Preventing Healthcare-Associated Legionellosis: Results after 3 Years of Continuous Disinfection of Hot Water with Monochloramine and an Effective Water Safety Plan

Coniglio, Maria Anna; Ferrante, Margherita; Yassin, Mohamed

doi:10.3390/ijerph15081594

Cited by 19 publications

(22 citation statements)

References 34 publications

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“…Nowadays, the prevention of Legionella dissemination has an important role in the control of its proliferation in water systems and many chemical disinfection methods have been proposed (Bonetta et al, 2018; Coniglio et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Thirty samples of tap-water were collected throughout a water distribution system without flushing and without flaming, according to the procedures reported in the Italian guidelines for Legionellosis Prevention (Ministero della Salute, 2016). Isolation of Legionella was performed in accordance with the standards procedures ISO 11731:1998, as described elsewhere (Coniglio et al, 2018). In brief, 1L of water from each sampling point was filtered using 0.2 μm polycarbonate filter (Sartorius Stedim Biotech GmbH, Goettingen, Germany) and each filter was vortexed for 15 min in 10 mL of the correspondent water sample to detach bacteria.…”

Section: Methodsmentioning

confidence: 99%

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Metabolic Characterization of Supernatants Produced by Lactobacillus spp. With in vitro Anti-Legionella Activity

et al. 2019

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Legionella pneumophila is an organism of public health interest for its presence in water supply systems and other humid thermal habitats. In this study, ten cell-free supernatants produced by Lactobacillus strains were evaluated for their ability to inhibit L. pneumophila strains isolated from hot tap water. Production of antimicrobial substances by Lactobacillus strains were assessed by agar well diffusion test on BCYE agar plates pre-inoculated with L. pneumophila. Cell-free supernatants (CFS) showed antimicrobial activity against all Legionella strains tested: L. rhamnosus and L. salivarius showed the highest activity. By means of a proton-based nuclear magnetic resonance ( 1 H-NMR) spectroscopy, we detected and quantified the Lactobacillus metabolites of these CFSs, so to gain information about which metabolic pathway was likely to be connected to the observed inhibition activity. A panel of metabolites with variations in concentration were revealed, but considerable differences among inter-species were not showed as reported in a similar work by Foschi et al. (2018) . More than fifty molecules belonging mainly to the groups of amino acids, organic acids, monosaccharides, ketones, and alcohols were identified in the metabolome. Significant differences were recorded comparing the metabolites found in the supernatants of strains grown in MRS with glycerol and the same strains grown in MRS without supplements. Indeed, pathway analysis revealed that glycine, serine and threonine, pyruvate, and sulfur metabolic pathways had a higher impact when strains were grown in MRS medium with a supplement such as glycerol. Among the metabolites identified, many were amino acids, suggesting the possible presence of bacteriocins which could be linked to the anti- Legionella activity shown by cell-free supernatants.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Metabolic Characterization of Supernatants Produced by Lactobacillus spp. With in vitro Anti-Legionella Activity

et al. 2019

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“…Among chemical disinfection treatments, the most popular are continuous systems such chlorine-based biocides and hydrogen peroxide [17]. All these methods have proven effective against Legionella and other waterborne pathogens, but active concentrations of biocide need to be continuously monitored since no one eliminates the bacteria once the water network is contaminated [12,13,18,19]. The main disadvantages associated with chemical treatments are corrosiveness and, limited to chlorine-based biocides, formation of toxic disinfection by-products (DBPs) [3,12,13,20].…”

Section: Introductionmentioning

confidence: 99%

Characterisation of Microbial Community Associated with Different Disinfection Treatments in Hospital hot Water Networks

Paduano

Marchesi

Casali

et al. 2020

IJERPH

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Many disinfection treatments can be adopted for controlling opportunistic pathogens in hospital water networks in order to reduce infection risk for immunocompromised patients. Each method has limits and strengths and it could determine modifications on bacterial community. The aim of our investigation was to study under real-life conditions the microbial community associated with different chemical (monochloramine, hydrogen peroxide, chlorine dioxide) and non-chemical (hyperthermia) treatments, continuously applied since many years in four hot water networks of the same hospital. Municipal cold water, untreated secondary, and treated hot water were analysed for microbiome characterization by 16S amplicon sequencing. Cold waters had a common microbial profile at genera level. The hot water bacterial profiles differed according to treatment. Our results confirm the effectiveness of disinfection strategies in our hospital for controlling potential pathogens such as Legionella, as the investigated genera containing opportunistic pathogens were absent or had relative abundances ≤1%, except for non-tuberculous mycobacteria, Sphingomonas, Ochrobactrum and Brevundimonas. Monitoring the microbial complexity of healthcare water networks through 16S amplicon sequencing is an innovative and effective approach useful for Public Health purpose in order to verify possible modifications of microbiota associated with disinfection treatments.

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“…Other studies report a lower prevalence of Legionella colonization in urban water supply systems, using monochloramine instead of free chlorine for disinfecting municipal drinking water [ 13 , 14 ]. On this basis, monochloramine has been used successfully for the secondary disinfection of hospital water networks [ 15 , 16 , 17 , 18 ] because it is less aggressive than chlorine and is more persistent in distribution systems. Chloramines produce lower DBP levels than chlorine [ 19 ], even if nitrogen by-products have been detected in chloraminated water, and there is much concern regarding nitrosamines due to their potential carcinogenic and genotoxic effects, even at nanogram doses [ 20 , 21 , 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Safety and Effectiveness of Monochloramine Treatment for Disinfecting Hospital Water Networks

Marchesi

Paduano

Frezza

et al. 2020

IJERPH

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The formation of potentially carcinogenic N-nitrosamines, associated with monochloramine, requires further research due to the growing interest in using this biocide for the secondary disinfection of water in public and private buildings. The aim of our study was to evaluate the possible formation of N-nitrosamines and other toxic disinfection by-products (DBPs) in hospital hot water networks treated with monochloramine. The effectiveness of this biocide in controlling Legionella spp. contamination was also verified. For this purpose, four different monochloramine-treated networks, in terms of the duration of treatment and method of biocide injection, were investigated. Untreated hot water, municipal cold water and, limited to N-nitrosamines analysis, hot water treated with chlorine dioxide were analyzed for comparison. Legionella spp. contamination was successfully controlled without any formation of N-nitrosamines. No nitrification or formation of the regulated DBPs, such as chlorites and trihalomethanes, occurred in monochloramine-treated water networks. However, a stable formulation of hypochlorite, its frequent replacement with a fresh product, and the routine monitoring of free ammonia are recommended to ensure a proper disinfection. Our study confirms that monochloramine may be proposed as an effective and safe strategy for the continuous disinfection of building plumbing systems, preventing vulnerable individuals from being exposed to legionellae and dangerous DBPs.

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Preventing Healthcare-Associated Legionellosis: Results after 3 Years of Continuous Disinfection of Hot Water with Monochloramine and an Effective Water Safety Plan

Cited by 19 publications

References 34 publications

Metabolic Characterization of Supernatants Produced by Lactobacillus spp. With in vitro Anti-Legionella Activity

Metabolic Characterization of Supernatants Produced by Lactobacillus spp. With in vitro Anti-Legionella Activity

Characterisation of Microbial Community Associated with Different Disinfection Treatments in Hospital hot Water Networks

Safety and Effectiveness of Monochloramine Treatment for Disinfecting Hospital Water Networks

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