Blood culture-negative endocarditis caused by Bartonella henselae: a case report

Bartonella henselae is well known as a causative organism of cat scratch disease. Although this bacterium infrequently involves the heart, the diagnosis is difficult to confirm. A 75-year-old woman who had a pet cat presented with pancytopenia, hepatosplenomegaly, and low-grade fever. Echocardiography depicted sessile nodules on the aortic valve. C-reactive protein concentration was low, and leukocytosis was not seen. Two sets of blood culture turned out negative. However, elevated B. henselae immunoglobulin G titer led us to the diagnosis of infective endocarditis. Minocycline was administered orally in combination with intravenous administration of gentamicin as an antimicrobial treatment. The patient underwent aortic valve replacement 2 months after her initial visit. Warthin-Starry silver staining did not show any bacterial bodies. The culture of the vegetation tissue was negative. Polymerase chain reaction testing of the excised valve tissue detected the deoxyribonucleic acid of the organism. The postoperative course was uneventful, and the patient was discharged home.