18/07/2025
Clostridium difficile Toxin Test
1. Objective
The objective of the test was to detect toxins A and/or B produced by Clostridium difficile in stool samples, which helped confirm the diagnosis of C. difficile-associated diarrhea or colitis.
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2. Principle
C. difficile releases enterotoxin A and cytotoxin B, which cause damage to the intestinal lining. The test used immunoassays (e.g., ELISA or rapid lateral flow) to detect these toxins in stool samples. Some tests also used nucleic acid amplification (NAAT) to identify the toxin genes.
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3. Materials
• Fresh stool sample
• C. difficile toxin ELISA kit or lateral flow test device
• Reagents: buffer, control solution, conjugate
• Micropipette
• Disposable stool applicators
• Test tubes or reaction wells
• Wash buffer, substrate, stop solution (for ELISA)
• Microplate reader (for ELISA)
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4. Procedure (Rapid Immunoassay / Lateral Flow)
1. A small amount of stool was mixed with buffer using a swab.
2. A few drops of the mixture were applied to the sample well of the test cassette.
3. The test was allowed to run for 15–20 minutes.
4. A colored line appeared to indicate the presence of toxin A and/or B.
5. For ELISA: multiple washing, incubation, and substrate steps were performed before reading absorbance.
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5. Result
• Positive: Detection of toxin A and/or B – Indicates active C. difficile infection
• Negative: No toxins detected – Less likely to be C. difficile-associated diarrhea
• Note: False negatives may occur if toxin degrades; testing should be done promptly after stool collection
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6. Uses
• Confirmed antibiotic-associated diarrhea or pseudomembranous colitis
• Guided isolation precautions and treatment decisions
• Aided in infection control surveillance in hospitals.
