Antibiotic Associated Diarrhoea and Clostridium Difficile

Antibiotic Associated Diarrhoea and Clostridium Difficile

Clostridium Difficile is found in the gut as part of our normal microbiota. When an individual has been taking a course of antibiotics and gets diahrea, it’s possible that C.diff is the cause; antibiotics may reduce the number of commensal bacteria which benefits the establishment of the opportunistic C.diff. ‘Clostridium difficile is a spore-forming Gram-positive rod shaped anaerobic bacillus that produces exotoxins, and is a common cause of antibiotic-associated diarrhoea (AAD)’[i]. These toxins can cause a number of diseases;Pseudomembranous colitis was first described as a complication of C. difficile infection in 1978 when a toxin was isolated from patients suffering from pseudomembranous colitis and Koch’s postulates were met such as Pseudomembranous colitis ‘which was first described as a complication of C.diff infection in 1978 when a toxin was isolated from patients suffering from pseudomembranous colitis and Koch’s postulates were met’[ii]. Pseudomembranous colitis was first described as a complication of C. difficile infection in 1978,[6] when a toxin was isolated from patients suffering from pseudomembranous colitis and Koch’s postulates were met

I am hypothesising that C.diff is a cause of AAD, as a number of tests can be carried out to prove this and Koch’s postulates are met.

Firstly, a large amount of C.diff is found in those individuals who are thought to have AAD (stool samples). It is key that C.diff is found in abundance in these individuals, as it is likely that C.diff would also be found in the stool samples of healthy individuals, since it’s  part of the normal microbiota. This can be tested using isolation methods from a stool specimen which is then examined for the presence of C. diff toxin (So C.diff could be isolated and grown in a pure culture) by using a cytotoxicity assay; a specific test for C.diff to look for the presence of toxins that are produced based on the fact that these toxins produce visible damage to cells maintained in tissue culture[iii] (as opposed to just taking a stool culture and looking for C.diff – this could provide us with misleading results/false positive due to the presence of non-toxigenic C.diff strains).

If this cultured C.diff sample is taken from the infected individual and introduced back into a healthy person, it is expected it would cause the healthy individual to have the same symptoms; not because of the C.diff (as the individual would already have a small amount of C.diff in the make up of their microbiota) but because of an abundance of C.diff. If this investigation was to be carried out, because we are investigating AAD, the individual could then be given a certain course of antibiotics, so as to reduce the numbers of other bacterium in their gut which would cause this opportunistic pathogen to thrive and produces it’s symptoms. Re-isolation of C.diff would then be carried out from this diseased experimental host’s stool sample and the toxins produced would be the same as those discovered when carrying out the cytotoxicity assay of the original sample of the infected individual.

So identification methods include immunologic tests, cytotoxicity tests.

If positive, it is known that C.diff toxin is causing the disease. If negative, colonoscopy tests could be carried out to inspect the patients colon.[iv]

Once C.diff toxin is the known cause of AAD, treatment can follow which can involve stopping the course of antibiotics.

 

 

 

 

 

 

 

 

 

 

 

 

 

[i] http://www.cdc.gov/hai/organisms/cdiff/cdiff_faqs_hcp.html. Accessed: 27/11/2013.

[ii] http://askville.amazon.com/Diff-Bacteria/AnswerViewer.do?requestId=9191771

[iii]http://www.health.harvard.edu/newsletters/Harvard_Mens_Health_Watch/2010/June/clostridium-difficile-an-intestinal-infection-on-the-rise

[iv]http://www.health.harvard.edu/newsletters/Harvard_Mens_Health_Watch/2010/June/clostridium-difficile-an-intestinal-infection-on-the-rise

 

 

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