A 10-year-old boy is brought to the physician by his mother because of a 2-week history of fever and pain in his right thigh that is causing him to limp. He has no history of recent trauma other than minor scrapes to his knees and elbows while playing outside . His immunizations are up-to-date. The patient appears well. He is at the 40th percentile for height and 45th percentile for weight. His temperature is 38.2°C (100.8°F), pulse is 100/min, respirations are 18/min, and blood pressure is 110/70 mm Hg. Examination shows swelling, tenderness, warmth, and mild erythema over the right upper thigh; range of motion is limited by pain. He has a right-sided antalgic gait. His leukocyte count is 12,300/mm3 and erythrocyte sedimentation rate is 40 mm/h. X-rays of the hips and lower extremities are unremarkable. An MRI of the right lower extremity shows increased T2 and decreased T1 signals over the right femur with periosteal elevation, multiple osteolytic areas in the femoral metaphysis, and bone marrow edema. Which of the following organisms is most likely responsible for this patient's symptoms?

Question

A 10-year-old boy is brought to the physician by his mother because of a 2-week history of fever and pain in his right thigh that is causing him to limp. He has no history of recent trauma other than minor scrapes to his knees and elbows while playing outside . His immunizations are up-to-date. The patient appears well. He is at the 40th percentile for height and 45th percentile for weight. His temperature is 38.2°C (100.8°F), pulse is 100/min, respirations are 18/min, and blood pressure is 110/70 mm Hg. Examination shows swelling, tenderness, warmth, and mild erythema over the right upper thigh; range of motion is limited by pain. He has a right-sided antalgic gait. His leukocyte count is 12,300/mm3 and erythrocyte sedimentation rate is 40 mm/h. X-rays of the hips and lower extremities are unremarkable. An MRI of the right lower extremity shows increased T2 and decreased T1 signals over the right femur with periosteal elevation, multiple osteolytic areas in the femoral metaphysis, and bone marrow edema.  Which of the following organisms is most likely responsible for this patient's symptoms?

Quizplus · Accepted Answer

Eductional Objective: Hematogenous osteomyelitis is predominantly a disease of children that most frequently affects the long bones.  Staphylococcus aureus is implicated in most cases secondary to a bacteremic event.  Streptococcus pyogenes (group A streptococcus) is the second most common cause of hematogenous osteomyelitis.

A 10-Year-Old Boy Is Brought to the Physician by His