Managing Legionella pneumophila in Water Systems

2020 ◽  
Vol 112 (2) ◽  
pp. 10-23 ◽  
Author(s):  
Mark W. LeChevallier
Keyword(s):  
Legionella Pneumophila ◽  
Water Systems

scholarly journals Highlighting the Potency of Biosurfactants Produced by Pseudomonas Strains as Anti-Legionella Agents

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Clémence Loiseau ◽  
Emilie Portier ◽  
Marie-Hélène Corre ◽  
Margot Schlusselhuber ◽  
Ségolène Depayras ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Close Association ◽  
Water Systems ◽  
Antagonistic Activity ◽  
Reverse Phase Hplc ◽  
Reverse Phase ◽  
Free Living ◽  
Legionnaires Disease ◽  
Culture Supernatants ◽  
Multispecies Biofilms

Legionella pneumophila, the causative agent of Legionnaires’ disease, is a waterborne bacterium mainly found in man-made water systems in close association with free-living amoebae and multispecies biofilms. Pseudomonas strains, originating from various environments including freshwater systems or isolated from hospitalized patients, were tested for their antagonistic activity towards L. pneumophila. A high amount of tested strains was thus found to be active. This antibacterial activity was correlated to the presence of tensioactive agents in culture supernatants. As Pseudomonas strains were known to produce biosurfactants, these compounds were specifically extracted and purified from active strains and further characterized using reverse-phase HPLC and mass spectrometry methods. Finally, all biosurfactants tested (lipopeptides and rhamnolipids) were found active and this activity was shown to be higher towards Legionella strains compared to various other bacteria. Therefore, described biosurfactants are potent anti-Legionella agents that could be used in the water treatment industry although tests are needed to evaluate how effective they would be under field conditions.

Disinfection of domestic water systems for Legionella pneumophila

2003 ◽  
Vol 52 (5) ◽  
pp. 341-354 ◽  
Author(s):  
C. Campos ◽  
J. F. Loret ◽  
A. J. Cooper ◽  
R. F. Kelly
Keyword(s):  
Legionella Pneumophila ◽  
Water Systems ◽  
Domestic Water

scholarly journals Necrotrophic Growth of Legionella pneumophila

2006 ◽  
Vol 72 (6) ◽  
pp. 4323-4328 ◽  
Author(s):  
R. Temmerman ◽  
H. Vervaeren ◽  
B. Noseda ◽  
N. Boon ◽  
W. Verstraete
Keyword(s):  
Flow Cytometry ◽  
Real Time ◽  
Legionella Pneumophila ◽  
Real Time Pcr ◽  
Water Systems ◽  
Saccharomyces Boulardii ◽  
Wall Structure ◽  
Lower Growth ◽  
Average Growth ◽  
Microbial Cells

ABSTRACT This study examined whether Legionella pneumophila is able to thrive on heat-killed microbial cells (necrotrophy) present in biofilms or heat-treated water systems. Quantification by means of plate counting, real-time PCR, and flow cytometry demonstrated necrotrophic growth of L. pneumophila in water after 96 h, when at least 100 dead cells are available to one L. pneumophila cell. Compared to the starting concentration of L. pneumophila, the maximum observed necrotrophic growth was 1.89 log units for real-time PCR and 1.49 log units for plate counting. The average growth was 1.57 � 0.32 log units (n = 5) for real-time PCR and 1.14 � 0.35 log units (n = 5) for plate counting. Viability staining and flow cytometry showed that the fraction of living cells in the L. pneumophila population rose from the initial 54% to 82% after 96 h. Growth was measured on heat-killed Pseudomonas putida, Escherichia coli, Acanthamoeba castellanii, Saccharomyces boulardii, and a biofilm sample. Gram-positive organisms did not result in significant growth of L. pneumophila, probably due to their robust cell wall structure. Although necrotrophy showed lower growth yields compared to replication within protozoan hosts, these findings indicate that it may be of major importance in the environmental persistence of L. pneumophila. Techniques aimed at the elimination of protozoa or biofilm from water systems will not necessarily result in a subsequent removal of L. pneumophila unless the formation of dead microbial cells is minimized.

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...

Effect of heat flushing on the concentrations of Legionella pneumophila and other heterotrophic microbes in hot water systems of apartment buildings

1996 ◽  
Vol 42 (8) ◽  
pp. 811-818 ◽  
Author(s):  
Outi M. Zacheus ◽  
Pertti J. Martikainen
Keyword(s):  
Water Temperature ◽  
Legionella Pneumophila ◽  
Heterotrophic Bacteria ◽  
Water System ◽  
Water Systems ◽  
Hot Water ◽  
Circulating Water ◽  
Heterotrophic Microbes ◽  
Before And After ◽  
Circulating Water System

The decontamination of Legionella pneumophila and other heterotrophic microbes by heat flushing in four legionellae-positive hot water systems was studied. Before the decontamination procedure, the concentration of legionellae varied from 3.0 × 10−3 to 3.5 × 10−5 cfu/L and the hot water temperature from 43.6 to 51.5 °C. During the contamination the temperature was raised to 60–70 °C. All taps and showers were cleaned from sediments and flushed with hot water twice a day for several minutes. The decontamination lasted for 2–4 weeks. In a few weeks the heat-flushing method reduced the concentration of legionellae below the detection limit (50 cfu/L) in the hot circulating water system just before and after the heat exchanger. The high hot water temperature also decreased the viable counts of heterotrophic bacteria, fungi, and total microbial cells determined by the epifluorescent microscopy. However, the eradication of legionellae failed in a water system where the water temperature remained below 60 °C in some parts of the system. After the decontamination, the temperature of hot water was lowered to 55 °C. Thereafter, all the studied hot water systems were recolonized by legionellae within a few months, showing that the decontamination by heat flushing was temporary. Also, the contamination of other bacteria increased in a few months to the level before decontamination.Key words: legionellae, hot water system, decontamination, water temperature, heterotrophic bacteria.

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 In-vitro activity of antibiotics against Legionella pneumophila isolates from water systems

1999 ◽  
Vol 44 (5) ◽  
pp. 693-695 ◽  
Author(s):  
A. Tsakris ◽  
S. Alexiou-Daniel ◽  
E. Souliou ◽  
A. Antoniadis
Keyword(s):  
Legionella Pneumophila ◽  
Water Systems ◽  
Vitro Activity ◽  
In Vitro Activity

Microbial risk assessment of dental unit water systems in general dental practice in Greece

2006 ◽  
Vol 54 (3) ◽  
pp. 269-273 ◽  
Author(s):  
A. Mavridou ◽  
J. Kamma ◽  
G. Mandilara ◽  
P. Delaportas ◽  
F. Komioti
Keyword(s):  
Risk Assessment ◽  
Legionella Pneumophila ◽  
Water Systems ◽  
Source Water ◽  
Dental Practice ◽  
Microbial Risk Assessment ◽  
Water Line ◽  
Microbial Risk ◽  
General Dental Practice ◽  
Mycobacterium Spp

Water was sampled from source water, the 3-in-1 syringe and the air rotor water line of dental unit water systems (DUWS) in general dental practice in Attica, Greece. A section of the water line supplying the 3-in-1 syringe was cut for biofilm analysis. High total viable counts, Mycobacterium spp. and Pseudomonas aeruginosa were detected in the samples. Back siphonage was evidenced by the presence of blood and the recovery of oral anaerobes from the samples. Legionella pneumophila was recovered from 16.1% of biofilm samples. All tested disinfectants reduced the total viable counts of the DUWS to <100 CFU/mL.

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