Sickle cell disease Quiz: Ace Your Exams

A 20-year-old woman presents to the emergency department complaining of fever and severe pain and swelling in her left thigh for 5 days. She has a history of less severe recurrent painful episodes in her long bones since childhood, and she had frequent middle ear infections as a child. She was adopted; she knows her biological mother was a Black woman of Nigerian descent who had a history of anemia, but she is unsure of the details. She is not sexually active. Her temperature is 39.2°C (102.5°F), blood pressure is 115/75 mm Hg, pulse is 110/min, respiratory rate is 21/min, and oxygen saturation is 96% on room air. Physical examination reveals pallor and scleral icterus. The left thigh is swollen, erythematous, warm, and tender to palpation. Blood culture reveals gram-negative rods. MRI of the thigh shows a focal area of increased signal intensity with surrounding edema. Which of the following is the most likely causative organism?