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Kalu CM, Mudau KL, Masindi V, Ijoma GN, Tekere M. Occurrences and implications of pathogenic and antibiotic-resistant bacteria in different stages of drinking water treatment plants and distribution systems. Heliyon 2024; 10:e26380. [PMID: 38434035 PMCID: PMC10906316 DOI: 10.1016/j.heliyon.2024.e26380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 12/05/2023] [Accepted: 02/12/2024] [Indexed: 03/05/2024] Open
Abstract
Different stages of drinking water treatment plants (DWTPs) play specific roles in diverse contaminants' removal present in natural water sources. Although the stages are recorded to promote adequate treatment of water, the occurrence of pathogenic bacteria (PB) and antibiotic-resistant bacteria (ARB) in the treated water and the changes in their diversity and abundance as it passed down to the end users through the drinking water distribution systems (DWDSs), is a great concern, especially to human health. This could imply that the different stages and the distribution system provide a good microenvironment for their growth. Hence, it becomes pertinent to constantly monitor and document the diversity of PB and ARB present at each stage of the treatment and distribution system. This review aimed at documenting the occurrence of PB and ARB at different stages of treatment and distribution systems as well as the implication of their occurrence globally. An exhaustive literature search from Web of Science, Science-Direct database, Google Scholar, Academic Research Databases like the National Center for Biotechnology Information, Scopus, and SpringerLink was done. The obtained information showed that the different treatment stages and distribution systems influence the PB and ARB that proliferate. To minimize the human health risks associated with the occurrence of these PB, the present review, suggests the development of advanced technologies that can promote quick monitoring of PB/ARB at each treatment stage and distribution system as well as reduction of the cost of environomics analysis to promote better microbial analysis.
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Affiliation(s)
- Chimdi M. Kalu
- Department of Environmental Science, College of Agriculture and Environmental Sciences, University of South Africa, Florida, 1710, South Africa
| | - Khuthadzo L. Mudau
- Department of Environmental Science, College of Agriculture and Environmental Sciences, University of South Africa, Florida, 1710, South Africa
| | - Vhahangwele Masindi
- Department of Environmental Science, College of Agriculture and Environmental Sciences, University of South Africa, Florida, 1710, South Africa
- Magalies Water, Scientific Services, Research & Development Division, Brits, South Africa
| | - Grace N. Ijoma
- Department of Environmental Science, College of Agriculture and Environmental Sciences, University of South Africa, Florida, 1710, South Africa
| | - Memory Tekere
- Department of Environmental Science, College of Agriculture and Environmental Sciences, University of South Africa, Florida, 1710, South Africa
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2
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Chen CH, Liao CC, Wang YJ, Huang FC, Lin WC. A. castellanii and P. aeruginosa mutually exacerbate damage to corneal cells during coinfection. Microbiol Spectr 2024; 12:e0268323. [PMID: 38095463 PMCID: PMC10783079 DOI: 10.1128/spectrum.02683-23] [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: 06/28/2023] [Accepted: 10/31/2023] [Indexed: 01/13/2024] Open
Abstract
IMPORTANCE At the National Cheng Kung University Hospital, numerous cases of amoebic keratitis had been identified with concurrent bacterial infections. Among these bacterial coinfections, Pseudomonas aeruginosa accounted for 50% of the reported cases. However, the impact of pathogenic bacteria on amoeba-induced corneal damage remains unclear. In our study, we successfully demonstrated that P. aeruginosa accumulated on the Acanthamoeba castellanii surface and caused more severe corneal damage. We also indicated that the exposure of P. aeruginosa to amoeba-soluble antigens enhanced its adhesion ability, promoted biofilm formation, and led to more severe corneal cell damage. These findings significantly contributed to our understanding of the risk associated with P. aeruginosa coinfection in the progression of amoeba keratitis.
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Affiliation(s)
- Chun-Hsien Chen
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chen-Chieh Liao
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Jen Wang
- Department of Parasitology, School of Medicine, China Medical University, Taichung, Taiwan
| | - Fu-Chin Huang
- Department of Ophthalmology, College of Medicine, National Cheng Kung University Hospital, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Chen Lin
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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3
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Cambronne ED, Ayres C, Dowdell KS, Lawler DF, Saleh NB, Kirisits MJ. Protozoan-Priming and Magnesium Conditioning Enhance Legionella pneumophila Dissemination and Monochloramine Resistance. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:14871-14880. [PMID: 37756220 DOI: 10.1021/acs.est.3c04013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Opportunistic pathogens (OPs) are of concern in drinking water distribution systems because they persist despite disinfectant residuals. While many OPs garner protection from disinfectants via a biofilm lifestyle, Legionella pneumophila (Lp) also gains disinfection resistance by being harbored within free-living amoebae (FLA). It has been long established, but poorly understood, that Lp grown within FLA show increased infectivity toward subsequent FLA or human cells (i.e., macrophage), via a process we previously coined "protozoan-priming". The objectives of this study are (i) to identify in Lp a key genetic determinant of how protozoan-priming increases its infectivity, (ii) to determine the chemical stimulus within FLA to which Lp responds during protozoan-priming, and (iii) to determine if more infectious forms of Lp also exhibit enhanced disinfectant resistance. Using Acanthamoeba castellanii as a FLA host, the priming effect was isolated to Lp's sidGV locus, which is activated upon sensing elevated magnesium concentrations. Supplementing growth medium with 8 mM magnesium is sufficient to produce Lp grown in vitro with an infectivity equivalent to that of Lp grown via the protozoan-primed route. Both Lp forms with increased infectivity (FLA-grown and Mg2+-supplemented) exhibit greater monochloramine resistance than Lp grown in standard media, indicating that passage through FLA not only increases Lp's infectivity but also enhances its monochloramine resistance. Therefore, laboratory-based testing of disinfection strategies should employ conditions that simulate or replicate intracellular growth to accurately assess disinfectant resistance.
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Affiliation(s)
- Eric D Cambronne
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Craig Ayres
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Katherine S Dowdell
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Desmond F Lawler
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Navid B Saleh
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Mary Jo Kirisits
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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4
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Wang L, Mai Y, Li S, Shu L, Fang J. Efficient inactivation of amoeba spores and their intraspore bacteria by solar/chlorine: Kinetics and mechanisms. WATER RESEARCH 2023; 242:120288. [PMID: 37419027 DOI: 10.1016/j.watres.2023.120288] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/21/2023] [Accepted: 06/28/2023] [Indexed: 07/09/2023]
Abstract
Amoebae are widespread in water and serve as environment vectors for pathogens, which may threaten public health. This study evaluated the inactivation of amoeba spores and their intraspore bacteria by solar/chlorine. Dictyostelium discoideum and Burkholderia agricolaris B1qs70 were selected as model amoebae and intraspore bacteria, respectively. Compared to solar irradiation and chlorine, solar/chlorine enhanced the inactivation of amoeba spores and intraspore bacteria, with 5.1 and 5.2-log reduction at 20 min, respectively. The enhancement was similar in real drinking water by solar/chlorine under natural sunlight. However, the spore inactivation decreased to 2.97-log by 20 min solar/chlorine under oxygen-free condition, indicating that ozone played a crucial role in the spore inactivation, as also confirmed by the scavenging test using tert‑butanol to scavenge the ground-state atomic oxygen (O(3P)) as a ozone precursor. Moreover, solar/chlorine induced the shape destruction and structural collapse of amoeba spores by scanning electron microscopy. As for intraspore bacteria, their inactivation was likely ascribed to endogenous reactive oxygen species. As pH increased from 5.0 to 9.0, the inactivation of amoeba spores decreased, whereas that of intraspore bacteria was similar at pH 5.0 and 6.5 during solar/chlorine treatment. This study first reports the efficient inactivation of amoeba spores and their intraspore pathogenic bacteria by solar/chlorine in drinking water.
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Affiliation(s)
- Liping Wang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 China
| | - Yingwen Mai
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 China
| | - Shenzhou Li
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 China
| | - Longfei Shu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 China.
| | - Jingyun Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 China.
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5
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Ashbolt NJ. Conceptual model to inform Legionella-amoebae control, including the roles of extracellular vesicles in engineered water system infections. Front Cell Infect Microbiol 2023; 13:1200478. [PMID: 37274310 PMCID: PMC10232903 DOI: 10.3389/fcimb.2023.1200478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 05/08/2023] [Indexed: 06/06/2023] Open
Abstract
Extracellular vesicles (EVs or exosomes) are well described for bacterial pathogens associated with our gastrointestinal system, and more recently as a novel mechanism for environmental persistence, dissemination and infection for human enteric viruses. However, the roles played by EVs in the ancient arms race that continues between amoebae and one of their prey, Legionella pneumophila, is poorly understood. At best we know of intracellular vesicles of amoebae containing a mix of bacterial prey species, which also provides an enhanced niche for bacteriophage infection/spread. Free-living amoeba-associated pathogens have recently been recognized to have enhanced resistance to disinfection and environmental stressors, adding to previously understood (but for relatively few species of) bacteria sequestered within amoebal cysts. However, the focus of the current work is to review the likely impacts of large numbers of respiratory-sized EVs containing numerous L. pneumophila cells studied in pure and biofilm systems with mixed prey species. These encapsulated pathogens are orders of magnitude more resistant to disinfection than free cells, and our engineered systems with residual disinfectants could promote evolution of resistance (including AMR), enhanced virulence and EV release. All these are key features for evolution within a dead-end human pathogen post lung infection. Traditional single-hit pathogen infection models used to estimate the probability of infection/disease and critical environmental concentrations via quantitative microbial risk assessments may also need to change. In short, recognizing that EV-packaged cells are highly virulent units for transmission of legionellae, which may also modulate/avoid human host immune responses. Key data gaps are raised and a previous conceptual model expanded upon to clarify where biofilm EVs could play a role promoting risk as well as inform a more wholistic management program to proactively control legionellosis.
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6
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Voglauer EM, Zwirzitz B, Thalguter S, Selberherr E, Wagner M, Rychli K. Biofilms in Water Hoses of a Meat Processing Environment Harbor Complex Microbial Communities. Front Microbiol 2022; 13:832213. [PMID: 35237250 PMCID: PMC8882869 DOI: 10.3389/fmicb.2022.832213] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/20/2022] [Indexed: 01/04/2023] Open
Abstract
Safe and hygienic water distribution is essential for maintaining product quality and safety. It is known that biofilms alter the appearance and microbial quality of water along the distribution chain. Yet, biofilms in water hoses throughout the food processing environment have not been investigated in detail. Here, microbial communities from water hoses and other environmental sites in contact with water, in addition to the source water itself, were studied in the meat processing environment. Biofilms were present in all water hoses as determined by the presence of bacterial DNA and biofilm matrix components (carbohydrates, extracellular DNA, and proteins). The microbial community of the biofilms was dominated by Proteobacteria, represented mainly by Comamonadaceae and Pseudoxanthomonas. Moreover, genera that are associated with an intracellular lifestyle (e.g., Neochlamydia and Legionella) were present. Overall, the microbial community of biofilms was less diverse than the water microbial community, while those from the different sample sites were distinct from each other. Indeed, only a few phyla were shared between the water hose biofilm and the source water or associated environmental samples. This study provides first insights towards understanding the microbiota of water hose biofilms in the food processing environment.
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Affiliation(s)
- Eva M. Voglauer
- FFoQSI GmbH—Austrian Competence Centre for Feed and Food Quality, Safety and Innovation, Tulln, Austria
| | - Benjamin Zwirzitz
- FFoQSI GmbH—Austrian Competence Centre for Feed and Food Quality, Safety and Innovation, Tulln, Austria
| | - Sarah Thalguter
- FFoQSI GmbH—Austrian Competence Centre for Feed and Food Quality, Safety and Innovation, Tulln, Austria
| | - Evelyne Selberherr
- Unit of Food Microbiology, Institute for Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Martin Wagner
- FFoQSI GmbH—Austrian Competence Centre for Feed and Food Quality, Safety and Innovation, Tulln, Austria
- Unit of Food Microbiology, Institute for Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Kathrin Rychli
- Unit of Food Microbiology, Institute for Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
- *Correspondence: Kathrin Rychli,
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7
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Hu D, Hong H, Rong B, Wei Y, Zeng J, Zhu J, Bai L, Guo F, Yu X. A comprehensive investigation of the microbial risk of secondary water supply systems in residential neighborhoods in a large city. WATER RESEARCH 2021; 205:117690. [PMID: 34614460 DOI: 10.1016/j.watres.2021.117690] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 09/15/2021] [Accepted: 09/19/2021] [Indexed: 06/13/2023]
Abstract
Secondary water supply systems (SWSSs) are characterized by long water stagnation and low levels of chlorine residuals, which may pose a high microbial risk to terminal users. In this study, the SWSSs of 12 residential neighborhoods in a metropolitan area of 5 million people in southeastern China were seasonally investigated to assess their microbial risks by determining more than 30 physicochemical and biological parameters. Although the microbiological quality of SWSS water met the requirements of the standards for drinking water quality of China, it did deteriorate in various aspects. The heterotrophic plate counts with R2A media were high (> 100 CFU/mL) in some SWSS tank and tap water samples. Propidium monoazide (PMA)-qPCR revealed a one magnitude higher abundance of viable bacteria in the tank and tap water samples (average 103.63±1.10 and 103.65±1.25 gene copies/mL, respectively) compared with the input water samples, and Enterococcus, Acanthamoeba, and Hartmannella vermiformis were only detected in the tanks. In particular, the high detection frequency of Legionella in 35% tank and 21% tap water samples suggested it is a supplementary microbial safety indicator in SWSSs. The microbial regrowth potential was more obvious in summer, and Illumina sequencing also demonstrated distinct seasonal changes in the relative abundance of bacterial gene sequences at the genus level. Turbidity and residual chlorine were closely connected with total bacterial biomass, and the latter seemed responsible for microbial community structure alteration. The extremely low chlorine residuals associated with a high abundance of total bacteria (as high as 106.48 gene copies/mL) and Legionella (as high as 106.71 gene copies/100 mL) in the closed valve tanks highlighted the high microbial risk increased by mishandling the operation of SWSSs. This study found that SWSSs possessed a higher microbial risk than the drinking water network, which suggested that the frequency and scope of monitoring the microbial risk of SWSSs in megacities should be strengthened for the purpose of waterborne epidemic disease prevention and control.
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Affiliation(s)
- Dong Hu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huarong Hong
- Xiamen Center for Disease Control and Prevention, Xiamen 361021, China
| | - Biao Rong
- Xiamen Center for Disease Control and Prevention, Xiamen 361021, China
| | - Yating Wei
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Jie Zeng
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Jun Zhu
- School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Lijun Bai
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Feng Guo
- School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Xin Yu
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China.
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Zhang X, Xia S, Ye Y, Wang H. Opportunistic pathogens exhibit distinct growth dynamics in rainwater and tap water storage systems. WATER RESEARCH 2021; 204:117581. [PMID: 34461496 DOI: 10.1016/j.watres.2021.117581] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/09/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Opportunistic pathogens (OPs) are emerging microbial contaminants in engineered water systems, yet their growth potential in rainwater systems has not been evaluated. The purpose of this study was to compare the growth dynamics of bacterial OPs and related genera (Pseudomonas aeruginosa, Legionella spp., L. pneumophila, Mycobacterium spp., and M. avium), two amoebal hosts (Acanthamoeba spp. and Vermamoeba vermiformis), and the fecal indicator Escherichia coli in simulated rainwater and tap water storage systems (SWSSs). Quantitative polymerase chain reaction (q-PCR) analysis of target microorganisms in SWSS influents and effluents demonstrated that P. aeruginosa and Legionella thrived in rainwater, but not in tap water. V. vermiformis proliferated in both rainwater and tap water polyvinyl chloride (PVC) SWSSs, while mycobacteria were largely absent in rainwater SWSSs. Tank materials exerted stronger influence on target microorganisms in rainwater SWSSs relative to tap water SWSSs, with species-specific responses noted in bulk water and biofilm. For instance, P. aeruginosa and V. vermiformis had the highest gene copy numbers in PVC rainwater SWSS effluents and biofilm, while Legionella peaked in stainless steel rainwater SWSS effluents and PVC rainwater SWSS biofilm. These results highlighted the OP contamination risks in rainwater storage systems and provided insights into rainwater system design and operation in terms of OP control.
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Affiliation(s)
- Xiaodong Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Chengtou Water Group Corporation, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Siqing Xia
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
| | - Yinyin Ye
- Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, New York 14260, USA
| | - Hong Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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9
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The role of Acanthamoeba spp. in biofilm communities: a systematic review. Parasitol Res 2021; 120:2717-2729. [PMID: 34292376 DOI: 10.1007/s00436-021-07240-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 07/01/2021] [Indexed: 12/16/2022]
Abstract
Acanthamoeba spp. have always caused disease in immunosuppressed patients, but since 1986, they have become a worldwide public health issue by causing infection in healthy contact lens wearers. Amoebae of the Acanthamoeba genus are broadly distributed in nature, living either freely or as parasites, and are frequently associated with biofilms throughout the environment. These biofilms provide the parasite with protection against external aggression, thus favoring its increased pathogeny. This review aims to assess observational studies on the association between Acanthamoeba spp. and biofilms, opening potential lines of research on this severe ocular infection. A systematic literature search was conducted in May 2020 in the following databases: PubMed Central®/Medline, LILACS, The Cochrane Library, and EMBASE®. The studies were selected following the inclusion and exclusion criteria specifically defined for this review. Electronic research recovered 353 publications in the literature. However, none of the studies met the inclusion criterion of biofilm-producing Acanthamoeba spp., inferring that the parasite does not produce biofilms. Nonetheless, 78 studies were classified as potentially included regarding any association of Acanthamoeba spp. and biofilms. These studies were allocated across six different locations (hospital, aquatic, ophthalmic and dental environments, biofilms produced by bacteria, and other places). Acanthamoeba species use biofilms produced by other microorganisms for their benefit, in addition to them providing protection to and facilitating the dissemination of pathogens residing in them.
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10
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Masaka E, Reed S, Davidson M, Oosthuizen J. Opportunistic Premise Plumbing Pathogens. A Potential Health Risk in Water Mist Systems Used as a Cooling Intervention. Pathogens 2021; 10:pathogens10040462. [PMID: 33921277 PMCID: PMC8068904 DOI: 10.3390/pathogens10040462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/29/2021] [Accepted: 04/07/2021] [Indexed: 11/16/2022] Open
Abstract
Water mist systems (WMS) are used for evaporative cooling in public areas. The health risks associated with their colonization by opportunistic premise plumbing pathogens (OPPPs) is not well understood. To advance the understanding of the potential health risk of OPPPs in WMS, biofilm, water and bioaerosol samples (n = 90) from ten (10) WMS in Australia were collected and analyzed by culture and polymerase chain reaction (PCR) methods to detect the occurrence of five representative OPPPs: Legionella pneumophila, Pseudomonas aeruginosa, Mycobacterium avium, Naegleria fowleri and Acanthamoeba. P. aeruginosa (44%, n = 90) occurred more frequently in samples, followed by L. pneumophila serogroup (Sg) 2–14 (18%, n = 90) and L. pneumophila Sg 1 (6%, n = 90). A negative correlation between OPPP occurrence and residual free chlorine was observed except with Acanthamoeba, rs (30) = 0.067, p > 0.05. All detected OPPPs were positively correlated with total dissolved solids (TDS) except with Acanthamoeba. Biofilms contained higher concentrations of L. pneumophila Sg 2–14 (1000–3000 CFU/mL) than water samples (0–100 CFU/mL). This study suggests that WMS can be colonized by OPPPs and are a potential health risk if OPPP contaminated aerosols get released into ambient atmospheres.
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Xue J, Zhang B, Lamori J, Shah K, Zabaleta J, Garai J, Taylor CM, Sherchan SP. Molecular detection of opportunistic pathogens and insights into microbial diversity in private well water and premise plumbing. JOURNAL OF WATER AND HEALTH 2020; 18:820-834. [PMID: 33095203 PMCID: PMC9115838 DOI: 10.2166/wh.2020.271] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Private well water systems in rural areas that are improperly maintained will result in poor drinking water quality, loss of water supply, and pose human health risk. The purpose of this study was to investigate the occurrence of fecal indicator bacteria (FIB) and opportunistic pathogens in private well water in rural areas surrounding New Orleans, Louisiana. Our results confirmed the ubiquitous nature of Legionella (86.7%) and mycobacteria (68.1%) in private well water in the study area, with gene concentration ranged from 0.60 to 5.53 and 0.67 to 5.95 Log10 of GC/100 mL, respectively. Naegleria fowleri target sequence was detected in 16.8% and Escherichia coli was detected in 43.4% of the water samples. Total coliform, as well as Legionella and mycobacteria genetic markers' concentrations were significantly reduced by 3-minute flushing. Next-generation sequencing (NGS) data indicated that the abundance of bacterial species was significantly increased in water collected in kitchens compared with samples from wells directly. This study provided integrated knowledge on the persistence of pathogenic organisms in private well water. Further study is needed to explore the presence of clinical species of those opportunistic pathogens in private well water systems to elucidate the health risk.
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Affiliation(s)
- Jia Xue
- Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, 70112, USA E-mail:
| | - Bowen Zhang
- Department of Natural Resources and Environmental Management, Ball State University, Muncie, Indiana, 47306, USA
| | - Jennifer Lamori
- Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, 70112, USA E-mail:
| | - Kinjal Shah
- Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, 70112, USA E-mail:
| | - Jovanny Zabaleta
- Department of Pediatrics and Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, Louisiana Cancer Research Center, New Orleans, Louisiana, 70112, USA
| | - Jone Garai
- Department of Pediatrics and Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, Louisiana Cancer Research Center, New Orleans, Louisiana, 70112, USA
| | - Christopher M Taylor
- Department of Microbiology, Immunology & Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, 70112, USA
| | - Samendra P Sherchan
- Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, 70112, USA E-mail:
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12
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Wagner EM, Pracser N, Thalguter S, Fischel K, Rammer N, Pospíšilová L, Alispahic M, Wagner M, Rychli K. Identification of biofilm hotspots in a meat processing environment: Detection of spoilage bacteria in multi-species biofilms. Int J Food Microbiol 2020; 328:108668. [PMID: 32474228 DOI: 10.1016/j.ijfoodmicro.2020.108668] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 04/03/2020] [Accepted: 05/18/2020] [Indexed: 12/15/2022]
Abstract
Biofilms are comprised of microorganisms embedded in a self-produced matrix that normally adhere to a surface. In the food processing environment they are suggested to be a source of contamination leading to food spoilage or the transmission of food-borne pathogens. To date, research has mainly focused on the presence of (biofilm-forming) bacteria within food processing environments, without measuring the associated biofilm matrix components. Here, we assessed the presence of biofilms within a meat processing environment, processing pork, poultry and beef, by the detection of microorganisms and at least two biofilm matrix components. Sampling included 47 food contact surfaces and 61 non-food contact surfaces from eleven rooms within an Austrian meat processing plant, either during operation or after cleaning and disinfection. The 108 samples were analysed for the presence of microorganisms by cultivation and targeted quantitative real-time PCR based on 16S rRNA. Furthermore, the presence of the major matrix components carbohydrates, extracellular DNA and proteins was evaluated. Overall, we identified ten biofilm hotspots, among them seven of which were sampled during operation and three after cleaning and disinfection. Five biofilms were detected on food contact surfaces (cutters and associated equipment and a screw conveyor) and five on non-food contact surfaces (drains and water hoses) resulting in 9.3 % of the sites being classified as biofilm positive. From these biofilm positive samples, we cultivated bacteria of 29 different genera. The most prevalent bacteria belonged to the genera Brochothrix (present in 80 % of biofilms), Pseudomonas and Psychrobacter (isolated from 70 % biofilms). From each biofilm we isolated bacteria from four to twelve different genera, indicating the presence of multi-species biofilms. This work ultimately determined the presence of multi-species biofilms within the meat processing environment, thereby identifying various sources of potential contamination. Especially the identification of biofilms in water hoses and associated parts highlights the need of a frequent monitoring at these sites. The knowledge gained about the presence and composition of biofilms (i.e. chemical and microbiological) will help to prevent and reduce biofilm formation within food processing environments.
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Affiliation(s)
- Eva M Wagner
- FFoQSI GmbH - Austrian Competence Centre for Feed and Food Quality, Safety and Innovation, 3430 Tulln, Austria
| | - Nadja Pracser
- University of Veterinary Medicine Vienna, Institute for Food Safety, Food Technology and Veterinary Public Health, Unit of Food Microbiology, 1210 Vienna, Austria
| | - Sarah Thalguter
- FFoQSI GmbH - Austrian Competence Centre for Feed and Food Quality, Safety and Innovation, 3430 Tulln, Austria
| | - Katharina Fischel
- University of Veterinary Medicine Vienna, Institute for Food Safety, Food Technology and Veterinary Public Health, Unit of Food Microbiology, 1210 Vienna, Austria
| | - Nicole Rammer
- University of Veterinary Medicine Vienna, Institute for Food Safety, Food Technology and Veterinary Public Health, Unit of Food Microbiology, 1210 Vienna, Austria
| | - Lucie Pospíšilová
- Veterinary Research Institute, Department of Bacteriology, 621 00 Brno, Czech Republic
| | - Merima Alispahic
- University of Veterinary Medicine Vienna, University Clinic for Poultry and Fish Medicine, Clinical Unit of Poultry Medicine, 1210 Vienna, Austria
| | - Martin Wagner
- FFoQSI GmbH - Austrian Competence Centre for Feed and Food Quality, Safety and Innovation, 3430 Tulln, Austria; University of Veterinary Medicine Vienna, Institute for Food Safety, Food Technology and Veterinary Public Health, Unit of Food Microbiology, 1210 Vienna, Austria
| | - Kathrin Rychli
- University of Veterinary Medicine Vienna, Institute for Food Safety, Food Technology and Veterinary Public Health, Unit of Food Microbiology, 1210 Vienna, Austria.
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Abstract
The amoeba-resistant bacterium Legionella pneumophila infects humans through aerosols and thereby can cause a life-threatening pneumonia termed Legionnaires' disease. In the environment L. pneumophila forms and colonizes biofilms, which usually comprise complex multispecies communities. In these biofilms L. pneumophila persists and replicates intracellularly in protozoa, such as the amoeba Acanthamoeba castellanii. The interactions between sessile L. pneumophila in biofilms and their natural protozoan hosts are not understood on a molecular level. Here, we describe a method to visualize by confocal microscopy the formation and architecture of mono-species L. pneumophila biofilms. Furthermore, we describe and quantify the migration or "grazing" of A. castellanii in the biofilm. This allows investigating on a molecular and cellular level L. pneumophila biofilm formation and Legionella-amoeba interactions within biofilms.
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Affiliation(s)
- Ramon Hochstrasser
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland.
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14
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Dey R, Rieger AM, Stephens C, Ashbolt NJ. Interactions of Pseudomonas aeruginosa with Acanthamoeba polyphaga Observed by Imaging Flow Cytometry. Cytometry A 2019; 95:555-564. [PMID: 30985067 DOI: 10.1002/cyto.a.23768] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/05/2019] [Accepted: 04/01/2019] [Indexed: 12/22/2022]
Abstract
Pseudomonas aeruginosa is a Gram-negative bacterium that is abundant in the environment and water systems, with strains that cause serious infections, especially in patients with compromised immune systems. In times of stress or as part of its natural life cycle, P. aeruginosa can adopt a viable but not culturable (VBNC) state, which renders it undetectable by current conventional food and water testing methods and makes it highly resistant to antibiotic treatment. Specific conditions can resuscitate these coccoid VBNC P. aeruginosa cells, which returns them to their active, virulent rod-shaped form. Underreporting the VBNC cells of P. aeruginosa by standard culture-based methods in water distribution systems may therefore pose serious risks to public health. As such, being able to accurately detect and quantify the presence of VBNC P. aeruginosa, especially in a hospital setting, is of critical importance. Herein, we describe a method to analyze VBNC P. aeruginosa using imaging flow cytometry. With this technique, we can accurately distinguish between active and VBNC forms. We also show here that association of VBNC P. aeruginosa with Acanthamoeba polyphaga results in resuscitation of P. aeruginosa to an active form within 2 h. Our approach could provide an alternative, reliable detection method of VBNC P. aeruginosa when coupled with species-specific staining. Most importantly, our experiments demonstrate that the coculture with amoebae can lead to a resuscitation of P. aeruginosa of culturable morphology after only 2 h, indicating that VBNC P. aeruginosa could potentially resuscitate in piped water (healthcare) environments colonized with amoebae. © 2019 International Society for Advancement of Cytometry.
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Affiliation(s)
- Rafik Dey
- School of Public Health, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Aja M Rieger
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Caroline Stephens
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Nicholas J Ashbolt
- School of Public Health, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada.,Provincial Laboratory for Public Health (ProvLab), Alberta Health Services, Edmonton, Alberta, Canada
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15
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Liu L, Xing X, Hu C, Wang H. One-year survey of opportunistic premise plumbing pathogens and free-living amoebae in the tap-water of one northern city of China. J Environ Sci (China) 2019; 77:20-31. [PMID: 30573084 DOI: 10.1016/j.jes.2018.04.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 04/20/2018] [Accepted: 04/20/2018] [Indexed: 05/21/2023]
Abstract
In this study, qPCR was used to quantify opportunistic premise plumbing pathogens (OPPPs) and free-living amoebae in 11 tap water samples collected over four seasons from a city in northern China. Results demonstrated that the average numbers of gene copies of Legionella spp. and Mycobacterium spp. were significantly higher than those of Aeromonas spp. (p < 0.05). Legionella spp. and Mycobacterium spp. were 100% (44/44) positively detected while P. aeruginosa and Aeromonas spp. were 79.54% (35/44) and 77.27% (34/44) positively detected. Legionella pneumophila was only detected in 4 samples (4/44), demonstrating its occasional occurrence. No Mycobacterium avium or Naegleria fowleri was detected in any of the samples. The average gene copy numbers of target OPPPs were the highest in summer, suggesting seasonal prevalence of OPPPs. Average gene copy numbers of OPPPs in the taps of low-use-frequency were higher than in taps of high-use-frequency, but the difference was not significant for some OPPPs (p > 0.05). Moderate negative correlations between the chlorine concentration and the gene copy numbers of OPPPs were observed by Spearman analysis (rs ranged from -0.311 to -0.710, p < 0.05). However, no significant correlations existed between OPPPs and AOC, BDOC, or turbidity. Moderate positive correlations were observed between the target microorganisms, especially for Acanthamoeba spp., through Spearman analysis (p < 0.05). Based on our studies, it is proposed that disinfectant concentration, season, taps with different-use frequency, OPPP species, and potential microbial correlations should be considered for control of OPPPs in tap water.
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Affiliation(s)
- Lizhong Liu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xueci Xing
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Chun Hu
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Institute of Environmental Research at Greater Bay, Guangzhou University, Guangzhou 510006, China
| | - Haibo Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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16
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Liu L, Xing X, Hu C, Wang H, Lyu L. Effect of sequential UV/free chlorine disinfection on opportunistic pathogens and microbial community structure in simulated drinking water distribution systems. CHEMOSPHERE 2019; 219:971-980. [PMID: 30682762 DOI: 10.1016/j.chemosphere.2018.12.067] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 12/04/2018] [Accepted: 12/08/2018] [Indexed: 06/09/2023]
Abstract
Drinking water distribution systems (DWDS) may be a "Trojan Horse" for some waterborne diseases caused by opportunistic pathogens (OPs). In this study, two simulated DWDS inoculated with groundwater were treated with chlorine (Cl2) and ultraviolet/chlorine (UV/Cl2) respectively to compare their effects on the OPs distributed in four different phases (bulk water, biofilms, corrosion products, and loose deposits) of DWDS. 16S rRNA genes sequencing and qPCR were used to profile microbial community and quantify target genes of OPs, respectively. Results showed that UV/Cl2 was more effective than single Cl2 to control the regrowth of OPs in the water with the same residual chlorine concentration. However, the OPs inhabiting the biofilms, corrosion products, and loose deposits seemed to be tolerant to UV/Cl2 and Cl2, demonstrating that OPs residing in these phases were resistant to the disinfection processes. Some significant microbial correlations between OPs and Acanthamoeba were found by Spearman correlative analysis (p < 0.05), demonstrating that the ecological interactions may exist in the DWDS. 16S rRNA genes sequencing of water samples revealed a significant different microbial community structure between UV/Cl2 and Cl2. This study may give some implications for controlling the OPs in the DWDS disinfected with UV/Cl2.
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Affiliation(s)
- Lizhong Liu
- Key Laboratory of Aquatic Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang City, Jiangxi 330013, China; School of Water Resource and Environmental Engineering, East China University of Technology, Nanchang City, Jiangxi 330013, China
| | - Xueci Xing
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Institute of Environmental Research at Greater Bay, Guangzhou University, Guangzhou 510006, China.
| | - Chun Hu
- Key Laboratory of Aquatic Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Institute of Environmental Research at Greater Bay, Guangzhou University, Guangzhou 510006, China
| | - Haibo Wang
- Key Laboratory of Aquatic Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Lai Lyu
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Institute of Environmental Research at Greater Bay, Guangzhou University, Guangzhou 510006, China
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17
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De Giglio O, Napoli C, Apollonio F, Brigida S, Marzella A, Diella G, Calia C, Scrascia M, Pacifico C, Pazzani C, Uricchio VF, Montagna MT. Occurrence of Legionella in groundwater used for sprinkler irrigation in Southern Italy. ENVIRONMENTAL RESEARCH 2019; 170:215-221. [PMID: 30594053 DOI: 10.1016/j.envres.2018.12.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/17/2018] [Accepted: 12/18/2018] [Indexed: 06/09/2023]
Abstract
Legionellae are opportunistic bacteria that cause various conditions after exposure to contaminated aerosols, ranging from a serious type of pneumonia to a mild case of an influenza-like illness. Despite the risks of exposure, little is known about the occurrence of Legionella in natural environments and, even though studies have shown that there is a potential risk of transmission via inhalation, it does not have to be detected in groundwater that is used for irrigation. The culture methods traditionally used to detect Legionella have several limits that can be partly solved by applying molecular techniques. Samples from 177 wells in Apulia, Southern Italy, were collected twice, in winter and in summer, and analyzed. When compared with the guidelines, 145 (81.9%) of the sampled wells were suitable for irrigation use. The culture-based method highlighted the presence of different species and serogroups of Legionella in 31 (21.2%) of the 145 wells that were shown to be suitable for irrigation use. A greater number of wells returned positive results for Legionella in summer than in winter (p = 0.023), and the median concentrations were mostly higher in summer (500 CFU/L) than in winter (300 CFU/L). The median temperature in the Legionella positive well waters was significantly higher than that in the negative ones, both in winter and in summer (p < 0.001). Using molecular techniques, Legionella non-pneumophila was found in 37 of the 114 wells earlier detected as suitable for irrigation use but negative for Legionella by the culture-based methods. The distribution of Legionella differ significantly in porous aquifers compared to the karst-fissured ones both with quantitative polymerase chain reaction (qPCR) (p = 0.0004) and viable cells by propidium monoazide (PMA-qPCR) (p = 0.0000). Legionella concentrations were weakly correlated with temperature of water both with qPCR (ρ = 0.47, p = 0.0033) and PMA-qPCR (ρ = 0.41, p = 0.0126). Our data suggest that water that aerosolizes when sprinkled on plants represents a potential source of Legionellosis, with a higher risk from exposure in summer. On a practical level, this finding is important for workers (farmers and gardeners) who are in contact with waters used for irrigation.
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Affiliation(s)
- Osvalda De Giglio
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Bari, Italy.
| | - Christian Napoli
- Department of Medical and Surgical sciences and translational Medicine, Sapienza University of Rome, Italy.
| | - Francesca Apollonio
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Bari, Italy.
| | - Silvia Brigida
- Water Research Institute, National Research Council, Bari, Italy.
| | - Angelo Marzella
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Bari, Italy.
| | - Giusy Diella
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Bari, Italy.
| | - Carla Calia
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Bari, Italy.
| | - Maria Scrascia
- Department of Biology, University of Bari "Aldo Moro", Bari, Italy.
| | - Claudia Pacifico
- Centre of Biostatistics for Clinical Epidemiology, School of Medicine and Surgery, University of Milano-Bicocca, Milano, Italy
| | - Carlo Pazzani
- Department of Biology, University of Bari "Aldo Moro", Bari, Italy.
| | | | - Maria Teresa Montagna
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Bari, Italy.
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18
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Wang H, Hu C, Zhang S, Liu L, Xing X. Effects of O 3/Cl 2 disinfection on corrosion and opportunistic pathogens growth in drinking water distribution systems. J Environ Sci (China) 2018; 73:38-46. [PMID: 30290870 DOI: 10.1016/j.jes.2018.01.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 01/11/2018] [Accepted: 01/11/2018] [Indexed: 06/08/2023]
Abstract
The effects of O3/Cl2 disinfection on corrosion and the growth of opportunistic pathogens in drinking water distribution systems were studied using annular reactors (ARs). The corrosion process and most probable number (MPN) analysis indicated that the higher content of iron-oxidizing bacteria and iron-reducing bacteria in biofilms of the AR treated with O3/Cl2 induced higher Fe3O4 formation in corrosion scales. These corrosion scales became more stable than the ones that formed in the AR treated with Cl2 alone. O3/Cl2 disinfection inhibited corrosion and iron release efficiently by changing the content of corrosion-related bacteria. Moreover, ozone disinfection inactivated or damaged the opportunistic pathogens due to its strong oxidizing properties. The damaged bacteria resulting from initial ozone treatment were inactivated by the subsequent chlorine disinfection. Compared with the AR treated with Cl2 alone, the opportunistic pathogens M. avium and L. pneumophila were not detectable in effluents of the AR treated with O3/Cl2, and decreased to (4.60±0.14) and (3.09±0.12) log10 (gene copies/g corrosion scales) in biofilms, respectively. The amoeba counts were also lower in the AR treated with O3/Cl2. Therefore, O3/Cl2 disinfection can effectively control opportunistic pathogens in effluents and biofilms of an AR used as a model for a drinking water distribution system.
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Affiliation(s)
- Haibo Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Chun Hu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Research Institute of Environmental Studies at Greater Bay, School of Environmental Sciences and Engineering, Guangzhou University, Guangzhou 510006, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Suona Zhang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lizhong Liu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xueci Xing
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
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19
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Steege L, Moore G. The presence and prevalence of Legionella spp in collected rainwater and its aerosolisation during common gardening activities. Perspect Public Health 2018; 138:254-260. [PMID: 29969060 DOI: 10.1177/1757913918786322] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
AIMS To determine the presence and prevalence of Legionella spp in domestic rainwater storage butts and to quantify its aerosolisation when collected rainwater is used for common gardening activities. METHODS Volunteers were asked to take a water sample from their garden rainwater storage butt. The presence of Legionella was determined using quantitative polymerase chain reaction (qPCR). Two new rainwater storage butts were installed on-site at PHE Porton and positioned in sunlight or in the shade. Ambient conditions and those within the two 'experimental' water butts were continually monitored. A cyclone air sampler was used to detect the presence of Legionella in the air when collected rainwater was poured from a watering can or delivered via a hosepipe attached to a submersible water butt pump. RESULTS A total of 63 volunteers provided water samples from 113 different rainwater storage butts. Legionella spp was detected in 107 of these samples at a mean concentration of 4.7 × 104 genomic units l-1. Two of these samples also contained L. pneumophila. The water butt positioned in the shade stored water at a significantly lower temperature than that exposed to sunlight. While the concentration of Legionella was significantly higher in this cooler water, meteorological conditions rather than conditions within the water butt had the greatest effect upon Legionella concentration. No Legionella was detected in the air when rainwater was poured from a watering can. However, using a hose pipe on a 'fine spray' setting increased both the number of organisms detected in the air and their dissemination. CONCLUSION In this study, Legionella spp were common contaminants of collected rainwater. However, the use of rainwater for common gardening activities should not be discouraged. Aerosolisation of Legionella when using a watering can is minimal and any increased risk associated with hose pipe use can be mitigated by using a coarse spray setting.
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Affiliation(s)
- L Steege
- Biosafety, Air and Water Microbiology Group, National Infection Service, Public Health England, Salisbury, UK.,School of Biosciences and Medicine, University of Surrey, Guildford, UK
| | - G Moore
- Biosafety, Air and Water Microbiology Group, National Infection Service, Public Health England, Porton Down, Salisbury SP4 0JG, UK
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20
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Li H, Li S, Tang W, Yang Y, Zhao J, Xia S, Zhang W, Wang H. Influence of secondary water supply systems on microbial community structure and opportunistic pathogen gene markers. WATER RESEARCH 2018; 136:160-168. [PMID: 29501760 DOI: 10.1016/j.watres.2018.02.031] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/10/2018] [Accepted: 02/12/2018] [Indexed: 06/08/2023]
Abstract
Secondary water supply systems (SWSSs) refer to the in-building infrastructures (e.g., water storage tanks) used to supply water pressure beyond the main distribution systems. The purpose of this study was to investigate the influence of SWSSs on microbial community structure and the occurrence of opportunistic pathogens, the latter of which are an emerging public health concern. Higher numbers of bacterial 16S rRNA genes, Legionella and mycobacterial gene markers were found in public building taps served by SWSSs relative to the mains, regardless of the flushing practice (P < 0.05). In residential buildings, genes of L. pneumomhila, Acanthamoeba and Vermamoeba vermiformis were primarily detected in tanks and taps compared to the mains. Long water retention time, warm temperature and loss of disinfectant residuals promoted microbial growth and colonization of potential pathogens in SWSSs. Varied levels of microbial community shifts were found in different types of SWSSs during water transportation from the distribution main to taps, highlighting the critical role of SWSSs in shaping the drinking water microbiota. Overall, the results provided insight to factors that might aid in controlling pathogen proliferation in real-world water systems using SWSSs.
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Affiliation(s)
- Huan Li
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Shang Li
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Wei Tang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Yang Yang
- Department of Thoracic Surgery, Tongji University Shanghai Pulmonary Hospital, Shanghai 200433, China
| | - Jianfu Zhao
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Siqing Xia
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Weixian Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Hong Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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21
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Perrin A, Herbelin P, Jorand FPA, Skali-Lami S, Mathieu L. Design of a rotating disk reactor to assess the colonization of biofilms by free-living amoebae under high shear rates. BIOFOULING 2018; 34:368-377. [PMID: 29745778 DOI: 10.1080/08927014.2018.1444756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 02/20/2018] [Indexed: 06/08/2023]
Abstract
The present study was aimed at designing and optimizing a rotating disk reactor simulating high hydrodynamic shear rates (γ), which are representative of cooling circuits. The characteristics of the hydrodynamic conditions in the reactor and the complex approach used to engineer it are described. A 60 l tank was filled with freshwater containing free-living amoebae (FLA) and bacteria. Adhesion of the bacteria and formation of a biofilm on the stainless steel coupons were observed. FLA were able to establish in these biofilms under γ as high as 85,000 s-1. Several physical mechanisms (convection, diffusion, sedimentation) could explain the accumulation of amoeboid cells on surfaces, but further research is required to fully understand and model the fine mechanisms governing such transport under γ similar to those encountered in the industrial environment. This technological advance may enable research into these topics.
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Affiliation(s)
- A Perrin
- a Université de Lorraine, CNRS, LCPME , F-54000 Nancy , France
- b EDF Recherche et Développement, Laboratoire National d'Hydraulique et Environnement , F-78401 Chatou , France
| | - P Herbelin
- b EDF Recherche et Développement, Laboratoire National d'Hydraulique et Environnement , F-78401 Chatou , France
| | - F P A Jorand
- a Université de Lorraine, CNRS, LCPME , F-54000 Nancy , France
| | - S Skali-Lami
- c Université de Lorraine, CNRS, LEMTA , F-54000 Nancy , France
| | - L Mathieu
- a Université de Lorraine, CNRS, LCPME , F-54000 Nancy , France
- d EPHE, PSL Research University, LCPME , F-54000 Nancy , France
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22
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Gomaa F, Gersh M, Cavanaugh CM. Diverse Legionella-Like Bacteria Associated with Testate Amoebae of the Genus Arcella (Arcellinida: Amoebozoa). J Eukaryot Microbiol 2018; 65:661-668. [PMID: 29443446 DOI: 10.1111/jeu.12511] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 01/03/2018] [Accepted: 02/03/2018] [Indexed: 12/11/2022]
Abstract
Diverse species of Legionella and Legionella-like amoebal pathogens (LLAPs) have been identified as intracellular bacteria in many amoeboid protists. There are, however, other amoeboid groups such as testate amoeba for which we know little about their potential to host such bacteria. In this study, we assessed the occurrence and diversity of Legionella spp. in cultures and environmental isolates of freshwater arcellinid testate amoebae species, Arcella hemispherica, Arcella intermedia, and Arcella vulgaris, via 16S rRNA gene sequence analyses and fluorescent in situ hybridization (FISH). Analysis of the 16S rRNA gene sequences indicated that A. hemispherica, A. intermedia, and A. vulgaris host Legionella-like bacteria with 94-98% identity to other Legionella spp. based on NCBI BLAST search. Phylogenetic analysis placed Legionella-like Arcella-associated bacteria (LLAB) in three different clusters within a tree containing all other members of Legionella and LLAPs. The intracellular localization of the Legionella within Arcella hosts was confirmed using FISH with a Legionella-specific probe. This study demonstrates that the host range of Legionella and Legionella-like bacteria in the Amoebozoa extends beyond members of "naked" amoebae species, with members of the testate amoebae potentially serving an ecological role in the dispersal, protection, and replication of Legionella spp. in natural environments.
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Affiliation(s)
- Fatma Gomaa
- Department of Organismic and Evolutionary Biology, Biological Laboratory, Harvard University, Cambridge, Massachusetts, 02138, USA
| | - Maxim Gersh
- Department of Organismic and Evolutionary Biology, Biological Laboratory, Harvard University, Cambridge, Massachusetts, 02138, USA
| | - Colleen M Cavanaugh
- Department of Organismic and Evolutionary Biology, Biological Laboratory, Harvard University, Cambridge, Massachusetts, 02138, USA
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23
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Boamah DK, Zhou G, Ensminger AW, O'Connor TJ. From Many Hosts, One Accidental Pathogen: The Diverse Protozoan Hosts of Legionella. Front Cell Infect Microbiol 2017; 7:477. [PMID: 29250488 PMCID: PMC5714891 DOI: 10.3389/fcimb.2017.00477] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 10/31/2017] [Indexed: 01/03/2023] Open
Abstract
The 1976 outbreak of Legionnaires' disease led to the discovery of the intracellular bacterial pathogen Legionella pneumophila. Given their impact on human health, Legionella species and the mechanisms responsible for their replication within host cells are often studied in alveolar macrophages, the primary human cell type associated with disease. Despite the potential severity of individual cases of disease, Legionella are not spread from person-to-person. Thus, from the pathogen's perspective, interactions with human cells are accidents of time and space—evolutionary dead ends with no impact on Legionella's long-term survival or pathogenic trajectory. To understand Legionella as a pathogen is to understand its interaction with its natural hosts: the polyphyletic protozoa, a group of unicellular eukaryotes with a staggering amount of evolutionary diversity. While much remains to be understood about these enigmatic hosts, we summarize the current state of knowledge concerning Legionella's natural host range, the diversity of Legionella-protozoa interactions, the factors influencing these interactions, the importance of avoiding the generalization of protozoan-bacterial interactions based on a limited number of model hosts and the central role of protozoa to the biology, evolution, and persistence of Legionella in the environment.
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Affiliation(s)
- David K Boamah
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Guangqi Zhou
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Alexander W Ensminger
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Public Health Ontario, Toronto, ON, Canada
| | - Tamara J O'Connor
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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24
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Wang H, Bédard E, Prévost M, Camper AK, Hill VR, Pruden A. Methodological approaches for monitoring opportunistic pathogens in premise plumbing: A review. WATER RESEARCH 2017; 117:68-86. [PMID: 28390237 PMCID: PMC5693313 DOI: 10.1016/j.watres.2017.03.046] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/19/2017] [Accepted: 03/22/2017] [Indexed: 05/06/2023]
Abstract
Opportunistic premise (i.e., building) plumbing pathogens (OPPPs, e.g., Legionella pneumophila, Mycobacterium avium complex, Pseudomonas aeruginosa, Acanthamoeba, and Naegleria fowleri) are a significant and growing source of disease. Because OPPPs establish and grow as part of the native drinking water microbiota, they do not correspond to fecal indicators, presenting a major challenge to standard drinking water monitoring practices. Further, different OPPPs present distinct requirements for sampling, preservation, and analysis, creating an impediment to their parallel detection. The aim of this critical review is to evaluate the state of the science of monitoring OPPPs and identify a path forward for their parallel detection and quantification in a manner commensurate with the need for reliable data that is informative to risk assessment and mitigation. Water and biofilm sampling procedures, as well as factors influencing sample representativeness and detection sensitivity, are critically evaluated with respect to the five representative bacterial and amoebal OPPPs noted above. Available culturing and molecular approaches are discussed in terms of their advantages, limitations, and applicability. Knowledge gaps and research needs towards standardized approaches are identified.
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Affiliation(s)
- Hong Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
| | - Emilie Bédard
- Department of Civil Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Anne K Camper
- Center for Biofilm Engineering and Department of Civil Engineering, Montana State University, Bozeman, MT 59717, USA
| | - Vincent R Hill
- Waterborne Disease Prevention Branch, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30329, USA
| | - Amy Pruden
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061, USA
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25
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van der Kooij D, Bakker GL, Italiaander R, Veenendaal HR, Wullings BA. Biofilm Composition and Threshold Concentration for Growth of Legionella pneumophila on Surfaces Exposed to Flowing Warm Tap Water without Disinfectant. Appl Environ Microbiol 2017; 83:e02737-16. [PMID: 28062459 PMCID: PMC5311405 DOI: 10.1128/aem.02737-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 12/13/2016] [Indexed: 02/07/2023] Open
Abstract
Legionella pneumophila in potable water installations poses a potential health risk, but quantitative information about its replication in biofilms in relation to water quality is scarce. Therefore, biofilm formation on the surfaces of glass and chlorinated polyvinyl chloride (CPVC) in contact with tap water at 34 to 39°C was investigated under controlled hydraulic conditions in a model system inoculated with biofilm-grown L. pneumophila The biofilm on glass (average steady-state concentration, 23 ± 9 pg ATP cm-2) exposed to treated aerobic groundwater (0.3 mg C liter-1; 1 μg assimilable organic carbon [AOC] liter-1) did not support growth of the organism, which also disappeared from the biofilm on CPVC (49 ± 9 pg ATP cm-2) after initial growth. L. pneumophila attained a level of 4.3 log CFU cm-2 in the biofilms on glass (1,055 ± 225 pg ATP cm-2) and CPVC (2,755 ± 460 pg ATP cm-2) exposed to treated anaerobic groundwater (7.9 mg C liter-1; 10 μg AOC liter-1). An elevated biofilm concentration and growth of L. pneumophila were also observed with tap water from the laboratory. The Betaproteobacteria Piscinibacter and Methyloversatilis and amoeba-resisting Alphaproteobacteria predominated in the clones and isolates retrieved from the biofilms. In the biofilms, the Legionella colony count correlated significantly with the total cell count (TCC), heterotrophic plate count, ATP concentration, and presence of Vermamoeba vermiformis This amoeba was rarely detected at biofilm concentrations of <100 pg ATP cm-2 A threshold concentration of approximately 50 pg ATP cm-2 (TCC = 1 × 106 to 2 × 106 cells cm-2) was derived for growth of L. pneumophila in biofilms.IMPORTANCELegionella pneumophila is the etiologic agent in more than 10,000 cases of Legionnaires' disease that are reported annually worldwide and in most of the drinking water-associated disease outbreaks reported in the United States. The organism proliferates in biofilms on surfaces exposed to warm water in engineered freshwater installations. An investigation with a test system supplied with different types of warm drinking water without disinfectant under controlled hydraulic conditions showed that treated aerobic groundwater (0.3 mg liter-1 of organic carbon) induced a low biofilm concentration that supported no or very limited growth of L. pneumophila Elevated biofilm concentrations and L. pneumophila colony counts were observed on surfaces exposed to two types of extensively treated groundwater, containing 1.8 and 7.9 mg C liter-1 and complying with the microbial water quality criteria during distribution. Control measures in warm tap water installations are therefore essential for preventing growth of L. pneumophila.
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Affiliation(s)
| | | | | | | | - Bart A Wullings
- KWR Watercycle Research Institute, Nieuwegein, the Netherlands
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26
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Shen Y, Huang C, Lin J, Wu W, Ashbolt NJ, Liu WT, Nguyen TH. Effect of Disinfectant Exposure on Legionella pneumophila Associated with Simulated Drinking Water Biofilms: Release, Inactivation, and Infectivity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:2087-2095. [PMID: 28085262 DOI: 10.1021/acs.est.6b04754] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Legionella pneumophila, the most commonly identified causative agent in drinking water associated with disease outbreaks, can be harbored by and released from drinking water biofilms. In this study, the release of biofilm-associated L. pneumophila under simulated drinking water flow containing a disinfectant residual was examined. Meanwhile, the inactivation and infectivity (to amoebae) of the released L. pneumophila were studied. To simulate drinking water system conditions, biofilms were prepared under either disinfectant exposure (predisinfected biofilms) or disinfectant-free (untreated biofilms) conditions, respectively. For experiments with water flow containing a disinfectant to release the biofilm-associated L. pneumophila from these two types of biofilms, the L. pneumophila release kinetics values from predisinfected and untreated biofilms under flow condition were not statistically different (one-way ANOVA, p > 0.05). However, inactivation of the L. pneumophila released from predisinfected biofilms was 1-2 times higher and amoeba infectivity was 2-29 times lower than that from untreated biofilms. The higher disinfectant resistance of L. pneumophila released from untreated biofilms was presumably influenced by the detachment of a larger amount of biofilm material (determined by 16S rRNA qPCR) surrounding the released L. pneumophila. This study highlights the interaction among disinfectant residual, biofilms, and L. pneumophila, which provides guidelines to assess and control pathogen risk.
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Affiliation(s)
- Yun Shen
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801-2352, United States
| | - Conghui Huang
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801-2352, United States
| | - Jie Lin
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801-2352, United States
| | - Wenjing Wu
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801-2352, United States
| | - Nicholas J Ashbolt
- School of Public Health, University of Alberta , Edminton, Alberta AB T6G 2G7, Canada
| | - Wen-Tso Liu
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801-2352, United States
| | - Thanh H Nguyen
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801-2352, United States
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27
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Multiplication of Legionella pneumophila Sequence Types 1, 47, and 62 in Buffered Yeast Extract Broth and Biofilms Exposed to Flowing Tap Water at Temperatures of 38°C to 42°C. Appl Environ Microbiol 2016; 82:6691-6700. [PMID: 27613680 DOI: 10.1128/aem.01107-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 09/01/2016] [Indexed: 12/11/2022] Open
Abstract
Legionella pneumophila proliferates in freshwater environments at temperatures ranging from 25 to 45°C. To investigate the preference of different sequence types (ST) for a specific temperature range, growth of L. pneumophila serogroup 1 (SG1) ST1 (environmental strains), ST47, and ST62 (disease-associated strains) was measured in buffered yeast extract broth (BYEB) and biofilms grown on plasticized polyvinyl chloride in flowing heated drinking water originating from a groundwater supply. The optimum growth temperatures in BYEB were approximately 37°C (ST1), 39°C (ST47), and 41°C (ST62), with maximum growth temperatures of 42°C (ST1) and 43°C (ST47 and ST62). In the biofilm at 38°C, the ST47 and ST62 strains multiplied equally well compared to growth of the environmental ST1 strain and an indigenous L. pneumophila non-SG1 strain, all attaining a concentration of approximately 107 CFU/cm-2 Raising the temperature to 41°C did not impact these levels within 4 weeks, but the colony counts of all strains tested declined (at a specific decline rate of 0.14 to 0.41 day-1) when the temperature was raised to 42°C. At this temperature, the concentration of Vermamoeba vermiformis in the biofilm, determined with quantitative PCR (qPCR), was about 2 log units lower than the concentration at 38°C. In columns operated at a constant temperature, ranging from 38 to 41°C, none of the tested strains multiplied in the biofilm at 41°C, in which also V. vermiformis was not detected. These observations suggest that strains of ST47 and ST62 did not multiply in the biofilm at a temperature of ≥41°C because of the absence of a thermotolerant host. IMPORTANCE Growth of Legionella pneumophila in tap water installations is a serious public health concern. The organism includes more than 2,100 varieties (sequence types). More than 50% of the reported cases of Legionnaires' disease are caused by a few sequence types which are very rarely detected in the environment. Strains of selected virulent sequence types proliferated in biofilms on surfaces exposed to warm (38°C) tap water to the same level as environmental varieties and multiplied well as pure culture in a nutrient-rich medium at temperatures of 42 and 43°C. However, these organisms did not grow in the biofilms at temperatures of ≥41°C. Typical host amoebae also did not multiply at these temperatures. Apparently, proliferation of thermotolerant host amoebae is needed to enable multiplication of the virulent L. pneumophila strains in the environment at elevated temperatures. The detection of these amoebae in water installations therefore is a scientific challenge with practical implications.
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28
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Shen Y, Monroy GL, Derlon N, Janjaroen D, Huang C, Morgenroth E, Boppart SA, Ashbolt NJ, Liu WT, Nguyen TH. Role of biofilm roughness and hydrodynamic conditions in Legionella pneumophila adhesion to and detachment from simulated drinking water biofilms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:4274-82. [PMID: 25699403 PMCID: PMC4472476 DOI: 10.1021/es505842v] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Biofilms in drinking water distribution systems (DWDS) could exacerbate the persistence and associated risks of pathogenic Legionella pneumophila (L. pneumophila), thus raising human health concerns. However, mechanisms controlling adhesion and subsequent detachment of L. pneumophila associated with biofilms remain unclear. We determined the connection between L. pneumophila adhesion and subsequent detachment with biofilm physical structure characterization using optical coherence tomography (OCT) imaging technique. Analysis of the OCT images of multispecies biofilms grown under low nutrient condition up to 34 weeks revealed the lack of biofilm deformation even when these biofilms were exposed to flow velocity of 0.7 m/s, typical flow for DWDS. L. pneumophila adhesion on these biofilm under low flow velocity (0.007 m/s) positively correlated with biofilm roughness due to enlarged biofilm surface area and local flow conditions created by roughness asperities. The preadhered L. pneumophila on selected rough and smooth biofilms were found to detach when these biofilms were subjected to higher flow velocity. At the flow velocity of 0.1 and 0.3 m/s, the ratio of detached cell from the smooth biofilm surface was from 1.3 to 1.4 times higher than that from the rough biofilm surface, presumably because of the low shear stress zones near roughness asperities. This study determined that physical structure and local hydrodynamics control L. pneumophila adhesion to and detachment from simulated drinking water biofilm, thus it is the first step toward reducing the risk of L. pneumophila exposure and subsequent infections.
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Affiliation(s)
- Yun Shen
- Department of Civil and Environmental Engineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Guillermo L. Monroy
- Department of Bioengineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Nicolas Derlon
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Dao Janjaroen
- Department of Civil and Environmental Engineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Conghui Huang
- Department of Civil and Environmental Engineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Eberhard Morgenroth
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
- ETH Zürich, Institute of Environmental Engineering, 8093 Zürich, Switzerland
| | - Stephen A. Boppart
- Department of Bioengineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
- Department of Electrical and Computer Engineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Nicholas J. Ashbolt
- School of Public Health, University of Alberta, Edmonton, Alberta T6G 2G7, Canada
| | - Wen-Tso Liu
- Department of Civil and Environmental Engineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Thanh H. Nguyen
- Department of Civil and Environmental Engineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
- Corresponding Author.
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