Document Type

Conference Proceeding

Publication Date

5-2-2025

Abstract

Introduction Infective endocarditis (IE) is a serious infection of the endocardium and the cardiac valves. Its incidence is on the rise, and this has been attributed to the aging population, healthcare-associated infections, and the growing use of intracardiac devices and prosthetic valves. IE is typically caused by gram positive cocci; although other more fastidious organisms can present in a subacute fashion. One such organism that is now becoming identified is Cutibacterium Acnes. It is a gram-positive anaerobe, most commonly known for causing acne. Given its ubiquity as skin flora, it can enter the blood stream and cause systemic infections. Here we present a case of Cutibacterium acnes endocarditis complicated by aortic root abscess. Case A 62-year-old male with history of bicuspid aortic stenosis status post bioprosthetic aortic valve with root repair (Bentall Procedure) 5 years prior, presented for evaluation of one week of fevers, chills, diaphoresis and acute onset confusion. His physical exam was significant for fever to 38.7C and an aortic systolic murmur without other stigmata. Inital studies were significant for leukocytosis of 25.4 with left shift and elevated troponins. ECG was non-ischemic but showed a 1st degree AV block, new from prior studies. Bedside echocardiography showed an aortic valve vegetation. Transesophageal echocardiogram confirmed the vegetation with an abscess involving the aortic annulus. The patient was initially started on IV vancomycin and cefepime; eventually doxycycline was added to cover fastidious organisms as cultures were slow to result. Blood cultures grew Cutibacterium acnes. Eventually the patient was taken to the OR for Redo-Bentall procedure which was complicated by the need for coronary artery bypass grafting with intraoperative coagulopathy and need for delayed closure. Intraoperative pathology was consistent infective endocarditis; although no infectious etiology was seen on gram stain. Following stabilization, the patient was ultimately discharged with 6 weeks of daptomycin, cefepime, and doxycycline. Discussion This case demonstrates an unusual causative organism of prosthetic aortic valve endocarditis and aortic root abscess. C.acnes is a fastidious bacterium that can take up to 14 days to grow, which can explain the limited identification in this case. Increasing case reports have demonstrated C.acnes to be a causative agent in culture negative endocarditis, especially in males. Besides involving the prosthetic aortic valve, there was also involvement of an aortic graft leading to an abscess. The patient underwent a Bentall procedure previously which involves the mechanical heart valve with placement of Dacron graft into a diseased aortic root. Given the synthetic nature of the graft, these are at higher risk for infections than native tissue. Treatment of aortic root abscess invariably involves repeat surgical repair which carries a 30-day mortality rate of 20-25%. Conclusion In patients with a history of cardiac valve replacement, who present with sepsis without a clear source, clinicians should consider IE and have a low threshold for imaging even with negative or atypical blood culture results. Organisms typically considered as normal flora, such as Cutibacterium Acnes can be the causative agents of culture-negative endocarditis in this population.

Comments

American College of Physicians Michigan Chapter and Society of Hospital Medicine Michigan Chapter Resident and Medical Student Day, May 2, 2025, Troy, MI

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