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Xi H, Ross KE, Hinds J, Molino PJ, Whiley H. Efficacy of chlorine-based disinfectants to control Legionella within premise plumbing systems. WATER RESEARCH 2024; 259:121794. [PMID: 38824796 DOI: 10.1016/j.watres.2024.121794] [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: 01/19/2024] [Revised: 05/14/2024] [Accepted: 05/16/2024] [Indexed: 06/04/2024]
Abstract
Legionella is an opportunistic waterborne pathogen that causes Legionnaires' disease. It poses a significant public health risk, especially to vulnerable populations in health care facilities. It is ubiquitous in manufactured water systems and is transmitted via inhalation or aspiration of aerosols/water droplets generated from water fixtures (e.g., showers and hand basins). As such, the effective management of premise plumbing systems (building water systems) in health care facilities is essential for reducing the risk of Legionnaires' disease. Chemical disinfection is a commonly used control method and chlorine-based disinfectants, including chlorine, chloramine, and chlorine dioxide, have been used for over a century. However, the effectiveness of these disinfectants in premise plumbing systems is affected by various interconnected factors that can make it challenging to maintain effective disinfection. This systematic literature review identifies all studies that have examined the factors impacting the efficacy and decay of chlorine-based disinfectant within premise plumbing systems. A total of 117 field and laboratory-based studies were identified and included in this review. A total of 20 studies directly compared the effectiveness of the different chlorine-based disinfectants. The findings from these studies ranked the typical effectiveness as follows: chloramine > chlorine dioxide > chlorine. A total of 26 factors were identified across 117 studies as influencing the efficacy and decay of disinfectants in premise plumbing systems. These factors were sorted into categories of operational factors that are changed by the operation of water devices and fixtures (such as stagnation, temperature, water velocity), evolving factors which are changed in-directly (such as disinfectant concentration, Legionella disinfectant resistance, Legionella growth, season, biofilm and microbe, protozoa, nitrification, total organic carbon(TOC), pH, dissolved oxygen(DO), hardness, ammonia, and sediment and pipe deposit) and stable factors that are not often changed(such as disinfectant type, pipe material, pipe size, pipe age, water recirculating, softener, corrosion inhibitor, automatic sensor tap, building floor, and construction activity). A factor-effect map of each of these factors and whether they have a positive or negative association with disinfection efficacy against Legionella in premise plumbing systems is presented. It was also found that evaluating the effectiveness of chlorine disinfection as a water risk management strategy is further complicated by varying disinfection resistance of Legionella species and the form of Legionella (culturable/viable but non culturable, free living/biofilm associated, intracellular replication within amoeba hosts). Future research is needed that utilises sensors and other approaches to measure these key factors (such as pH, temperature, stagnation, water age and disinfection residual) in real time throughout premise plumbing systems. This information will support the development of improved models to predict disinfection within premise plumbing systems. The findings from this study will inform the use of chlorine-based disinfection within premise plumbing systems to reduce the risk of Legionnaires disease.
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Affiliation(s)
- Hao Xi
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia; Enware Pty Ltd, Caringbah, NSW, Australia.
| | - Kirstin E Ross
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Jason Hinds
- ARC Training Centre for Biofilm Research and Innovation, Flinders University, Bedford Park, SA, Australia; Enware Pty Ltd, Caringbah, NSW, Australia
| | | | - Harriet Whiley
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia; ARC Training Centre for Biofilm Research and Innovation, Flinders University, Bedford Park, SA, Australia
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Zhang C, Sienkiewicz N, Struewing I, Mistry JH, Buse H, Hu Z, Lu J. Reconsider the burn: The transient effect of a chlorine burn on controlling opportunistic pathogens in a full-scale chloraminated engineered water system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 933:172690. [PMID: 38670361 DOI: 10.1016/j.scitotenv.2024.172690] [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: 12/19/2023] [Revised: 04/20/2024] [Accepted: 04/20/2024] [Indexed: 04/28/2024]
Abstract
Nitrification is a serious water-quality issue in chloraminated engineered water systems (EWSs). Nitrification is often remediated by a chlorine burn (i.e., a free‑chlorine conversion), a short-term switch from chloramination to chlorination in EWSs. Opportunistic pathogens (OPs) are the dominant infectious agents in EWSs. However, the responses of OPs to a chlorine burn are unknown. This study for the first time assessed how a chlorine burn affected OPs in a full-scale EWS. We determined the impact of a 1.5-month chlorine burn on four dominant OPs (Legionella, Mycobacterium, Pseudomonas, and Vermamoeba vermiformis) in a representative full-scale chloraminated EWS in the United States. Legionella and Mycobacterium were the most abundant OPs. In the water main, the summed concentration of the four OPs during the chlorine burn [3.27 ± 1.58 log10(GCN·L-1); GCN: genome or gene copy number] was lower (p ≤ 0.001) than before the burn [4.83 ± 0.50 log10(GCN·L-1)]. After the burn, the summed concentration increased to 4.27 ± 0.68 log10(GCN·L-1), comparable to before the burn (p > 0.05), indicating a transient effect of the chlorine burn in the water main. At the residential sites, the summed concentrations of the four OPs were comparable (p > 0.05) at 5.50 ± 0.84, 5.27 ± 1.44, and 5.08 ± 0.71 log10(GCN·L-1) before, during, and after the chlorine burn, respectively. Therefore, the chlorine burn was less effective in suppressing OP (re)growth in the premise plumbing. The low effectiveness might be due to more significant water stagnation and disinfectant residual decay in the premise plumbing. Indeed, for the entire sampling period, the total chlorine residual concentration in the premise plumbing (1.8 mg Cl2·L-1) was lower than in the water main (2.4 mg Cl2·L-1). Consequently, for the entire sampling period, the summed concentration of the four OPs in the premise plumbing [5.26 ± 1.08 log10(GCN·L-1)] was significantly higher (p < 0.001) than in the water main [4.04 ± 1.25 log10(GCN·L-1)]. In addition, the chlorine burn substantially increased the levels of disinfection by-products (DBPs) in the water main. Altogether, a chlorine burn is transient or even ineffective in suppressing OP (re)growth but raises DBP concentrations in chloraminated EWSs. Therefore, the practice of chlorine burns to control nitrification should be optimized, reconsidered, or even replaced.
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Affiliation(s)
- Chiqian Zhang
- Civil Engineering Program, College of Engineering & Computer Science, Arkansas State University, AR 72467, United States
| | - Nathan Sienkiewicz
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH 45268, United States
| | - Ian Struewing
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH 45268, United States
| | - Jatin H Mistry
- United States Environmental Protection Agency, Region 6, Dallas, TX 75270, United States
| | - Helen Buse
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH 45268, United States
| | - Zhiqiang Hu
- Department of Civil & Environmental Engineering, University of Missouri, Columbia, MO 65211, United States
| | - Jingrang Lu
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH 45268, United States.
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LeChevallier MW, Prosser T, Stevens M. Opportunistic Pathogens in Drinking Water Distribution Systems-A Review. Microorganisms 2024; 12:916. [PMID: 38792751 PMCID: PMC11124194 DOI: 10.3390/microorganisms12050916] [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: 04/01/2024] [Revised: 04/24/2024] [Accepted: 04/25/2024] [Indexed: 05/26/2024] Open
Abstract
In contrast to "frank" pathogens, like Salmonella entrocolitica, Shigella dysenteriae, and Vibrio cholerae, that always have a probability of disease, "opportunistic" pathogens are organisms that cause an infectious disease in a host with a weakened immune system and rarely in a healthy host. Historically, drinking water treatment has focused on control of frank pathogens, particularly those from human or animal sources (like Giardia lamblia, Cryptosporidium parvum, or Hepatitis A virus), but in recent years outbreaks from drinking water have increasingly been due to opportunistic pathogens. Characteristics of opportunistic pathogens that make them problematic for water treatment include: (1) they are normally present in aquatic environments, (2) they grow in biofilms that protect the bacteria from disinfectants, and (3) under appropriate conditions in drinking water systems (e.g., warm water, stagnation, low disinfectant levels, etc.), these bacteria can amplify to levels that can pose a public health risk. The three most common opportunistic pathogens in drinking water systems are Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa. This report focuses on these organisms to provide information on their public health risk, occurrence in drinking water systems, susceptibility to various disinfectants, and other operational practices (like flushing and cleaning of pipes and storage tanks). In addition, information is provided on a group of nine other opportunistic pathogens that are less commonly found in drinking water systems, including Aeromonas hydrophila, Klebsiella pneumoniae, Serratia marcescens, Burkholderia pseudomallei, Acinetobacter baumannii, Stenotrophomonas maltophilia, Arcobacter butzleri, and several free-living amoebae including Naegleria fowleri and species of Acanthamoeba. The public health risk for these microbes in drinking water is still unclear, but in most cases, efforts to manage Legionella, mycobacteria, and Pseudomonas risks will also be effective for these other opportunistic pathogens. The approach to managing opportunistic pathogens in drinking water supplies focuses on controlling the growth of these organisms. Many of these microbes are normal inhabitants in biofilms in water, so the attention is less on eliminating these organisms from entering the system and more on managing their occurrence and concentrations in the pipe network. With anticipated warming trends associated with climate change, the factors that drive the growth of opportunistic pathogens in drinking water systems will likely increase. It is important, therefore, to evaluate treatment barriers and management activities for control of opportunistic pathogen risks. Controls for primary treatment, particularly for turbidity management and disinfection, should be reviewed to ensure adequacy for opportunistic pathogen control. However, the major focus for the utility's opportunistic pathogen risk reduction plan is the management of biological activity and biofilms in the distribution system. Factors that influence the growth of microbes (primarily in biofilms) in the distribution system include, temperature, disinfectant type and concentration, nutrient levels (measured as AOC or BDOC), stagnation, flushing of pipes and cleaning of storage tank sediments, and corrosion control. Pressure management and distribution system integrity are also important to the microbial quality of water but are related more to the intrusion of contaminants into the distribution system rather than directly related to microbial growth. Summarizing the identified risk from drinking water, the availability and quality of disinfection data for treatment, and guidelines or standards for control showed that adequate information is best available for management of L. pneumophila. For L. pneumophila, the risk for this organism has been clearly established from drinking water, cases have increased worldwide, and it is one of the most identified causes of drinking water outbreaks. Water management best practices (e.g., maintenance of a disinfectant residual throughout the distribution system, flushing and cleaning of sediments in pipelines and storage tanks, among others) have been shown to be effective for control of L. pneumophila in water supplies. In addition, there are well documented management guidelines available for the control of the organism in drinking water distribution systems. By comparison, management of risks for Mycobacteria from water are less clear than for L. pneumophila. Treatment of M. avium is difficult due to its resistance to disinfection, the tendency to form clumps, and attachment to surfaces in biofilms. Additionally, there are no guidelines for management of M. avium in drinking water, and one risk assessment study suggested a low risk of infection. The role of tap water in the transmission of the other opportunistic pathogens is less clear and, in many cases, actions to manage L. pneumophila (e.g., maintenance of a disinfectant residual, flushing, cleaning of storage tanks, etc.) will also be beneficial in helping to manage these organisms as well.
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Affiliation(s)
| | - Toby Prosser
- Melbourne Water, Melbourne, VIC 3001, Australia; (T.P.); (M.S.)
| | - Melita Stevens
- Melbourne Water, Melbourne, VIC 3001, Australia; (T.P.); (M.S.)
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Rello J, Allam C, Ruiz-Spinelli A, Jarraud S. Severe Legionnaires' disease. Ann Intensive Care 2024; 14:51. [PMID: 38565811 PMCID: PMC10987467 DOI: 10.1186/s13613-024-01252-y] [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: 10/14/2023] [Accepted: 01/18/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Legionnaires' disease (LD) is a common but under-diagnosed cause of community-acquired pneumonia (CAP), although rapid detection of urine antigen testing (UAT) and advances in molecular testing have improved the diagnosis. LD entails intensive care unit (ICU) admission in almost one-third of cases, and the mortality rate ranges from 4% to 40%. This review aims to discuss recent advances in the study of this condition and to provide an update on the diagnosis, pathogenesis and management of severe LD. RESULTS The overall incidence of LD has increased worldwide in recent years due to the higher number of patients with risk factors, especially immunosuppression, and to improvements in diagnostic methods. Although LD is responsible for only around 5% of all-cause CAP, it is one of the three most common causes of CAP requiring ICU admission. Mortality in ICU patients, immunocompromised patients or patients with a nosocomial source of LD can reach 40% despite appropriate antimicrobial therapy. Regarding pathogenesis, no Legionella-specific virulence factors have been associated with severity; however, recent reports have found high pulmonary Legionella DNA loads, and impairments in immune response and lung microbiome in the most severe cases. The clinical picture includes severe lung injury requiring respiratory and/or hemodynamic support, extrapulmonary symptoms and non-specific laboratory findings. LD diagnostic methods have improved due to the broad use of UAT and the development of molecular methods allowing the detection of all Lp serogroups. Therapy is currently based on macrolides, quinolones, or a combination of the two, with prolonged treatment in severe cases. CONCLUSIONS Numerous factors influence the mortality rate of LD, such as ICU admission, the underlying immune status, and the nosocomial source of the infection. The host immune response (hyperinflammation and/or immunoparalysis) may also be associated with increased severity. Given that the incidence of LD is rising, studies on specific biomarkers of severity may be of great interest. Further assessments comparing different regimens and/or evaluating host-directed therapies are nowadays needed.
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Affiliation(s)
- Jordi Rello
- Global Health ECore, Vall d'Hebron Institut of Research (VHIR), Barcelona, Spain
- Formation Recherche Evaluation (FOREVA) Research Group, CHU Nîmes, Nîmes, France
| | - Camille Allam
- Institut des Agents Infectieux, Centre National de Référence des Légionelles, Hospices Civils de Lyon, Lyon, France
- Centre International de Recherche en Infectiologie (CIRI), Équipe Pathogenèse des Légionelles, Université Lyon, Inserm, U1111,Université Claude Bernard Lyon 1, CNRS, UMR5308,École Normale Supérieure de Lyon, Lyon, France
| | | | - Sophie Jarraud
- Institut des Agents Infectieux, Centre National de Référence des Légionelles, Hospices Civils de Lyon, Lyon, France.
- Centre International de Recherche en Infectiologie (CIRI), Équipe Pathogenèse des Légionelles, Université Lyon, Inserm, U1111,Université Claude Bernard Lyon 1, CNRS, UMR5308,École Normale Supérieure de Lyon, Lyon, France.
- Centre National de Reference des Légionelles, Institut des Agents Infectieux, Hospices Civils de Lyon, 103 Grande rue de la Croix Rousse, 69317, Lyon Cedex 04, France.
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Abaasa CN, Ayesiga S, Lejju JB, Andama M, Tamwesigire IK, Bazira J, Byarugaba F. Assessing the quality of drinking water from selected water sources in Mbarara city, South-western Uganda. PLoS One 2024; 19:e0297794. [PMID: 38547180 PMCID: PMC10977771 DOI: 10.1371/journal.pone.0297794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 01/12/2024] [Indexed: 04/02/2024] Open
Abstract
This study assessed the physical, chemical, and microbiological quality with emphasis on risk score, source apportionment, geochemistry, feacal coliforms and water quality index of drinking water from selected water sources. A cross-sectional study was conducted in six villages in Mbarara city, south-western Uganda. Each selected source was inspected using a WHO-adopted sanitary inspection questionnaire. Each source's risk score was calculated. Thirty-seven samples were taken from one borehole, nine open dug wells, four rain harvest tanks, and twenty-three taps. The values for apparent color and phosphate were higher than the permissible level as set by the World Health Organization and Ugandan standards (US EAS 12). The isolated organisms were Klebsiella spp. (8.11%), Citrobacter divergens (62.16%), Citrobacter fluendii (2.7%), E. coli (35.14%), Enterobacter aerogenes (8.11%), Enterobacter agglomerus (5.4%), Proteus spp. (2.7%), Enterobacter cloacae (13.5%), and Proteus mirabilis (2.7%). Twelve water sources (32.4%) had water that was unfit for human consumption that was unfit for human consumption (Grade E), Five sources (13.5%) had water that had a very poor index (Grade D), nine (24.3%) had water of poor index (Grade C), eight (21.6%) had water of good water index (Grade B), and only three (8.1%) had water of excellent water quality index (Grade A). The piper trilinear revealed that the dominant water type of the area were Mgso4 and Caso4 type. Gibbs plot represents precipitation dominance. PCA for source apportionment showed that well, tap and borehole water account for the highest variations in the quality of drinking water. These results suggest that drinking water from sources in Mbarara city is not suitable for direct human consumption without treatment. We recommend necessary improvements in water treatment, distribution, and maintenance of all the available water sources in Mbarara City, South Western Uganda.
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Affiliation(s)
- Catherine N. Abaasa
- Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Savino Ayesiga
- Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Julius B. Lejju
- Faculty of Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | | | | | - Joel Bazira
- Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Frederick Byarugaba
- Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda
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6
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Zhao B, Liu R, Li Y, Xu H, Li X, Gu J, Zhang X, Wang Y, Wang Y. Changes of putative pathogenic species within the water bacterial community in large-scale drinking water treatment and distribution systems. WATER RESEARCH 2024; 249:120947. [PMID: 38043356 DOI: 10.1016/j.watres.2023.120947] [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: 07/06/2023] [Revised: 11/23/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
Although the management of microbes in drinking water is of paramount importance for public health, there remain challenges in comprehensively examining pathogenic bacteria in the water supply system at the species level. In this study, high-throughput sequencing of nearly full-length 16S rRNA genes was performed to investigate the changes of the water bacterial community in three large-scale drinking water treatment plants (DWTPs) and their corresponding distribution systems during winter and summer. Our findings revealed significant differences in the bacterial community structure between winter and summer water samples for each DWTP and its distribution management area (DMA). In the groundwater-fed DWTP, selective enrichment of mycobacterial species was observed in both seasons, and the subsequent DMA also exhibited strong selection for specific mycobacterial species. In one of the surface water-fed DWTPs, certain Legionella species present in the source water in winter were selectively enriched in the bacterial community after pre-oxidation, although they were susceptible to the subsequent purification steps. A variety of putative pathogenic species (n = 83) were identified based on our pathogen identification pipeline, with the dominant species representing opportunistic pathogens commonly found in water supply systems. While pathogen removal primarily occurred during the purification processes of DWTPs, especially for surface water-fed plants, the relative abundance of pathogenic bacteria in the DMA water flora was lower than that in the DWTP effluent flora, indicating a diminished competitiveness of pathogens within the DMA ecosystem.
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Affiliation(s)
- Bei Zhao
- Beijing Waterworks Group Co., Ltd, Beijing, PR China; Beijing Engineering Research Center for Drinking Water Quality, Beijing, PR China
| | - Ruyin Liu
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, PR China; Weiqiao-UCAS Science and Technology Park, Binzhou Institute of Technology, Binzhou, Shandong, PR China.
| | - Yuxian Li
- Beijing Waterworks Group Co., Ltd, Beijing, PR China; Beijing Engineering Research Center for Drinking Water Quality, Beijing, PR China
| | - Hao Xu
- Beijing Waterworks Group Co., Ltd, Beijing, PR China; Beijing Engineering Research Center for Drinking Water Quality, Beijing, PR China
| | - Xiangyi Li
- Beijing Waterworks Group Co., Ltd, Beijing, PR China; Beijing Engineering Research Center for Drinking Water Quality, Beijing, PR China
| | - Junnong Gu
- Beijing Waterworks Group Co., Ltd, Beijing, PR China; Beijing Engineering Research Center for Drinking Water Quality, Beijing, PR China
| | - Xiaolan Zhang
- Beijing Waterworks Group Co., Ltd, Beijing, PR China; Beijing Engineering Research Center for Drinking Water Quality, Beijing, PR China
| | - Yue Wang
- Beijing Waterworks Group Co., Ltd, Beijing, PR China
| | - Yansong Wang
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, PR China
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7
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Cullom A, Spencer MS, Williams MD, Falkinham JO, Brown C, Edwards MA, Pruden A. Premise Plumbing Pipe Materials and In-Building Disinfectants Shape the Potential for Proliferation of Pathogens and Antibiotic Resistance Genes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:21382-21394. [PMID: 38071676 DOI: 10.1021/acs.est.3c05905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
In-building disinfectants are commonly applied to control the growth of pathogens in plumbing, particularly in facilities such as hospitals that house vulnerable populations. However, their application has not been well optimized, especially with respect to interactive effects with pipe materials and potential unintended effects, such as enrichment of antibiotic resistance genes (ARGs) across the microbial community. Here, we used triplicate convectively mixed pipe reactors consisting of three pipe materials (PVC, copper, and iron) for replicated simulation of the distal reaches of premise plumbing and evaluated the effects of incrementally increased doses of chlorine, chloramine, chlorine dioxide, and copper-silver disinfectants. We used shotgun metagenomic sequencing to characterize the resulting succession of the corresponding microbiomes over the course of 37 weeks. We found that both disinfectants and pipe material affected ARG and microbial community taxonomic composition both independently and interactively. Water quality and total bacterial numbers were not found to be predictive of pathogenic species markers. One result of particular concern was the tendency of disinfectants, especially monochloramine, to enrich ARGs. Metagenome assembly indicated that many ARGs were enriched specifically among the pathogenic species. Functional gene analysis was indicative of a response of the microbes to oxidative stress, which is known to co/cross-select for antibiotic resistance. These findings emphasize the need for a holistic evaluation of pathogen control strategies for plumbing.
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Affiliation(s)
- Abraham Cullom
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, Virginia 24061, United States
| | - Matheu Storme Spencer
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, Virginia 24061, United States
| | - Myra D Williams
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Joseph O Falkinham
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Connor Brown
- Department of Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, Virginia 24061, 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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8
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Cullom A, Spencer MS, Williams MD, Falkinham JO, Pruden A, Edwards MA. Influence of pipe materials on in-building disinfection of P. aeruginosa and A. baumannii in simulated hot water plumbing. WATER RESEARCH X 2023; 21:100189. [PMID: 38098877 PMCID: PMC10719577 DOI: 10.1016/j.wroa.2023.100189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 04/20/2023] [Accepted: 06/12/2023] [Indexed: 12/17/2023]
Abstract
A framework is needed to account for interactive effects of plumbing materials and disinfectants on opportunistic pathogens (OPs) in building water systems. Here we evaluated free chlorine, monochloramine, chlorine dioxide, and copper-silver ionization (CSI) for controlling Pseudomonas aeruginosa and Acinetobacter baumannii as two representative OPs that colonize hot water plumbing, in tests using polyvinylchloride (PVC), copper-PVC, and iron-PVC convectively-mixed pipe reactors (CMPRs). Pipe materials vulnerable to corrosion (i.e., iron and copper) altered the pH, dissolved oxygen, and disinfectant levels in a manner that influenced growth trends of the two OPs and total bacteria. P. aeruginosa grew well in PVC CMPRs, poorly in iron-PVC CMPRs, and was best controlled by CSI disinfection, whereas A. baumannii showed the opposite trend for pipe material and was better controlled by chlorine and chlorine dioxide. Various scenarios were identified in which pipe material and disinfectant can interact to either hinder or accelerate growth of OPs, illustrating the difficulties of controlling OPs in portions of plumbing systems experiencing warm, stagnant water.
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Affiliation(s)
- Abraham Cullom
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
| | - Mattheu Storme Spencer
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
| | - Myra D. Williams
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Joseph O. Falkinham
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Amy Pruden
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
| | - Marc A. Edwards
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
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Gomez-Alvarez V, Ryu H, Tang M, McNeely M, Muhlen C, Urbanic M, Williams D, Lytle D, Boczek L. Assessing residential activity in a home plumbing system simulator: monitoring the occurrence and relationship of major opportunistic pathogens and phagocytic amoebas. Front Microbiol 2023; 14:1260460. [PMID: 37915853 PMCID: PMC10616306 DOI: 10.3389/fmicb.2023.1260460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 09/28/2023] [Indexed: 11/03/2023] Open
Abstract
Opportunistic premise plumbing pathogens (OPPPs) have been detected in buildings' plumbing systems causing waterborne disease outbreaks in the United States. In this study, we monitored the occurrence of OPPPs along with free-living amoeba (FLA) and investigated the effects of residential activities in a simulated home plumbing system (HPS). Water samples were collected from various locations in the HPS and analyzed for three major OPPPs: Legionella pneumophila, nontuberculous mycobacterial species (e.g., Mycobacterium avium, M. intracellulare, and M. abscessus), and Pseudomonas aeruginosa along with two groups of amoebas (Acanthamoeba and Vermamoeba vermiformis). A metagenomic approach was also used to further characterize the microbial communities. Results show that the microbial community is highly diverse with evidence of spatial and temporal structuring influenced by environmental conditions. L. pneumophila was the most prevalent pathogen (86% of samples), followed by M. intracellulare (66%) and P. aeruginosa (21%). Interestingly, M. avium and M. abscessus were not detected in any samples. The data revealed a relatively low prevalence of Acanthamoeba spp. (4%), while V. vermiformis was widely detected (81%) across all the sampling locations within the HPS. Locations with a high concentration of L. pneumophila and M. intracellulare coincided with the highest detection of V. vermiformis, suggesting the potential growth of both populations within FLA and additional protection in drinking water. After a period of stagnation lasting at least 2-weeks, the concentrations of OPPPs and amoeba immediately increased and then decreased gradually back to the baseline. Furthermore, monitoring the microbial population after drainage of the hot water tank and partial drainage of the entire HPS demonstrated no significant mitigation of the selected OPPPs. This study demonstrates that these organisms can adjust to their environment during such events and may survive in biofilms and/or grow within FLA, protecting them from stressors in the supplied water.
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Affiliation(s)
- Vicente Gomez-Alvarez
- Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, United States
| | - Hodon Ryu
- Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, United States
| | - Min Tang
- Oak Ridge for Science and Education Research Fellow at U.S. Environmental Protection Agency, Cincinnati, OH, United States
| | - Morgan McNeely
- Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, United States
| | - Christy Muhlen
- Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, United States
| | - Megan Urbanic
- Oak Ridge for Science and Education Research Fellow at U.S. Environmental Protection Agency, Cincinnati, OH, United States
| | - Daniel Williams
- Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, United States
| | - Darren Lytle
- Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, United States
| | - Laura Boczek
- Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, United States
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10
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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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11
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Lopez AE, Grigoryeva LS, Barajas A, Cianciotto NP. Legionella pneumophila Rhizoferrin Promotes Bacterial Biofilm Formation and Growth within Amoebae and Macrophages. Infect Immun 2023; 91:e0007223. [PMID: 37428036 PMCID: PMC10429650 DOI: 10.1128/iai.00072-23] [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: 02/15/2023] [Accepted: 06/20/2023] [Indexed: 07/11/2023] Open
Abstract
Previously, we showed that Legionella pneumophila secretes rhizoferrin, a polycarboxylate siderophore that promotes bacterial growth in iron-deplete media and the murine lung. Yet, past studies failed to identify a role for the rhizoferrin biosynthetic gene (lbtA) in L. pneumophila infection of host cells, suggesting the siderophore's importance was solely linked to extracellular survival. To test the possibility that rhizoferrin's relevance to intracellular infection was missed due to functional redundancy with the ferrous iron transport (FeoB) pathway, we characterized a new mutant lacking both lbtA and feoB. This mutant was highly impaired for growth on bacteriological media that were only modestly depleted of iron, confirming that rhizoferrin-mediated ferric iron uptake and FeoB-mediated ferrous iron uptake are critical for iron acquisition. The lbtA feoB mutant, but not its lbtA-containing complement, was also highly defective for biofilm formation on plastic surfaces, demonstrating a new role for the L. pneumophila siderophore in extracellular survival. Finally, the lbtA feoB mutant, but not its complement containing lbtA, proved to be greatly impaired for growth in Acanthamoeba castellanii, Vermamoeba vermiformis, and human U937 cell macrophages, revealing that rhizoferrin does promote intracellular infection by L. pneumophila. Moreover, the application of purified rhizoferrin triggered cytokine production from the U937 cells. Rhizoferrin-associated genes were fully conserved across the many sequenced strains of L. pneumophila examined but were variably present among strains from the other species of Legionella. Outside of Legionella, the closest match to the L. pneumophila rhizoferrin genes was in Aquicella siphonis, another facultative intracellular parasite of amoebae.
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Affiliation(s)
- Alberto E. Lopez
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, Illinois, USA
| | - Lubov S. Grigoryeva
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, Illinois, USA
| | - Armando Barajas
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, Illinois, USA
| | - Nicholas P. Cianciotto
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, Illinois, USA
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12
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Song Y, Pruden A, Rhoads WJ, Edwards MA. Pilot-scale assessment reveals effects of anode type and orthophosphate in governing antimicrobial capacity of copper for Legionella pneumophila control. WATER RESEARCH 2023; 242:120178. [PMID: 37307684 DOI: 10.1016/j.watres.2023.120178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/07/2023] [Accepted: 06/05/2023] [Indexed: 06/14/2023]
Abstract
Copper (Cu) is sometimes applied as an antimicrobial for controlling Legionella in hot water plumbing systems, but its efficacy is inconsistent. Here we examined the effects of Cu (0 - 2 mg/L), orthophosphate corrosion inhibitor (0 or 3 mg/L as phosphate), and water heater anodes (aluminum, magnesium, and powered anodes) on both bulk water and biofilm-associated L. pneumophila in pilot-scale water heater systems. Soluble, but not total, Cu was a good predictor of antimicrobial capacity of Cu. Even after months of exposure to very high Cu levels (>1.2 mg/L) and low pH (<7), which increases solubility and enhances bioavailability of Cu, culturable L. pneumophila was only reduced by ∼1-log. Cu antimicrobial capacity was shown to be limited by various factors, including binding of Cu ions by aluminum hydroxide precipitates released from corrosion of aluminum anodes, higher pH due to magnesium anode corrosion, and high Cu tolerance of the outbreak-associated L. pneumophila strain that was inoculated into the systems. L. pneumophila numbers were also higher in several instances when Cu was dosed together with orthophosphate (e.g., with an Al anode), revealing at least one scenario where high levels of total Cu appeared to stimulate Legionella. The controlled, pilot-scale nature of this study provides new understanding of the limitations of Cu as an antimicrobial in real-world plumbing systems.
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Affiliation(s)
- Yang Song
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061; Utilities Department, Town of Cary, 316 N. Academy St., Cary, NC, 27512.
| | - Amy Pruden
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061
| | - William J Rhoads
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061; Black & Veatch, 8400 Ward Pkwy, Kansas City, MO, 64114
| | - Marc A Edwards
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA, 24061.
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13
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Logan-Jackson AR, Batista MD, Healy W, Ullah T, Whelton AJ, Bartrand TA, Proctor C. A Critical Review on the Factors that Influence Opportunistic Premise Plumbing Pathogens: From Building Entry to Fixtures in Residences. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:6360-6372. [PMID: 37036108 DOI: 10.1021/acs.est.2c04277] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Residential buildings provide unique conditions for opportunistic premise plumbing pathogen (OPPP) exposure via aerosolized water droplets produced by showerheads, faucets, and tubs. The objective of this review was to critically evaluate the existing literature that assessed the impact of potentially enhancing conditions to OPPP occurrence associated with residential plumbing and to point out knowledge gaps. Comprehensive studies on the topic were found to be lacking. Major knowledge gaps identified include the assessment of OPPP growth in the residential plumbing, from building entry to fixtures, and evaluation of the extent of the impact of typical residential plumbing design (e.g., trunk and branch and manifold), components (e.g., valves and fixtures), water heater types and temperature setting of operation, and common pipe materials (copper, PEX, and PVC/CPVC). In addition, impacts of the current plumbing code requirements on OPPP responses have not been assessed by any study and a lack of guidelines for OPPP risk management in residences was identified. Finally, the research required to expand knowledge on OPPP amplification in residences was discussed.
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Affiliation(s)
- Alshae' R Logan-Jackson
- Building Energy and Environment Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Marylia Duarte Batista
- Building Energy and Environment Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - William Healy
- Building Energy and Environment Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Tania Ullah
- Building Energy and Environment Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Andrew J Whelton
- Lyles School of Civil Engineering, Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Timothy A Bartrand
- Environmental Science, Policy, and Research Institute, Bala Cynwyd, Pennsylvania 19004, United States
| | - Caitlin Proctor
- Agricultural and Biological Engineering, Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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14
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Gea-Izquierdo E, Gil-de-Miguel Á, Rodríguez-Caravaca G. Legionella pneumophila Risk from Air–Water Cooling Units Regarding Pipe Material and Type of Water. Microorganisms 2023; 11:microorganisms11030638. [PMID: 36985212 PMCID: PMC10053303 DOI: 10.3390/microorganisms11030638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Legionellosis is a respiratory disease related to environmental health. There have been manifold studies of pipe materials, risk installations and legionellosis without considering the type of transferred water. The objective of this study was to determine the potential development of the causative agent Legionella pneumophila regarding air–water cooling units, legislative compliance, pipe material and type of water. Forty-four hotel units in Andalusia (Spain) were analysed with respect to compliance with Spanish health legislation for the prevention of legionellosis. The chi-square test was used to explain the relationship between material–water and legislative compliance, and a biplot of the first two factors was generated. Multiple correspondence analysis (MCA) was performed on the type of equipment, legislative compliance, pipe material and type of water, and graphs of cases were constructed by adding confidence ellipses by categories of the variables. Pipe material–type of water (p value = 0.29; p < 0.05) and legislative compliance were not associated (p value = 0.15; p < 0.05). Iron, stainless steel, and recycled and well water contributed the most to the biplot. MCA showed a global pattern in which lead, iron and polyethylene were well represented. Confidence ellipses around categories indicated significant differences among categories. Compliance with Spanish health legislation regarding the prevention and control of legionellosis linked to pipe material and type of water was not observed.
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Affiliation(s)
- Enrique Gea-Izquierdo
- Preventive Medicine and Public Health, Rey Juan Carlos University, 28922 Madrid, Spain
- Maria Zambrano Program, European Union, Spain
- Correspondence:
| | - Ángel Gil-de-Miguel
- Preventive Medicine and Public Health, Rey Juan Carlos University, 28922 Madrid, Spain
- CIBER of Respiratory Diseases (CIBERES), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Gil Rodríguez-Caravaca
- Preventive Medicine and Public Health, Rey Juan Carlos University, 28922 Madrid, Spain
- Department of Preventive Medicine, Hospital Universitario Fundación Alcorcón, Universidad Rey Juan Carlos, 28922 Madrid, Spain
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15
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Molina JJ, Bennassar M, Palacio E, Crespi S. Impact of prolonged hotel closures during the COVID-19 pandemic on Legionella infection risks. Front Microbiol 2023; 14:1136668. [PMID: 36910223 PMCID: PMC9998907 DOI: 10.3389/fmicb.2023.1136668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 02/10/2023] [Indexed: 03/14/2023] Open
Abstract
In general, it is accepted that water stagnation and lack or poor maintenance in buildings are risk factors for Legionella growth. Then, in theory, the prolonged hotel closures due to the COVID-19 pandemic may have increased the risk of Legionella infections. However, there are very few field studies comparing the level of Legionella colonization in buildings before the pandemic and the new situation created after the lockdown. The objective of this study was to analyze these differences in a group of hotels that experienced prolonged closures in 2020 due to the COVID-19 pandemic. We have studied the Legionella spp. results, analyzed by standard culture, from the domestic water distribution systems of 73 hotels that experienced closures (from 1 to >4 months) during 2020, immediately after the reopening. The results were compared with those obtained in similar samplings of 2019. For the comparative analysis, we divided the hotels in two groups: Group A that have suffered closures for ≤3 months and Group B that remained closed for more than 3 months, both in relation to the opening period of 2019. In the Group B (36 sites), the frequency of positive samples in the hot water system increased from 6.7% in 2019 to 14.0% in 2020 (p < 0.05). In the Group A (37 sites), no significant differences were observed. No statistically significant differences were observed in terms of positive sites (defined as hotels with at least 1 positive sample), Legionella spp. concentrations and prevalence of Legionella pneumophila sg1 between the samplings of the two periods studied. The results suggest that hotels that suffered the longest prolonged closures (> 3 months) could have carried a higher risk of exposure to Legionella in the domestic hot water system. These findings highlight the importance of adequate preopening cleaning and disinfection procedures for hotel water systems, and the convenience of considering the most effective disinfection methods especially for hot water systems and after prolonged closure periods.
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Affiliation(s)
- Jhon J Molina
- Environmental Health and Laboratory Services, Biolinea Int., Palma, Spain.,Environmental Analytical Chemistry Laboratory, Department of Chemistry, University of the Balearic Islands, Palma, Spain
| | | | - Edwin Palacio
- Environmental Analytical Chemistry Laboratory, Department of Chemistry, University of the Balearic Islands, Palma, Spain
| | - Sebastian Crespi
- Environmental Health and Laboratory Services, Biolinea Int., Palma, Spain
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16
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Lu J, Yu Z, Ding P, Guo J. Triclosan Promotes Conjugative Transfer of Antibiotic Resistance Genes to Opportunistic Pathogens in Environmental Microbiome. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:15108-15119. [PMID: 36251935 DOI: 10.1021/acs.est.2c05537] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Although triclosan, as a widely used antiseptic chemical, is known to promote the transmission of antibiotic resistance to diverse hosts in pure culture, it is still unclear whether and how triclosan could affect the transmission of broad-host-range plasmids among complex microbial communities. Here, bacterial culturing, fluorescence-based cell sorting, and high-throughput 16S rRNA gene amplicon sequencing were combined to investigate contributions of triclosan on the transfer rate and range of an IncP-type plasmid from a proteobacterial donor to an activated sludge microbiome. Our results demonstrate that triclosan significantly enhances the conjugative transfer of the RP4 plasmid among activated sludge communities at environmentally relevant concentrations. High-throughput 16S rRNA gene sequencing on sorted transconjugants demonstrates that triclosan not only promoted the intergenera transfer but also the intragenera transfer of the RP4 plasmid among activated sludge communities. Moreover, triclosan mediated the transfer of the RP4 plasmid to opportunistic human pathogens, for example, Legionella spp. The mechanism of triclosan-mediated conjugative transfer is primarily associated with excessive oxidative stress, followed by increased membrane permeability and provoked SOS response. Our findings offer insights into the impacts of triclosan on the dissemination of antibiotic resistance in the aquatic environmental microbiome.
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Affiliation(s)
- Ji Lu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Zhigang Yu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Pengbo Ding
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Jianhua Guo
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
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17
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A Metagenomic Investigation of Spatial and Temporal Changes in Sewage Microbiomes across a University Campus. mSystems 2022; 7:e0065122. [PMID: 36121163 PMCID: PMC9599454 DOI: 10.1128/msystems.00651-22] [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] [Indexed: 12/24/2022] Open
Abstract
Wastewater microbial communities are not static and can vary significantly across time and space, but this variation and the factors driving the observed spatiotemporal variation often remain undetermined. We used a shotgun metagenomic approach to investigate changes in wastewater microbial communities across 17 locations in a sewer network, with samples collected from each location over a 3-week period. Fecal material-derived bacteria constituted a relatively small fraction of the taxa found in the collected samples, highlighting the importance of environmental sources to the sewage microbiome. The prokaryotic communities were highly variable in composition depending on the location within the sampling network, and this spatial variation was most strongly associated with location-specific differences in sewage pH. However, we also observed substantial temporal variation in the composition of the prokaryotic communities at individual locations. This temporal variation was asynchronous across sampling locations, emphasizing the importance of independently considering both spatial and temporal variation when assessing the wastewater microbiome. The spatiotemporal patterns in viral community composition closely tracked those of the prokaryotic communities, allowing us to putatively identify the bacterial hosts of some of the dominant viruses in these systems. Finally, we found that antibiotic resistance gene profiles also exhibit a high degree of spatiotemporal variability, with most of these genes unlikely to be derived from fecal bacteria. Together, these results emphasize the dynamic nature of the wastewater microbiome, the challenges associated with studying these systems, and the utility of metagenomic approaches for building a multifaceted understanding of these microbial communities and their functional attributes. IMPORTANCE Sewage systems harbor extensive microbial diversity, including microbes derived from both human and environmental sources. Studies of the sewage microbiome are useful for monitoring public health and the health of our infrastructure, but the sewage microbiome can be highly variable in ways that are often unresolved. We sequenced DNA recovered from wastewater samples collected over a 3-week period at 17 locations in a single sewer system to determine how these communities vary across time and space. Most of the wastewater bacteria, and the antibiotic resistance genes they harbor, were not derived from human feces, but human usage patterns did impact how the amounts and types of bacteria and bacterial genes we found in these systems varied over time. Likewise, the wastewater communities, including both bacteria and their viruses, varied depending on location within the sewage network, highlighting the challenges and opportunities in efforts to monitor and understand the sewage microbiome.
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18
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Donohue MJ, Mistry JH, Tucker N, Vesper SJ. Hot water plumbing in residences and office buildings have distinctive risk of Legionella pneumophila contamination. Int J Hyg Environ Health 2022; 245:114023. [PMID: 36058110 PMCID: PMC9848435 DOI: 10.1016/j.ijheh.2022.114023] [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: 03/30/2022] [Revised: 07/22/2022] [Accepted: 08/09/2022] [Indexed: 01/21/2023]
Abstract
AIM To observe how Legionella pneumophila, the causative agent for legionellosis, can transmit through the hot water plumbing of residences and office buildings. METHOD AND RESULTS Using qPCR, L. pneumophila and L. pneumophila Serogroup (Sg)1 were measured in hot water samples collected from 100 structures, consisting of 70 residences and 30 office buildings. The hot water samples collected from office buildings had a higher L. pneumophila detection frequency of 53% (16/30) than residences, with a 103 GU/L (median) concentration. An office building's age was not a statistically significant predictor of contamination, but its area (>100,000 sq. ft.) was, P = <0.001. Hot water samples collected at residences had a lower L. pneumophila detection frequency of 36% (25/70) than office buildings, with a 100 GU/L (median) concentration. A residence's age was a significant predictor of contamination, P = 0.009, but not its area. The water's secondary disinfectant type did not affect L. pneumophila detection frequency nor its concentration in residences, but the secondary disinfectant type did affect results in office buildings. Legionella pneumophila's highest detection frequencies were in samples collected in March-August for office buildings and in June-November for residences. CONCLUSION This study revealed that the built environment influences L. pneumophila transport and fate. Residential plumbing could be a potential "conduit" for L. pneumophila exposure from a source upstream of the hot water environment. Both old and newly built office buildings had an equal probability of L. pneumophila contamination. Legionella-related remediation efforts in office buildings (that contain commercial functions only) might not significantly improve a community's public health.
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Affiliation(s)
- Maura J Donohue
- United States Environmental Protection Agency, Cincinnati, OH, 45268, USA.
| | - Jatin H Mistry
- United States Environmental Protection Agency, Region 6, Dallas, TX, 75270, USA
| | - Nicole Tucker
- United States Environmental Protection Agency, Washington, DC, 20464, USA
| | - Stephen J Vesper
- United States Environmental Protection Agency, Cincinnati, OH, 45268, USA
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19
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Jereb G, Eržen I, Oder M, Poljšak B. Phosphate drinking water softeners promote Legionella growth. JOURNAL OF WATER AND HEALTH 2022; 20:1084-1090. [PMID: 35902990 DOI: 10.2166/wh.2022.055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Phosphate-based drinking water softeners are commonly used to prevent scale formation in drinking water distribution infrastructure. The main reason for drinking water softening is primarily economic (protection of pipes and extension of equipment life), while the health aspect of such treatment is usually neglected. The aim of this work is to investigate the effects of phosphate-based drinking water softeners on growth stimulation of Legionella pneumophila. Bacterial growth was observed at two different phosphate concentrations. On average, an increase in growth of 1.19-1.28 log CFU/mL was observed in selected samples with added phosphates compared with the control. The results of the in vitro experiment confirmed that the added phosphates stimulate the growth of L. pneumophila; growth stimulation could therefore be expected in drinking water distribution systems (DWDS) when phosphates are used as well. The availability of phosphorus in DWDS may be a crucial limiting factor for biofouling control. Consequently, phosphate-based chemicals for drinking water should be avoided or used with prudence, especially in drinking water with high concentrations of other nutrients.
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Affiliation(s)
- Gregor Jereb
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia E-mail: ; Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Ivan Eržen
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia; The National Institute of Public Health, Trubarjeva 2, 1000 Ljubljana, Slovenia
| | - Martina Oder
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia E-mail:
| | - Borut Poljšak
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia E-mail:
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20
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Rakić A, Vukić Lušić D, Jurčev Savičević A. Influence of Metal Concentration and Plumbing Materials on Legionella Contamination. Microorganisms 2022; 10:1051. [PMID: 35630493 PMCID: PMC9147233 DOI: 10.3390/microorganisms10051051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 12/07/2022] Open
Abstract
Legionella colonization of water supply pipes is a significant public health problem. The objective of this work was to evaluate Legionella colonization in hotel hot water systems and to investigate the relationship between metal concentrations, piping materials (galvanized iron pipes and plastic pipes), and Legionella proliferation. Concentrations of calcium and magnesium ions and the presence of Legionella pneumophila were determined in a total of 108 water samples from the hot water systems of four hotels in Split-Dalmatia County over a 12-month period, and additional data on piping materials were collected. L. pneumophila was isolated in 23.1% of all samples-in 28.8% (15/52) of water samples from galvanized iron pipes and in 17.8% (10/56) of samples from plastic pipes. L. pneumophila serogroups 2-14 were isolated from all samples. This study found higher prevalence of L. pneumophila at higher concentrations of Ca and Mg ions (except for Mg and plastic pipes). The metal parts of the water supply may be important factors in Legionella contamination due to the possibility of lime scale or roughness of the pipes. Higher Ca and Mg ion concentrations increased the risk of Legionella colonization.
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Affiliation(s)
- Anita Rakić
- Public Health Institute of Split-Dalmatia County, Vukovarska 46, 21000 Split, Croatia;
| | - Darija Vukić Lušić
- Department of Environmental Health, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
- Department of Environmental Health, Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia
- Center for Advanced Computing and Modeling, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia
| | - Anamarija Jurčev Savičević
- Public Health Institute of Split-Dalmatia County, Vukovarska 46, 21000 Split, Croatia;
- Department of Health Studies, University of Split, 35 P.P. 464, Ruđera Boškovića Street, 21000 Split, Croatia
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21
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Practitioners’ Perspective on the Prevalent Water Quality Management Practices for Legionella Control in Large Buildings in the United States. WATER 2022. [DOI: 10.3390/w14040663] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Managing building water systems is complicated by the need to maintain hot water temperatures high enough to control the growth of Legionella spp. while minimizing the risk of scalding. This study assessed water quality management practices in large buildings in the United States. Surveys conducted with building water quality managers found that more than 85% of buildings have hot water temperatures that are consistent with scald risk mitigation guidelines (i.e., <122 °F/50 °C). However, nearly two thirds and three quarters of buildings do not comply with the common temperature guidance for opportunistic pathogen control, i.e., water heater setpoint > 140 °F (60 °C) and recirculation loop > 122 °F (50 °C), respectively; median values for both setpoint and recirculation loop temperatures are 10 °F (6 °C) or more below temperatures recommended for opportunistic pathogen control. These observations suggest that many buildings are prone to Legionella spp. risk. The study also found that 27% of buildings do not comply with guidelines for time to equilibrium hot water temperature, over 33% fail to monitor temperature in the recirculation loop, more than 70% fail to replace or disinfect showerheads, more than 40% lack a written management plan, and only a minority conduct any monitoring of residual disinfectant levels or microbiological quality. Given the rise in Legionellosis infections in recent years, coupled with highlighted water quality concerns because of prolonged water stagnation in plumbing, such as in buildings closed due to COVID-19, current management practices, which appear to be focused on scald risk, may need to be broadened to include greater attention to control of opportunistic pathogens. To accomplish this, there is a need for formal training and resources for facility managers.
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Talapko J, Frauenheim E, Juzbašić M, Tomas M, Matić S, Jukić M, Samardžić M, Škrlec I. Legionella pneumophila-Virulence Factors and the Possibility of Infection in Dental Practice. Microorganisms 2022; 10:microorganisms10020255. [PMID: 35208710 PMCID: PMC8879694 DOI: 10.3390/microorganisms10020255] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/08/2022] [Accepted: 01/21/2022] [Indexed: 02/07/2023] Open
Abstract
Legionella pneumophila is defined as a bacterium that can cause severe pneumonia. It is found in the natural environment and in water, and is often found in water tanks. It can be an integral part of biofilms in nature, and the protozoa in which it can live provide it with food and protect it from harmful influences; therefore, it has the ability to move into a sustainable but uncultured state (VBNC). L. pneumophila has been shown to cause infections in dental practices. The most common transmission route is aerosol generated in dental office water systems, which can negatively affect patients and healthcare professionals. The most common way of becoming infected with L. pneumophila in a dental office is through water from dental instruments, and the dental unit. In addition to these bacteria, patients and the dental team may be exposed to other harmful bacteria and viruses. Therefore, it is vital that the dental team regularly maintains and decontaminates the dental unit, and sterilizes all accessories that come with it. In addition, regular water control in dental offices is necessary.
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Affiliation(s)
- Jasminka Talapko
- Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, HR-31000 Osijek, Croatia; (J.T.); (E.F.); (M.J.); (M.T.); (S.M.); (M.J.); (M.S.)
| | - Erwin Frauenheim
- Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, HR-31000 Osijek, Croatia; (J.T.); (E.F.); (M.J.); (M.T.); (S.M.); (M.J.); (M.S.)
| | - Martina Juzbašić
- Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, HR-31000 Osijek, Croatia; (J.T.); (E.F.); (M.J.); (M.T.); (S.M.); (M.J.); (M.S.)
| | - Matej Tomas
- Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, HR-31000 Osijek, Croatia; (J.T.); (E.F.); (M.J.); (M.T.); (S.M.); (M.J.); (M.S.)
| | - Suzana Matić
- Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, HR-31000 Osijek, Croatia; (J.T.); (E.F.); (M.J.); (M.T.); (S.M.); (M.J.); (M.S.)
- Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, Josipa Huttlera 4, HR-31000 Osijek, Croatia
| | - Melita Jukić
- Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, HR-31000 Osijek, Croatia; (J.T.); (E.F.); (M.J.); (M.T.); (S.M.); (M.J.); (M.S.)
- General Hospital Vukovar, Županijska 35, HR-32000 Vukovar, Croatia
| | - Marija Samardžić
- Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, HR-31000 Osijek, Croatia; (J.T.); (E.F.); (M.J.); (M.T.); (S.M.); (M.J.); (M.S.)
| | - Ivana Škrlec
- Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, HR-31000 Osijek, Croatia; (J.T.); (E.F.); (M.J.); (M.T.); (S.M.); (M.J.); (M.S.)
- Correspondence:
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Leonov V, Leonova L, Cherepanov D, Savin L, Tkalich A, Petrovskaya Y, Trizna E, Ananina I. The Growth Kinetics of Pathogenic Microorganisms Under Conditions Modelling the Vital Functions of Iron-Oxidizing Bacteria. BIONANOSCIENCE 2022. [DOI: 10.1007/s12668-021-00929-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Huang CK, Weerasekara A, Bond PL, Weynberg KD, Guo J. Characterizing the premise plumbing microbiome in both water and biofilms of a 50-year-old building. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 798:149225. [PMID: 34340073 DOI: 10.1016/j.scitotenv.2021.149225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 07/18/2021] [Accepted: 07/20/2021] [Indexed: 05/22/2023]
Abstract
The premise plumbing portion of drinking water distribution systems (DWDS) has several characteristics that may favor microbial growth in the form of biofilms. These microbial communities are implicated as infectious sources for the spread of opportunistic waterborne pathogens by supporting their complex ecology and transmission through DWDS outlets to susceptible individuals. However, there is limited understanding of the drinking water biofilms in real premise plumbing networks due to challenges with accessibility. Using a combination of culture-dependent and culture-independent approaches, this study comprehensively characterized the premise plumbing microbiome of a 50-year-old university building, inclusive of water and biofilm samples. Microbial diversity in the water samples were more taxonomically diverse in comparison to the mature drinking water biofilms, which were dominated with biofilm-formers and opportunistic pathogens, such as Mycobacterium spp. A model opportunistic pathogen, Legionella spp., was only detectable in water samples using quantitative PCR but could not be detected in any of the drinking water biofilms using either qPCR or culture-dependent approaches, highlighting the limitations of detection methods in these environments. This study presents preliminary findings on the microbial dynamics and complexity in premise plumbing networks, which may support public health management and the development of strategies to eliminate microbial risks to human health.
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Affiliation(s)
- Casey K Huang
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia; Queensland Alliance for Environmental Health Sciences (QAEHS), The University of Queensland, Woolloongabba, Brisbane, QLD 4102, Australia
| | - Anjani Weerasekara
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia; Queensland Alliance for Environmental Health Sciences (QAEHS), The University of Queensland, Woolloongabba, Brisbane, QLD 4102, Australia
| | - Philip L Bond
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia; Centre for Microbiome Research, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Karen D Weynberg
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Jianhua Guo
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
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Zhang C, Lu J. Legionella: A Promising Supplementary Indicator of Microbial Drinking Water Quality in Municipal Engineered Water Systems. FRONTIERS IN ENVIRONMENTAL SCIENCE 2021; 9:1-22. [PMID: 35004706 PMCID: PMC8740890 DOI: 10.3389/fenvs.2021.684319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Opportunistic pathogens (OPs) are natural inhabitants and the predominant disease causative biotic agents in municipal engineered water systems (EWSs). In EWSs, OPs occur at high frequencies and concentrations, cause drinking-water-related disease outbreaks, and are a major factor threatening public health. Therefore, the prevalence of OPs in EWSs represents microbial drinking water quality. Closely or routinely monitoring the dynamics of OPs in municipal EWSs is thus critical to ensuring drinking water quality and protecting public health. Monitoring the dynamics of conventional (fecal) indicators (e.g., total coliforms, fecal coliforms, and Escherichia coli) is the customary or even exclusive means of assessing microbial drinking water quality. However, those indicators infer only fecal contamination due to treatment (e.g., disinfection within water utilities) failure and EWS infrastructure issues (e.g., water main breaks and infiltration), whereas OPs are not contaminants in drinking water. In addition, those indicators appear in EWSs at low concentrations (often absent in well-maintained EWSs) and are uncorrelated with OPs. For instance, conventional indicators decay, while OPs regrow with increasing hydraulic residence time. As a result, conventional indicators are poor indicators of OPs (the major aspect of microbial drinking water quality) in EWSs. An additional or supplementary indicator that can well infer the prevalence of OPs in EWSs is highly needed. This systematic review argues that Legionella as a dominant OP-containing genus and natural inhabitant in EWSs is a promising candidate for such a supplementary indicator. Through comprehensively comparing the behavior (i.e., occurrence, growth and regrowth, spatiotemporal variations in concentrations, resistance to disinfectant residuals, and responses to physicochemical water quality parameters) of major OPs (e.g., Legionella especially L. pneumophila, Mycobacterium, and Pseudomonas especially P. aeruginosa), this review proves that Legionella is a promising supplementary indicator for the prevalence of OPs in EWSs while other OPs lack this indication feature. Legionella as a dominant natural inhabitant in EWSs occurs frequently, has a high concentration, and correlates with more microbial and physicochemical water quality parameters than other common OPs. Legionella and OPs in EWSs share multiple key features such as high disinfectant resistance, biofilm formation, proliferation within amoebae, and significant spatiotemporal variations in concentrations. Therefore, the presence and concentration of Legionella well indicate the presence and concentrations of OPs (especially L. pneumophila) and microbial drinking water quality in EWSs. In addition, Legionella concentration indicates the efficacies of disinfectant residuals in EWSs. Furthermore, with the development of modern Legionella quantification methods (especially quantitative polymerase chain reactions), monitoring Legionella in ESWs is becoming easier, more affordable, and less labor-intensive. Those features make Legionella a proper supplementary indicator for microbial drinking water quality (especially the prevalence of OPs) in EWSs. Water authorities may use Legionella and conventional indicators in combination to more comprehensively assess microbial drinking water quality in municipal EWSs. Future work should further explore the indication role of Legionella in EWSs and propose drinking water Legionella concentration limits that indicate serious public health effects and require enhanced treatment (e.g., booster disinfection).
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Affiliation(s)
- Chiqian Zhang
- Pegasus Technical Services, Inc., Cincinnati, OH, United States
| | - Jingrang Lu
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH, United States
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Abstract
Reconstructing microbial genomes from metagenomic short-read data can be challenging due to the unknown and uneven complexity of microbial communities. This complexity encompasses highly diverse populations, which often includes strain variants. Reconstructing high-quality genomes is a crucial part of the metagenomic workflow, as subsequent ecological and metabolic inferences depend on their accuracy, quality, and completeness. In contrast to microbial communities in other ecosystems, there has been no systematic assessment of genome-centric metagenomic workflows for drinking water microbiomes. In this study, we assessed the performance of a combination of assembly and binning strategies for time series drinking water metagenomes that were collected over 6 months. The goal of this study was to identify the combination of assembly and binning approaches that result in high-quality and -quantity metagenome-assembled genomes (MAGs), representing most of the sequenced metagenome. Our findings suggest that the metaSPAdes coassembly strategies had the best performance, as they resulted in larger and less fragmented assemblies, with at least 85% of the sequence data mapping to contigs greater than 1 kbp. Furthermore, a combination of metaSPAdes coassembly strategies and MetaBAT2 produced the highest number of medium-quality MAGs while capturing at least 70% of the metagenomes based on read recruitment. Utilizing different assembly/binning approaches also assists in the reconstruction of unique MAGs from closely related species that would have otherwise collapsed into a single MAG using a single workflow. Overall, our study suggests that leveraging multiple binning approaches with different metaSPAdes coassembly strategies may be required to maximize the recovery of good-quality MAGs. IMPORTANCE Drinking water contains phylogenetic diverse groups of bacteria, archaea, and eukarya that affect the esthetic quality of water, water infrastructure, and public health. Taxonomic, metabolic, and ecological inferences of the drinking water microbiome depend on the accuracy, quality, and completeness of genomes that are reconstructed through the application of genome-resolved metagenomics. Using time series metagenomic data, we present reproducible genome-centric metagenomic workflows that result in high-quality and -quantity genomes, which more accurately signifies the sequenced drinking water microbiome. These genome-centric metagenomic workflows will allow for improved taxonomic and functional potential analysis that offers enhanced insights into the stability and dynamics of drinking water microbial communities.
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Zhang C, Struewing I, Mistry JH, Wahman DG, Pressman J, Lu J. Legionella and other opportunistic pathogens in full-scale chloraminated municipal drinking water distribution systems. WATER RESEARCH 2021; 205:117571. [PMID: 34628111 PMCID: PMC8629321 DOI: 10.1016/j.watres.2021.117571] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 08/02/2021] [Accepted: 08/13/2021] [Indexed: 05/06/2023]
Abstract
Water-based opportunistic pathogens (OPs) are a leading cause of drinking-water-related disease outbreaks, especially in developed countries such as the United States (US). Physicochemical water quality parameters, especially disinfectant residuals, control the (re)growth, presence, colonization, and concentrations of OPs in drinking water distribution systems (DWDSs), while the relationship between OPs and those parameters remain unclear. This study aimed to quantify how physicochemical parameters, mainly monochloramine residual concentration, hydraulic residence time (HRT), and seasonality, affected the occurrence and concentrations of four common OPs (Legionella, Mycobacterium, Pseudomonas, and Vermamoeba vermiformis) in four full-scale DWDSs in the US. Legionella as a dominant OP occurred in 93.8% of the 64 sampling events and had a mean density of 4.27 × 105 genome copies per liter. Legionella positively correlated with Mycobacterium, Pseudomonas, and total bacteria. Multiple regression with data from the four DWDSs showed that Legionella had significant correlations with total chlorine residual level, free ammonia concentration, and trihalomethane concentration. Therefore, Legionella is a promising indicator of water-based OPs, reflecting microbial water quality in chloraminated DWDSs. The OP concentrations had strong seasonal variations and peaked in winter and/or spring possibly because of reduced water usage (i.e., increased water stagnation or HRT) during cold seasons. The OP concentrations generally increased with HRT presumably because of disinfectant residual decay, indicating the importance of well-maintaining disinfectant residuals in DWDSs for OP control. The concentrations of Mycobacterium, Pseudomonas, and V. vermiformis were significantly associated with total chlorine residual concentration, free ammonia concentration, and pH and trihalomethane concentration, respectively. Overall, this study demonstrates how the significant spatiotemporal variations of OP concentrations in chloraminated DWDSs correlated with critical physicochemical water quality parameters such as disinfectant residual levels. This work also indicates that Legionella is a promising indicator of OPs and microbial water quality in chloraminated DWDSs.
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Affiliation(s)
- Chiqian Zhang
- Pegasus Technical Services, Inc., Cincinnati, Ohio, USA
| | - Ian Struewing
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Jatin H Mistry
- United States Environmental Protection Agency, Region 6, Dallas, Texas, USA
| | - David G Wahman
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Jonathan Pressman
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Jingrang Lu
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, USA.
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Causes, Factors, and Control Measures of Opportunistic Premise Plumbing Pathogens—A Critical Review. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11104474] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review critically analyses the chemical and physical parameters that influence the occurrence of opportunistic pathogens in the drinking water distribution system, specifically in premise plumbing. A comprehensive literature review reveals significant impacts of water age, disinfectant residual (type and concentration), temperature, pH, and pipe materials. Evidence suggests that there is substantial interplay between these parameters; however, the dynamics of such relationships is yet to be elucidated. There is a correlation between premise plumbing system characteristics, including those featuring water and energy conservation measures, and increased water quality issues and public health concerns. Other interconnected issues exacerbated by high water age, such as disinfectant decay and reduced corrosion control efficiency, deserve closer attention. Some common features and trends in the occurrence of opportunistic pathogens have been identified through a thorough analysis of the available literature. It is proposed that the efforts to reduce or eliminate their incidence might best focus on these common features.
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Song Y, Pruden A, Edwards MA, Rhoads WJ. Natural Organic Matter, Orthophosphate, pH, and Growth Phase Can Limit Copper Antimicrobial Efficacy for Legionella in Drinking Water. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:1759-1768. [PMID: 33428375 DOI: 10.1021/acs.est.0c06804] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Copper (Cu) is a promising antimicrobial for premise plumbing, where ions can be dosed directly via copper silver ionization or released naturally via corrosion of Cu pipes, but Cu sometimes inhibits and other times stimulates Legionella growth. Our overarching hypothesis was that water chemistry and growth phase control the net effect of Cu on Legionella. The combined effects of pH, phosphate concentration, and natural organic matter (NOM) were comprehensively examined over a range of conditions relevant to drinking water in bench-scale pure culture experiments, illuminating the effects of Cu speciation and precipitation. It was found that cupric ions (Cu2+) were drastically reduced at pH > 7.0 or in the presence of ligand-forming phosphates or NOM. Further, exponential phase L. pneumophila were 2.5× more susceptible to Cu toxicity relative to early stationary phase cultures. While Cu2+ ion was the most effective biocidal form of Cu, other inorganic ligands also had some biocidal impacts. A comparison of 33 large drinking water utilities' field-data from 1990 and 2018 showed that Cu2+ levels likely decreased more dramatically (>10×) than did the total or soluble Cu (2×) over recent decades. The overall findings aid in improving the efficacy of Cu as an actively dosed or passively released antimicrobial against L. pneumophila.
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Affiliation(s)
- Yang Song
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, 418 Durham Hall, Blacksburg, Virginia 24061, United States
| | - Amy Pruden
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, 418 Durham Hall, Blacksburg, Virginia 24061, United States
| | - Marc A Edwards
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, 418 Durham Hall, Blacksburg, Virginia 24061, United States
| | - William J Rhoads
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry Street, 418 Durham Hall, Blacksburg, Virginia 24061, United States
- Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf 8600, Switzerland
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Chambers ST, Slow S, Scott-Thomas A, Murdoch DR. Legionellosis Caused by Non- Legionella pneumophila Species, with a Focus on Legionella longbeachae. Microorganisms 2021; 9:291. [PMID: 33572638 PMCID: PMC7910863 DOI: 10.3390/microorganisms9020291] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/23/2021] [Accepted: 01/26/2021] [Indexed: 12/13/2022] Open
Abstract
Although known as causes of community-acquired pneumonia and Pontiac fever, the global burden of infection caused by Legionella species other than Legionella pneumophila is under-recognised. Non-L. pneumophila legionellae have a worldwide distribution, although common testing strategies for legionellosis favour detection of L. pneumophila over other Legionella species, leading to an inherent diagnostic bias and under-detection of cases. When systematically tested for in Australia and New Zealand, L. longbeachae was shown to be a leading cause of community-acquired pneumonia. Exposure to potting soils and compost is a particular risk for infection from L. longbeachae, and L. longbeachae may be better adapted to soil and composting plant material than other Legionella species. It is possible that the high rate of L. longbeachae reported in Australia and New Zealand is related to the composition of commercial potting soils which, unlike European products, contain pine bark and sawdust. Genetic studies have demonstrated that the Legionella genomes are highly plastic, with areas of the chromosome showing high levels of recombination as well as horizontal gene transfer both within and between species via plasmids. This, combined with various secretion systems and extensive effector repertoires that enable the bacterium to hijack host cell functions and resources, is instrumental in shaping its pathogenesis, survival and growth. Prevention of legionellosis is hampered by surveillance systems that are compromised by ascertainment bias, which limits commitment to an effective public health response. Current prevention strategies in Australia and New Zealand are directed at individual gardeners who use potting soils and compost. This consists of advice to avoid aerosols generated by the use of potting soils and use masks and gloves, but there is little evidence that this is effective. There is a need to better understand the epidemiology of L. longbeachae and other Legionella species in order to develop effective treatment and preventative strategies globally.
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Affiliation(s)
- Stephen T. Chambers
- Department of Pathology and Biomedical Science, University of Otago, Christchurch 8011, New Zealand; (S.S.); (A.S.-T.); (D.R.M.)
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Editorial Comments to the Special Issue: " Legionella Contamination in Water Environment". Pathogens 2020; 9:pathogens9121017. [PMID: 33276607 PMCID: PMC7761553 DOI: 10.3390/pathogens9121017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 12/01/2020] [Indexed: 11/29/2022] Open
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