2nd August 2023

A 50-year-old man was admitted with fever and confusion with flu-like symptoms.

A 50-year-old man was admitted with fever and confusion with flu-like symptoms. On brief questioning, he tells you he was unwell with a sore throat, myalgia, fevers, and a dry cough approximately two weeks ago. In the last 4 days, he has developed a productive cough with green sputum and has pain on deep inspiration. On examination, he looks unwell, with a faint purpuric rash on his feet and abdomen. He has no past medical history and does not take any regular medications.

You review his blood tests and note platelets of 90 (150-400), creatinine 210 (60-110), INR 1.7 (<1), APTT 50s (21-35), serum glucose 9, and CRP 350. A cardiac monitor shows sinus tachycardia and a chest x-ray shows bilateral patchy consolidation. He requires 15L oxygen via an NRB mask to maintain saturations around 95%.

Which of the following is the most likely cause of his presentation?

Select the SINGLE most appropriate option from the list below. Select ONE option only.