58-year-old man with fever, back pain, and new murmur
A 58-year-old man with poorly controlled type 2 diabetes and stage 3 chronic kidney disease is admitted with 5 days of fever, fatigue, and low back pain. Two weeks ago, he had a tunneled hemodialysis catheter removed after transition to a functioning AV fistula. Temperature is 38.6 C (101.5 F), blood pressure 128/62 mm Hg, heart rate 102/min. Examination shows a new holosystolic murmur at the apex and splinter hemorrhages. Leukocyte count is 15,400/mm3, creatinine is 2.1 mg/dL, and 2 of 2 blood culture sets grow methicillin-sensitive Staphylococcus aureus. Transthoracic echocardiography shows no vegetation. Which of the following is the most appropriate next step in management?
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A
Explanation
Clinical Pearl:
Staphylococcus aureus bacteremia with a new murmur or other signs of endovascular infection should prompt evaluation for infective endocarditis with transesophageal echocardiography when transthoracic imaging is nondiagnostic. For methicillin-sensitive S aureus, a beta-lactam such as cefazolin is preferred over vancomycin when tolerated.
Explanation:
This patient has complicated Staphylococcus aureus bacteremia with a new murmur and peripheral stigmata of endocardial infection, making infective endocarditis the leading concern despite a negative transthoracic study. Current practice favors transesophageal echocardiography because it is substantially more sensitive than transthoracic echocardiography for detecting valvular vegetations and related complications in high-risk patients. Cefazolin is an appropriate targeted treatment for methicillin-sensitive S aureus bacteremia and possible native-valve endocarditis, and beta-lactams are associated with better outcomes than vancomycin in this setting. Oral linezolid is not appropriate initial therapy for S aureus bacteremia or suspected endocarditis. Waiting a week to repeat cultures delays necessary management, and blood cultures should instead be followed promptly to document clearance while treatment is underway. Vancomycin alone is inferior targeted therapy for methicillin-sensitive isolates, and delaying therapy to pursue spine MRI is unsafe, although MRI may later be appropriate if vertebral osteomyelitis is suspected from persistent back pain.
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