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Liu H, Jiao P, Guan L, Wang C, Zhang XX, Ma L. Functional traits and health implications of the global household drinking-water microbiome retrieved using an integrative genome-centric approach. WATER RESEARCH 2024; 250:121094. [PMID: 38183799 DOI: 10.1016/j.watres.2023.121094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 12/15/2023] [Accepted: 12/29/2023] [Indexed: 01/08/2024]
Abstract
The biological safety of drinking water plays a crucial role in public health protection. However, research on the drinking water microbiome remains in its infancy, especially little is known about the potentially pathogenic bacteria in and functional characteristics of the microbiome in household tap water that people are directly exposed to. In this study, we used a genomic-centric approach to construct a genetic catalogue of the drinking water microbiome by analysing 116 metagenomic datasets of household tap water worldwide, spanning nine countries/regions on five continents. We reconstructed 859 high-quality metagenome-assembled genomes (MAGs) spanning 27 bacterial and 2 archaeal phyla, and found that the core MAGs belonging to the phylum Proteobacteria encoded the highest metabolic functional diversity of the 33 key complete metabolic modules. In particular, we found that two core MAGs of Brevibacillus and Methylomona encoded genes for methane metabolism, which may support the growth of heterotrophic organisms observed in the oligotrophic ecosystem. Four MAGs of complete ammonia oxidation (comammox) Nitrospira were identified and functional metabolic analysis suggested these may enable mixotrophic growth and encode genes for reactive oxygen stress defence and arsenite reduction that could aid survival in the environment of oligotrophic drinking water systems. Four MAGs were annotated as potentially pathogenic bacteria (PPB) and thus represented a possible public health concern. They belonged to the genera Acinetobacter (n = 3) and Mycobacterium (n = 1), with a total relative abundance of 1.06 % in all samples. The genomes of PPB A. junii and A. ursingii were discovered to contain antibiotic resistance genes and mobile genetic elements that could contribute to antimicrobial dissemination in drinking water. Further network analysis suggested that symbiotic microbes which support the growth of pathogenic bacteria can be targets for future surveillance and removal.
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Affiliation(s)
- Huafeng Liu
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, PR China
| | - Pengbo Jiao
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, PR China
| | - Lei Guan
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, PR China
| | - Chen Wang
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, PR China
| | - Xu-Xiang Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Liping Ma
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, PR China; Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, Technology Innovation Center for Land Spatial Eco-restoration in Metropolitan Area, Ministry of Natural Resources, Shanghai 200062, PR China.
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Xu L, Sigler A, Chernatynskaya A, Rasmussen L, Lu J, Sahle-Demessie E, Westenberg D, Yang H, Shi H. Study of Legionella pneumophila treatment with copper in drinking water by single cell-ICP-MS. Anal Bioanal Chem 2024; 416:419-430. [PMID: 37962610 DOI: 10.1007/s00216-023-05033-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/16/2023] [Accepted: 10/31/2023] [Indexed: 11/15/2023]
Abstract
Legionella pneumophila is a persistent opportunistic pathogen that poses a significant threat to domestic water systems. Previous studies suggest that copper (Cu) is an effective antimicrobial in water systems. A rapid and sensitive quantification method is desired to optimize the conditions of L. pneumophila treatment by Cu and to better understand the interaction mechanisms between Cu and cells. In this study, we developed a highly sensitive single cell (SC)-ICP-MS method to monitor L. pneumophila cell concentration and track their uptake of Cu. The SC-ICP-MS method showed excellent sensitivity (with a cell concentration detection limit of 1000 cells/mL), accuracy (good agreement with conventional hemocytometry method), and precision (relative standard deviation < 5%) in drinking water matrix. The cupric ions (Cu2+) treatment results indicated that the total L. pneumophila cell concentration, Cu mass per cell, colony-forming unit counting, and Cu concentration in supernatant all exhibited a dose-dependent trend, with 800-1200 µg/L reaching high disinfection rates in drinking water. The investigation of percentages of viable and culturable, viable but nonculturable (VBNC), and lysed cells suggested there always were VBNC present at any Cu concentration. Experimental results of different Cu2+ treatment times further suggested that L. pneumophila cells developed an antimicrobial resistant mechanism with the prolonged Cu exposure. This is the first quantification study on the interactions of Cu and L. pneumophila in drinking water using SC-ICP-MS.
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Affiliation(s)
- Lei Xu
- Linda and Bipin Doshi Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, Rolla, MO, 65409, USA
| | - Austin Sigler
- Department of Chemistry and Center for Research in Energy and Environment, Missouri University of Science and Technology, Rolla, MO, 65409, USA
| | - Anna Chernatynskaya
- Linda and Bipin Doshi Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, Rolla, MO, 65409, USA
| | - Lindsey Rasmussen
- Department of Chemistry and Center for Research in Energy and Environment, Missouri University of Science and Technology, Rolla, MO, 65409, USA
| | - Jingrang Lu
- Office of Research and Development, US Environmental Protection Agency, Cincinnati, OH, USA
| | | | - David Westenberg
- Department of Biological Sciences, Missouri University of Science and Technology, Rolla, MO, 65409, USA
| | - Hu Yang
- Linda and Bipin Doshi Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, Rolla, MO, 65409, USA.
| | - Honglan Shi
- Department of Chemistry and Center for Research in Energy and Environment, Missouri University of Science and Technology, Rolla, MO, 65409, USA.
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Cullom A, Spencer MS, Williams MD, Falkinham JO, Pruden A, Edwards MA. Influence of pipe materials on in-building disinfection of P. aeruginosa and A. baumannii in simulated hot water plumbing. WATER RESEARCH X 2023; 21:100189. [PMID: 38098877 PMCID: PMC10719577 DOI: 10.1016/j.wroa.2023.100189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 04/20/2023] [Accepted: 06/12/2023] [Indexed: 12/17/2023]
Abstract
A framework is needed to account for interactive effects of plumbing materials and disinfectants on opportunistic pathogens (OPs) in building water systems. Here we evaluated free chlorine, monochloramine, chlorine dioxide, and copper-silver ionization (CSI) for controlling Pseudomonas aeruginosa and Acinetobacter baumannii as two representative OPs that colonize hot water plumbing, in tests using polyvinylchloride (PVC), copper-PVC, and iron-PVC convectively-mixed pipe reactors (CMPRs). Pipe materials vulnerable to corrosion (i.e., iron and copper) altered the pH, dissolved oxygen, and disinfectant levels in a manner that influenced growth trends of the two OPs and total bacteria. P. aeruginosa grew well in PVC CMPRs, poorly in iron-PVC CMPRs, and was best controlled by CSI disinfection, whereas A. baumannii showed the opposite trend for pipe material and was better controlled by chlorine and chlorine dioxide. Various scenarios were identified in which pipe material and disinfectant can interact to either hinder or accelerate growth of OPs, illustrating the difficulties of controlling OPs in portions of plumbing systems experiencing warm, stagnant water.
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Affiliation(s)
- Abraham Cullom
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
| | - Mattheu Storme Spencer
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
| | - Myra D. Williams
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Joseph O. Falkinham
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Amy Pruden
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
| | - Marc A. Edwards
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
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Cambronne ED, Ayres C, Dowdell KS, Lawler DF, Saleh NB, Kirisits MJ. Protozoan-Priming and Magnesium Conditioning Enhance Legionella pneumophila Dissemination and Monochloramine Resistance. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:14871-14880. [PMID: 37756220 DOI: 10.1021/acs.est.3c04013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
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 Mg2+-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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Affiliation(s)
- Eric D Cambronne
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Craig Ayres
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Katherine S Dowdell
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Desmond F Lawler
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Navid B Saleh
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Mary Jo Kirisits
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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Song Y, Pruden A, Rhoads WJ, Edwards MA. Pilot-scale assessment reveals effects of anode type and orthophosphate in governing antimicrobial capacity of copper for Legionella pneumophila control. WATER RESEARCH 2023; 242:120178. [PMID: 37307684 DOI: 10.1016/j.watres.2023.120178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/07/2023] [Accepted: 06/05/2023] [Indexed: 06/14/2023]
Abstract
Copper (Cu) is sometimes applied as an antimicrobial for controlling Legionella in hot water plumbing systems, but its efficacy is inconsistent. Here we examined the effects of Cu (0 - 2 mg/L), orthophosphate corrosion inhibitor (0 or 3 mg/L as phosphate), and water heater anodes (aluminum, magnesium, and powered anodes) on both bulk water and biofilm-associated L. pneumophila in pilot-scale water heater systems. Soluble, but not total, Cu was a good predictor of antimicrobial capacity of Cu. Even after months of exposure to very high Cu levels (>1.2 mg/L) and low pH (<7), which increases solubility and enhances bioavailability of Cu, culturable L. pneumophila was only reduced by ∼1-log. Cu antimicrobial capacity was shown to be limited by various factors, including binding of Cu ions by aluminum hydroxide precipitates released from corrosion of aluminum anodes, higher pH due to magnesium anode corrosion, and high Cu tolerance of the outbreak-associated L. pneumophila strain that was inoculated into the systems. L. pneumophila numbers were also higher in several instances when Cu was dosed together with orthophosphate (e.g., with an Al anode), revealing at least one scenario where high levels of total Cu appeared to stimulate Legionella. The controlled, pilot-scale nature of this study provides new understanding of the limitations of Cu as an antimicrobial in real-world plumbing systems.
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Affiliation(s)
- Yang Song
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061; Utilities Department, Town of Cary, 316 N. Academy St., Cary, NC, 27512.
| | - Amy Pruden
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
| | - William J Rhoads
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061; Black & Veatch, 8400 Ward Pkwy, Kansas City, MO, 64114
| | - Marc A Edwards
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061.
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Nawaz R, Nasim I, Irfan A, Islam A, Naeem A, Ghani N, Irshad MA, Latif M, Nisa BU, Ullah R. Water Quality Index and Human Health Risk Assessment of Drinking Water in Selected Urban Areas of a Mega City. TOXICS 2023; 11:577. [PMID: 37505543 PMCID: PMC10385057 DOI: 10.3390/toxics11070577] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/14/2023] [Accepted: 06/27/2023] [Indexed: 07/29/2023]
Abstract
The present study was conducted to evaluate the quality of drinking water and assess the potential health hazards due to water contaminants in selected urban areas of Lahore, Pakistan. Water samples were collected from ten sites and analyzed for different physico-chemical parameters including turbidity, color, pH, total dissolved solids (TDS), nitrates, fluoride, residual chlorine, and total hardness. Additionally, heavy metal (arsenic) and microbial parameters (E. coli) were also determined in the water samples. Drinking water quality evaluation indices, including the water quality index (WQI) for physico-chemical and biological parameters and human health risk assessment (HHRA) for heavy metal were estimated using the analytical results of the target parameters. It was found in most of the areas that the levels of arsenic, fluoride, TDS, and residual chlorine were higher than those recommended by the National Environmental Quality Standard (NEQS) and World Health Organization (WHO) guidelines. In addition to the physico-chemical parameters, microbial content (E. coli) was also found in the drinking water samples of the selected areas. Statistical analysis of the results indicated that levels of target parameters in drinking water samples are significantly different between sampling sites. The WQI for all physico-chemical and microbial parameters indicated that drinking water in most of the areas was unfit and unsuitable (WQI > 100) for drinking purposes except for the water of Bhatti Gate and Chota Gaon Shahdara with a WQI of 87 and 91, respectively. Drinking water in these areas had a very poor WQI rating. According to HHRA, drinking water from the selected sites was found to be of high risk to children and adults. The carcinogenic risk of arsenic indicated that all samples were of high risk to both adults and children (4.60 and 4.37 × 10-3, respectively). Regular monitoring of drinking water quality is essential, and proactive measures must be implemented to ensure the treatment and availability of safe drinking water in urban areas.
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Affiliation(s)
- Rab Nawaz
- Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
- Research and Knowledge Transfer, INTI International University, Putra Nilai 71800, Malaysia
| | - Iqra Nasim
- Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
- Department of Environmental Sciences, Lahore College for Women University, Lahore 54000, Pakistan
| | - Ali Irfan
- Department of Chemistry, Government College University Faisalabad, Faisalabad 38000, Pakistan
| | - Amjad Islam
- College of Chemistry and Chemical Engineering, Shantou University, Shantou 515031, China
| | - Ayesha Naeem
- Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
| | - Nadia Ghani
- Department of Environmental Sciences, Lahore College for Women University, Lahore 54000, Pakistan
| | - Muhammad Atif Irshad
- Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
| | - Maria Latif
- Department of Environmental Sciences, The University of Lahore, Lahore 54000, Pakistan
| | - Badar Un Nisa
- Department of Chemistry, The University of Lahore, Sargodha 40100, Pakistan
| | - Riaz Ullah
- Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
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Cheng Z, Jin X, Liu Y, Zheng L, He H. An ESIPT-Based Fluorescent Probe for Aqueous Cu + Detection through Strip, Nanofiber and Living Cells. Molecules 2023; 28:molecules28093725. [PMID: 37175135 PMCID: PMC10179813 DOI: 10.3390/molecules28093725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
Constructed on the benzothiazole-oxanthracene structure, a fluorescent probe RBg for Cu+ was designed under the ESIPT mechanism and synthesized by incorporating amide bonds as the connecting group and glyoxal as the identifying group. Optical properties revealed a good sensitivity and a good linear relationship of the probe RBg with Cu+ in the concentration range of [Cu+] = 0-5.0 μmol L-1. Ion competition and fluorescence-pH/time stability experiments offered further possibilities for dynamic Cu+ detection in an aqueous environment. HRMS analysis revealed a possible 1:1 combination of RBg and Cu+. In addition, colorimetric Cu+ detection and lysosome-targeted properties of the probe RBg were analyzed through RBg-doped PVDF nanofiber/test strips and RBg-Mito/Lyso trackers that were co-stained in living HeLa cells, enabling the probe's future applications as real-time detection methods for dynamic Cu+ tracking in the lysosomes and Cu+ detection under diversified conditions.
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Affiliation(s)
- Zhao Cheng
- School of Pharmacy, Xi'an Medical University, Xi'an 710021, China
| | - Xilang Jin
- School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an 710032, China
| | - Yinggang Liu
- School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an 710032, China
| | - Lei Zheng
- School of Pharmacy, Xi'an Medical University, Xi'an 710021, China
| | - Hao He
- School of Pharmacy, Xi'an Medical University, Xi'an 710021, China
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Cheng Z, Jin X, Liu Y, Zhang X. A PET Fluorescent Probe for Dynamic Pd 2+ Tracking with Imaging Applications in the Nanofiber and Living Cells. Molecules 2023; 28:molecules28073065. [PMID: 37049828 PMCID: PMC10095779 DOI: 10.3390/molecules28073065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/27/2023] [Accepted: 03/28/2023] [Indexed: 04/14/2023] Open
Abstract
Constructed on the moiety of a lactam screw ring, a near-infrared fluorescent probe RCya for Pd2+ was designed under the PET mechanism and synthesized by incorporating 2,4-dihydroxybenzaldehyde as the recognition group. Dynamic detection of aqueous Pd2+ by the probe RCya could be accomplished through ion competition, linear response, fluorescence-pH/time stabilities, and other optical tests. Moreover, the high selectivity, low cytotoxicity, cell permeability, and lysosome accumulation properties of RCya enabled the imaging applications on solid-state RCya-PAN composite nanofibers and in living cells. The recognition mechanism of probe RCya toward Pd2+ was further studied through simulation calculation and MS analysis.
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Affiliation(s)
- Zhao Cheng
- School of Pharmacy, Xi'an Medical University, Xi'an 710021, China
| | - Xilang Jin
- School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an 710032, China
| | - Yinggang Liu
- School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an 710032, China
| | - Xuejiao Zhang
- School of Pharmacy, Xi'an Medical University, Xi'an 710021, China
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Jereb G, Eržen I, Oder M, Poljšak B. Phosphate drinking water softeners promote Legionella growth. JOURNAL OF WATER AND HEALTH 2022; 20:1084-1090. [PMID: 35902990 DOI: 10.2166/wh.2022.055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Phosphate-based drinking water softeners are commonly used to prevent scale formation in drinking water distribution infrastructure. The main reason for drinking water softening is primarily economic (protection of pipes and extension of equipment life), while the health aspect of such treatment is usually neglected. The aim of this work is to investigate the effects of phosphate-based drinking water softeners on growth stimulation of Legionella pneumophila. Bacterial growth was observed at two different phosphate concentrations. On average, an increase in growth of 1.19-1.28 log CFU/mL was observed in selected samples with added phosphates compared with the control. The results of the in vitro experiment confirmed that the added phosphates stimulate the growth of L. pneumophila; growth stimulation could therefore be expected in drinking water distribution systems (DWDS) when phosphates are used as well. The availability of phosphorus in DWDS may be a crucial limiting factor for biofouling control. Consequently, phosphate-based chemicals for drinking water should be avoided or used with prudence, especially in drinking water with high concentrations of other nutrients.
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Affiliation(s)
- Gregor Jereb
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia E-mail: ; Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Ivan Eržen
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia; The National Institute of Public Health, Trubarjeva 2, 1000 Ljubljana, Slovenia
| | - Martina Oder
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia E-mail:
| | - Borut Poljšak
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia E-mail:
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Bédard E, Trigui H, Liang J, Doberva M, Paranjape K, Lalancette C, Allegra S, Faucher SP, Prévost M. Local Adaptation of Legionella pneumophila within a Hospital Hot Water System Increases Tolerance to Copper. Appl Environ Microbiol 2021; 87:e00242-21. [PMID: 33674435 PMCID: PMC8117758 DOI: 10.1128/aem.00242-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 02/25/2021] [Indexed: 11/20/2022] Open
Abstract
In large-building water systems, Legionella pneumophila is exposed to common environmental stressors such as copper. The aim of this study was to evaluate the susceptibility to copper of L. pneumophila isolates recovered from various sites: two clinical and seven environmental isolates from hot water system biofilm and water and from cooling tower water. After a 1-week acclimation in simulated drinking water, strains were exposed to various copper concentrations (0.8 to 5 mg/liter) for over 672 h. Complete loss of culturability was observed for three isolates following copper exposure to 5 mg/liter for 672 h. Two sequence type 1427 (ST1427)-like isolates were highly sensitive to copper, while the other two, isolated from biofilm samples, maintained higher culturability. The expression of the copper resistance gene copA evaluated by reverse transcription-quantitative PCR (RT-qPCR) was significantly higher for the biofilm isolates. All four ST1427-like isolates were recovered from the same water system during an outbreak. Whole-genome sequencing results confirmed that the four isolates are very close phylogenetically, differing by only 29 single nucleotide polymorphisms, suggesting in situ adaptation to microenvironmental conditions, possibly due to epigenetic regulation. These results indicate that the immediate environment within a building water distribution system influences the tolerance of L. pneumophila to copper. Increased contact of L. pneumophila biofilm strains with copper piping or copper alloys in the heat exchanger might lead to local adaptation. The phenotypic differences observed between water and biofilm isolates from the hot water system of a health care facility warrants further investigation to assess the relevance of evaluating disinfection performances based on water sampling alone.IMPORTANCELegionella pneumophila is a pathogen indigenous to natural and large building water systems in the bulk and the biofilm phases. The immediate environment within a system can impact the tolerance of L. pneumophila to environmental stressors, including copper. In health care facilities, copper levels in water can vary, depending on water quality, plumbing materials, and age. This study evaluated the impact of the isolation site (water versus biofilm, hot water system versus cooling tower) within building water systems. Closely related strains isolated from a health care facility hot water system exhibited variable tolerance to copper stress, shown by differential expression of copA, with biofilm isolates displaying highest expression and tolerance. Relying on the detection of L. pneumophila in water samples following exposure to environmental stressors such as copper may underestimate the prevalence of L. pneumophila, leading to inappropriate risk management strategies and increasing the risk of exposure for vulnerable patients.
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Affiliation(s)
- Emilie Bédard
- Department of Civil Engineering, Polytechnique Montréal, Montréal, Quebec, Canada
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Hana Trigui
- Department of Civil Engineering, Polytechnique Montréal, Montréal, Quebec, Canada
| | - Jeffrey Liang
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Margot Doberva
- Department of Civil Engineering, Polytechnique Montréal, Montréal, Quebec, Canada
| | - Kiran Paranjape
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Cindy Lalancette
- Laboratoire de Santé Publique du Québec, Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Séverine Allegra
- University of Lyon, UJM-Saint-Etienne, UMR 5600 CNRS, EVS-ISTHME, Saint-Etienne, France
| | - Sebastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montréal, Montréal, Quebec, Canada
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