僧帽弁逸脱症にpeptostreptococcusによる感染性心内膜炎を来した1例

Mitral Valve Prolapse-complicated Infectious Endocarditis Caused by Peptostreptococcus: A case report

要旨　感染性心内膜炎は，その起因菌として緑色連鎖球菌，黄色ブドウ球菌，腸球菌，グラム陰性桿菌haemophilus sp，actinobacillus，cardiobacterium，eikenella，kingella(HACEK群)，真菌などが知られている．Peptostreptococcusは，弱毒性の嫌気性菌であり，口腔や消化管，尿路，皮膚に常在する．感染性心内膜炎の原因菌となることは稀である．今回，その1例を経験したので，報告する．症例は53歳女性，44歳時より拡張型心筋症，僧帽弁閉鎖不全症III度，僧帽弁逸脱症で外来治療を受けていた．2007年8月，肺炎を契機に発熱，軽快を繰り返し，心エコーで明らかな疣贅は認めなかったが，血液培養でpeptostreptococcusを8回認めたため，感染性心内膜炎と診断した．感染ルートは，う歯，歯周炎によるものと考えられ，歯科治療後に僧帽弁形成術を施行した．

　A 53-year-old woman was admitted to our hospital because of recurrent fever. She was diagnosed and treated for dilated cardiomyopathy and mitral valve regurgitation due to mitral valve prolapse at the age of 44. Infectious endocarditis(IE) was suspected as the origin of the fever, but although transthoracic and transesophageal echocardiography showed mitral valve prolapse and regurgitation but no vegetation clearly. Anaerobic bacteria peptostreptococcus were cultured 8 times from venous blood, so IE was diagnosed. Following 4 weeks of penicillinG administration, mitral valve plasty was performed successfully. The bacteria causing IE were noted as streptococcus viridans, staphylococcus aureus, enterococcus, haemophilus sp, actinobacillus, cardiobacterium, eikenella, kingella(HACEK) and fungus. Peptostreptococcus were anaerobic bacteria, which are part of normal flora of oral, gastrointestinal, kin and the urinary tract, but cause IE only rarely. We thus report a rare case of IE caused by peptostreptococcus.