mrcem2-0920

mrcem2-0920

A 68 year old male attends the emergency department with a member of staff from his nursing home who is concerned that the patient has had diarrhea for the past 2 days. The patient complains of cramping pains to the lower abdomen. The carer tells you the patient has been having frequent episodes of watery foul smelling diarrhea. There is no associated vomiting and no blood in the stool. You note the patient has recently completed a 5 day course of amoxicillin for a respiratory infection that failed to resolve with a 3 day course of azithromycin treatment. The patient’s regular medications are:
Lansoprazole 30 mg once daily
Acetaminophen 1g four times daily
Ibuprofen 400 mg three times daily as required for joint pain
On examination the patient’s abdomen is soft with some tenderness on deep palpation of the lower quadrants but no guarding or rigidity. The patient’s observations are shown below:

Temperature 37.3ºC
Blood pressure 144/84 mmHg
Pulse 88 bpm
Respiratory rate 18 bpm
Oxygen saturations 97% on air

What organism is most likely to be causing this patient’s symptoms?