Osteomyelitis and discitis — formative SAQs

SAQ 1 — The febrile child with a painful limb (10 marks)

Stem: A three-year-old boy presents to the emergency department with three days of fever, increasing pain in the right leg, and a refusal to walk. On examination he is febrile at 39 degrees, holds the right leg still, and has exquisite tenderness over the distal tibial metaphysis. His C-reactive protein is 95 milligrams per litre, his erythrocyte sedimentation rate is 55 millimetres per hour, and his white cell count is 16,000. Plain radiographs are normal. ^{[1] [4]}

a) State the most likely diagnosis and explain why the normal radiograph does not exclude it. (2 marks) ^{[1] [4]}

b) Outline the pathophysiology of this condition, explaining the anatomical basis for the metaphyseal site of infection. (3 marks) ^[4]

c) Describe the appropriate empirical antibiotic regimen for this child, including the organisms that must be covered and the rationale for the age-stratified microbiology. (3 marks) ^{[1] [6]}

d) State the criteria for switching from intravenous to oral antibiotic therapy and the recommended total duration of treatment for uncomplicated disease. (2 marks)