Journal Article 療養環境の清掃・消毒の効果に関する検証
Verification of the Effects of Cleaning and Disinfection in Medical Treatment Environments

東野, 督子  ,  神谷, 和人  ,  藤井, 徹也

 医療施設において耐性菌で最も多く分離されるmethicillin-resistant Staphylococcus aureus(MRSA )は、材質によっては30 日以上の生存が確認され、殺菌効果があるとされる銅や真鍮においても牛胎児血清が加わるとS. aureus の15日以上の生存が示された(東野・神谷、2011、2012)。本研究では、療養環境に生存する病原微生物を除去できる住宅用洗剤の使用に関する検討を行う。 方法は、EN 13697(European Norm:欧州標準規格)を踏まえて、日本石鹸洗剤工業界の方法を参考にして、牛胎児血清が加わったMRSA などの疑似汚染における水拭き清掃と環境消毒剤含有の環境用合成洗剤を使用した細菌の生菌数の減少率を比較した。試験菌の付着片作成法:非耐性株であるmethicillin-sensitive Staphylococcus aureus〔MSSA( ATCC29213 株)〕、及びMRSA であるATCC43300 株を用いた。試験菌の付着片は、ステンレス片を2cm× 2cm 大にカットし滅菌した後に牛胎児性血清を含む菌液を滴下しデシケーター中で乾燥させ作成した。試験菌の回収は、供試薬剤100μℓ を1 分間作用させた後、消毒効果を止めるための中和剤の使用の有無の比較で行った。 四級アンモニウム塩の効果は1 分以上の作用を必要とする。四級アンモニウム塩を含む環境用合成洗剤であっても、1 分より短い接触時間で乾燥する程度の使用量では、四級アンモニウム塩配合の効果を期待できない。
 Methicillin-resistant Staphylococcus aureus (MRSA), the most frequently isolated resistant bacterium in medical institutions, has been demonstrated to survive for over 30 days, depending on the materials on which they grow. S. aureus has been shown to have the ability to survive for over 15 days even on copper and brass, which are said to be bactericidal, in the presence of fetal bovine serum (FBS) (Higashino and Kamiya,2011,2012). In this study, the efficacy of environmental detergents in eliminating pathogenic microbes surviving in medical treatment environments was evaluated. Based on EN 13697 (European Norm), taking into account the method recommended by the Japan Soap and Detergent Association, the rates of decrease of the viable bacteria were compared between wiping with water alone and wiping with a environmental detergent containing an environmental disinfectant for pseudo contamination, such as MRSA growing in FBS. Method of preparation of the small pieces of material carrying the test bacteria: Methicillin-sensitive Staphylococcus aureus (MSSA [ATCC29213]), which is non-resistant strain, and the MRSA strain, ATCC43300, were used. Small pieces carrying the test bacteria were prepared by cutting a stainless steel plate into 2 cm × 2 cm pieces, sterilizing the pieces, dropping bacterial solution containing FBS on them, and then drying the pieces in a desiccator. The test bacteria were recovered after applying 100 μℓ of the test detergent to the pieces for one minute and then using a neutralizing agent. Environmental detergents containing quaternary ammonium salt were bactericidal only when the application time was longer than one minute. Bactericidal effects cannot be expected of environmental detergents, even when they contain quaternary ammonium salt, if the contents of these compounds are so small as to cause drying of the detergent within one minute of application.

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