ノカルジア脳膿瘍：外科治療と術後抗菌剤併用の有用性

Nocardial Brain Abscess：Surgery and Postoperative Antibiotic Therapy

　Ⅰ．はじめに

ノカルジア（Nocardia）はおもに土中に常在する放線菌類で，膠原病，糖尿病，慢性閉塞性肺疾患などの基礎疾患を持つ患者や，副腎皮質ホルモン，免疫抑制剤，抗癌剤などを投与されている患者，成人免疫不全症候群などの免疫低下状態における日和見感染症として増加傾向にある^4,11)．通常，肺ノカルジア症を発症し，そのうち20～30％が中枢神経系に血行性転移を来すが，中枢神経系原発のノカルジア症も報告されている．中枢神経系ノカルジア症の多くは脳膿瘍の形態をとる^3,15,16)．ノカルジア脳膿瘍は一般の抗生剤治療に抵抗性であることが多く，他の細菌性脳膿瘍と比べて死亡率が高い^7,15,20,26)．診断・治療の進歩により転帰は改善しつつあるが，死亡率は30％に達する⁵⁾．最近われわれは排膿ドレナージ・被膜外摘出を含めた外科治療と術後に比較的短期間の抗菌剤投与を組み合わせることで良好な結果を得ている．われわれの経験したノカルジア脳膿瘍4例を報告し，外科治療と術後抗菌剤併用の有用性について検討する．

　Nocardial infections in an immunocompromised host have been increasingly reported. Nocardial brain abscess,the most common presentation of nocardiosis in the central nervous system,is associated with a high mortality rate because of its delayed diagnosis and its unresponsiveness to the usual antibiotic therapy. We report four patients who experienced a long-term cure of nocardial brain abscess due to treatment by a combination of surgery and postoperative antibiotic therapy ; 1 man and 3 women,ages ranging from 43 to 67 years old. Two patients were associated with systemic lupus erythematosus and two with autoimmune hemolytic anemia. Patients underwent surgical aspiration and drainage of brain abscess. Nocardia was identified from the aspirated specimen and postoperative antibiotic therapy for 5-6 weeks was performed using effective antibiotic agents ; sulfamethoxazole/trimethoprim (ST),imipenem/cilastatin and minocycline (MINO) in Case 1,ST and MINO in Case 2,erythromycin in Case 3,and panipenem/betamipron and cefotaxime in Case 4. Case 3 and Case 4 with multilobulated brain abscess underwent total excision of the brain abscess. All patients showed successful cure of nocardial brain abscess with no recurrence for the period of 1-8 years. The combination of surgery and postoperative antibiotic therapy provides a good prognosis for nocardial brain abscess.