Associate Professor of Medicine University of Rochester, United States
Introduction: We describe a case of Bartonella endocarditis that presented initially with glomerulonephritis and a normal echocardiogram (ECHO) leading to delayed diagnosis and treatment.
Description: A 57-year-old immunocompetent man with a bioprosthetic aortic valve and repaired aortic root aneurysm presented with fatigue, fever, and 55-pound weight loss. He owned 3 cats who recently had fleas. Labs revealed a creatinine (Cr) of 2.9mg/dL (from normal), elevated PR3-ANCA antibody, and multiple negative blood cultures. Initial ECHO showed functioning aortic valve without vegetations. A renal biopsy, which revealed immune complex glomerulonephritis (ICGN) with an IgA-dominant full house stain pattern, prompted treatment with prednisone. 14 days later, the patient developed dyspnea, leg edema, hemoptysis, and Cr of 9mg/dL. CT chest showed bilateral ground-glass opacities. Given the PR3-ANCA positivity, there was concern for vasculitis with pulmonary-renal syndrome, and he received three days of pulse-dose methylprednisolone. A few days later, repeat ECHO showed new biventricular failure, thickened aortic valve with severe stenosis and vegetation. Further testing revealed positive Bartonella henselae serology (IgG titer >1:1024, IgM titer 1:256) and serum DNA PCR. The patient developed cardiogenic shock requiring intubation and vasopressor support. Despite initiation of rifampin and doxycycline, he developed refractory shock and fatal multi-system organ failure.
Discussion: Bartonella henselae is a common cause of culture-negative infectious endocarditis (IE), especially in patients with risk factors including cat and flea exposure and valvular disease. Case reports have documented PR3-ANCA positivity in patients with Bartonella endocarditis. IE is a known cause of glomerulonephritis (GN); IE-associated GN has variable histopathologic patterns, most typically IgM-dominant ICGN or pauci-immune GN. In this case, the unique combination of atypical biopsy findings (IgA-dominant ICGN), PR3-ANCA positivity, and initial normal ECHO resulted in delayed diagnosis and treatment. Culture-negative endocarditis should be considered in all patients with known valve disease and new glomerulonephritis, as ECHO findings may be delayed and falsely reassuring early in the disease course.
