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Staphylococcus aureus bacteremia — ABIM Board MCQ

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HardInfectious DiseaseStaphylococcus aureus bacteremiaABIM Board

A 58-year-old man receiving maintenance hemodialysis through a tunneled central venous catheter is hospitalized with fever. Multiple blood cultures grow methicillin-susceptible Staphylococcus aureus, and appropriately dosed intravenous cefazolin is started. Follow-up blood cultures obtained 48 hours later remain positive. Examination reveals no focal musculoskeletal or neurologic findings, and transthoracic echocardiography shows no vegetation. No source other than the dialysis catheter is identified. Which of the following is the most appropriate next step in management?

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Correct answer: A — Remove the catheter, continue intravenous cefazolin, and obtain transesophageal echocardiography

The tunneled catheter is the presumed source and must be removed for definitive source control. Cefazolin is an appropriate targeted intravenous agent for MSSA bacteremia and should be continued with hemodialysis-adjusted dosing. Persistent bacteremia at 48 hours indicates increased risk of endocarditis and other metastatic infection; therefore, a negative transthoracic study does not eliminate the need for transesophageal echocardiography. Catheter retention or guidewire exchange is inappropriate for persistent S aureus bacteremia because retained infected material promotes treatment failure and metastatic seeding. Vancomycin is less appropriate than a beta-lactam for susceptible isolates, and changing antibiotics does not replace source control. Oral linezolid is not appropriate definitive treatment for this high-risk bacteremia.

Reference: Tong SYC, Fowler VG Jr, Skalla L, Holland TL. Management of Staphylococcus aureus Bacteremia: A Review. JAMA. 2025;334(9):798-808. https://pubmed.ncbi.nlm.nih.gov/40193249/