Canterbury DHB


Diarrhoea and C. difficile

Investigation and management of diarrhoea is outlined in Hospital HealthPathways. However, for immunosuppressed, intensively treated haematology, the order of investigations is slightly different. C. difficile may be a particular problem in our patients, and its management is outlined below.

In This Section

Faecal Specimen Testing

Clostridium Difficile

Faecal Specimen Testing

Diarrhoea is a common problem in our patients. It is an expected side effect of conditioning regimens that contain melphalan. These patients don’t require microbiological investigations.

However, when a patient is admitted from the community with diarrhoea, send a faecal sample to test for giardia/cryptosporidia and culture for bacterial pathogens. If the diarrhoea is severe, and especially if accompanied by vomiting, add testing for viral causes.

In persistent unexplained community onset diarrhoea, request full parasitology work-up. Send 3 samples in a PVA container on 3 consecutive days.

When someone has been an inpatient for a number of days and develops diarrhoea, test for C. difficile only in the first instance. If C. difficile is negative and diarrhoea persists, test for viral causes. It is unusual for inpatients to pick up standard bacterial infections that cause diarrhoea.

Clostridium Difficile

C. difficile colitis occurs frequently in hospitalised patients taking antibiotics. About 20% relapse after initial improvement.

Careful hand washing remains a central part of care. Alcohol hand wash is ineffective.

Antibiotics are known to disrupt the colonic microflora, permitting C. difficile colonisation and growth. Infection can result in a wide range of signs and symptoms – frequent bowel motions, abdominal pain, and fever.

Do not use antidiarrhoeal agents such as loperamide or codeine, as this can lead to the development of a toxic megacolon. Loperamide or codeine should not be used on any patient who has had recent antibiotics until the C. difficile result comes back negative.


Vancomycin administered intravenously does not get into the gut. If intravenous therapy is required (toxic megacolon, poor oral intake or absorption) use intravenous metronidazole 500 mg TDS IV.

For more information about metronidazole and vancomycin, see the Data Sheets on Medsafe.


Taking samples after diarrhoea has resolved is not recommended. Once diarrhoea and other symptoms have abated, the patient may still be infectious and shed the organism, therefore hand hygiene and standard precautions should be practised until discharge. If the patient is readmitted and has previously had C. difficile, it is not useful to take further stool samples unless the patient has diarrhoea. Careful hand washing remains a central part of care. Alcohol hand wash is ineffective.

About this Canterbury DHB document (5023):

Document Owner:

Andrew Butler (see Who's Who)

Last Reviewed:

May 2021

Next Review:

May 2023


Note: Only the electronic version is controlled. Once printed, this is no longer a controlled document. Disclaimer

Topic Code: 5023