Dr Freya Langham1,2, Georgia Duncombe2, Lisa Thomas2, Jan Williamson1, A/Prof Louise Cooley1, Dr Michael O'Connor1
1Microbiology and Infectious diseases, Royal Hobart Hospital, Hobart, Australia, 2Infection Prevention and Control Unit, Royal Hobart Hospital, Hobart, Australia
Biography:
Freya is an Infectious diseases physician and the medical lead for Infection Prevention and Control at the Royal Hobart Hospital.
Abstract:
Problem
We identified rising rates of C. difficile infection (CDI) and use of second line therapies including faecal microbiota transplant in our institution. Clinical review of cases raised the possibility of over-diagnosis and over-treatment of CDI.
Solution
We identified the diagnostic pathway for C. difficile as a potential contributing factor: immunoassay for C. difficile antigen and toxin are performed for all specimens, with a reflex toxin PCR for discrepant results (antigen detected/toxin not detected). Due to the high sensitivity of PCR, we may be detecting low-level toxin production that was not contributing to patients’ clinical presentation.
In April 2025, reflex PCR testing on samples with discrepant results was ceased. A comment was added to the result report requesting clinicians contact the laboratory and arrange further sampling for PCR if there was high clinical suspicion for CDI.
Results
In the first month since making this change, there have been seven patients with discrepant results. On clinical review of these cases: two patients had an alternative infectious cause (Campylobacter, norovirus), three patients had clear non-infectious aetiologies, and two patients had clinically diagnosed relapsed CDI.
We will present six months of data in November 2025 comparing rates of CDI and prescribing pre and post this change. We will also investigate the Infection prevention implications of these changes.
Conclusions/Lessons learnt
We highlight the importance of close collaboration between Infection prevention and Clinical microbiology to address diagnosis and management of hospital-acquired infections, which has significant ramifications for isolation requirements, antibiotic usage, and length of stay.