Clostridioides difficile infection (CDI)

Clostridioides difficile (previously known as Clostridium difficile) is a spore-forming, anaerobic bacillus (bacterium) that is responsible for diarrhoeal illness associated with the consumption of antibiotics. The severity of illness can range from a mild diarrhoea of variable duration to a severe inflammation of the colon (colitis), toxic megacolon and necrosis of the large bowel. Severe cases are associated with a significant morbidity and mortality.

C. difficile is found as part of the normal bowel flora of many animal species, including cattle, horses, pigs, dogs and cats. Spores can be recovered from soil and from environmental surfaces of rooms where patients with CDI are housed. Ingestion of small numbers of C. difficile spores does not usually lead to disease, but disturbance of the normal gut flora by the consumption of antibiotics is considered a key factor in the pathogenesis of intestinal disease caused by this organism.


The epidemiology of CDI is complex, and there are many different strains found using molecular typing methods, some of which appear to be associated with a higher propensity for spread within hospitals and the community, and may be associated with more severe forms of the disease. These strains have been referred to as "hypervirulent" or "epidemic" strains in the literature.

Mode of transmission

The main sources of CDI in the hospital setting are the environment surrounding patients with CDI. The spores can be spread to other patients via inadequately decontaminated hands of staff and indirectly via the environment (contaminated surfaces and equipment). C. difficile spores are capable of prolonged survival on environmental surfaces, but can be removed by thorough cleaning of bathrooms and frequently touched surfaces, followed by disinfection with a sporicidal agent. There is some evidence for prolonged shedding of the spores following resolution of symptoms.


The prevention of cross-infection with C. difficile involves the simultaneous application of a number of strategies:

Further information

For further information about Clostridiodes difficile see the Fact sheet for Healthcare Workers (PDF 92KB) or contact SA Health's Infection Control Service.