Aerococcus christensenii native aortic valve subacute bacterial endocarditis (SBE) presenting as culture negative endocarditis (CNE) mimicking marantic endocarditis

This is a case report of an adult who presented, with apparent culture negative endocarditis (CNE) thought to be marantic endocarditis due to, a B-cell lymphoproliferative disorder. This was a most perplexing case and was eventually diagnosed as subacute bacterial endocarditis (SBE) due to a rare slow growing organism. Against the diagnosis of SBE was the lack of fever, hepatomegaly, peripheral manifestations and microscopic hematuria. Also, against a diagnosis of SBE was another explanation for the patient's abnormal findings, e.g., elevated ferritin levels, elevated alpha(1)/alpha(2) globulins on SPEP, an elevated alkaline phosphatase, flow cytometry showing B-lymphocytes expressing CD5, and a bone lesion in the right iliac. Findings compatible with both SBE and marantic endocarditis due to a B-cell lymphoproliferative disorder included an eleyated ESR, and splenomegaly. Blood cultures eventually became positive during hospitalization. We report a case of native aortic valve (AV) subacute bacterial endocarditis (SBE) due to Aerococcus christensenii mimicking marantic endocarditis clue to a B-cell lymphoproliferative disorder. To the best of our knowledge, this is the first reported case of native AV SBE due to A. christensenii presenting as marantic endocarditis. (C) 2014 Elsevier Inc. All rights reserved.