Clostridium difficile infection laboratory findings: Difference between revisions
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===Enzyme-linked immunoabsorbant assay (ELISA) for toxin=== | ===Enzyme-linked immunoabsorbant assay (ELISA) for toxin=== | ||
Assessment of the A and B toxins by [[ELISA|enzyme-linked immunoabsorbant assay]] (ELISA) for toxin A or B (or both) has: | Assessment of the A and B toxins by [[ELISA|enzyme-linked immunoabsorbant assay]] (ELISA) for toxin A or B (or both) has: | ||
* [[sensitivity (tests)| | * [[sensitivity (tests)|Sensitivity]] 63-99% | ||
* [[specificity (tests)| | * [[specificity (tests)|Specificity]] 93-100% | ||
At a prevalence of 15%, this leads to: | At a prevalence of 15%, this leads to: | ||
* [[ | * [[Positive predictive value]] 73% | ||
* [[ | * [[Negative predictive value]] 96% | ||
Experts recommend sending as many as three samples to rule-out disease if initial tests are negative. ''C. difficile'' toxin should clear from the stool of previously infected patients if treatment is effective. | Experts recommend sending as many as three samples to rule-out disease if initial tests are negative. ''C. difficile'' toxin should clear from the stool of previously infected patients if treatment is effective. | ||
Unfortunately, many hospitals only test for the prevalent toxin A. Strains that express only the B toxin are now present in many hospitals and ordering both toxins should occur. Not testing for both may contribute to a delay in obtaining laboratory results, which is often the cause of prolonged illness and poor outcomes. | Unfortunately, many hospitals only test for the prevalent toxin A. Strains that express only the B toxin are now present in many hospitals and ordering both toxins should occur. Not testing for both may contribute to a delay in obtaining laboratory results, which is often the cause of prolonged illness and poor outcomes. | ||
===Other | ===Other Stool Tests=== | ||
Stool [[leukocyte]] measurements and stool [[lactoferrin]] levels have also been proposed as diagnostic tests, but may have limited diagnostic accuracy.<ref name=Vaishnavi_2000>{{cite journal |author=Vaishnavi C, Bhasin D, Kochhar R, Singh K |title=Clostridium difficile toxin and faecal lactoferrin assays in adult patients |journal=Microbes Infect |volume=2 |issue=15 |pages=1827-30 |year=2000 |pmid=11165926}}</ref> | Stool [[leukocyte]] measurements and stool [[lactoferrin]] levels have also been proposed as diagnostic tests, but may have limited diagnostic accuracy.<ref name=Vaishnavi_2000>{{cite journal |author=Vaishnavi C, Bhasin D, Kochhar R, Singh K |title=Clostridium difficile toxin and faecal lactoferrin assays in adult patients |journal=Microbes Infect |volume=2 |issue=15 |pages=1827-30 |year=2000 |pmid=11165926}}</ref> | ||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
[[Category:Disease]] | [[Category:Disease]] | ||
[[Category:Gastroenterology]] | [[Category:Gastroenterology]] | ||
[[Category:Needs overview]] | [[Category:Needs overview]] | ||
[[Category:Infectious disease]] | |||
{{WH}} | |||
{{WS}} | |||
Revision as of 17:34, 7 December 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Laboratory Findings
Cytotoxicity assay
C. difficile toxin detection as cytopathic effect in cell culture, and neutralized with specific anti-sera is the practical gold standard for studies investigating new CDAD diagnostic techniques. Toxigenic culture, in which organisms are cultured on selective medium and tested for toxin production remains the gold standard and is the most sensitive and specific test, although it is slow and labour-intensive.[1]
Enzyme-linked immunoabsorbant assay (ELISA) for toxin
Assessment of the A and B toxins by enzyme-linked immunoabsorbant assay (ELISA) for toxin A or B (or both) has:
- Sensitivity 63-99%
- Specificity 93-100%
At a prevalence of 15%, this leads to:
Experts recommend sending as many as three samples to rule-out disease if initial tests are negative. C. difficile toxin should clear from the stool of previously infected patients if treatment is effective.
Unfortunately, many hospitals only test for the prevalent toxin A. Strains that express only the B toxin are now present in many hospitals and ordering both toxins should occur. Not testing for both may contribute to a delay in obtaining laboratory results, which is often the cause of prolonged illness and poor outcomes.
Other Stool Tests
Stool leukocyte measurements and stool lactoferrin levels have also been proposed as diagnostic tests, but may have limited diagnostic accuracy.[2]
References
- ↑ Murray PR, Baron EJ, Pfaller EA, Tenover F, Yolken RH (editors) (2003). Manual of Clinical Microbiology (8th ed ed.). Washington DC: ASM Press. ISBN 1-55581-255-3 Check
|isbn=value: checksum (help).