Faecal Transplant & Antibiotics for CDAD
Antibiotics
Whilst a wide range of antibiotics are known to place patients at risk of C. difficle related diarrhoea (CDAD) by virtue of their detrimental effects on the wider colonic microbiome a number of antibiotics are used to treat the disease. Unfortunately drug resistance is common and the further depletion of the colonic microbiome to perhaps 300 to 400 species, by the repeated administration of antibiotics may put patients at further risk. It is believed that in patients who relapse soon after completing antibiotic treatment the risk of relapse often relates to a failure of the normal colonic diversity, of perhaps 500 to 1500 specie, to return.
Whilst a wide range of antibiotics have been used to treat CDAD, including rifaximin, three drugs remain in common usage across the world. These are metronidazole, vancomycin and fidaxomicin. Metronidazole in most countries is cheap ( a few pounds)and a ten day course can be expected to achieve cure in 70% of patients. Vancomycin is more expensive and achieves remission in approximately 85% of cases, though a proportion may relapse within 30 days. Fidaxomicin is expensive in many countries, with a course costing over £1000 in the UK. Fidaxomicin achieves remission in a similar number of patients to vancomycin, but relapse rates may be lower.
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Faecal Transplant
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Faecal transplantation for C. difficile related diarrhoea
C. difficile
C. difficile is a bug which lives in the gut of approximately 5% of healthy individuals, usually with several thousand other species (types) of bugs. Unfortunately when some patients receive antibiotics or chemotherapy the balance of bugs within the gut is disturbed and there is an overgrowth of C. difficile, which then leads to symptoms. In more severe cases infections with C. difficile may cause serious, life threatening or recurrent illness.
Faecal Microbiota Transplantation (FMT)
Whilst initial treatment of C. difficile is usually with antibiotics for those with recurring infection faecal microbiota transplantation is sometimes considered. This aims to restore the balance of healthy bacteria within the gut by donating a suspension of a donor’s stool and the associated bugs to the patient with C. difficile related diarrhoea (recipient).
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Donors
Donors may be relatives or unrelated to the recipient. All donors should be tested for a wide array of bacterial and parasitic infections this requires them to provide blood tests and a stool test. In the UK all stools should now be provided via an MHRA registered stool bank. Prospective donors with risk factors for HIV and viral hepatitis are excluded from donating. Those with significant gastrointestinal or autoimmune disease, or with a history of cancer are not acceptable donors. Donors who meet the criteria undergo blood testing for a range of infectious diseases, including HIV, hepatitis A, B and C, and syphilis. Ideal donors also have a healthy diet and lifestyle.
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Why should I have FMT (recipients)?
Clostridium difficile infection can often return following apparently successful treatment. After one episode of Clostridium difficile infection, there is a one in four or one in five (20–25%) chance that it will come back. Patients who have had C. difficile related diarrhoea more than once are at even greater risk of recurrence. Treating recurrent episodes of Clostridium difficile can be difficult, as the standard antibiotic therapy becomes less effective. In such cases FMT may be indicated. FMT has approximately a 90% success rate in treating recurrent C. difficile infection.
What are the risks?
Stool is considered to be a bodily fluid, so it is essential that thorough donor screening and testing is carried out. Donors complete a screening questionnaire similar to those used at blood banks and for organ or tissue transplants. Whilst donor stools are screened for agents, which are known to cause disease there is a small risk that the donor may carry a disease which is not identified. You will be asked to sign a consent form acknowledging the risks of undergoing a colonoscopy or flexible sigmoidoscopy if the stool is being delivered by this route, alternatively you may be offered oral or nasogastric routes. As well as theoretical risks related to the faecal transplant itself (infection, allergic or immune reaction, or other disease transmissions) there are some risks associated with such procedures as endoscopy and NG tube insertion.
Faecal Transplant for other conditions
In general faecal transplant for other disease is not indicated except within the context of properly constructed clinical trials.
To date trials in inflammatory bowel disease have suggested marginal benefit, which appears to be largely conferred by one or two members of the donor community whose faeces confer a benefit not apparent in other donor’s stools It is likely that this reflect the metabolic product of one of the strains within their microbiome. As yet which strains confer benefit is not clearly elucidated, but it is known that certain strains are more prevelant during remission of disease and other strains more prevalent during relapse. For example numbers of Faecalibacterium prausnitzii drop dramatically prior to relapse and recover as patients with Crohn’s disease are going into remission.
Trials in irritable bowel syndrome are few, at last count in October 2018, there were 7 properly constructed randomised studies and the best two of these suggested that faecal transplant may actually cause harm in more patients than it benefits.