山田 博胤^{1, 5}, 田中 秀和², 宮原 俊介³, 尾形 竜郎⁴, 楠瀬 賢也¹, 西尾 進⁵, 鳥居 裕太⁵, 平田 有紀奈⁵, 大北 裕³, 佐田 政隆^{1, 5}

Hirotsugu YAMADA^{1, 5}, Hidekazu TANAKA², Shunsuke MIYAHARA³, Tatsuro OGATA⁴, Kenya KUSUNOSE¹, Susumu NISHIO⁵, Yuta TORII⁵, Yukina HIRATA⁵, Yutaka OKITA³, Masataka SATA^{1, 5}

¹徳島大学病院循環器内科, ²神戸大学大学院医学研究科循環器内科, ³神戸大学大学院心臓血管外科, ⁴独立行政法人徳島県鳴門病院, ⁵徳島大学病院超音波センター

¹Department of Cardiovascular Medicine, Tokushima University Hospital, ²Department of Cardiovascular Medicine, Kobe University Graduate School of Medicine, ³Department of Cardiovascular Surgery, Kobe University Graduate School of Medicine, ⁴Local Incorporated Administrative Agency Tokushima Prefecture Naruto Hospital, ⁵Ultrasound Examination Center, Tokushima University Hospital

キーワード : infectious endocarditis, superficial ultrasound examination, echocardiography, mitral valve prolapse, Staphylococcus warneri

症例は，46歳男性，循環器内科医師，主訴は左足関節内果部と上腕の疼痛である．僧帽弁逸脱症による僧帽弁逆流と発作性心房細動の既往がある．足関節の疼痛は蜂窩織炎を疑って，血液検査と表在エコー図検査を行った．疼痛部は皮下浮腫が著明であったが，軟部組織の血流シグナルが乏しく，後脛骨動脈の血管壁を主体とした炎症と，同動脈の閉塞が確認された．一方，左手関節近位の尺骨動脈は逆行性血流を示しており，左尺骨動脈分岐部直後で閉塞していた．これらの所見から多発性血管閉塞性動脈炎と診断し，その原因究明のために直ちに心エコー図検査を施行した．その結果，僧帽弁に可動性を有する棍棒状の異常構造物を認め，僧帽弁逆流は高度に増悪しており，感染性心内膜炎と診断された．頭部MRI検査で異常を認めなかったため，外科的加療（疣腫摘除術，僧帽弁形成術，左房縫縮術，左心耳閉鎖術，Maze手術）が行われた．血液培養は陰性であったが，摘出した疣腫の培養からStaphylococcus warneriが同定された．Staphylococcus warneriは皮膚常在菌であり，本病原体による自己弁の感染性心内膜炎は報告が少ない．術後の経過は良好であり，抗生剤を6週間静脈投与した後に社会復帰した．患者が循環器内科医であり，自身の足関節および上腕の疼痛を契機に，表在エコー図検査と心エコー図検査を用いることで，感染性心内膜炎を迅速に診断した稀有な症例であり，かつ，感染性心内膜炎の起炎菌としては稀なStaphylococcus warneriが同定されたので，文献的な考察を加えて報告する．

A 46-year old male cardiologist, who had been diagnosed with mitral valve prolapse with moderate mitral regurgitation, complained of pain in his left ankle and left upper arm. He requested a blood test and superrficial ultrasound examination on his foot as he suspected that he was suffering from cellulitis. The ultrasound examination revealed that the pain in his left ankle and upper arm was due to arterial occlusive vasculitis. Subsequently, echocardiography was performed, and vegetation on the mitral valve was observed. As his brain MRI was normal, surgical treatment was selected. Resection of the vegetation, mitral valve plasty, left atrial plication, and Maze operation were successfully performed. Although multiple sets of blood culture were negative, Staphylococcus warneri was identified from the culture of the resected vegetation. Staphylococcus warneri is a normal skin flora, and infectious endocarditis as a result of the organism has rarely been reported. His postoperative clinical course was uneventful, and antibiotics were administrated intravenously for 6 weeks. In the present case, superficial ultrasound examination for the pain in his ankle and upper arm and subsequent echocardiography resulted in an instantaneous diagnosis of his infective endocarditis. Infective endocarditis of the native valve caused by Staphylococcus warneri is also rare.