Abstract 17436: A Diagnostic Copycat: Culture Negative Endocarditis of A Bioprosthetic Valve Presenting as ANCA Vasculitis

Abstract

A 59-year-old female with a history of bicuspid aortic valve (AV) complicated by aortic stenosis and ascending aortic aneurysm s/p bioprosthetic AV and ascending aorta replacement presented with a 6-month history of weight loss, fatigue, and lower extremity rash. Initial laboratory workup identified anemia, leukopenia, and acute kidney injury with proteinuria and microscopic hematuria. Further workup included negative blood cultures, elevated inflammatory markers, elevated rheumatoid factor, hypocomplimentemia, and ANCA positivity (PR3 Ab positive). Biopsy of her palpable purpuric rash demonstrated vascular immune deposition pattern consistent with leukocytoclastic vasculitis. Renal biopsy revealed focal and crescentic glomerulonephritis with immune complex deposition. CT abdomen noted mesenteric lymphadenopathy with fluid surrounding the thoracic aortic graft. Surface echocardiogram showed bioprosthetic AV replacement with diffuse cusp thickening without stenosis or regurgitation. At this point, a multidisciplinary team offered a broad differential diagnosis of inflammatory vasculitis versus culture-negative endocarditis with plan for further testing. Follow-up whole-body and cardiac PET scan identified FDG-avid abnormalities involving the aortic graft and AV with hypermetabolic soft tissue thickening surrounding the aortic root. Transesophageal echocardiogram confirmed AV thickening with a 1 cm mobile echodensity. Additional serologic testing identified positive Bartonella henselae IgG (1:8192) and IgM (>1:20) titers. The final diagnosis was B. henselae prosthetic AV endocarditis and ascending aortic graft infection. She underwent repeat AV and ascending aortic graft replacement, with graft material positive for B. henselae PCR and was treated with a course of doxycycline and rifampin. B. henselae is a fastidious gram-negative bacterium that can cause culture negative endocarditis but is very rarely associated with aortic graft infection. This case highlights (1) a rare example of B. henselae aortic graft infection, (2) the difficulty in differentiating B. henselae endocarditis from inflammatory vasculitis, and (3) the importance of engaging multidisciplinary teams to solve difficult diagnostic cases.