Mikiko ITO¹, Daisuke ABE¹, Koichi YURI²

¹Department of Cardiology, Tokyo Metropolitan Bokutoh Hospital, ²Department of Cardiovascular Surgery, Tokyo Metropolitan Bokutoh Hospital

キーワード : blood culture-negative infective endocarditis, <I>Bartonella spp.</I>, <I>Bartonella henselae</I>

A 64-year-old man was admitted to our hospital with fever and fatigue. Blood cultures yielded negative results. Repeated echocardiography during hospitalization revealed marked exacerbation of mitral valve regurgitation, and transesophageal echocardiography revealed a vegetation (2.65 × 1.51 cm) attached to the mitral valve and perforation of the anterior leaflet. Blood culture-negative infective endocarditis due to Bartonella henselae was considered because of his cat ownership. The mitral valve was replaced. Polymerase chain reaction of the valve revealed B. henselae DNA. Minocycline was administered for 6 weeks, and gentamicin was administered for 2 weeks. No fever was observed after treatment, and the patient was discharged to home. As in this case, blood culture-negative infective endocarditis caused by B. henselae is difficult to diagnose because B. henselae is a fastidious microorganism that does not cause typical symptoms, such as fever and elevated white blood cell counts. The findings in this case, i.e., those revealed by repeated echocardiography, are important in diagnosing blood culture-negative infective endocarditis due to B. henselae. Additionally, diagnosis is time-consuming, and the infection tends to progress. Therefore, surgical intervention should be considered when it is diagnosed.