scholarly journals Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems

Pathogens ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 286 ◽  
Author(s):  
Muhammad Atif Nisar ◽  
Kirstin E. Ross ◽  
Melissa H. Brown ◽  
Richard Bentham ◽  
Harriet Whiley
Keyword(s):  
Legionella Pneumophila ◽  
Distribution Systems ◽  
Water Distribution ◽  
Potable Water ◽  
Water Systems ◽  
Water Disinfection ◽  
Health Concern ◽  
Waterborne Pathogen ◽  
Microbial Biofilms ◽  
Pontiac Fever

Legionella pneumophila is an opportunistic waterborne pathogen of public health concern. It is the causative agent of Legionnaires’ disease (LD) and Pontiac fever and is ubiquitous in manufactured water systems, where protozoan hosts and complex microbial communities provide protection from disinfection procedures. This review collates the literature describing interactions between L. pneumophila and protozoan hosts in hospital and municipal potable water distribution systems. The effectiveness of currently available water disinfection protocols to control L. pneumophila and its protozoan hosts is explored. The studies identified in this systematic literature review demonstrated the failure of common disinfection procedures to achieve long term elimination of L. pneumophila and protozoan hosts from potable water. It has been demonstrated that protozoan hosts facilitate the intracellular replication and packaging of viable L. pneumophila in infectious vesicles; whereas, cyst-forming protozoans provide protection from prolonged environmental stress. Disinfection procedures and protozoan hosts also facilitate biogenesis of viable but non-culturable (VBNC) L. pneumophila which have been shown to be highly resistant to many water disinfection protocols. In conclusion, a better understanding of L. pneumophila-protozoan interactions and the structure of complex microbial biofilms is required for the improved management of L. pneumophila and the prevention of LD.

scholarly journals MUWS (Microbiology in Urban Water Systems) – an interdisciplinary approach to study microbial communities in urban water systems

2010 ◽  
Vol 3 (2) ◽  
pp. 91-99 ◽  
Author(s):  
P. Deines ◽  
R. Sekar ◽  
H. S. Jensen ◽  
S. Tait ◽  
J. B. Boxall ◽  
...  
Keyword(s):  
Microbial Ecology ◽  
Distribution Systems ◽  
Water Distribution ◽  
Potable Water ◽  
Water Distribution Systems ◽  
Water Systems ◽  
Urban Water ◽  
Infrastructure Systems ◽  
Urban Water Systems ◽  
Sewer Networks

Abstract. Microbiology in Urban Water Systems (MUWS) is an integrated project, which aims to characterize the microorganisms found in both potable water distribution systems and sewer networks. These large infrastructure systems have a major impact on our quality of life, and despite the importance of these systems as major components of the water cycle, little is known about their microbial ecology. Potable water distribution systems and sewer networks are both large, highly interconnected, dynamic, subject to time and varying inputs and demands, and difficult to control. Their performance also faces increasing loading due to increasing urbanization and longer-term environmental changes. Therefore, understanding the link between microbial ecology and any potential impacts on short or long-term engineering performance within urban water infrastructure systems is important. By combining the strengths and research expertise of civil-, biochemical engineers and molecular microbial ecologists, we ultimately aim to link microbial community abundance, diversity and function to physical and engineering variables so that novel insights into the performance and management of both water distribution systems and sewer networks can be explored. By presenting the details and principals behind the molecular microbiological techniques that we use, this paper demonstrates the potential of an integrated approach to better understand how urban water system function, and so meet future challenges.

Fungi from Potable Water: Interaction with Chlorine and Engineering Effects

1988 ◽  
Vol 20 (11-12) ◽  
pp. 153-159 ◽  
Author(s):  
William D. Rosenzweig ◽  
Wesley O. Pipes
Keyword(s):  
Water Samples ◽  
Distribution Systems ◽  
Water Distribution ◽  
Potable Water ◽  
Fungal Spores ◽  
Water Distribution Systems ◽  
Water Systems ◽  
Storage Tanks ◽  
Water Interaction ◽  
Low Concentrations

In recent years various types of imperfect fungi have been isolated from water systems. Fungal spores and mycelia can be inactivated by low concentrations of chlorine in the laboratory but survive in some habitats in water distribution systems. This report describes a field study which provides evidence that some types of fungi are able to grow in water distribution systems. Replicate samples from private residences were used to demonstrate that fungal densities are sometimes much greater than the levels which could be explained by adventitious spores. The microbiological content of water samples from fire hydrants was often significantly different from that of water samples from nearby private residences. The treated water input to distribution systems was found to be significantly lower in fungus content than water from private residences. Elevated storage tanks open to the atmosphere appear to be significant sources of fungal input to some systems.

scholarly journals MUWS (Microbiology in Urban Water Systems) – an interdisciplinary approach to study microbial communities in urban water systems

2010 ◽  
Vol 3 (1) ◽  
pp. 43-64
Author(s):  
P. Deines ◽  
R. Sekar ◽  
H. S. Jensen ◽  
S. Tait ◽  
J. B. Boxall ◽  
...  
Keyword(s):  
Microbial Ecology ◽  
Distribution Systems ◽  
Water Distribution ◽  
Potable Water ◽  
Water Distribution Systems ◽  
Water Systems ◽  
Urban Water ◽  
Microbiological Methods ◽  
Urban Water Systems ◽  
Sewer Networks

Abstract. Microbiology in Urban Water Systems (MUWS) is an integrated project, which aims to characterize the microorganisms found in both potable water distribution systems and sewer networks. These large infrastructure systems have a major impact on our quality of life, and despite the importance of these systems as major components of the water cycle, little is known about their microbial ecology. Potable water distribution systems are large, highly interconnected and dynamic, and difficult to control. Sewer systems are also large and subject to time varying inputs and demands. Their performance also faces increasing loading due to increasing urbanization and longer-term environmental changes. Therefore, understanding the link between microbial ecology and any potential impacts on short or long-term engineering performance is important. By combining the strengths and research expertise of civil-, biochemical engineers and molecular microbial ecologists, we aim to link the abundance and diversity of microorganisms to physical and engineering variables so that novel insights into the ecology of microorganisms within both water distribution systems and sewer networks can be explored. By presenting the details of this multidisciplinary approach, and the principals behind the molecular microbiological methods and techniques that we use, this paper will demonstrate the potential of an integrated approach to better understand urban water system function and so meet future challenges.

scholarly journals Role of biofilms in the survival of Legionella pneumophila to sodium chloride treatment

2021 ◽  
Author(s):  
Abdelwahid Assaidi ◽  
Mostafa Ellouali ◽  
Hassan Latrache ◽  
Hafida Zahir ◽  
El Mostafa Mliji
Keyword(s):  
Sodium Chloride ◽  
Legionella Pneumophila ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Chloride Concentration ◽  
Health Concern ◽  
Bacterial Strains ◽  
Planktonic Cells

Background and Objectives: Legionnaires’ disease continues to be a public health concern. Colonized water distribution systems are often implicated in Legionella transmission, despite the use of various disinfection strategies, the bacterium is capable to persist and survive in water systems. The aim of this study was to investigate the persistence of Legionella pneumophila to sodium chloride over time at different temperatures and analysing the role of biofilms in the survival of this bacteria. Materials and Methods: L. pneumophila serogroup 1 and L. pneumophila serogroup 2-15 were used to study the effect of sodium chloride on planktonic and sessile cells. The tested concentrations were: 0.5%, 1%, 2%, 3%, 4%, 6% and 8% (W/V) NaCl. Biofilms were grown on 24-well microplates. Results: At 20°C, L. pneumophila planktonic cells were able to survive in sodium chloride concentrations up to 2%. How- ever, at 37°C, a sodium chloride concentration over 1.5%, reduced systematically the numbers of bacterial cells. Biofilms were grown for 20 days in the absence and presence of sodium chloride. The results show that bacterial strains were able to survive and regrow after the sodium chloride shock (2-3%). Moreover, it seems that this effect is less expressed with the age of the biofilm; old biofilms were more persistent than the young ones. Conclusion: Results from this study demonstrate that the sodium chloride disinfection strategy was effective on Legionella pneumophila planktonic cells but not on biofilms, which demonstrate the role of biofilms in the persistence and recoloniza- tion of L. pneumophila in water distribution systems.

scholarly journals Legionella pneumophila’s Tsp is important for surviving thermal stress in water and inside amoeba

2020 ◽  
Author(s):  
Joseph Saoud ◽  
Thangadurai Mani ◽  
Sébastien P. Faucher
Keyword(s):  
Heat Treatment ◽  
Thermal Stress ◽  
Heat Shock ◽  
Legionella Pneumophila ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Water Systems ◽  
Exponential Phase ◽  
Hot Water

ABSTRACTLegionella pneumophila (Lp) is an inhabitant of natural and man-made water systems where it replicates within amoebae and ciliates and survives within biofilms. When Lp-contaminated aerosols are breathed in, Lp will enter the lungs and infect human alveolar macrophages, causing a severe pneumonia known as Legionnaires Disease. Lp is often found in hot water distribution systems (HWDS), which are linked to nosocomial outbreaks. Heat treatment is used to disinfect HWDS and reduce the concentration of Lp. However, Lp is often able to recolonize these water systems, indicating an efficient heat-shock response. Tail-specific proteases (Tsp) are typically periplasmic proteases implicated in degrading aberrant proteins in the periplasm and important for surviving thermal stress. In this paper, we show that Tsp, encoded by the lpg0499 gene in Lp Philadelphia-1, is important for surviving thermal stress in water and for optimal infection of amoeba when a shift in temperature occurs during intracellular growth. Tsp is expressed in the post-exponential phase but repressed in the exponential phase. The cis-encoded small regulatory RNA Lpr17 shows opposite expression, suggesting that it represses translation of tsp. In addition, tsp is regulated by CpxR, a major regulator in Lp, in a Lpr17-independent manner. Deletion of CpxR also reduced the ability of Lp to survive heat shock. In conclusion, this study shows that Tsp is an important factor for the survival and growth of Lp in water systems.IMPORTANCELegionella pneumophila (Lp) is a major cause of nosocomial and community-acquired pneumonia. Lp is found in water systems including hot water distribution systems. Heat treatment is a method of disinfection often used to limit Lp’s presence in such systems; however, the benefit is usually short term as Lp is able to quickly recolonize these systems. Presumably, Lp respond efficiently to thermal stress, but so far not much is known about the genes involved. In this paper, we show that the Tail-specific protease (Tsp) and the two-component system CpxRA are required for resistance to thermal stress, when Lp is free in water and when it is inside host cells. Our study identifies critical systems for the survival of Lp in its natural environment under thermal stress.

scholarly journals The Tail-Specific Protease Is Important for Legionella pneumophila To Survive Thermal Stress in Water and inside Amoebae

2021 ◽  
Vol 87 (9) ◽  
Author(s):  
Joseph Saoud ◽  
Thangadurai Mani ◽  
Sébastien P. Faucher
Keyword(s):  
Heat Treatment ◽  
Thermal Stress ◽  
Heat Shock ◽  
Legionella Pneumophila ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Water Systems ◽  
Hot Water ◽  
Host Cells

ABSTRACT Legionella pneumophila (Lp) is an inhabitant of natural and human-made water systems, where it replicates within amoebae and ciliates and survives within biofilms. When Lp-contaminated aerosols are breathed in, Lp can enter the lungs and may infect human alveolar macrophages, causing severe pneumonia known as Legionnaires’ disease. Lp is often found in hot water distribution systems (HWDS), which are linked to nosocomial outbreaks. Heat treatment is used to disinfect HWDS and reduce the concentration of Lp. However, Lp is often able to recolonize these water systems, indicating an efficient heat shock response. Tail-specific proteases (Tsp) are typically periplasmic proteases implicated in degrading aberrant proteins in the periplasm and important for surviving thermal stress. In Lp Philadelphia-1, Tsp is encoded by the lpg0499 gene. In this paper, we show that Tsp is important for surviving thermal stress in water and for optimal infection of amoeba when a shift in temperature occurs during intracellular growth. We also demonstrate that Tsp is expressed in the postexponential phase but repressed in the exponential phase and that the cis-encoded small regulatory RNA Lpr17 shows the opposite expression, suggesting that it represses translation of tsp. In addition, our results show that tsp is regulated by CpxR, a major regulator in Lp, in an Lpr17-independent manner. Deletion of CpxR also reduced the ability of Lp to survive heat shock. In conclusion, our study shows that Tsp is likely an important factor for the survival and growth of Lp in water systems. IMPORTANCE Lp is a major cause of nosocomial and community-acquired pneumonia. Lp is found in water systems, including hot water distribution systems. Heat treatment is a method of disinfection often used to limit the presence of Lp in such systems; however, the benefit is usually short term, as Lp is able to quickly recolonize these systems. Presumably, Lp responds efficiently to thermal stress, but so far, not much is known about the genes involved. In this paper, we show that the Tsp and the two-component system CpxRA are required for resistance to thermal stress when Lp is free in water and when it is inside host cells. Our study identifies critical systems for the survival of Lp in its natural environment under thermal stress.

Computational framework for evaluating risk trade-offs in costs associated with Legionnaires’ Disease risk, energy, and scalding risk for hospital hot water systems

2021 ◽  
Author(s):  
Ashley Heida ◽  
Alexis Mraz ◽  
Mark Hamilton ◽  
Mark Weir ◽  
Kerry A Hamilton
Keyword(s):  
Legionella Pneumophila ◽  
Disease Risk ◽  
Disease Outbreaks ◽  
Febrile Illness ◽  
Water Systems ◽  
Hot Water ◽  
Computational Framework ◽  
Trade Offs ◽  
Pontiac Fever ◽  
Legionnaires Disease

Legionella pneumophila are bacteria that when inhaled cause Legionnaires’ Disease (LD) and febrile illness Pontiac Fever. As of 2014, LD is the most frequent cause of waterborne disease outbreaks due...

Determinants of Legionella pneumophila Contamination of Water Distribution Systems: 15-Hospital Prospective Study

1987 ◽  
Vol 8 (9) ◽  
pp. 357-363 ◽  
Author(s):  
Richard M. Vickers ◽  
Victor L. Yu ◽  
S. Sue Hanna ◽  
Paul Muraca ◽  
Warren Diven ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Cold Water ◽  
Physicochemical Characteristics ◽  
Hot Water ◽  
Environmental Study ◽  
Water Tank ◽  
One Year

AbstractWe conducted a prospective environmental study for Legionella pneumophila in 15 hospitals in Pennsylvania. Hot water tanks, cold water sites, faucets, and show-erheads were surveyed four times over a one-year period. Sixty percent (9/15) of hospitals surveyed were contaminated with L pneumophila. Although contamination could not be linked to a specific municipal water supplier, most of the contaminated supplies came from rivers. Parameters found to be significantly associated with contamination included elevated hot water temperature, vertical configuration of the hot water tank, older tanks, and elevated calcium and magnesium concentrations of the water (P < 0.05). This study suggests that L pneumophila contamination could be predicted based on design of the distribution system, as well as physicochemical characteristics of the water.

scholarly journals How Molecular Typing Can Support Legionella Environmental Surveillance in Hot Water Distribution Systems: A Hospital Experience

2020 ◽  
Vol 17 (22) ◽  
pp. 8662
Author(s):  
Luna Girolamini ◽  
Silvano Salaris ◽  
Jessica Lizzadro ◽  
Marta Mazzotta ◽  
Maria Rosaria Pascale ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Molecular Typing ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Gene Sequencing ◽  
Culture Technique ◽  
Hot Water ◽  
Environmental Surveillance ◽  
Risk Map

In this study, we aimed to associate the molecular typing of Legionella isolates with a culture technique during routine Legionella hospital environmental surveillance in hot water distribution systems (HWDSs) to develop a risk map able to be used to prevent nosocomial infections and formulate appropriate preventive measures. Hot water samples were cultured according to ISO 11731:2017. The isolates were serotyped using an agglutination test and genotyped by sequence-based typing (SBT) for Legionella pneumophila or macrophage infectivity potentiator (mip) gene sequencing for non-pneumophila Legionella species. The isolates’ relationship was phylogenetically analyzed. The Legionella distribution and level of contamination were studied in relation to temperature and disinfectant residues. The culture technique detected 62.21% of Legionella positive samples, characterized by L. pneumophila serogroup 1, Legionella non-pneumophila, or both simultaneously. The SBT assigned two sequence types (STs): ST1, the most prevalent in Italy, and ST104, which had never been isolated before. The mip gene sequencing detected L. anisa and L. rubrilucens. The phylogenetic analysis showed distinct clusters for each species. The distribution of Legionella isolates showed significant differences between buildings, with a negative correlation between the measured level of contamination, disinfectant, and temperature. The Legionella molecular approach introduced in HWDSs environmental surveillance permits (i) a risk map to be outlined that can help formulate appropriate disinfection strategies and (ii) rapid epidemiological investigations to quickly identify the source of Legionella infections.

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