Chlorine Disinfection of Legionella spp., L. pneumophila, and Acanthamoeba under Warm Water Premise Plumbing Conditions

Martin, Rebekah L.; Harrison, Kara; Proctor, Caitlin R.; Martín, Amanda; Williams, Krista; Pruden, Amy; Edwards, Marc

doi:10.3390/microorganisms8091452

Cited by 12 publications

(15 citation statements)

References 68 publications

(101 reference statements)

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“…Attenuated (Δ cpxA ) and infectious (WT) Lp (described in Table ) were the most susceptible to both disinfectants, while the highly infectious cells (Mg-Spike and Protozoan-Primed) were the most resistant to both disinfectants. Interestingly, Martin et al found little efficacy of free chlorine treatment of Lp in the presence of a magnesium anode as compared to its absence in simulated glass water heaters containing 1 mg/L total organic carbon …”

Section: Resultsmentioning

confidence: 99%

Protozoan-Priming and Magnesium Conditioning Enhance Legionella pneumophila Dissemination and Monochloramine Resistance

Cambronne,

Ayres,

Dowdell

et al. 2023

Environ. Sci. Technol.

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Opportunistic pathogens (OPs) are of concern in drinking water distribution systems because they persist despite disinfectant residuals. While many OPs garner protection from disinfectants via a biofilm lifestyle, Legionella pneumophila (Lp) also gains disinfection resistance by being harbored within free-living amoebae (FLA). It has been long established, but poorly understood, that Lp grown within FLA show increased infectivity toward subsequent FLA or human cells (i.e., macrophage), via a process we previously coined "protozoan-priming". The objectives of this study are (i) to identify in Lp a key genetic determinant of how protozoan-priming increases its infectivity, (ii) to determine the chemical stimulus within FLA to which Lp responds during protozoan-priming, and (iii) to determine if more infectious forms of Lp also exhibit enhanced disinfectant resistance. Using Acanthamoeba castellanii as a FLA host, the priming effect was isolated to Lp's sidGV locus, which is activated upon sensing elevated magnesium concentrations. Supplementing growth medium with 8 mM magnesium is sufficient to produce Lp grown in vitro with an infectivity equivalent to that of Lp grown via the protozoan-primed route. Both Lp forms with increased infectivity (FLA-grown and Mg 2+ -supplemented) exhibit greater monochloramine resistance than Lp grown in standard media, indicating that passage through FLA not only increases Lp's infectivity but also enhances its monochloramine resistance. Therefore, laboratory-based testing of disinfection strategies should employ conditions that simulate or replicate intracellular growth to accurately assess disinfectant resistance.

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Section: Resultsmentioning

confidence: 99%

Protozoan-Priming and Magnesium Conditioning Enhance Legionella pneumophila Dissemination and Monochloramine Resistance

Cambronne,

Ayres,

Dowdell

et al. 2023

Environ. Sci. Technol.

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“…PVC pipes generally have lower scale potential than metal pipes [ 26 ]. Surprisingly, chlorine concentration values in the warmest part of the year (3rd quarter) were significantly higher than in the 1st and 4th quarters, considering that higher water temperature accelerates the rate of chlorine degradation in water distribution systems [ 27 ].…”

Section: Resultsmentioning

confidence: 99%

Influence of Metal Concentration and Plumbing Materials on Legionella Contamination

2022

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Legionella colonization of water supply pipes is a significant public health problem. The objective of this work was to evaluate Legionella colonization in hotel hot water systems and to investigate the relationship between metal concentrations, piping materials (galvanized iron pipes and plastic pipes), and Legionella proliferation. Concentrations of calcium and magnesium ions and the presence of Legionella pneumophila were determined in a total of 108 water samples from the hot water systems of four hotels in Split-Dalmatia County over a 12-month period, and additional data on piping materials were collected. L. pneumophila was isolated in 23.1% of all samples—in 28.8% (15/52) of water samples from galvanized iron pipes and in 17.8% (10/56) of samples from plastic pipes. L. pneumophila serogroups 2–14 were isolated from all samples. This study found higher prevalence of L. pneumophila at higher concentrations of Ca and Mg ions (except for Mg and plastic pipes). The metal parts of the water supply may be important factors in Legionella contamination due to the possibility of lime scale or roughness of the pipes. Higher Ca and Mg ion concentrations increased the risk of Legionella colonization.

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“…Variations in water temperature throughout the hydraulic circuit of the installation, together with stagnation and the presence of biofilms or biolayers, calcareous incrustations, corrosion or mineral precipitates, are factors that favour the proliferation of Legionella [ 31 , 32 ]. Likewise, the materials that make up the hydraulic circuit must resist the aggressive action of water and chlorine or other disinfectants to avoid corrosion phenomena [ 33 ]. Materials that favour the development of bacteria and fungi, such as leather, wood, fibre cement, concrete or cellulose derivatives, should be avoided.…”

Section: Discussionmentioning

confidence: 99%

Legionella pneumophila Risk from Air–Water Cooling Units Regarding Pipe Material and Type of Water

2023

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Legionellosis is a respiratory disease related to environmental health. There have been manifold studies of pipe materials, risk installations and legionellosis without considering the type of transferred water. The objective of this study was to determine the potential development of the causative agent Legionella pneumophila regarding air–water cooling units, legislative compliance, pipe material and type of water. Forty-four hotel units in Andalusia (Spain) were analysed with respect to compliance with Spanish health legislation for the prevention of legionellosis. The chi-square test was used to explain the relationship between material–water and legislative compliance, and a biplot of the first two factors was generated. Multiple correspondence analysis (MCA) was performed on the type of equipment, legislative compliance, pipe material and type of water, and graphs of cases were constructed by adding confidence ellipses by categories of the variables. Pipe material–type of water (p value = 0.29; p < 0.05) and legislative compliance were not associated (p value = 0.15; p < 0.05). Iron, stainless steel, and recycled and well water contributed the most to the biplot. MCA showed a global pattern in which lead, iron and polyethylene were well represented. Confidence ellipses around categories indicated significant differences among categories. Compliance with Spanish health legislation regarding the prevention and control of legionellosis linked to pipe material and type of water was not observed.

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Chlorine Disinfection of Legionella spp., L. pneumophila, and Acanthamoeba under Warm Water Premise Plumbing Conditions

Cited by 12 publications

References 68 publications

Protozoan-Priming and Magnesium Conditioning Enhance Legionella pneumophila Dissemination and Monochloramine Resistance

Protozoan-Priming and Magnesium Conditioning Enhance Legionella pneumophila Dissemination and Monochloramine Resistance

Influence of Metal Concentration and Plumbing Materials on Legionella Contamination

Legionella pneumophila Risk from Air–Water Cooling Units Regarding Pipe Material and Type of Water

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