Osteomyelitis Quiz: Ace Your Exams

A 35-year-old woman presents to the emergency department for three weeks of severe lower back pain that is worse with movement, chills, and intermittent fevers. She has a history of injection drug use. Temperature is 39.2°C (102.6°F), heart rate is 112/min, blood pressure is 120/80 mm Hg, and respiratory rate is 22/min. Physical examination reveals tenderness over the lumbar spine at L3 and a 4/6 holosystolic murmur is best heard at the left sternal border. Neurological examination is within normal limits. Laboratory findings are significant for a white blood cell (WBC) count of 15,500/μL, C-reactive protein (CRP) of 130 mg/L, and an erythrocyte sedimentation rate (ESR) of 120 mm/h. Spine x-rays show L3 vertebral body destruction and collapse of the intervertebral disc space. Which of the following organisms is the most likely cause of this patient’s condition?