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Cavallaro A, Gabrielli M, Hammes F, Rhoads WJ. The impact of DNA extraction on the quantification of Legionella, with implications for ecological studies. Microbiol Spectr 2024:e0071324. [PMID: 38953325 DOI: 10.1128/spectrum.00713-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 06/06/2024] [Indexed: 07/04/2024] Open
Abstract
Monitoring the levels of opportunistic pathogens in drinking water is important to plan interventions and understand the ecological niches that allow them to proliferate. Quantitative PCR is an established alternative to culture methods that can provide a faster, higher-throughput, and more precise enumeration of the bacteria in water samples. However, PCR-based methods are still not routinely applied for Legionella monitoring, and techniques, such as DNA extraction, differ notably between laboratories. Here, we quantify the impact that DNA extraction methods had on downstream PCR quantification and community sequencing. Through a community science campaign, we collected 50 water samples and corresponding shower hoses, and compared two commonly used DNA extraction methodologies to the same biofilm and water phase samples. The two methods showed clearly different extraction efficacies, which were reflected in both the quantity of DNA extracted and the concentrations of Legionella enumerated in both the matrices. Notably, one method resulted in higher enumeration in nearly all samples by about one order of magnitude and detected Legionella in 21 samples that remained undetected by the other method. 16S rRNA amplicon sequencing revealed that the relative abundance of individual taxa, including sequence variants of Legionella, significantly varied depending on the extraction method employed. Given the implications of these findings, we advocate for improvement in documentation of the performance of DNA extraction methods used in drinking water to detect and quantify Legionella, and characterize the associated microbial community.IMPORTANCEMonitoring for the presence of the waterborne opportunistic pathogen Legionella is important to assess the risk of infection and plan remediation actions. While monitoring is traditionally carried on through cultivation, there is an ever-increasing demand for rapid and high-throughput molecular-based approaches for Legionella detection. This paper provides valuable insights on how DNA extraction affects downstream molecular analysis such as the quantification of Legionella through droplet digital PCR and the characterization of natural microbial communities through sequencing analysis. We analyze the results from a risk-assessment, legislative, and ecological perspective, showing how initial DNA processing is an important step to take into account when shifting to molecular-based routine monitoring and discuss the central role of consistent and detailed reporting of the methods used.
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Affiliation(s)
- Alessio Cavallaro
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zürich, Switzerland
| | - Marco Gabrielli
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Frederik Hammes
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - William J Rhoads
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
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2
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Schwaiger G, Matt M, Streich P, Bromann S, Clauß M, Elsner M, Seidel M. Standard addition method for rapid, cultivation-independent quantification of Legionella pneumophila cells by qPCR in biotrickling filters. Analyst 2024; 149:2978-2987. [PMID: 38602145 DOI: 10.1039/d3an02207b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Cultivation-independent molecular biological methods are essential to rapidly quantify pathogens like Legionella pneumophila (L. pneumophila) which is important to control aerosol-generating engineered water systems. A standard addition method was established to quantify L. pneumophila in the very complex matrix of process water and air of exhaust air purification systems in animal husbandry. Therefore, cryopreserved standards of viable L. pneumophila were spiked in air and water samples to calibrate the total bioanalytical process which includes cell lysis, DNA extraction, and qPCR. A standard addition algorithm was employed for qPCR to determine the initial concentration of L. pneumophila. In mineral water, the recovery rate of this approach (73%-134% within the concentration range of 100-5000 Legionella per mL) was in good agreement with numbers obtained from conventional genomic unit (GU) calibration with DNA standards. In air samples of biotrickling filters, in contrast, the conventional DNA standard approach resulted in a significant overestimation of up to 729%, whereas our standard addition gave a more realistic recovery of 131%. With this proof-of-principle study, we were able to show that the molecular biology-based standard addition approach is a suitable method to determine realistic concentrations of L. pneumophila in air and process water samples of biotrickling filter systems. Moreover, this quantification strategy is generally a promising method to quantify pathogens in challenging samples containing a complex microbiota and the classical GU approach used for qPCR leads to unreliable results.
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Affiliation(s)
- Gerhard Schwaiger
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Marco Matt
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Philipp Streich
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Sarah Bromann
- Thuenen-Institute for Agricultural Technology, Bundesallee 47, D-38116 Braunschweig, Germany
| | - Marcus Clauß
- Thuenen-Institute for Agricultural Technology, Bundesallee 47, D-38116 Braunschweig, Germany
| | - Martin Elsner
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Michael Seidel
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
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3
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Kanatani JI, Fujiyoshi S, Isobe J, Kimata K, Watahiki M, Maenishi E, Izumiyama S, Amemura-Maekawa J, Maruyama F, Oishi K. Correlation between bacterial microbiome and Legionella species in water from public bath facilities by 16S rRNA gene amplicon sequencing. Microbiol Spectr 2024; 12:e0345923. [PMID: 38363136 PMCID: PMC10986325 DOI: 10.1128/spectrum.03459-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/24/2024] [Indexed: 02/17/2024] Open
Abstract
Public bath facilities are a major source of Legionella infections in Japan. In this study, we performed 16S rRNA gene amplicon sequencing to characterize the bacterial community in bath and shower water from public bath facilities, along with chemical parameters, and investigated the effect of the bacterial microbiome on the presence of Legionella species. Although no significant difference in bacterial community richness was observed between bath and shower water samples, there was a remarkable difference in the bacterial community structure between them. Distance-based redundancy analysis revealed that several factors (free residual chlorine, pH, and conductivity) were correlated with the bacterial community in bath water. The most abundant bacterial genera in the samples were Pseudomonas (13.7%) in bath water and Phreatobacter (13.6%) in shower water, as indicated by the taxonomic composition, and the dominant bacteria differed between these environmental samples. Legionella pneumophila was the most frequently detected Legionella species, with additional 15 other Legionella species detected in water samples. In Legionella-positive water samples, several unassigned and uncultured bacteria were enriched together. In addition, the co-occurrence network showed that Legionella was strongly interconnected with two uncultured bacteria. Corynebacterium and Sphingomonas negatively correlated with Legionella species. The present study reveals the ecology of Legionella species, especially their interactions with other bacteria that are poorly understood to date. IMPORTANCE Public bath facilities are major sources of sporadic cases and outbreaks of Legionella infections. Recently, 16S rRNA gene amplicon sequencing has been used to analyze bacterial characteristics in various water samples from both artificial and natural environments, with a particular focus on Legionella bacterial species. However, the relationship between the bacterial community and Legionella species in the water from public bath facilities remains unclear. In terms of hygiene management, it is important to reduce the growth of Legionella species by disinfecting the water in public bath facilities. Our findings contribute to the establishment of appropriate hygiene management practices and provide a basis for understanding the potential health effects of using bath and shower water available in public bath facilities.
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Affiliation(s)
- Jun-ichi Kanatani
- Department of Bacteriology, Toyama Institute of Health, Imizu, Toyama, Japan
| | - So Fujiyoshi
- Section of Microbial Genomics and Ecology, Hiroshima University, Hiroshima, Japan
| | - Junko Isobe
- Department of Bacteriology, Toyama Institute of Health, Imizu, Toyama, Japan
| | - Keiko Kimata
- Department of Bacteriology, Toyama Institute of Health, Imizu, Toyama, Japan
| | - Masanori Watahiki
- Department of Bacteriology, Toyama Institute of Health, Imizu, Toyama, Japan
| | - Emi Maenishi
- Department of Bacteriology, Toyama Institute of Health, Imizu, Toyama, Japan
| | - Shinji Izumiyama
- Department of Parasitology, National Institute of Infectious Diseases, Toyama, Japan
| | - Junko Amemura-Maekawa
- Department of Bacteriology, National Institute of Infectious Diseases, Toyama, Japan
| | - Fumito Maruyama
- Section of Microbial Genomics and Ecology, Hiroshima University, Hiroshima, Japan
| | - Kazunori Oishi
- Department of Bacteriology, Toyama Institute of Health, Imizu, Toyama, Japan
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Klopper KB, Bester E, van Schalkwyk M, Wolfaardt GM. Highlighting the limitations of static microplate biofilm assays for industrial biocide effectiveness compared to dynamic flow conditions. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13214. [PMID: 38015101 PMCID: PMC10866068 DOI: 10.1111/1758-2229.13214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 11/01/2023] [Indexed: 11/29/2023]
Abstract
The minimal inhibitory concentration of an antimicrobial required to inhibit the growth of planktonic populations (minimum inhibitory concentration [MIC]) remains the 'gold standard' even though biofilms are acknowledged to be recalcitrant to concentrations that greatly exceed the MIC. As a result, most studies focus on biofilm tolerance to high antimicrobial concentrations, whereas the effect of environmentally relevant sub-MIC on biofilms is neglected. The effect of the MIC and sub-MIC of an isothiazolinone biocide on a microbial community isolated from an industrial cooling system was assessed under static and flow conditions. The differential response of planktonic and sessile populations to these biocide concentrations was discerned by modifying the broth microdilution assay. However, the end-point analysis of biofilms cultivated in static microplates obscured the effect of sub-MIC and MIC on biofilms. A transition from batch to the continuous flow system revealed a more nuanced response of biofilms to these biocide concentrations, where biofilm-derived planktonic cell production was maintained despite an increase in the frequency and extent of biofilm sloughing. A holistic, 'best of both worlds' approach that combines the use of static and continuous flow systems is useful to investigate the potential for the development of persistent biofilms under conditions where exposure to sub-MIC and MIC may occur.
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Affiliation(s)
- Kyle B. Klopper
- Department of MicrobiologyStellenbosch UniversityStellenboschSouth Africa
| | - Elanna Bester
- Department of MicrobiologyStellenbosch UniversityStellenboschSouth Africa
| | | | - Gideon M. Wolfaardt
- Department of MicrobiologyStellenbosch UniversityStellenboschSouth Africa
- Department of Chemistry and BiologyToronto Metropolitan UniversityTorontoOntarioCanada
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5
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Shi Q, Chen Z, Yan H, Xu M, Cao KF, Mao Y, Chen X, Hu HY. Identification of significant live bacterial community shifts in different reclaimed waters during ozone and chlorine disinfection. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 896:165199. [PMID: 37391159 DOI: 10.1016/j.scitotenv.2023.165199] [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: 03/11/2023] [Revised: 06/12/2023] [Accepted: 06/27/2023] [Indexed: 07/02/2023]
Abstract
Ozone and chlorine are the most widely used disinfectants for water and wastewater disinfection. They play important role in microbial inactivation but could also pose a considerable selection effect on the microbial community of reclaimed water. Classical culture-based methods that rely on the assessment of conventional bacterial indicators (e.g., coliform bacteria) could hardly reflect the survival of disinfection residual bacteria (DRB) and hidden microbial risks in disinfected effluents. Hence, this study investigated the shifts of live bacterial community during ozone and chlorine disinfection in three reclaimed waters (i.e., two secondary effluents and one tertiary effluent), adopting Illumina Miseq sequencing technology in combination with a viability assay, propidium monoazide (PMA) pretreatment. Notably, statistical analyses of Wilcoxon rank-sum test confirmed the existance of distinct differences in bacterial community structure between samples with or without PMA pretreatment. On the phylum level, Proteobacteria commonly dominated in three undisinfected reclaimed waters, while ozone and chlorine disinfection posed varied effects on its relative abundance among different influents. On the genus level, ozone and chlorine disinfection significantly changed the bacterial composition and dominant species in reclaimed waters. Specifically, the typical DRB identified in ozone disinfected effluents were Pseudomonas, Nitrospira and Dechloromonas, while for chlorine disinfected effluents, Pseudomonas, Legionella, Clostridium, Mycobacterium and Romboutsia were recognized as typical DRB, which call for much attention. The Alpha and Beta diversity analysis results also suggested that different influent compositions greatly affected the bacterial community structure during disinfection processes. Since the experiments in present study were conducted in a short period and the dataset was relatively limited, prolonged experiment under different operational conditions are needed in future to illustrate the potential long-term effects of disinfection on the microbial community structure. The findings of this study could provide insights into microbial safety concern and control after disinfection for sustainable water reclamation and reuse.
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Affiliation(s)
- Qi Shi
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Zhuo Chen
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China; State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China; Beijing Laboratory for Environmental Frontier Technologies, Beijing 100084, PR China.
| | - Han Yan
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Meiying Xu
- State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China
| | - Ke-Fan Cao
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Yu Mao
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Xiaowen Chen
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Hong-Ying Hu
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China; Beijing Laboratory for Environmental Frontier Technologies, Beijing 100084, PR China; Research Institute for Environmental Innovation (Suzhou), Tsinghua, Jiangsu, Suzhou, 215163, PR China
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6
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Song Y, Finkelstein R, Rhoads W, Edwards MA, Pruden A. Shotgun Metagenomics Reveals Impacts of Copper and Water Heater Anodes on Pathogens and Microbiomes in Hot Water Plumbing Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:13612-13624. [PMID: 37643149 PMCID: PMC10501123 DOI: 10.1021/acs.est.3c03568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 08/31/2023]
Abstract
Hot water building plumbing systems are vulnerable to the proliferation of opportunistic pathogens (OPs), including Legionella pneumophila and Mycobacterium avium. Implementation of copper as a disinfectant could help reduce OPs, but a mechanistic understanding of the effects on the microbial community under real-world plumbing conditions is lacking. Here, we carried out a controlled pilot-scale study of hot water systems and applied shotgun metagenomic sequencing to examine the effects of copper dose (0-2 mg/L), orthophosphate corrosion control agent, and water heater anode materials (aluminum vs magnesium vs powered anode) on the bulk water and biofilm microbiome composition. Metagenomic analysis revealed that, even though a copper dose of 1.2 mg/L was required to reduce Legionella and Mycobacterium numbers, lower doses (e.g., ≤0.6 mg/L) measurably impacted the broader microbial community, indicating that the OP strains colonizing these systems were highly copper tolerant. Orthophosphate addition reduced bioavailability of copper, both to OPs and to the broader microbiome. Functional gene analysis indicated that both membrane damage and interruption of nucleic acid replication are likely at play in copper inactivation mechanisms. This study identifies key factors (e.g., orthophosphate, copper resistance, and anode materials) that can confound the efficacy of copper for controlling OPs in hot water plumbing.
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Affiliation(s)
- Yang Song
- Civil
and Environmental Engineering, Virginia
Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, Virginia 24061, United States
- Utilities
Department, Town of Cary, 316 N. Academy St., Cary, North Carolina 27512, United States
| | - Rachel Finkelstein
- Civil
and Environmental Engineering, Virginia
Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, Virginia 24061, United States
- AECOM, 3101 Wilson Boulevard, Arlington, Virginia 22201, United States
| | - William Rhoads
- Civil
and Environmental Engineering, Virginia
Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, Virginia 24061, United States
- Black
& Veatch, 8400 Ward
Pkwy, Kansas City, Missouri 64114, United States
| | - Marc A. Edwards
- Civil
and Environmental Engineering, Virginia
Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, Virginia 24061, United States
| | - Amy Pruden
- Civil
and Environmental Engineering, Virginia
Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, Virginia 24061, United States
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7
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Cavallaro A, Rhoads WJ, Sylvestre É, Marti T, Walser JC, Hammes F. Legionella relative abundance in shower hose biofilms is associated with specific microbiome members. FEMS MICROBES 2023; 4:xtad016. [PMID: 37705999 PMCID: PMC10496943 DOI: 10.1093/femsmc/xtad016] [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: 05/16/2023] [Revised: 07/13/2023] [Accepted: 08/14/2023] [Indexed: 09/15/2023] Open
Abstract
Legionella are natural inhabitants of building plumbing biofilms, where interactions with other microorganisms influence their survival, proliferation, and death. Here, we investigated the associations of Legionella with bacterial and eukaryotic microbiomes in biofilm samples extracted from 85 shower hoses of a multiunit residential building. Legionella spp. relative abundance in the biofilms ranged between 0-7.8%, of which only 0-0.46% was L. pneumophila. Our data suggest that some microbiome members were associated with high (e.g. Chthonomonas, Vrihiamoeba) or low (e.g. Aquabacterium, Vannella) Legionella relative abundance. The correlations of the different Legionella variants (30 Zero-Radius OTUs detected) showed distinct patterns, suggesting separate ecological niches occupied by different Legionella species. This study provides insights into the ecology of Legionella with respect to: (i) the colonization of a high number of real shower hoses biofilm samples; (ii) the ecological meaning of associations between Legionella and co-occurring bacterial/eukaryotic organisms; (iii) critical points and future directions of microbial-interaction-based-ecological-investigations.
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Affiliation(s)
- Alessio Cavallaro
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zürich, Switzerland
| | - William J Rhoads
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Émile Sylvestre
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Thierry Marti
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zürich, Switzerland
| | - Jean-Claude Walser
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zürich, Switzerland
- Department of Environmental Systems Science, Genetic Diversity Centre (GDC), ETH Zurich, 8092 Zürich, Switzerland
| | - Frederik Hammes
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
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Ouradou A, Veillette M, Bélanger Cayouette A, Corbin S, Boulanger C, Dorner S, Duchaine C, Bédard E. Effect of odor treatment systems on bioaerosol microbial concentration and diversity from wastewater treatment plants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 874:162419. [PMID: 36858219 DOI: 10.1016/j.scitotenv.2023.162419] [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: 12/06/2022] [Revised: 01/30/2023] [Accepted: 02/19/2023] [Indexed: 06/18/2023]
Abstract
Biofiltration, activated carbon and chemical scrubbing are technologies used for odor control in wastewater treatment plants. These systems may also influence the airborne microbial load in treated air. The study objectives were to 1) evaluate the capacity of three odor control system technologies to reduce the airborne concentration of total bacteria, Legionella, L. pneumophila, non-tuberculous mycobacteria (NTM) and Cladosporium in winter and summer seasons and 2) to describe the microbial ecology of the biofiltration system and evaluate its impact on treated air microbial diversity. A reduction of the total bacterial concentration up to 25 times was observed after odor treatment. Quantification by qPCR revealed the presence of Legionella spp. in all air samples ranging between 26 and 1140 GC/m3, while L. pneumophila was not detected except for three samples below the limit of quantification. A significant increase of up to 25-fold of Legionella spp. was noticed at the outlet of two of the three treatment systems. NTM were ubiquitously detected before air treatment (up to 2500 GC/m3) and were significantly reduced by all 3 systems (up to 13-fold). Cladosporium was measured at low concentrations for each system (< 190 GC/m3), with 68 % of the air samples below the limit of detection. Biodiversity results revealed that biofiltration system is an active process that adapts to air pollutants over time. Legionella spp. were detected in significant abundance in the air once treated in winter (up to 27 %). Nevertheless, the abundance of protozoan hosts is low and does not explain the multiplication of Legionella spp. The season remains the most influential factor shaping biodiversity. In summer only, air biofiltration caused a significant enrichment of the biodiversity. Although odor control technologies are not designed for bacterial mitigation, findings from this study suggest their potential to reduce the abundance of some genera harboring pathogenic species.
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Affiliation(s)
- A Ouradou
- Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, Montréal, QC, Canada.
| | - M Veillette
- Research Center of the University Institute of Cardiology and Pneumology of Quebec-University Laval, Québec, QC, Canada.
| | - A Bélanger Cayouette
- Research Center of the University Institute of Cardiology and Pneumology of Quebec-University Laval, Québec, QC, Canada; Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, University Laval, Québec, QC, Canada.
| | - S Corbin
- City of Repentigny, Repentigny, QC, Canada.
| | | | - S Dorner
- Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, Montréal, QC, Canada.
| | - C Duchaine
- Research Center of the University Institute of Cardiology and Pneumology of Quebec-University Laval, Québec, QC, Canada; Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, University Laval, Québec, QC, Canada; Canada Research Chair on Bioaerosols, University Laval, Québec, QC, Canada.
| | - E Bédard
- Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, Montréal, QC, Canada.
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9
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Lombardi A, Borriello T, De Rosa E, Di Duca F, Sorrentino M, Torre I, Montuori P, Trama U, Pennino F. Environmental Monitoring of Legionella in Hospitals in the Campania Region: A 5-Year Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:ijerph20085526. [PMID: 37107807 PMCID: PMC10138562 DOI: 10.3390/ijerph20085526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/06/2023] [Accepted: 04/13/2023] [Indexed: 05/11/2023]
Abstract
Legionella is a pathogen that colonizes soils, freshwater, and building water systems. People who are most affected are those with immunodeficiencies, so it is necessary to monitor its presence in hospitals. The purpose of this study was to evaluate the presence of Legionella in water samples collected from hospitals in the Campania region, Southern Italy. A total of 3365 water samples were collected from January 2018 to December 2022 twice a year in hospital wards from taps and showers, tank bottoms, and air-treatment units. Microbiological analysis was conducted in accordance with the UNI EN ISO 11731:2017, and the correlations between the presence of Legionella and water temperature and residual chlorine were investigated. In total, 708 samples (21.0%) tested positive. The most represented species was L. pneumophila 2-14 (70.9%). The serogroups isolated were 1 (27.7%), 6 (24.5%), 8 (23.3%), 3 (18.9%), 5 (3.1%), and 10 (1.1%). Non-pneumophila Legionella spp. represented 1.4% of the total. Regarding temperature, the majority of Legionella positive samples were found in the temperature range of 26.0-40.9 °C. An influence of residual chlorine on the presence of the bacterium was observed, confirming that chlorine disinfection is effective for controlling contamination. The positivity for serogroups other than serogroup 1 suggested the need to continue environmental monitoring of Legionella and to focus on the clinical diagnosis of other serogroups.
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Affiliation(s)
- Annalisa Lombardi
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Tonia Borriello
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Elvira De Rosa
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Fabiana Di Duca
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Michele Sorrentino
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Ida Torre
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Paolo Montuori
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Ugo Trama
- General Directorate of Health, Campania Region, Centro Direzionale C3, 80143 Naples, Italy
| | - Francesca Pennino
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
- Correspondence:
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10
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Heterotrophic Plate Count Can Predict the Presence of Legionella spp. in Cooling Towers. Pathogens 2023; 12:pathogens12030466. [PMID: 36986388 PMCID: PMC10059076 DOI: 10.3390/pathogens12030466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/10/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
Legionella pneumophila (Lp) colonizes aquatic environments and is a potential pathogen to humans, causing outbreaks of Legionnaire’s disease. It is mainly associated with contaminated cooling towers (CTs). Several regulations, including Spanish legislation (Sl), have introduced the analysis of heterotrophic plate count (HPC) bacteria and Legionella spp. (Lsp) in management plans to prevent and control Legionella outbreaks from CTs. The 2003 Sl for CTs (RD 865/2003) considered that concentrations of HPC bacteria ≤10,000 cfu/mL and of Lsp ≤100 cfu/L are safe; therefore, no action is required, whereas management actions should be implemented above these standards. We have investigated to what extent the proposed standard for HPC bacteria is useful to predict the presence of Lsp in cooling waters. For this, we analyzed Lsp and HPC concentrations, water temperature, and the levels of chlorine in 1376 water samples from 17 CTs. The results showed that in the 1138 water samples negative for Legionella spp. (LN), the HPC geometric mean was significantly lower (83 cfu/mL, p < 0.05) than in the positive Lsp. samples (135 cfu/mL). Of the 238 (17.3%) LP samples, 88.4% (210/238) were associated with values of HPC ≤10,000 cfu/mL and most of them showed HPC concentrations ≤100 (53.7%). In addition, a relatively low percentage of LP (28/238, 11.6%) samples were associated with HPC bacteria concentrations >10,000 cfu/mL, indicating that this standard does not predict the colonization risk for Legionella in the CTs studied. The present study has demonstrated that a threshold concentration ≤100 cfu/mL of HPC bacteria could better predict the higher concentration of Legionella in CTs, which will aid in preventing possible outbreaks.
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Campaña M, Del Hoyo R, Monleón-Getino A, Checa J. Predicting Legionella contamination in cooling towers and evaporative condensers from microbiological and physicochemical parameters. Int J Hyg Environ Health 2023; 248:114117. [PMID: 36708652 DOI: 10.1016/j.ijheh.2023.114117] [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: 09/14/2022] [Revised: 12/30/2022] [Accepted: 01/22/2023] [Indexed: 01/27/2023]
Abstract
BACKGROUND Inhalation of Legionella-containing aerosols generated by cooling towers (CT) and evaporative condensers (EC) where water risk management is not performed correctly has been linked to a high percentage of community outbreaks of Legionnaires' disease (LD). Likewise, microbiological and physicochemical characteristics of the water in these facilities have been associated with this bacterium. The main aim of this study was to assess the risk of Legionella colonization in CT and EC based on the data for microbiological and physicochemical water quality provided by the Environmental Health Department and Laboratory of the City Council of L'Hospitalet de Llobregat (Barcelona, Spain). METHODS Legionella was analysed in 789 samples collected from 127 CT and EC in 46 companies in Catalonia from 2002 to 2019. A two-step logistic regression analysis was carried out to assess the risk of colonization by Legionella in the studied facilities according to the microbiological (aerobic heterotrophic bacteria) and physicochemical (pH, alkalinity, hardness, turbidity, conductivity, total iron and Langelier Index) water parameters. The optimal cut-off points for the water parameters predictive of Legionella contamination were defined as the values on the receiver operating characteristic (ROC) curve where sensitivity and specificity were jointly maximized. RESULTS Legionella was isolated in 8.49% of the 789 analysed samples, 22.39% of which were heavily contaminated (with counts higher than 1.0 × 104 CFU/l). L. pneumophila was isolated in 82.09% of the samples, with 41.82% belonging to serogroup 1. Logistic regression analysis revealed that aerobic heterotrophic bacteria concentrations ≥6.90 × 102 CFU/ml [Odds ratios (OR) (95% CI) = 3.56 (1.39-9.43), p = 0.01], a pH ≥ 8.70 [OR (95% CI) = 3.60 (1.34-10.09), p = 0.01], and water hardness ≥5.72 × 102 mg/l [OR (95% CI) = 6.30 (2.34-18.56), p < 0.001] were each independently associated with a higher risk of CT and EC colonization by Legionella. CONCLUSIONS The present study shows the importance of risk assessment for improving the control measures aimed at preventing or reducing Legionella populations in CT and EC, thus minimizing potential dangers for public health.
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Affiliation(s)
- María Campaña
- BIOST(3). GRBIO. Department of Genetics, Microbiology and Statistics (Section of Statistics), Faculty of Biology, University of Barcelona, Diagonal 645, 08028, Barcelona, Spain.
| | - Rafael Del Hoyo
- Environmental Health Department and Laboratory, City Council of L'Hospitalet de Llobregat, Cobalt Building. Cobalt Street, 57-59, 2nd Floor, 08907, L'Hospitalet de Llobregat, Barcelona, Spain.
| | - Antonio Monleón-Getino
- BIOST(3). GRBIO. Department of Genetics, Microbiology and Statistics (Section of Statistics), Faculty of Biology, University of Barcelona, Diagonal 645, 08028, Barcelona, Spain.
| | - Javier Checa
- Environmental Health Department and Laboratory, City Council of L'Hospitalet de Llobregat, Cobalt Building. Cobalt Street, 57-59, 2nd Floor, 08907, L'Hospitalet de Llobregat, Barcelona, Spain.
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Valciņa O, Pūle D, Ķibilds J, Lazdāne A, Trofimova J, Makarova S, Konvisers G, Ķimse L, Krūmiņa A, Bērziņš A. Prevalence and Genetic Diversity of Legionella spp. in Hotel Water-Supply Systems in Latvia. Microorganisms 2023; 11:microorganisms11030596. [PMID: 36985170 PMCID: PMC10055240 DOI: 10.3390/microorganisms11030596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 03/02/2023] Open
Abstract
Legionella is one of the most important waterborne pathogens that can lead to both outbreaks and sporadic cases. The majority of travel-associated Legionnaires’ disease (TALD) cases are contracted during hotel stays. The aim of this study was to evaluate the prevalence and genetic diversity of Legionella spp. in hotel water supply systems in Latvia. In total, 834 hot water samples were collected from the water systems of 80 hotels in Latvia. At least one Legionella spp. positive sample was detected in 47 out of 80 hotels (58.8%). Overall, 235 out of 834 samples (28.2%) were Legionella spp. positive. The average hot water temperature in Latvian hotels was 49.8 °C. The most predominant L. pneumophila serogroup (SG) was SG3 which was found in 113 (49.8%) positive samples from 27 hotels. For 79 sequenced L. pneumophila isolates, 21 different sequence types (ST) were obtained, including 3 new types—ST2582, ST2579, and ST2580. High Legionella contamination and high genetic diversity were found in the hotel water supply systems in Latvia, which, together with the insufficient hot water temperature, may indicate that the lack of regulation and control measures may promote the proliferation of Legionella.
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Affiliation(s)
- Olga Valciņa
- Institute of Food Safety, Animal Health and Environment “BIOR”, 1076 Rīga, Latvia
| | - Daina Pūle
- Institute of Food Safety, Animal Health and Environment “BIOR”, 1076 Rīga, Latvia
- Department of Water Engineering and Technology, Riga Technical University, 1048 Rīga, Latvia
| | - Juris Ķibilds
- Institute of Food Safety, Animal Health and Environment “BIOR”, 1076 Rīga, Latvia
| | - Andžela Lazdāne
- Department of Metabolic Genetics Laboratory, Children’s Clinical University Hospital, 1004 Rīga, Latvia
| | - Jūlija Trofimova
- National Reference Laboratory, Riga East University Hospital, 1038 Rīga, Latvia
| | - Svetlana Makarova
- Institute of Food Safety, Animal Health and Environment “BIOR”, 1076 Rīga, Latvia
| | - Genadijs Konvisers
- Institute of Food Safety, Animal Health and Environment “BIOR”, 1076 Rīga, Latvia
| | - Laima Ķimse
- Institute of Food Safety, Animal Health and Environment “BIOR”, 1076 Rīga, Latvia
| | - Angelika Krūmiņa
- Department of Infectology, Riga Stradiņš University, 1007 Rīga, Latvia
| | - Aivars Bērziņš
- Institute of Food Safety, Animal Health and Environment “BIOR”, 1076 Rīga, Latvia
- Correspondence: ; Tel.: +371-6780-8972
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Cavallaro A, Rhoads WJ, Huwiler SG, Stachler E, Hammes F. Potential probiotic approaches to control Legionella in engineered aquatic ecosystems. FEMS Microbiol Ecol 2022; 98:6604835. [PMID: 35679082 PMCID: PMC9333994 DOI: 10.1093/femsec/fiac071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 05/20/2022] [Accepted: 06/07/2022] [Indexed: 11/25/2022] Open
Abstract
Opportunistic pathogens belonging to the genus Legionella are among the most reported waterborne-associated pathogens in industrialized countries. Legionella colonize a variety of engineered aquatic ecosystems and persist in biofilms where they interact with a multitude of other resident microorganisms. In this review, we assess how some of these interactions could be used to develop a biological-driven “probiotic” control approach against Legionella. We focus on: (i) mechanisms limiting the ability of Legionella to establish and replicate within some of their natural protozoan hosts; (ii) exploitative and interference competitive interactions between Legionella and other microorganisms; and (iii) the potential of predatory bacteria and phages against Legionella. This field is still emergent, and we therefore specifically highlight research for future investigations, and propose perspectives on the feasibility and public acceptance of a potential probiotic approach.
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Affiliation(s)
- Alessio Cavallaro
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.,Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zurich, Switzerland
| | - William J Rhoads
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Simona G Huwiler
- Department of Plant and Microbial Biology, University of Zurich, 8008 Zurich, Switzerland
| | - Elyse Stachler
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Frederik Hammes
- Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
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Faucher SP, Matthews S, Nickzad A, Vounba P, Shetty D, Bédard É, Prévost M, Déziel E, Paranjape K. Toxoflavin secreted by Pseudomonas alcaliphila inhibits the growth of Legionella pneumophila and Vermamoeba vermiformis. WATER RESEARCH 2022; 216:118328. [PMID: 35364354 DOI: 10.1016/j.watres.2022.118328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/07/2022] [Accepted: 03/17/2022] [Indexed: 06/14/2023]
Abstract
Legionella pneumophila is a natural inhabitant of water systems. From there, it can be transmitted to humans by aerosolization resulting in severe pneumonia. Most large outbreaks are caused by cooling towers colonized with L. pneumophila. The resident microbiota of the cooling tower is a key determinant for the colonization and growth of L. pneumophila. In our preceding study, the genus Pseudomonas correlated negatively with the presence of L. pneumophila in cooling towers, but it was not clear which species was responsible. Therefore, we identified the Pseudomonas species inhabiting 14 cooling towers using a Pseudomonas-specific 16S rRNA amplicon sequencing strategy. We found that cooling towers that are free of L. pneumophila contained a high relative abundance of members from the Pseudomonas alcaliphila/oleovorans phylogenetic cluster. P. alcaliphila JCM 10630 inhibited the growth of L. pneumophila on agar plates. Analysis of the P. alcaliphila genome revealed the presence of a gene cluster predicted to produce toxoflavin. L. pneumophila growth was inhibited by pure toxoflavin and by extracts from P. alcaliphila culture found to contain toxoflavin by liquid chromatography coupled with mass spectrometry. In addition, toxoflavin inhibits the growth of Vermameoba vermiformis, a host cell of L. pneumophila. Our study indicates that P. alcaliphila may be important to restrict growth of L. pneumophila in water systems through the production of toxoflavin. A sufficiently high concentration of toxoflavin is likely not achieved in the bulk water but might have a local inhibitory effect such as near or in biofilms.
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Affiliation(s)
- Sebastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Sara Matthews
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Arvin Nickzad
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, QC, Canada
| | - Passoret Vounba
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Deeksha Shetty
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Émilie Bédard
- Department of Civil Engineering, Polytechnique Montréal, Montréal, Québec, Canada
| | - Michele Prévost
- Department of Civil Engineering, Polytechnique Montréal, Montréal, Québec, Canada
| | - Eric Déziel
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, QC, Canada
| | - Kiran Paranjape
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada; Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
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15
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Gattuso G, Rizzo R, Lavoro A, Spoto V, Porciello G, Montagnese C, Cinà D, Cosentino A, Lombardo C, Mezzatesta ML, Salmeri M. Overview of the Clinical and Molecular Features of Legionella Pneumophila: Focus on Novel Surveillance and Diagnostic Strategies. Antibiotics (Basel) 2022; 11:antibiotics11030370. [PMID: 35326833 PMCID: PMC8944609 DOI: 10.3390/antibiotics11030370] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 12/04/2022] Open
Abstract
Legionella pneumophila (L. pneumophila) is one of the most threatening nosocomial pathogens. The implementation of novel and more effective surveillance and diagnostic strategies is mandatory to prevent the occurrence of legionellosis outbreaks in hospital environments. On these bases, the present review is aimed to describe the main clinical and molecular features of L. pneumophila focusing attention on the latest findings on drug resistance mechanisms. In addition, a detailed description of the current guidelines for the disinfection and surveillance of the water systems is also provided. Finally, the diagnostic strategies available for the detection of Legionella spp. were critically reviewed, paying the attention to the description of the culture, serological and molecular methods as well as on the novel high-sensitive nucleic acid amplification systems, such as droplet digital PCR.
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Affiliation(s)
- Giuseppe Gattuso
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (G.G.); (R.R.); (A.L.); (V.S.); (A.C.); (C.L.); (M.L.M.)
| | - Roberta Rizzo
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (G.G.); (R.R.); (A.L.); (V.S.); (A.C.); (C.L.); (M.L.M.)
| | - Alessandro Lavoro
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (G.G.); (R.R.); (A.L.); (V.S.); (A.C.); (C.L.); (M.L.M.)
| | - Vincenzoleo Spoto
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (G.G.); (R.R.); (A.L.); (V.S.); (A.C.); (C.L.); (M.L.M.)
| | - Giuseppe Porciello
- Epidemiology and Biostatistics Unit, National Cancer Institute IRCCS Fondazione G. Pascale, 80131 Naples, Italy; (G.P.); (C.M.)
| | - Concetta Montagnese
- Epidemiology and Biostatistics Unit, National Cancer Institute IRCCS Fondazione G. Pascale, 80131 Naples, Italy; (G.P.); (C.M.)
| | - Diana Cinà
- Health Management of the “Cannizzaro” Emergency Hospital of Catania, 95126 Catania, Italy;
- Clinical Pathology and Clinical Molecular Biology Unit, “Garibaldi Centro” Hospital, ARNAS Garibaldi, 95123 Catania, Italy
| | - Alessia Cosentino
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (G.G.); (R.R.); (A.L.); (V.S.); (A.C.); (C.L.); (M.L.M.)
| | - Cinzia Lombardo
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (G.G.); (R.R.); (A.L.); (V.S.); (A.C.); (C.L.); (M.L.M.)
| | - Maria Lina Mezzatesta
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (G.G.); (R.R.); (A.L.); (V.S.); (A.C.); (C.L.); (M.L.M.)
| | - Mario Salmeri
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (G.G.); (R.R.); (A.L.); (V.S.); (A.C.); (C.L.); (M.L.M.)
- Correspondence: ; Tel.: +39-095-478-1244
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16
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Kang D, Liu W, Kakahi FB, Delvigne F. Combined utilization of metabolic inhibitors to prevent synergistic multi-species biofilm formation. AMB Express 2022; 12:32. [PMID: 35244796 PMCID: PMC8897544 DOI: 10.1186/s13568-022-01363-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/12/2022] [Indexed: 12/04/2022] Open
Abstract
Biofilm is ubiquitous in industrial water systems, causing biofouling and leading to heat transfer efficiency decreases. In particular, multi-species living in biofilms could boost biomass production and enhance treatment resistance. In this study, a total of 37 bacterial strains were isolated from a cooling tower biofilm where acetic acid and propionic acid were detected as the main carbon sources. These isolates mainly belonged to Proteobacteria and Firmicutes, which occupied more than 80% of the total strains according to the 16S rRNA gene amplicon sequencing. Four species (Acinetobacter sp. CTS3, Corynebacterium sp. CTS5, Providencia sp. CTS12, and Pseudomonas sp. CTS17) were observed co-existing in the synthetic medium. Quantitative comparison of biofilm biomass from mono- and multi-species showed a synergistic effect towards biofilm formation among these four species. Three metabolic inhibitors (sulfathiazole, 3-bromopyruvic acid, and 3-nitropropionic acid) were employed to prevent biofilm formation based on their inhibitory effect on corresponding metabolic pathways. All of them displayed evident inhibition profiles to biofilm formation. Notably, combining these three inhibitors possessed a remarkable ability to block the multi-species biofilm development with lower concentrations, suggesting an enhanced effect appeared in simultaneous use. This study demonstrates that combined utilization of metabolic inhibitors is an alternative strategy to prevent multi-species biofilm formation. 37 bacterial strains were isolated and identified from a cooling tower biofilm. Synergistic effect of biofilm formation was observed among four species. Three metabolic inhibitors showed effective inhibition against biofilm formation. Targeting cellular metabolism is an effective way to inhibit biofilm formation.
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17
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Proctor C, Garner E, Hamilton KA, Ashbolt NJ, Caverly LJ, Falkinham JO, Haas CN, Prevost M, Prevots DR, Pruden A, Raskin L, Stout J, Haig SJ. Tenets of a holistic approach to drinking water-associated pathogen research, management, and communication. WATER RESEARCH 2022; 211:117997. [PMID: 34999316 PMCID: PMC8821414 DOI: 10.1016/j.watres.2021.117997] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 12/13/2021] [Accepted: 12/19/2021] [Indexed: 05/10/2023]
Abstract
In recent years, drinking water-associated pathogens that can cause infections in immunocompromised or otherwise susceptible individuals (henceforth referred to as DWPI), sometimes referred to as opportunistic pathogens or opportunistic premise plumbing pathogens, have received considerable attention. DWPI research has largely been conducted by experts focusing on specific microorganisms or within silos of expertise. The resulting mitigation approaches optimized for a single microorganism may have unintended consequences and trade-offs for other DWPI or other interests (e.g., energy costs and conservation). For example, the ecological and epidemiological issues characteristic of Legionella pneumophila diverge from those relevant for Mycobacterium avium and other nontuberculous mycobacteria. Recent advances in understanding DWPI as part of a complex microbial ecosystem inhabiting drinking water systems continues to reveal additional challenges: namely, how can all microorganisms of concern be managed simultaneously? In order to protect public health, we must take a more holistic approach in all aspects of the field, including basic research, monitoring methods, risk-based mitigation techniques, and policy. A holistic approach will (i) target multiple microorganisms simultaneously, (ii) involve experts across several disciplines, and (iii) communicate results across disciplines and more broadly, proactively addressing source water-to-customer system management.
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Affiliation(s)
- Caitlin Proctor
- Department of Agricultural and Biological Engineering, Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, IN, USA
| | - Emily Garner
- Wadsworth Department of Civil & Environmental Engineering, West Virginia University, Morgantown, WV, USA
| | - Kerry A Hamilton
- School of Sustainable Engineering and the Built Environment and The Biodesign Centre for Environmental Health Engineering, Arizona State University, Tempe, AZ, USA
| | - Nicholas J Ashbolt
- Faculty of Science and Engineering, Southern Cross University, Gold Coast. Queensland, Australia
| | - Lindsay J Caverly
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI, USA
| | | | - Charles N Haas
- Department of Civil, Architectural & Environmental Engineering, Drexel University, Philadelphia, PA, USA
| | - Michele Prevost
- Department of Civil, Geological and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, Canada
| | - D Rebecca Prevots
- Epidemiology Unit, Laboratory of Clinical Immunology and Microbiology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Amy Pruden
- Department of Civil & Environmental Engineering, Virginia Tech, Blacksburg, VA USA
| | - Lutgarde Raskin
- Department of Civil & Environmental Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Janet Stout
- Department of Civil & Environmental Engineering, University of Pittsburgh, and Special Pathogens Laboratory, Pittsburgh, PA, USA
| | - Sarah-Jane Haig
- Department of Civil & Environmental Engineering, and Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA.
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Bacterial Antagonistic Species of the Pathogenic Genus Legionella Isolated from Cooling Tower. Microorganisms 2022; 10:microorganisms10020392. [PMID: 35208847 PMCID: PMC8877877 DOI: 10.3390/microorganisms10020392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/28/2022] [Accepted: 01/29/2022] [Indexed: 12/02/2022] Open
Abstract
Legionella pneumophila is the causative agent of Legionnaires’ disease, a severe pneumonia. Cooling towers are a major source of large outbreaks of the disease. The growth of L. pneumophila in these habitats is influenced by the resident microbiota. Consequently, the aim of this study was to isolate and characterize bacterial species from cooling towers capable of inhibiting several strains of L. pneumophila and one strain of L. quinlivanii. Two cooling towers were sampled to isolate inhibiting bacterial species. Seven inhibitory isolates were isolated, through serial dilution plating and streaking on agar plates, belonging to seven distinct species. The genomes of these isolates were sequenced to identify potential genetic elements that could explain the inhibitory effect. The results showed that the bacterial isolates were taxonomically diverse and that one of the isolates may be a novel species. Genome analysis showed a high diversity of antimicrobial gene products identified in the genomes of the bacterial isolates. Finally, testing different strains of Legionella demonstrated varying degrees of susceptibility to the antimicrobial activity of the antagonistic species. This may be due to genetic variability between the Legionella strains. The results demonstrate that though cooling towers are breeding grounds for L. pneumophila, the bacteria must contend with various antagonistic species. Potentially, these species could be used to create an inhospitable environment for L. pneumophila, and thus decrease the probability of outbreaks occurring.
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Zhang Z, Zhang Q, Lu T, Zhang J, Sun L, Hu B, Hu J, Peñuelas J, Zhu L, Qian H. Residual chlorine disrupts the microbial communities and spreads antibiotic resistance in freshwater. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:127152. [PMID: 34537643 PMCID: PMC9758890 DOI: 10.1016/j.jhazmat.2021.127152] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/05/2021] [Accepted: 09/03/2021] [Indexed: 05/04/2023]
Abstract
Chlorine disinfection is a key global public health strategy for the prevention and control of diseases, such as COVID-19. However, little is known about effects of low levels of residual chlorine on freshwater microbial communities and antibiotic resistomes. Here, we treated freshwater microcosms with continuous low concentrations of chlorine and quantified the effects on aquatic and zebrafish intestinal microbial communities and antibiotic resistomes, using shotgun metagenome and 16S rRNA gene sequencing. Although chlorine rapidly degraded, it altered the aquatic microbial community composition over time and disrupted interactions among microbes, leading to decreases in community complexity and stability. However, community diversity was unaffected. The majority of ecological functions, particularly metabolic capacities, recovered after treatment with chlorine for 14 d, due to microbial community redundancy. There were also increased levels of antibiotic-resistance gene dissemination by horizontal and vertical gene transfer under chlorine treatment. Although the zebrafish intestinal microbial community recovered from temporary dysbiosis, growth and behavior of zebrafish adults were negatively affected by chlorine. Overall, our findings demonstrate the negative effects of residual chlorine on freshwater ecosystems and highlight a possible long-term risk to public health.
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Affiliation(s)
- Zhenyan Zhang
- College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
| | - Qi Zhang
- College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
| | - Tao Lu
- College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
| | - Jieyu Zhang
- College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
| | - Liwei Sun
- College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
| | - Baolan Hu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, PR China
| | - Jun Hu
- College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
| | - Josep Peñuelas
- CSIC, Global Ecology Unit CREAF-CSIC-UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain; CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
| | - Lizhong Zhu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, PR China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, PR China.
| | - Haifeng Qian
- College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China.
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Cameron ES, Schmidt PJ, Tremblay BJM, Emelko MB, Müller KM. Enhancing diversity analysis by repeatedly rarefying next generation sequencing data describing microbial communities. Sci Rep 2021; 11:22302. [PMID: 34785722 PMCID: PMC8595385 DOI: 10.1038/s41598-021-01636-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/27/2021] [Indexed: 12/13/2022] Open
Abstract
Amplicon sequencing has revolutionized our ability to study DNA collected from environmental samples by providing a rapid and sensitive technique for microbial community analysis that eliminates the challenges associated with lab cultivation and taxonomic identification through microscopy. In water resources management, it can be especially useful to evaluate ecosystem shifts in response to natural and anthropogenic landscape disturbances to signal potential water quality concerns, such as the detection of toxic cyanobacteria or pathogenic bacteria. Amplicon sequencing data consist of discrete counts of sequence reads, the sum of which is the library size. Groups of samples typically have different library sizes that are not representative of biological variation; library size normalization is required to meaningfully compare diversity between them. Rarefaction is a widely used normalization technique that involves the random subsampling of sequences from the initial sample library to a selected normalized library size. This process is often dismissed as statistically invalid because subsampling effectively discards a portion of the observed sequences, yet it remains prevalent in practice and the suitability of rarefying, relative to many other normalization approaches, for diversity analysis has been argued. Here, repeated rarefying is proposed as a tool to normalize library sizes for diversity analyses. This enables (i) proportionate representation of all observed sequences and (ii) characterization of the random variation introduced to diversity analyses by rarefying to a smaller library size shared by all samples. While many deterministic data transformations are not tailored to produce equal library sizes, repeatedly rarefying reflects the probabilistic process by which amplicon sequencing data are obtained as a representation of the amplified source microbial community. Specifically, it evaluates which data might have been obtained if a particular sample's library size had been smaller and allows graphical representation of the effects of this library size normalization process upon diversity analysis results.
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Affiliation(s)
- Ellen S Cameron
- Department of Biology, University of Waterloo, 200 University Ave. W, Waterloo, ON, N2L 3G1, Canada
| | - Philip J Schmidt
- Department of Civil and Environmental Engineering, University of Waterloo, 200 University Ave. W, Waterloo, ON, N2L 3G1, Canada
| | - Benjamin J-M Tremblay
- Department of Biology, University of Waterloo, 200 University Ave. W, Waterloo, ON, N2L 3G1, Canada
| | - Monica B Emelko
- Department of Civil and Environmental Engineering, University of Waterloo, 200 University Ave. W, Waterloo, ON, N2L 3G1, Canada
| | - Kirsten M Müller
- Department of Biology, University of Waterloo, 200 University Ave. W, Waterloo, ON, N2L 3G1, Canada.
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Glažar Ivče D, Rončević D, Šantić M, Cenov A, Tomić Linšak D, Mićović V, Lušić D, Glad M, Ljubas D, Vukić Lušić D. Is a Proactive Approach to Controlling Legionella in the Environment Justified? Food Technol Biotechnol 2021; 59:314-324. [PMID: 34759763 PMCID: PMC8542184 DOI: 10.17113/ftb.59.03.21.7016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 06/24/2021] [Indexed: 11/29/2022] Open
Abstract
Research background Legionella are Gram-negative bacteria that are ubiquitous in the natural environment. Contaminated water in man-made water systems is a potential source of transmission of legionnaires’ disease. The aim of this study is to explore the prevalence of Legionella pneumophila in the drinking water distribution system (DWDS) of Primorje-Gorski Kotar (PGK) County, Croatia, for the period 2013-2019, coupled with the incidence of legionnaires’ disease. A number of L. pneumophila-positive samples (>100 CFU/L), serogroup distribution and the degree of contamination of specific facilities (health and aged care, tourism, and sports) were assessed. Based on the obtained results, the reasoning for the implementation of a mandatory Legionella environmental surveillance program was assessed. Experimental approach Sample testing for Legionella was carried out according to the standard method for enumeration of this bacterium. A heterotrophic plate count (HPC) and Pseudomonas aeruginosa number were analysed along with the basic physicochemical indicators of drinking water quality. The research period was divided into two parts, namely, the 2013-2018 period (before implementation of the prevention program, after the outbreak of legionnaires’ disease), and the year 2019 (proactive approach, no disease cases recorded). Results and conclusion During the 7-year observation period in PGK County, an increase in the number of samples tested for Legionella was found. An increase in Legionella-positive samples (particularly pronounced during the warmer part of the year) was recorded, along with a growing trend in the number of reported legionnaires’ disease cases. In addition to hot water systems, the risk of Legionella colonisation also applies to cold water systems. Health and aged care facilities appear to be at highest risk. In addition to the higher proportion of positive samples and a higher degree of microbiological load in these facilities, the highest proportion of L. pneumophila SGs 2-14 was identified. Due to the diagnostic limitations of the applied tests, the number of legionnaires’ disease cases is underdiagnosed. Novelty and scientific contribution The introduction of a mandatory preventive approach to monitoring Legionella in DWDS water samples, along with the definition of national criteria for the interpretation of the results will create the preconditions for diagnosis and adequate treatment of larger numbers of legionnaires’ disease cases.
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Affiliation(s)
- Daniela Glažar Ivče
- Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia
| | - Dobrica Rončević
- Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia.,Faculty of Health Studies, Viktora cara Emina 5, 51000 Rijeka, Croatia
| | - Marina Šantić
- Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
| | - Arijana Cenov
- Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia
| | - Dijana Tomić Linšak
- Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia.,Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
| | - Vladimir Mićović
- Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia.,Faculty of Health Studies, Viktora cara Emina 5, 51000 Rijeka, Croatia.,Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
| | - Dražen Lušić
- Faculty of Health Studies, Viktora cara Emina 5, 51000 Rijeka, Croatia.,Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia.,Center for Advanced Computing and Modelling, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia
| | - Marin Glad
- Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia
| | - Davor Ljubas
- Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, Zagreb, Croatia
| | - Darija Vukić Lušić
- Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia.,Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia.,Center for Advanced Computing and Modelling, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia
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23
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Zhang X, Xia S, Ye Y, Wang H. Opportunistic pathogens exhibit distinct growth dynamics in rainwater and tap water storage systems. WATER RESEARCH 2021; 204:117581. [PMID: 34461496 DOI: 10.1016/j.watres.2021.117581] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/09/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Opportunistic pathogens (OPs) are emerging microbial contaminants in engineered water systems, yet their growth potential in rainwater systems has not been evaluated. The purpose of this study was to compare the growth dynamics of bacterial OPs and related genera (Pseudomonas aeruginosa, Legionella spp., L. pneumophila, Mycobacterium spp., and M. avium), two amoebal hosts (Acanthamoeba spp. and Vermamoeba vermiformis), and the fecal indicator Escherichia coli in simulated rainwater and tap water storage systems (SWSSs). Quantitative polymerase chain reaction (q-PCR) analysis of target microorganisms in SWSS influents and effluents demonstrated that P. aeruginosa and Legionella thrived in rainwater, but not in tap water. V. vermiformis proliferated in both rainwater and tap water polyvinyl chloride (PVC) SWSSs, while mycobacteria were largely absent in rainwater SWSSs. Tank materials exerted stronger influence on target microorganisms in rainwater SWSSs relative to tap water SWSSs, with species-specific responses noted in bulk water and biofilm. For instance, P. aeruginosa and V. vermiformis had the highest gene copy numbers in PVC rainwater SWSS effluents and biofilm, while Legionella peaked in stainless steel rainwater SWSS effluents and PVC rainwater SWSS biofilm. These results highlighted the OP contamination risks in rainwater storage systems and provided insights into rainwater system design and operation in terms of OP control.
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Affiliation(s)
- Xiaodong Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Chengtou Water Group Corporation, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Siqing Xia
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
| | - Yinyin Ye
- Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, New York 14260, USA
| | - Hong Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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24
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Environmental Surveillance of Legionella spp. in an Italian University Hospital Results of 10 Years of Analysis. WATER 2021. [DOI: 10.3390/w13162304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The occurrence of Legionella spp. in the water distribution systems of large hospitals and other healthcare facilities is considered particularly dangerous, due to the critical nature of the hospitalized patients. The aim of this study is to present a pluri-annual environmental surveillance in a large university hospital assessing the prevalence of Legionella spp. and underlining its variability over the years. The samples of water were collected in accordance with the Italian National Guidelines and the sampling sites considered in this study were selected favoring wards with very high-risk patients and with patients at increased risk. The laboratory analyzed a total of 305 water samples deriving from 24 different sampling points. Legionella spp. were detected in 39.4% of samples, the majority of which were contaminated by Legionella pneumophila serogroups 2–14 (68.7%). Statistically significant differences were found among different seasons with a linear trend in positive proportion from summer to spring. Several experimental interventions to prevent and reduce Legionella colonization were attempted, but there is no a definitive method for the complete eradication of this microorganism. The permanent monitoring of hospital water distribution systems is fundamental to preventing the potential risk of nosocomial Legionellosis and to implementing procedures to minimize the risk of Legionella spp. colonization.
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25
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Pereira A, Silva AR, Melo LF. Legionella and Biofilms-Integrated Surveillance to Bridge Science and Real-Field Demands. Microorganisms 2021; 9:microorganisms9061212. [PMID: 34205095 PMCID: PMC8228026 DOI: 10.3390/microorganisms9061212] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/28/2021] [Accepted: 05/31/2021] [Indexed: 11/16/2022] Open
Abstract
Legionella is responsible for the life-threatening pneumonia commonly known as Legionnaires’ disease or legionellosis. Legionellosis is known to be preventable if proper measures are put into practice. Despite the efforts to improve preventive approaches, Legionella control remains one of the most challenging issues in the water treatment industry. Legionellosis incidence is on the rise and is expected to keep increasing as global challenges become a reality. This puts great emphasis on prevention, which must be grounded in strengthened Legionella management practices. Herein, an overview of field-based studies (the system as a test rig) is provided to unravel the common roots of research and the main contributions to Legionella’s understanding. The perpetuation of a water-focused monitoring approach and the importance of protozoa and biofilms will then be discussed as bottom-line questions for reliable Legionella real-field surveillance. Finally, an integrated monitoring model is proposed to study and control Legionella in water systems by combining discrete and continuous information about water and biofilm. Although the successful implementation of such a model requires a broader discussion across the scientific community and practitioners, this might be a starting point to build more consistent Legionella management strategies that can effectively mitigate legionellosis risks by reinforcing a pro-active Legionella prevention philosophy.
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26
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Pinel ISM, Hankinson PM, Moed DH, Wyseure LJ, Vrouwenvelder JS, van Loosdrecht MCM. Efficient cooling tower operation at alkaline pH for the control of Legionella pneumophila and other pathogenic genera. WATER RESEARCH 2021; 197:117047. [PMID: 33799081 DOI: 10.1016/j.watres.2021.117047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 03/07/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
Efficient control of pathogenic bacteria, specifically Legionella pneumophila, is one of the main concerns when operating industrial cooling towers. Common practices to limit proliferation involves use of disinfectants, leading to formation of disinfection by-product and increase in water corrosiveness. A disinfectant-free Legionella control method would make the industry more environmentally friendly. A pilot-scale cooling tower (1 m3/h) operated with demineralized water was used to investigate the potential of high-pH conditioning as a disinfectant-free alternative for control of L. pneumophila and other pathogens. One control experiment was performed under standard full-scale operation involving sodium hypochlorite dosage. Thereafter 3 alkaline pHs of the cooling water were tested: 9.0, 9.4 and 9.6. The tests lasted between 25 and 35 days. The cooling water from the basins were analysed for total cell count by flow cytometry, L. pneumophila concentration by plate count and occasional qPCR analyses targeting the mip-gene, bacterial and eukaryotic community analyses with 16S and 18S rRNA gene amplicon sequencing, relative abundance of eukaryotic to prokaryotic DNA by qPCR of the 16S and 18S rRNA gene. The L. pneumophila analyses showed considerable growth at pH 9.0 and pH 9.4 but was maintained below detection limit (< 100 CFU/L) at pH 9.6 without disinfection. Interestingly, the results correlated with the overall abundance of protozoa in the water samples but not directly with the relative abundance of specific reported protozoan hosts of Legionella. The pathogenicity based on 16S rRNA gene amplicon sequencing of the cooling water DNA decreased with increasing pH with a strong decline between pH 9.0 and pH 9.4, from 7.1% to 1.6% of relative abundance of pathogenic genera respectively. A strong shift in microbiome was observed between each tested pH and reproducibility of the experiment at pH 9.6 was confirmed with a duplicate test lasting 80 days. High-pH conditioning ≥ 9.6 is therefore considered as an efficient disinfectant-free cooling tower operation for control of pathogenicity, including L. pneumophila.
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Affiliation(s)
- I S M Pinel
- Delft University of Technology, Faculty of Applied Sciences, Department of Biotechnology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands.
| | - P M Hankinson
- Evides Industriewater, Schaardijk 150, 3063 NH Rotterdam, the Netherlands
| | - D H Moed
- Evides Industriewater, Schaardijk 150, 3063 NH Rotterdam, the Netherlands
| | - L J Wyseure
- Evides Industriewater, Schaardijk 150, 3063 NH Rotterdam, the Netherlands
| | - J S Vrouwenvelder
- Delft University of Technology, Faculty of Applied Sciences, Department of Biotechnology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands; King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia
| | - M C M van Loosdrecht
- Delft University of Technology, Faculty of Applied Sciences, Department of Biotechnology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands
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27
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Garner E, Davis BC, Milligan E, Blair MF, Keenum I, Maile-Moskowitz A, Pan J, Gnegy M, Liguori K, Gupta S, Prussin AJ, Marr LC, Heath LS, Vikesland PJ, Zhang L, Pruden A. Next generation sequencing approaches to evaluate water and wastewater quality. WATER RESEARCH 2021; 194:116907. [PMID: 33610927 DOI: 10.1016/j.watres.2021.116907] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/15/2021] [Accepted: 02/03/2021] [Indexed: 05/24/2023]
Abstract
The emergence of next generation sequencing (NGS) is revolutionizing the potential to address complex microbiological challenges in the water industry. NGS technologies can provide holistic insight into microbial communities and their functional capacities in water and wastewater systems, thus eliminating the need to develop a new assay for each target organism or gene. However, several barriers have hampered wide-scale adoption of NGS by the water industry, including cost, need for specialized expertise and equipment, challenges with data analysis and interpretation, lack of standardized methods, and the rapid pace of development of new technologies. In this critical review, we provide an overview of the current state of the science of NGS technologies as they apply to water, wastewater, and recycled water. In addition, a systematic literature review was conducted in which we identified over 600 peer-reviewed journal articles on this topic and summarized their contributions to six key areas relevant to the water and wastewater fields: taxonomic classification and pathogen detection, functional and catabolic gene characterization, antimicrobial resistance (AMR) profiling, bacterial toxicity characterization, Cyanobacteria and harmful algal bloom identification, and virus characterization. For each application, we have presented key trends, noteworthy advancements, and proposed future directions. Finally, key needs to advance NGS technologies for broader application in water and wastewater fields are assessed.
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Affiliation(s)
- Emily Garner
- Wadsworth Department of Civil and Environmental Engineering, West Virginia University, 1306 Evansdale Drive, Morgantown, WV 26505, United States.
| | - Benjamin C Davis
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Erin Milligan
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Matthew Forrest Blair
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Ishi Keenum
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Ayella Maile-Moskowitz
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Jin Pan
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Mariah Gnegy
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Krista Liguori
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Suraj Gupta
- The Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, VA 24061, United States
| | - Aaron J Prussin
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Linsey C Marr
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Lenwood S Heath
- Department of Computer Science, Virginia Tech, 225 Stranger Street, Blacksburg, VA 24061, United States
| | - Peter J Vikesland
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States
| | - Liqing Zhang
- Department of Computer Science, Virginia Tech, 225 Stranger Street, Blacksburg, VA 24061, United States
| | - Amy Pruden
- Charles E. Via, Jr. Department of Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, Blacksburg, VA 24061, United States.
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Saad M, Faucher SP. Aptamers and Aptamer-Coupled Biosensors to Detect Water-Borne Pathogens. Front Microbiol 2021; 12:643797. [PMID: 33679681 PMCID: PMC7933031 DOI: 10.3389/fmicb.2021.643797] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/01/2021] [Indexed: 12/12/2022] Open
Abstract
Aptamers can serve as efficient bioreceptors for the development of biosensing detection platforms. Aptamers are short DNA or RNA oligonucleotides that fold into specific structures, which enable them to selectively bind to target analytes. The method used to identify aptamers is Systematic Evolution of Ligands through Exponential Enrichment (SELEX). Target properties can have an impact on aptamer efficiencies. Therefore, characteristics of water-borne microbial targets must be carefully considered during SELEX for optimal aptamer development. Several aptamers have been described for key water-borne pathogens. Here, we provide an exhaustive overview of these aptamers and discuss important microbial aspects to consider when developing such aptamers.
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Affiliation(s)
- Mariam Saad
- Department of Natural Resources, Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Université de Montréal, Faculté de Médecine Vétérinaire, Saint-Hyacinthe, QC, Canada
| | - Sebastien P. Faucher
- Department of Natural Resources, Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Université de Montréal, Faculté de Médecine Vétérinaire, Saint-Hyacinthe, QC, Canada
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Brigmon RL, Turick CE, Knox AS, Burckhalter CE. The Impact of Storms on Legionella pneumophila in Cooling Tower Water, Implications for Human Health. Front Microbiol 2020; 11:543589. [PMID: 33362725 PMCID: PMC7758282 DOI: 10.3389/fmicb.2020.543589] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 11/02/2020] [Indexed: 12/03/2022] Open
Abstract
At the U.S. Department of Energy’s Savannah River Site (SRS) in Aiken, SC, cooling tower water is routinely monitored for Legionella pneumophila concentrations using a direct fluorescent antibody (DFA) technique. Historically, 25–30 operating SRS cooling towers have varying concentrations of Legionella in all seasons of the year, with patterns that are unpredictable. Legionellosis, or Legionnaires’ disease (LD), is a pneumonia caused by Legionella bacteria that thrive both in man-made water distribution systems and natural surface waters including lakes, streams, and wet soil. Legionnaires’ disease is typically contracted by inhaling L. pneumophila, most often in aerosolized mists that contain the bacteria. At the SRS, L. pneumophila is typically found in cooling towers ranging from non-detectable up to 108 cells/L in cooling tower water systems. Extreme weather conditions contributed to elevations in L. pneumophila to 107–108 cells/L in SRS cooling tower water systems in July–August 2017. L. pneumophila concentrations in Cooling Tower 785-A/2A located in SRS A-Area, stayed in the 108 cells/L range despite biocide addition. During this time, other SRS cooling towers did not demonstrate this L. pneumophila increase. No significant difference was observed in the mean L. pneumophila mean concentrations for the towers (p < 0.05). There was a significant variance observed in the 285-2A/A Tower L. pneumophila results (p < 0.05). Looking to see if we could find “effects” led to model development by analyzing 13 months of water chemistry and microbial data for the main factors influencing the L. pneumophila concentrations in five cooling towers for this year. It indicated chlorine and dissolved oxygen had a significant impact (p < 0.0002) on cooling tower 785A/2A. Thus, while the variation in the log count data for the A-area tower is statistically greater than that of the other four towers, the average of the log count data for the A-Area tower was in line with that of the other towers. It was also observed that the location of 785A/2A and basin resulted in more debris entering the system during storm events. Our results suggest that future analyses should evaluate the impact of environmental conditions and cooling tower design on L. pneumophila water concentrations and human health.
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Affiliation(s)
- Robin L Brigmon
- Savannah River National Laboratory, Environmental Science and Biotechnology Group, Aiken, SC, United States
| | - Charles E Turick
- Savannah River National Laboratory, Environmental Science and Biotechnology Group, Aiken, SC, United States
| | - Anna S Knox
- Savannah River National Laboratory, Environmental Science and Biotechnology Group, Aiken, SC, United States
| | - Courtney E Burckhalter
- Savannah River National Laboratory, Environmental Science and Biotechnology Group, Aiken, SC, United States
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30
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Persistence of Legionella in Routinely Disinfected Heater-Cooler Units and Heater Units assessed by Propidium Monoazide qPCR. Pathogens 2020; 9:pathogens9110978. [PMID: 33238543 PMCID: PMC7700499 DOI: 10.3390/pathogens9110978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/20/2020] [Accepted: 11/21/2020] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Evidence to date indicates that heater-cooler units (HCUs) and heater units (HUs) can generate potentially infectious aerosols containing a range of opportunistic pathogens such as Mycobacterium chimaera, other non-tuberculous mycobacterial (NTM) species, Pseudomonas aeruginosa and Legionella spp. Our purpose was to determine the extent of Legionella contamination and total viable count (TVC) in HCUs and HUs and to analyze the relationship by water system design of devices of two different brands (LivaNova vs. Maquet). METHODS Legionella spp. were detected and quantified by our optimized PMA-qPCR protocol; TVCs were assessed according to ISO protocol 6222. Analyses were performed in the first sampling round and after six months of surveillance. RESULTS Overall, Legionella spp. was detected in 65.7% of devices. In the second sampling round, Legionella positivity rates were significantly lower in water samples from the Maquet devices compared to the LivaNova ones (27.3% vs. 61.5%). LivaNova HCUs also yielded more Legionella, and aquatic bacteria counts than Maquet in both first and second-round samples. CONCLUSIONS We recommend that all surgical patients and staff exposed to aerosols from thermoregulatory devices should be followed up for Legionella infection and that microbiological surveillance on such devices should be conducted regularly as precautionary principle.
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Cullom AC, Martin RL, Song Y, Williams K, Williams A, Pruden A, Edwards MA. Critical Review: Propensity of Premise Plumbing Pipe Materials to Enhance or Diminish Growth of Legionella and Other Opportunistic Pathogens. Pathogens 2020; 9:E957. [PMID: 33212943 PMCID: PMC7698398 DOI: 10.3390/pathogens9110957] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/20/2022] Open
Abstract
Growth of Legionella pneumophila and other opportunistic pathogens (OPs) in drinking water premise plumbing poses an increasing public health concern. Premise plumbing is constructed of a variety of materials, creating complex environments that vary chemically, microbiologically, spatially, and temporally in a manner likely to influence survival and growth of OPs. Here we systematically review the literature to critically examine the varied effects of common metallic (copper, iron) and plastic (PVC, cross-linked polyethylene (PEX)) pipe materials on factors influencing OP growth in drinking water, including nutrient availability, disinfectant levels, and the composition of the broader microbiome. Plastic pipes can leach organic carbon, but demonstrate a lower disinfectant demand and fewer water chemistry interactions. Iron pipes may provide OPs with nutrients directly or indirectly, exhibiting a high disinfectant demand and potential to form scales with high surface areas suitable for biofilm colonization. While copper pipes are known for their antimicrobial properties, evidence of their efficacy for OP control is inconsistent. Under some circumstances, copper's interactions with premise plumbing water chemistry and resident microbes can encourage growth of OPs. Plumbing design, configuration, and operation can be manipulated to control such interactions and health outcomes. Influences of pipe materials on OP physiology should also be considered, including the possibility of influencing virulence and antibiotic resistance. In conclusion, all known pipe materials have a potential to either stimulate or inhibit OP growth, depending on the circumstances. This review delineates some of these circumstances and informs future research and guidance towards effective deployment of pipe materials for control of OPs.
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Affiliation(s)
- Abraham C. Cullom
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
| | - Rebekah L. Martin
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
- Civil and Environmental Engineering, Virginia Military Institute, Lexington, VA 24450, USA
| | - Yang Song
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
| | | | - Amanda Williams
- c/o Marc Edwards, Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA;
| | - Amy Pruden
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
| | - Marc A. Edwards
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
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Paranjape K, Bédard É, Shetty D, Hu M, Choon FCP, Prévost M, Faucher SP. Unravelling the importance of the eukaryotic and bacterial communities and their relationship with Legionella spp. ecology in cooling towers: a complex network. MICROBIOME 2020; 8:157. [PMID: 33183356 PMCID: PMC7664032 DOI: 10.1186/s40168-020-00926-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/20/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Cooling towers are a major source of large community-associated outbreaks of Legionnaires' disease, a severe pneumonia. This disease is contracted when inhaling aerosols that are contaminated with bacteria from the genus Legionella, most importantly Legionella pneumophila. How cooling towers support the growth of this bacterium is still not well understood. As Legionella species are intracellular parasites of protozoa, it is assumed that protozoan community in cooling towers play an important role in Legionella ecology and outbreaks. However, the exact mechanism of how the eukaryotic community contributes to Legionella ecology is still unclear. Therefore, we used 18S rRNA gene amplicon sequencing to characterize the eukaryotic communities of 18 different cooling towers. The data from the eukaryotic community was then analysed with the bacterial community of the same towers in order to understand how each community could affect Legionella spp. ecology in cooling towers. RESULTS We identified several microbial groups in the cooling tower ecosystem associated with Legionella spp. that suggest the presence of a microbial loop in these systems. Dissolved organic carbon was shown to be a major factor in shaping the eukaryotic community and may be an important factor for Legionella ecology. Network analysis, based on co-occurrence, revealed that Legionella was correlated with a number of different organisms. Out of these, the bacterial genus Brevundimonas and the ciliate class Oligohymenophorea were shown, through in vitro experiments, to stimulate the growth of L. pneumophila through direct and indirect mechanisms. CONCLUSION Our results suggest that Legionella ecology depends on the host community, including ciliates and on several groups of organisms that contribute to its survival and growth in the cooling tower ecosystem. These findings further support the idea that some cooling tower microbiomes may promote the survival and growth of Legionella better than others. Video Abstract.
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Affiliation(s)
- Kiran Paranjape
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Émilie Bédard
- Department of Civil Engineering, Polytechnique Montreal, Montréal, QC, Canada
| | - Deeksha Shetty
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Mengqi Hu
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Fiona Chan Pak Choon
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montreal, Montréal, QC, Canada
| | - Sébastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada.
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Paniagua AT, Paranjape K, Hu M, Bédard E, Faucher SP. Impact of temperature on Legionella pneumophila, its protozoan host cells, and the microbial diversity of the biofilm community of a pilot cooling tower. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 712:136131. [PMID: 31931228 DOI: 10.1016/j.scitotenv.2019.136131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 12/13/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
Legionella pneumophila is a waterborne bacterium known for causing Legionnaires' Disease, a severe pneumonia. Cooling towers are a major source of outbreaks, since they provide ideal conditions for L. pneumophila growth and produce aerosols. In such systems, L. pneumophila typically grow inside protozoan hosts. Several abiotic factors such as water temperature, pipe material and disinfection regime affect the colonization of cooling towers by L. pneumophila. The local physical and biological factors promoting the growth of L. pneumophila in water systems and its spatial distribution are not well understood. Therefore, we built a lab-scale cooling tower to study the dynamics of L. pneumophila colonization in relationship to the resident microbiota and spatial distribution. The pilot was filled with water from an operating cooling tower harboring low levels of L. pneumophila. It was seeded with Vermamoeba vermiformis, a natural host of L. pneumophila, and then inoculated with L. pneumophila. After 92 days of operation, the pilot was disassembled, the water was collected, and biofilm was extracted from the pipes. The microbiome was studied using 16S rRNA and 18S rRNA genes amplicon sequencing. The communities of the water and of the biofilm were highly dissimilar. The relative abundance of Legionella in water samples reached up to 11% whereas abundance in the biofilm was extremely low (≤0.5%). In contrast, the host cells were mainly present in the biofilm. This suggests that L. pneumophila grows in host cells associated with biofilm and is then released back into the water following host cell lysis. In addition, water temperature shaped the bacterial and eukaryotic community of the biofilm, indicating that different parts of the systems may have different effects on Legionella growth.
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Affiliation(s)
- Adriana Torres Paniagua
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada
| | - Kiran Paranjape
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada
| | - Mengqi Hu
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada
| | - Emilie Bédard
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada; Department of Civil Engineering, Polytechnique Montreal, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec H3C 3A7, Canada.
| | - Sébastien P Faucher
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
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