海外から移入されたコリスチン低感受性多剤耐性アシネトバクター・バウマニによる脳神経外科術後脳膿瘍の1例

A Case of Post-Operative Cerebral Abscess Caused by Multidrug-Resistant Acinetobacter baumannii―Possibly Originating Abroad,and Poorly Susceptible to Colistin

Ⅰ．はじめに

　脳神経外科領域の手術部位感染の発生率は，数％程度と言われている．しかし，ventriculo-peritoneal（V-P）shuntや人工硬膜，人工骨などの異物を使用する手術での手術部位感染では，再手術を余儀なくされるため，患者に大きな負担となる場合が多い^4,6,9,12)．

　近年，多剤耐性菌の出現が大きな社会問題となり，World Health Organization（WHO）やCenters for Disease Control and Prevention（CDC）などでもさまざまな対策が行われている．多剤耐性アシネトバクター（multidrug-resistant Acinetobacter baumannii：MRAB）は有効な抗菌薬が極めて限られていることから，multidrug-resistant Pseudomonas aeruginosa（MDRP）と同様に，感染症治療上多くの問題をはらんでいる．医療機関における感染制御の上でも重要な位置を占め，既に本邦でもMRABによる病院内アウトブレイクが報告されている．今回われわれは，他国より移入されたMRABによる脳神経外科術後感染例を経験し，適切な対応により院内汚染や院内での交差感染を防ぐことができ，感染症治療にも成功した症例を経験した．

　We report a case of post-neurosurgical meningitis,subdural empyema,and cerebral abscess caused by multidrug-resistant Acinetobacter baumannii (MRAB) poorly susceptible to colistin. A 49-year-old man was transferred to our hospital after surgical treatment for putaminal hemorrhage in a foreign country hospital. Several examinations revealed surgical site infection (SSI). From cerebro-spinal fluid examination via ventricular drainage,MRAB was recovered. The minimum inhibitory concentration (MIC) of colistin was 2 μg/mL. Intravenous administration of colistin with ceftazidime and rifampicin was started,with intrathecal colistin administration,based on the results of a Break-point Checkerboard examination,and resulted in effective infection control. Nosocomial infection by MRAB has become an emergent problem in many countries. In Japan,several outbreak accidents caused by MRAB have been reported so far. In this case,genetic analysis revealed that the pathogen had originated from a foreign country,and the prevalence of colistin-resistant pathogens has also increased in these countries. Besides adequate isolation precautions,strategies for post-neurosurgical SSI management and establishment of effective treatments are necessary against neurosurgical SSIs caused by colistin-resistant MRAB.