A 69-year-old female with history of rheumatic mitral stenosis presents to the intensive care unit with 5 days of fevers and night sweats, malaise, and multiple small erythematous lesions on the soles of the feet. The patient develops an escalating pressor requirement, and a bedside echocardiogram reveals severe mitral regurgitation that was not seen a month earlier on a formal echocardiogram.
Which of the following is the MOST likely organism to be isolated from blood cultures?
A. CNSCorrect Answer: D
This patient satisfies the Duke criteria for the diagnosis of endocarditis with the major criteria satisfied by endocardial involvement assessed with echocardiogram and the three minor criteria satisfied by the patient’s fevers, Janeway lesions, and predisposing heart condition of rheumatic heart disease. The most common organisms for endocarditis from most to least common include Staphylococcus aureus (31%), viridans Streptococcus (17%), CNS (11%), Enterococci (11%), Streptococcus bovis (7%), other Streptococci (5%), fungi (2%), gram-negative HACEK bacilli (2%), and gramnegative non-HACEK bacilli (2%). Endocardial involvement as a major criteria can be satisfied by new valvular regurgitant lesions, vegetations, abscesses, or dehiscence of prosthetic valves.
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