Effect of monochloramine treatment on the microbial ecology of Legionella and associated bacterial populations in a hospital hot water system

Baron, Julianne L.; Harris, J. Kirk; Holinger, Eric P.; Duda, Scott; Stevens, Mark J.; Robertson, Charles E.; Ross, Kimberly A.; Pace, Norman R.; Stout, Janet E.

doi:10.1016/j.syapm.2015.02.006

Cited by 19 publications

(11 citation statements)

References 34 publications

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“…In contrast to previous reports of the dominant effect of chloramine versus chlorine in shaping microbial composition [ 3 , 29 , 59 , 72 ], we observed limited effect of disinfectant type on microbiome composition of the building plumbing microbiome relative to the other factors investigated ( Table 2 ). Greater dissimilarity in microbiome composition occurred among chlorinated systems, relative to paired comparisons with the chloraminated utility ( S5 Table ).…”

Section: Discussioncontrasting

confidence: 99%

“…Thus, a firm understanding of the microbial ecology of building plumbing systems is needed, and recent advances in the application of next generation sequencing technology [ 28 ] provides the opportunity to advance towards this goal. Next generation sequencing has successfully captured driving influence of on-site monochloramine to bacterial ecology in a hospital’s hot water system [ 29 , 30 ] and also served to map point-of-use tap water microbiome across seventeen cities along the Arkansas and lower Mississippi rivers [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

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Impact of Water Chemistry, Pipe Material and Stagnation on the Building Plumbing Microbiome

et al. 2015

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A unique microbiome establishes in the portion of the potable water distribution system within homes and other buildings (i.e., building plumbing). To examine its composition and the factors that shape it, standardized cold water plumbing rigs were deployed at the treatment plant and in the distribution system of five water utilities across the U.S. Three pipe materials (copper with lead solder, CPVC with brass fittings or copper/lead combined pipe) were compared, with 8 hour flush cycles of 10 minutes to simulate typical daily use patterns. High throughput Illumina sequencing of 16S rRNA gene amplicons was employed to profile and compare the resident bulk water bacteria and archaea. The utility, location of the pipe rig, pipe material and stagnation all had a significant influence on the plumbing microbiome composition, but the utility source water and treatment practices were dominant factors. Examination of 21 water chemistry parameters suggested that the total chlorine concentration, pH, P, SO4 2- and Mg were associated with the most of the variation in bulk water microbiome composition. Disinfectant type exerted a notably low-magnitude impact on microbiome composition. At two utilities using the same source water, slight differences in treatment approaches were associated with differences in rare taxa in samples. For genera containing opportunistic pathogens, Utility C samples (highest pH of 9–10) had the highest frequency of detection for Legionella spp. and lowest relative abundance of Mycobacterium spp. Data were examined across utilities to identify a true universal core, special core, and peripheral organisms to deepen insight into the physical and chemical factors that shape the building plumbing microbiome.

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Section: Discussioncontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of Water Chemistry, Pipe Material and Stagnation on the Building Plumbing Microbiome

et al. 2015

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“…Indeed, the negative, although not significant, correlation between the OTUs number and each biocide concentration suggests a decrease number of bacterial species with the increasing disinfectant concentration. A recent study about monochloramine impact on the microbiota of a hospital water network confirmed a lower bacterial richness in treated samples compared to control [71].…”

Section: Discussionmentioning

confidence: 87%

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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“…Major advances have been made in recent years in applying next-generation DNA sequencing toward investigating hot water plumbing microbiomes using an amplicon sequencing ( Baron et al, 2015 ; Ma et al, 2015 ; Ji et al, 2017 ; Haig et al, 2018 ), but characterization of bacterial and archaeral populations may be biased, potentially missing over half of the full diversity ( Klappenbach et al, 2001 ; Hong et al, 2009 ; Pinto and Raskin, 2012 ; Sun et al, 2013 ). Amplicon sequencing also overlooks non-targeted kingdoms (e.g., amoeba, virus) and does not provide direct information about function.…”

Section: Introductionmentioning

confidence: 99%

Shotgun Metagenomics Reveals Taxonomic and Functional Shifts in Hot Water Microbiome Due to Temperature Setting and Stagnation

et al. 2018

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Hot water premise plumbing has emerged as a critical nexus of energy, water, and public health. The composition of hot water microbiomes is of special interest given daily human exposure to resident flora, especially opportunistic pathogens (OPs), which rely on complex microbial ecological interactions for their proliferation. Here, we applied shotgun metagenomic sequencing to characterize taxonomic and functional shifts in microbiomes as a function of water heater temperature setting, stagnation in distal pipes, and associated shifts in water chemistry. A cross-section of samples from controlled, replicated, pilot-scale hot water plumbing rigs representing different temperature settings (39, 42, and 51°C), stagnation periods (8 h vs. 7 days), and time-points, were analyzed. Temperature setting exhibited an overarching impact on taxonomic and functional gene composition. Further, distinct taxa were selectively enriched by specific temperature settings (e.g., Legionella at 39°C vs. Deinococcus at 51°C), while relative abundances of genes encoding corresponding cellular functions were highly consistent with expectations based on the taxa driving these shifts. Stagnation in distal taps diminished taxonomic and functional differences induced by heating the cold influent water to hot water in recirculating line. In distal taps relative to recirculating hot water, reads annotated as being involved in metabolism and growth decreased, while annotations corresponding to stress response (e.g., virulence disease and defense, and specifically antibiotic resistance) increased. Reads corresponding to OPs were readily identified by metagenomic analysis, with L. pneumophila reads in particular correlating remarkably well with gene copy numbers measured by quantitative polymerase chain reaction. Positive correlations between L. pneumophila reads and those of known protozoan hosts were also identified. Elevated proportions of genes encoding metal resistance and hydrogen metabolism were noted, which was consistent with elevated corrosion-induced metal concentrations and hydrogen generation. This study provided new insights into real-world factors influencing taxonomic and functional compositions of hot water microbiomes. Here metagenomics is demonstrated as an effective tool for screening for potential presence, and even quantities, of pathogens, while also providing diagnostic capabilities for assessing functional responses of microbiomes to various operational conditions. These findings can aid in informing future monitoring and intentional control of hot water microbiomes.

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Effect of monochloramine treatment on the microbial ecology of Legionella and associated bacterial populations in a hospital hot water system

Cited by 19 publications

References 34 publications

Impact of Water Chemistry, Pipe Material and Stagnation on the Building Plumbing Microbiome

Impact of Water Chemistry, Pipe Material and Stagnation on the Building Plumbing Microbiome

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

Shotgun Metagenomics Reveals Taxonomic and Functional Shifts in Hot Water Microbiome Due to Temperature Setting and Stagnation

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