Clostridiodes difficile: Colonisation versus Infection - The importance of appropriate laboratory testing to minimise risk of overdiagnosis and overtreatment

Clostridiodes difficile (C. difficile) colonisation rates have been reported as ranging from 4-15% in healthy adults to 4-51% in long term care facilities. Inappropriate treatment for C. difficile colonisation alters gut microbiota and can consequently result in C. difficileInfection (CDI). Laboratory testing needs to aid diagnosis while at the same time minimising risk of overdiagnosis and overtreatment.

Methods

An audit was conducted of the number of patients with indeterminate and positive results between 01.09.16 and 31.08.18 to determine the impact of Scottish National C. difficile laboratory testing and CDI case definition Guidance re-inforcement in September/October 2017. A question was also added at sample requesting stage re Pseudomembranous colitis/Toxic megacolon to ensure appropriate testing.

After Guidance re-inforcement, a rapid fall in number of indeterminate results (av. 34/month to 15/month) was observed. Decrease was most marked for GP patients (av. 12/month to 3/month). There was also a decrease in the number of patients with confirmed positive results (av. 9/month to 5/month).

Alignment with National Guidance resulted in significant reduction in patient indeterminate and positive results and assisted clinicians in the clinical diagnosis of CDI. There was also a reduction in the number of laboratory tests and repeat tests for indeterminate results. Therefore, this alignment with National Guidance resulted in Infection Prevention and Control Team, clinical and laboratory time and cost savings.