Mitral Valve Subacute Endocarditis Caused by Abiotrophia Defectiva: A Case Report

Association of infective endocarditis caused by Abiotrophia defectiva with mycotic aneurysm formation: A case report and the review of the literature

A 74-year-old woman with a history of mitral valve prolapse with mitral regurgitation was transferred to our hospital due to infective endocarditis. Blood culture revealed Abiotrophia defectiva which is known as a nutritional variant streptococcus. Transesophageal echocardiography revealed posterior leaflet (P2) prolapse due to rupture of tendon chordae with severe mitral regurgitation and vegetation on posterior leaflet. Magnetic resonance imaging (MRI) revealed multiple infarction lesions in left temporal lobe and parietal lobe and mycotic aneurysm formation of right middle cerebral artery. Because A. defectiva cannot be cultured on non-supplemented media, their prevalence may be underreported.

Learning objective

A number of causative microorganisms of infective endocarditis have been identified. Streptococci and staphylococci account for 80 % of cases of infective endocarditis. Abiotrophia defectiva does not grow in ordinary growth media and its prevalence may be underreported. It is important to know A. defectiva causes infective endocarditis with mycotic aneurysm formation.

Frenemies within: An Endocarditis Case in Behçet's Disease

A 57-year female patient diagnosed with Behçet's disease, on azathioprine, was noticed to have at a routine examination antinuclear and antiphospholipid antibodies. An overlapping lupus-like syndrome was diagnosed; hydroxychloroquine and aspirin were added. Three years later, the patient presented with dyspnea and sweating, with no fever. A cardiac bruit was noted; a giant vegetation was detected by echocardiography. Laboratory revealed severe thrombocytopenia, antiphospholipid antibodies and low complement. Blood cultures were positive for Abiotrophia defectiva serology and also revealed a chronic Coxiella burnetii infection. Antibiotic therapy, low-dose anticoagulation and control of the underlying disease mildly improved the platelet count, which fully recovered only after cardiac valve replacement. However, the Behçet's disease, initially quiescent, flared after the therapy of infections. We discuss potential links between Behçet's disease and the occurrence of antinuclear and antiphospholipid antibodies and Coxiella endocarditis in this setting. We also highlight the differences between the endocarditis in Behçet's disease, antiphospholipid syndrome, Coxiella burnetii and Abiotrophia defectiva infection, respectively. Intracellular infections may modify the presentation of autoimmune diseases. Confounding clinical features of Coxiella persistent infection and non-bacterial thrombotic endocarditis in Behçet's disease warrant further insight.