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Pseudomembranous colitis - Diagnosis
Medical expert of the article
Last reviewed: 04.07.2025
Study of toxin in cell culture
This method was the first to be introduced, but due to its complexity it is not used for routine diagnostics. In addition, the toxin is very unstable, being destroyed at room temperature within 2 hours after taking stool samples for testing. To avoid false negative results, if the sample is not tested immediately, it should be stored in the refrigerator.
Stool culture for isolation of Clostridium difficile
This requires anaerobic conditions, a special selective environment, and accurate identification of this genus of clostridia can be difficult, especially in small microbiological laboratories. In addition, false-positive test results may occur when strains of C. difficile that do not produce exotoxin are isolated. The results of laboratory testing can be obtained within 48-96 hours.
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Rapid diagnostics of pseudomembranous colitis
- Latex agglutination or immunochromatographic method for detecting C. difficile antigen. Rapid test (less than 1 hour) for detecting antigen. Must be used simultaneously with the exotoxin test.
- The enzyme immunoassay detects toxin A, toxin B, or both. Results can be obtained within a business day. It is less sensitive than the tissue culture cytotoxicity test and is suitable for hospital laboratories that do not use tissue culture or cannot isolate C. difficile from stool.
- Tissue culture cytotoxicity test. In principle, it is possible to determine only toxin B. The most expensive method, the test duration is 24-48 hours before the final result is obtained. It has low sensitivity and specificity, i.e. it cannot indicate that the cause of the disease was Clostridium difficile.
- PCR - the ability to determine toxins A and B is currently at the stage of scientific development.
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Endoscopy
This method is used in cases where it is necessary to differentiate diarrhea from another diagnosis that can be confirmed by endoscopy. Endoscopy reveals yellowish deposits in the distal colon, sometimes they can be located more proximally and can be missed during a regular sigmoidoscopy (10-30% of cases). Therefore, colonoscopy is considered a more adequate diagnostic method.
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CT scan of the abdominal cavity
It is performed in cases where colonoscopy is contraindicated, but there are no specific signs of colitis caused by C. difficile. Usually, indirect signs are considered to be thickening of the intestinal wall with filling of the bends with a contrast agent, which have a characteristic appearance (the "accordion symptom").
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Barium irrigoscopy
In severe cases, megacolon, perforations and other complications can be detected, but this method is considered unsafe and is therefore generally not recommended.