adults who come in contact with C. diff won't get sick.

What does positive C. difficile GDH antigen mean?

If the result is GDH positive a second test is performed to look for toxins that are produced when C. diff is causing an infection. If the second stage of testing shows you do not have the toxins present, this means you do not have a C. diff infection, but you carry the C. diff bacteria in your bowels.