Question 1

With respect to Clostridium Difficile (CD) colitis:

  1. List five risk factors for infection. (10% marks)
  2. What infection control measures would you take in a patient diagnosed with CD?  (30% marks)
  3. Outline the approach to diagnosis and pharmacological management of severe CD colitis. Include the rationale for Faecal Microbial Transplantation and under what circumstances you would consider its use.  (60% marks)

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College answer

a) List 5 risk factors for infection. 
Antimicrobial use, especially fluoroquinolones, clindamycin, broad spectrum penicillins and cephalosporins. (Specific antibiotics expected) 
Increasing age use of PPI,  
inflammatory bowel disease,  
organ transplants, chemotherapy, chronic kidney disease, immune deficiency exposure to an infected individual,  Nursing home/health care facility resident 

b) What infection control measures would you take in a patient diagnosed with CD?  

Strict contact precautions  Isolation in single room 
PPE: healthcare workers should wear gloves, gowns, 5 moments of hand hygiene should be observed 
Use of soap and water more effective than alcohol based had wash (spores are resistant to killing by alcohol) in outbreak situations. Use of disposable equipment when possible 
Post discharge disinfection of the room  

c) Outline the approach to diagnosis and pharmacological management for severe CD colitis. Include the rationale for Faecal Microbial Transplantation and under what circumstances you would consider its use.


Radiographic evidence of ileus or megacolon 
Positive stool testing - either ELISA or PCR 
Presence of pseudomembranes on sigmoidoscopy 
Pharmacological Management 
Severe CD colitis – oral vancomycin (or fidaxamicin) and iv metronidazole. 

Fidaxamicin may be an alternative if vancomycin is not available or not tolerated. Vancomycin can be given rectally if there is severe ileus 
Faecal Microbial Transplantation (FMT)  

The human colonic microbiota, which provides colonization resistance against bacterial pathogens, is a key determinant in the pathogenesis of C. difficile. After exposure to oral antibiotics, a decline in faecal microbial diversity is common and may last many months. FMT reconstitutes healthy microbiota. 
Primarily indicated for recurrent disease that has not responded to antibiotic treatment 
Examiners Comments: 
Candidates need to read the question carefully; part c) specified severe infection which was not addressed in some answers. 



This question falls into the growing group of SAQs which ask for a considerable amount of detail about this organism, known commonly as Clostridium difficile  because of a post-Linnaean convention of binomial nomenclature where we do not capitalise the species name, even when it is based on an otherwise capitalised personal or place name. That nerdgasm notwithstanding, the question itself is fairly similar to all the others before it, and contains all the familiar elements (risk factors, infection control measures, diagnosis and management). The only novel curveball was the additional need to discuss a faecal microbiota transplant, which was also weirdly capitalised. It is unclear how much of the 60% mark was allocated to the discussion of this exotic therapy.

Risk factors for C.difficile colitis (from Deshpande et al, 2015, and Leffler et al, 2015, where paragraphs of the latter bear a striking resemblance to the college answer, suggesting its origin)

  • Renal impairment
  • Severe underlying illness (i.e. ICU patients in general)
  • Non-surgical gastrointestinal procedures
  • Presence of an NG tube
  • Inflammatory bowel disease
  • exposure to an infected individual
  • Nursing home/health care facility resident 

Infection control measures:


Clinical suspicion

  • Watery diarrhoea (≥3 loose stools in 24 hours)
  • History of antibiotic exposure 
  • Fever, abdominal pain, distension

Radiological diagnosis:

  • Bowel dilatation
  • Mural thickening and haustral fold thickening ("thumbprinting")
  • Toxic megacolon
  • Perforation and free intraperitoneal gas

Biochemical diagnosis: the current recommendations are:

  • PCR is better than toxin A or B identification
  • You should only test loose stools
  • You should not re-test.

Sigmoidoscopy (endoscopic diagnosis)

  • Pseudomembranes
  • Confirming biopsy and culture

Pharmacological management

Mild-moderate C.difficile infection:

  • Treat empirically in the absence of positive results, if the pre-test suspicion is strong.
  • Stop the inciting antibiotics
  • Give oral metronidazole for 10 days
    • Change metronidazole to vancomycin if there is no response in 5-7 days
  • For severe infection, just give oral vancomycin straight away(125mg qid for 10 days)
  • Vancomycin enemas are an option
  • Avoid anti-diarrhoea medications

Severe and complicated C.difficile infection:

  • CT of the abdomen is indicated
  • Oral vacomycin PLUS intravenous metronidazole are indicated
  • If there is significant abdominal distension, the vancomycin should be given as an enema

Recurrent C.difficile infection:

  • First recurrence: treat in the same way as the first episode
  • Second recurrence: change to vancomycin
  • Third recurrence: consider a faecal microbiota transplant

Faecal microbial transplant


  • C.difficile colitis is characterised by a loss of colonic biodiversity, which is attributed to the abuse of broad-spectrum antibiotics
  • Processed stool from healthy donors can promote a restoration of this "dysbiosis"

Circumstances for use:

  • Guidelines (ISDA/SHEA, 2018) recommend faecal microbiota transplantation for patients with multiple recurrences of C.difficile infection who have failed appropriate antibiotic treatments


Parker C, Tindall B, Garrity G. " International Code of Nomenclature of Prokaryotes" November 2015, International Journal of Systematic and Evolutionary Microbiology

Deshpande, Abhishek, et al. "Risk factors for recurrent Clostridium difficile infection: a systematic review and meta-analysis." infection control & hospital epidemiology 36.4 (2015): 452-460.

Leffler, Daniel A., and J. Thomas Lamont. "Clostridium difficile infection." New England Journal of Medicine 372.16 (2015): 1539-1548.

McDonald, L. Clifford, et al. "Clinical practice guidelines for Clostridium difficile infection in adults and children: 2017 update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA)." Clinical infectious diseases 66.7 (2018): e1-e48.