Prosthetic valve infective endocarditis with severe mitral stenosis caused by Cutibacterium acnes: a case report

Infective endocarditis rarely results in mitral stenosis. This report presents a case of prosthetic valve infective endocarditis caused by Cutibacterium acnes infection, which resulted in mitral stenosis and was difficult to diagnose.

A 78-year-old Japanese man underwent aortic and mitral bioprosthetic valve replacement six years prior to the initiation of hormone therapy for prostate cancer. Three weeks after hormone therapy initiation, the patient developed exertional dyspnoea that progressively worsened and ultimately led to orthopnoea. Chest radiography revealed pulmonary congestion, and transthoracic echocardiography revealed mitral stenosis that was not present three months previously. The patient progressed to heart failure, and bicuspid valve replacement was performed. The excised aortic and mitral bioprosthetic valves were covered with vegetations, and pathological examination confirmed the presence of C. acnes. Therefore, the cause of mitral stenosis was infective endocarditis.

In patient with rapidly progressive prosthetic valve stenosis after valve replacement, infective endocarditis due to C. acnes should be suspected even if blood cultures are negative.