Clostridium difficile Toxin A and B Quantitative Culture
This test detects the presence of *Clostridium difficile* toxins A and B in your stool, which can cause severe diarrhea and intestinal inflammation. It also involves growing the bacteria in a lab to confirm infection.
["Helps diagnose *Clostridium difficile* infection, a common cause of antibiotic-related diarrhea."]
Key facts at a glance
- LOINC
- 562-9
- Short code
- CDIFCULT
- Synonyms
- C diff Stl Ql Cult
- Category
- chemistry
- Sample
- stool
- Container
- Sterile, leak-proof, wide-mouth container with screw-cap lid; anaerobic transport swab or stool culture transport system (e.g., Cary-Blair medium) for culture preservation; do not use preservative tubes (such as those containing formalin or PVA) intended for parasitology
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- organism-specific-culture
- CPT
- 87081
- SNOMED
- 121000599106
- Specimen volume
- 5-10 grams of fresh stool (approximately 1-2 teaspoons); a minimum of 1-2 mL of liquid stool or 5 g of formed stool is generally required. Rectal swabs are acceptable alternatives in patients unable to produce stool, particularly in cases of ileus.
- Stability
- Unpreserved stool: room temperature (20-25°C) for up to 2 hours; refrigerated (2-8°C) for up to 24-48 hours (preferably process within 24 hours). In anaerobic or Cary-Blair transport medium: room temperature up to 24-48 hours; refrigerated (2-8°C) up to 72 hours. Do not freeze. Specimens delayed beyond recommended stability may yield false-negative results due to organism die-off.
- TAT
- 48–120 hours
- Order
- routine
Why This Test Is Done
Your doctor may recommend this test if you have symptoms like severe diarrhea, abdominal pain, or fever—especially after taking antibiotics, which can disrupt healthy gut bacteria. It’s also used in hospital settings to monitor patients with recurrent infections.
What to Expect Before the Test
No special preparation is needed. Bring any medications you’re taking, as some antibiotics may affect results. Avoid certain foods or supplements (like probiotics) that could interfere with testing, but check with your provider first.
How the Test Works
A small sample of your stool is collected and sent to a lab. The sample is tested for toxins A and B using a specialized culture method to identify *Clostridium difficile* bacteria. Results confirm whether the bacteria are producing harmful toxins.
What the Results Mean
Positive results indicate the presence of *Clostridium difficile* toxins, which can lead to infection. Negative results mean no toxins were detected, but further testing (like a stool antigen test) may still be needed to rule out other causes of symptoms.
Reference range
Negative for Clostridioides difficile by culture. Culture is generally considered positive when toxigenic C. difficile is isolated; however, recovery of the organism by culture alone does not differentiate toxigenic from non-toxigenic strains. Results should be interpreted in conjunction with clinical findings, stool consistency (typically only unformed/loose stools are tested), and patient history including recent antibiotic exposure.N/A
No fasting required. Patient should ideally not be on anti-diarrheal medications (e.g., loperamide, diphenoxylate/atropine) prior to specimen collection as these may interfere with recovery of the organism. Specimens should be collected before initiating empirical anti-C. difficile antibiotic therapy (e.g., metronidazole, vancomycin, fidaxomicin) whenever possible. Patients should avoid contaminating stool with urine or toilet water. Inform laboratory if patient has been hospitalized, resides in a long-term care facility, or has a recent history of antibiotic use within the past 8 weeks.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
C. diff Toxin Test (Culture-Based)
Frequently asked questions
How often do I need this test?
What are the most common symptoms of *Clostridium difficile* infection?
Can I prevent *Clostridium difficile* infection?
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 15, 2026. · Read our editorial policy