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Long-term persistence of infectious Legionella with free-living amoebae in drinking water biofilms6.63 MB
Published (Version of record)CC BY-NC-ND V4.0, Open Access
Published (Version of record)CC BY-NC-ND V4.0, Open
Journal article
Long-term persistence of infectious Legionella with free-living amoebae in drinking water biofilms
International journal of hygiene and environmental health, Vol.222(4), pp.678-686
05/2019
PMID: 31036480
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Source: InCites
Abstract
Prolific growth of pathogenic Legionella pneumophila within engineered water systems and premise plumbing, and human exposure to aerosols containing this bacterium results in the leading health burden of any water-related pathogen in developed regions. Ecologically, free-living amoebae (FLA) are an important group of the microbial community that influence biofilm bacterial diversity in the piped-water environment. Using fluorescent microscopy, we studied in-situ the colonization of L. pneumophila in the presence of two water-related FLA species, Willaertia magna and Acanthamoeba polyphaga in drinking water biofilms. During water flow as well as after periods of long-stagnation, the attachment and colonization of L. pneumophila to predeveloped water-biofilm was limited. Furthermore, W. magna and A. polyphaga showed no immediate interactions with L. pneumophila when introduced to the same natural biofilm environment. A. polyphaga encysted within 5-7 d after introduction to the tap-water biofilms and mostly persisted in cysts till the end of the study period (850 d). W. magna trophozoites, however, exhibited a time delay in feeding on Legionella and were observed with internalized L. pneumophila cells after 3 weeks from their introduction to the end of the study period and supported putative (yet limited) intracellular growth. The culturable L.pneumophila in the bulk water was reduced by 2-log over 2 years at room temperature but increased (without a change in mip gene copies by qPCR) when the temperature was elevated to 40 °C within the same closed-loop tap-water system without the addition of nutrients or fresh water. The overall results suggest that L. pneumophila maintains an ecological balance with FLA within the biofilm environment, and higher temperature improve the viability of L. pneumophila cells, and intracellular growth of Legionella is possibly cell-concentration dependent. Observing the preferential feeding behavior, we hypothesize that an initial increase of FLA numbers through feeding on a range of other available bacteria could lead to an enrichment of L. pneumophila, and later force predation of Legionella by the amoeba trophozoites results in rapid intracellular replication, leading to problematic concentration of L. pneumophila in water. In order to find sustainable control options for legionellae and various other saprozoic, amoeba-resisting bacterial pathogens, this work emphasizes the need for better understanding of the FLA feeding behavior and the range of ecological interactions impacting microbial population dynamics within engineered water systems.
Details
- Title
- Long-term persistence of infectious Legionella with free-living amoebae in drinking water biofilms
- Creators
- Mohamed Shaheen - University of AlbertaCandis Scott - University of AlbertaNicholas J Ashbolt - University of Alberta
- Publication Details
- International journal of hygiene and environmental health, Vol.222(4), pp.678-686
- Publisher
- Elsevier
- Grant note
- 372150 / CIHR
- Identifiers
- 991013097816702368
- Copyright
- © 2019 The Authors. Published by Elsevier GmbH. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
- Academic Unit
- Faculty of Science and Engineering
- Language
- English
- Resource Type
- Journal article