A search of risk factors associated Legionella spp. in water distribution systems from multifaceted perspective

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K06275
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Civil and environmental engineering
• Research Institution: Azabu University
• Principal Investigator: Ohkouchi Yumiko 麻布大学, 生命・環境科学部, 准教授 (00391079)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: レジオネラ / 自由生活性アメーバ / 貯水槽水道 / 従属栄養細菌 / 残留塩素 / 滞留水

Outline of Final Research Achievements

Legionella spp. is known as a high-priority pathogen in microbial risk management in water distribution systems, and this investigation, therefore, attempted to determine risk factors of Legionella spp.. In particular, water samples from the faucets located in distribution systems via cisterns were taken to survey regrowth of Legionella spp. and free-living amoeba (FLA) and to check possibility of Legionella and heterotrophic bacteria regrowth in water with/without FLA after quenching chlorine residual. The regrowth or survival of Legionella spp. was tended to be higher in the unfiltered (FLA possibly living) water samples, while HPC was tended to increase in the filtered (FLA removed) samples. This result suggests that HPC can be escaped from FLA predation in filtered water samples, but that Legionella spp. prefers conditions with FLA to survive in water distribution systems. Also, in water with chlorine residual above 0.4 mg/L, no FLA detection was observed.

Free Research Field

環境微生物　水道工学　微生物リスク