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Infective endocarditis — ABIM Board MCQ

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ModerateCardiovascularInfective endocarditisABIM Board

A 49-year-old man with a prosthetic aortic valve presents with 2 weeks of fever, malaise, and progressive low back pain. His temperature is 38.6°C (101.5°F), and cardiac examination reveals a new diastolic murmur. Three blood-culture sets obtained before antibiotics grow Enterococcus faecalis; urine culture and abdominal imaging reveal no extracardiac source. Urinalysis shows microscopic hematuria and red blood cell casts. Transthoracic echocardiography shows no vegetation. Which of the following is the most likely unifying diagnosis?

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Correct answer: D — Prosthetic valve infective endocarditis

Explanation lettering: D = shown as A · A = shown as C · C = shown as D

C is correct. A prosthetic valve, persistent Enterococcus faecalis bacteremia without another source, fever, and new valvular regurgitation strongly indicate prosthetic valve infective endocarditis. Red blood cell casts suggest immune-complex glomerulonephritis, an extracardiac manifestation of endocarditis. A negative transthoracic echocardiogram does not exclude prosthetic valve endocarditis because prosthetic material can obscure vegetations; transesophageal echocardiography is required. Vertebral osteomyelitis may account for the back pain and can occur as a metastatic complication, but it does not explain the new murmur and glomerulonephritis. Prosthetic valve thrombosis does not cause persistent bacteremia. Nonbacterial thrombotic and Libman-Sacks endocarditis produce sterile vegetations and are associated with malignancy or autoimmune disease rather than repeated positive bacterial cultures.

Reference: Otto CM, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease, Diagnosis of Infective Endocarditis and Modified Duke Criteria, 2020. https://www.heart.org/en/-/media/phd-files-2/science-news/2/2020/2020_acc_aha_guideline_for_the_management_of_patients_with_valvular_heart_disease_slide_set.pdf