C. difficile **Toxin A/B Detection by Nucleic Acid Amplification Probe (Qualitative)
This test checks for the presence of toxins produced by *Clostridium difficile* bacteria, which can cause severe diarrhea and gut inflammation.
["Detects harmful toxins linked to *C. difficile* infections, a common cause of antibiotic-related gut problems."]
Key facts at a glance
- LOINC
- 93403-4
- Short code
- Citrobac sp DNA Bld Pos Ql NAA+probe
- Synonyms
- Citrobac sp DNA Bld Pos Ql NAA+probe
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- probe-amp-tar
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Your doctor ordered this test to help check how your body is working and to look for signs of a medical condition that may need attention. The results give your care team important information that cannot be seen during a routine physical exam, which helps them make an accurate diagnosis and choose the treatment plan that is right for you.
Your doctor may order this test if you have symptoms like severe diarrhea, bloating, or abdominal pain—especially after taking antibiotics, which can disrupt healthy gut bacteria. It’s also used to confirm a *C. difficile* infection in people with unexplained diarrhea or colitis.
During the test, a small sample or measurement is collected so it can be examined in a laboratory or by specialized equipment. The sample is analyzed for specific markers that show how certain organs or systems in your body are functioning. Trained professionals review the data and send a report to your doctor, who will explain what the findings mean for you.
A small sample of your stool is tested using a probe that detects genetic material from *C. difficile* toxins A and B. The test is highly sensitive and doesn’t require culturing live bacteria.
Before your test, your care team will explain the procedure and answer any questions you may have. You may receive specific instructions, such as adjusting certain medications or avoiding some activities for a short time. Plan to arrive a little early, wear comfortable clothing, and bring a list of the medicines you currently take along with your insurance information.
No special preparation is needed. You may collect a stool sample at home or provide a sample during a doctor’s visit. Avoid using laxatives or stool softeners unless instructed, as they could affect results.
Test results are usually described as normal, borderline, or abnormal. A normal result generally means there are no signs of the condition being checked for. If your results are abnormal, it does not always mean you are seriously ill, and additional testing may be needed to understand why. Your doctor will contact you to discuss the findings and recommend next steps, which may include follow-up visits, further tests, or starting a treatment plan.
A positive result means toxins are present, strongly suggesting a *C. difficile* infection. A negative result means no toxins were found, but other causes of diarrhea may still exist. Follow your doctor’s advice for further testing or treatment.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
C. difficile Toxin Test
Frequently asked questions
This test is critical for diagnosing *C. difficile* infections, which can cause life-threatening complications like severe dehydration, bowel damage, or even death if untreated. Early detection allows for prompt treatment with antibiotics or other therapies to reduce symptoms and prevent complications.
A positive result confirms the presence of *C. difficile* toxins in your stool, indicating an active infection. Your doctor will likely recommend treatment with antibiotics (like vancomycin or fidaxomicin) to kill the bacteria and reduce toxin production.
Yes, you can eat and drink normally before the test unless your doctor specifies otherwise. Avoid using stool softeners or laxatives unless instructed, as they may interfere with the test results.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy