Improving clostridium difficile diagnosis

In summary

Clostridium difficile (C diff) causes diarrhoea and severe bowel inflammation, leading to around 3,000 deaths annually in the UK.

Patients on antibiotics and the elderly are most at risk. Existing tests were inaccurate, leading to many false positives and negatives.

What did we explore and how?

Dr Timothy Planche, consultant microbiologist and lead researcher, conducted a systematic review of 18 studies and found that 20% of positive results were incorrect and 20% of infections missed.

He recommended a two-stage testing process using two different assays: a quick initial test to rule out negatives, followed by a second confirmatory test for positives.

In 2009, Dr Planche validated this two-stage process at St George’s Hospital with 700 stool samples.

A subsequent large multicentre study funded by the Department of Health and Health Protection Agency analysed over 12,000 stool samples across England.

This study confirmed the poor performance of single tests, identified the optimal combination of dual assays, and showed the cytotoxin assay’s importance in predicting mortality.

Benefits and influence of this research

The two-stage testing procedure has been widely adopted by the NHS, Europe, and the US. Since its introduction, C diff infection rates in the UK have reduced by 74%.

While increased staff awareness, hospital cleanliness, and prescribing habits also contributed, the improved accuracy of the tests allowed early intervention, patient isolation, and better outcomes.