Evaluation of heat and chlorine disinfection efficiency on Legionella pneumophila

• Main Authors: Wan-Yun Cheng, 鄭宛芸
• Other Authors: 黃耀輝
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/47977625831148418083

碩士 === 國立臺灣大學 === 職業醫學與工業衛生研究所 === 93 === Legionella pneumophila is widely spread in both natural and man-made environment. The cooling tower of office buildings and the drinking water of hospitals are both likely to habit L. pneumophila. In order to protect the workers from L. pneumophila infection, it is necessary to eliminate or inhibit the growth of L. pneumophila in aquatic environment. In this study, we evaluated the effectiveness of heat and chlorine disinfection. The culturability of L. pneumophila was lost rapidly under the disinfection condition of 60℃ and 0.5 mg/L free chlorine. The membrane integrant cell percentages were reduced down to 5 % when treated with 0.5 mg/L free chlorine and protein mass was reduced substantially. However, 5~40% cells remained membrane integrant after heat disinfection at 60℃ and 70℃ for 30 min while protein mass was not affected. As incubation temperature back to 37℃, there is a possibility for percentage of membrane integrant cells to increase after heat disinfection. In contrast, no similar observations were found in chlorine-disinfected L. pneumophila. As for protein profile of the heat-disinfected L. pneumophila, host-invasion related proteins were particularly up-regulated in 24 hr heating, implying the survival and infectious potential for the long-term heat disinfected L. pneumophila. Based on the above results, chlorination is better than heating terms of the disinfection efficiency on L. pneumophila. To control L. pneumophila in environments, it is suggested to apply chlorination as the disinfection strategy for the non-potable water system. The route surveillance with non-culture assay methods (e.g., Polymerase Chain reaction) should be performed for L. pneumophila examination in the hot water supply system when the heat treatment is served as the control method.