公衆衛生81巻10号

2017年10月発行

特集 薬剤耐性(AMR)対策

水環境に拡散する抗菌薬，薬剤耐性遺伝子の汚染実態と課題

著者： 鈴木聡¹ 高田秀重²

所属機関： ¹愛媛大学沿岸環境科学研究センター生態系解析部門 ²東京農工大学大学院農学研究院環境資源科学科

ページ範囲：P.828 - P.833

下水中の抗菌薬
　水環境中の抗菌薬のモニタリング・動態把握は，薬剤耐性の誘導の可能性や誘導の起こる場を考えるうえで重要である．水環境中で安定して存在する抗菌薬は薬剤耐性菌や薬剤耐性遺伝子の拡散を考えるための指標，マーカーとして捉えることもできる．水環境へはヒト用および動物用(畜産用，水産用)の抗菌薬が負荷される．ヒトが服用した抗菌薬のうち未代謝のものが屎尿に排出されるため，下水がヒト用抗菌薬の主な負荷源となる．
　東京都内の下水処理場への流入下水中では，スルファピリジン，スルファメトキサゾール，アジスロマイシン，エリスロマイシン(脱水体)，クラリスロマイシンなどの抗菌薬がそれぞれ数百ng/L(サブppb)のレベルで検出された¹⁾．わが国では，通常は屎尿排水は下水処理場で一次処理と二次処理を受けてから河川や海域へ放流されるが，一次処理は沈殿による粒子状の汚染物質の除去，二次処理は活性汚泥処理による微生物による異化・同化であるため，水溶性で微生物活動を抑制する抗菌薬の除去は不十分である．実際に，下水処理(一次処理と二次処理)において，抗菌薬は最大でも70%しか除去されない．そもそも，現在の下水処理が抗菌薬などの水溶性の難微生物分解性の汚染物質の除去のために設計されているわけでないので，当然の結果である．

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