Infective endocarditis with negative blood culture and negative echocardiographic findings.

A 61-year-old male presented with fever. He had a history of aortic valve replacement, and infective endocarditis was suspected. The transthoracic and transesophageal echocardiography on admission could not detect vegetation, and all blood cultures obtained were negative. We concluded that infective endocarditis was not likely. However, repeated echocardiography revealed paravalvular regurgitation and paravalvular abscess. Serum antibody testing for Bartonella henselae was positive, leading to the diagnosis of blood culture-negative endocarditis. Even when blood cultures and echocardiography were negative on initial examination, careful history-taking, blood tests accounting for these pathogens, and repeated echocardiography are crucial for diagnosis.