A 66-year woman presented to our hospital with a 6-week history of watery diarrhoea and central abdominal pain. She was taking naproxen occasionally with omeprazole for osteoarthritis but was not on any other regular medications. She had no significant medical history.

On admission, physical examination was unremarkable. Laboratory evaluation showed an elevated C reactive protein of 95 mg/L and white cell count of 11.8×109/L. The remainder of her routine biochemistry was within normal ranges. On admission, faecal pathogen PCR panel for bacterial infection including Clostridioides difficile (C. difficile) was negative. Abdominal X-ray showed …