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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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2
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Montalbano Di Filippo M, Boni A, Chiani P, Marra M, Carollo M, Cristofari L, Minelli F, Knijn A, Morabito S. Exploring the nature of interaction between shiga toxin producing Escherichia coli (STEC) and free-living amoeba - Acanthamoeba sp. Front Cell Infect Microbiol 2022; 12:926127. [PMID: 36159652 PMCID: PMC9504058 DOI: 10.3389/fcimb.2022.926127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Free-living amoebae (FLA) are widely distributed protozoa in nature, known to cause severe eye infections and central nervous system disorders. There is growing attention to the potential role that these protozoa could act as reservoirs of pathogenic bacteria and, consequently, to the possibility that, the persistence and spread of the latter may be facilitated, by exploiting internalization into amoebae. Shiga toxin-producing strains of Escherichia coli (STEC) are zoonotic agents capable of causing serious diseases, such as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). Cattle represent the main natural reservoir of STEC, which are frequently found also in other domestic and wild ruminants, often without causing any evident symptoms of disease. The aspects related to the ecology of STEC strains in animal reservoirs and the environment are poorly known, including the persistence of these microorganisms within niches unfavorable to survival, such as soils or waters. In this study we investigated the interaction between STEC strains of serotype O157: H7 with different virulence gene profiles, and a genus of a wild free-living amoeba, Acanthamoeba sp. Our results confirm the ability of STEC strains to survive up to 20 days within a wild Acanthamoeba sp., in a quiescent state persisting in a non-cultivable form, until they reactivate following some stimulus of an unknown nature. Furthermore, our findings show that during their internalization, the E. coli O157 kept the set of the main virulence genes intact, preserving their pathogenetic potential. These observations suggest that the internalization in free-living amoebae may represent a means for STEC to resist in environments with non-permissive growth conditions. Moreover, by staying within the protozoa, STEC could escape their detection in the vehicles of infections and resist to the treatments used for the disinfection of the livestock environment.
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Affiliation(s)
- Margherita Montalbano Di Filippo
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
- *Correspondence: Margherita Montalbano Di Filippo,
| | - Arianna Boni
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Paola Chiani
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Manuela Marra
- Core Facilities, Istituto Superiore di Sanità, Rome, Italy
| | - Maria Carollo
- Core Facilities, Istituto Superiore di Sanità, Rome, Italy
| | - Lucrezia Cristofari
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Fabio Minelli
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Arnold Knijn
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Stefano Morabito
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
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Kawashiro A, Okubo T, Nakamura S, Thapa J, Miyake M, Yamaguchi H. Wild ciliates differ in susceptibility to Legionella pneumophila JR32. MICROBIOLOGY-SGM 2021; 167. [PMID: 34402779 DOI: 10.1099/mic.0.001078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We investigated how Legionella pneumophila (Lp) JR32 interacts with Anteglaucoma CS11A and Colpoda E6, two ciliates that we isolated from sewage and sink trap sludge, respectively, using a handmade maze device containing a 96-well crafting plate. Our 18S rDNA-based phylogenetic analysis showed that Anteglaucoma CS11A and Colpoda E6 formed distinct clades. Scanning electron microscopy showed that Anteglaucoma CS11A had a bigger-sized body than Colpoda E6 and, unlike Tetrahymena IB (the reference strain), neither ciliate produced pellets, which are extracellular vacuoles. Fluorescence microscopic observations revealed that although the intake amounts differed, all three ciliates rapidly ingested LpJR32 regardless of the presence or absence of the icm/dot virulence genes, indicating that they all interacted with LpJR32. In co-cultures with Anteglaucoma CS11A, the LpJR32 levels were maintained but fell dramatically when the co-culture contained the LpJR32 icm/dot deletion mutant instead. Anteglaucoma CS11A died within 2 days of co-culture with LpJR32, but survived co-culture with the deletion mutant. In co-cultures with Colpoda E6, LpJR32 levels were maintained but temporarily decreased independently of the virulence gene. Concurrently, the Colpoda E6 ciliates survived by forming cysts, which may enable them to resist harsh environments, and by diminishing the sensitivity of trophozoites to Lp. In the Tetrahymena IB co-cultures with LpJR32 or Δicm/dot, the Lp levels were maintained, albeit with temporal decreases, and the Tetrahymena IB levels were also maintained. We conclude that unlike Tetrahymena IB with pellet production, Anteglaucoma CS11A can be killed by LpJR32 infection, and Colpoda E6 can resist LpJR32 infection through cyst formation and the low sensitivity of trophozoites to Lp. Thus, the two ciliates that we isolated had different susceptibilities to LpJR32 infection.
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Affiliation(s)
- Airi Kawashiro
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Torahiko Okubo
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Shinji Nakamura
- Division of Biomedical Imaging Research, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Jeewan Thapa
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.,Division of Bioresources Research Center for Zoonosis Control, Hokkaido University, Hokkaido, Sapporo, Japan
| | - Masaki Miyake
- Laboratory of Microbiology and Immunology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Hiroyuki Yamaguchi
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
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Lanzoni O, Plotnikov A, Khlopko Y, Munz G, Petroni G, Potekhin A. The core microbiome of sessile ciliate Stentor coeruleus is not shaped by the environment. Sci Rep 2019; 9:11356. [PMID: 31388025 PMCID: PMC6684585 DOI: 10.1038/s41598-019-47701-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 07/22/2019] [Indexed: 12/29/2022] Open
Abstract
Microbiomes of multicellular organisms are one of the hottest topics in microbiology and physiology, while only few studies addressed bacterial communities associated with protists. Protists are widespread in all environments and can be colonized by plethora of different bacteria, including also human pathogens. The aim of this study was to characterize the prokaryotic community associated with the sessile ciliate Stentor coeruleus. 16S rRNA gene metabarcoding was performed on single cells of S. coeruleus and on their environment, water from the sewage stream. Our results showed that the prokaryotic community composition differed significantly between Stentor cells and their environment. The core microbiome common for all ciliate specimens analyzed could be defined, and it was composed mainly by representatives of bacterial genera which include also potential human pathogens and commensals, such as Neisseria, Streptococcus, Capnocytophaga, Porphyromonas. Numerous 16S rRNA gene contigs belonged to endosymbiont “Candidatus Megaira polyxenophila”. Our data suggest that each ciliate cell can be considered as an ecological microniche harboring diverse prokaryotic organisms. Possible benefits for persistence and transmission in nature for bacteria associated with protists are discussed. Our results support the hypothesis that ciliates attract potentially pathogenic bacteria and play the role of natural reservoirs for them.
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Affiliation(s)
| | - Andrey Plotnikov
- Center of Shared Scientific Equipment, Institute for Cellular and Intracellular Symbiosis, Ural Division of RAS, Orenburg, Russia
| | - Yuri Khlopko
- Center of Shared Scientific Equipment, Institute for Cellular and Intracellular Symbiosis, Ural Division of RAS, Orenburg, Russia
| | - Giulio Munz
- Department of Civil and Environmental Engineering, University of Florence, Florence, Italy
| | | | - Alexey Potekhin
- Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia.
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Swart AL, Harrison CF, Eichinger L, Steinert M, Hilbi H. Acanthamoeba and Dictyostelium as Cellular Models for Legionella Infection. Front Cell Infect Microbiol 2018; 8:61. [PMID: 29552544 PMCID: PMC5840211 DOI: 10.3389/fcimb.2018.00061] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 02/13/2018] [Indexed: 12/20/2022] Open
Abstract
Environmental bacteria of the genus Legionella naturally parasitize free-living amoebae. Upon inhalation of bacteria-laden aerosols, the opportunistic pathogens grow intracellularly in alveolar macrophages and can cause a life-threatening pneumonia termed Legionnaires' disease. Intracellular replication in amoebae and macrophages takes place in a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). LCV formation requires the bacterial Icm/Dot type IV secretion system, which translocates literally hundreds of "effector" proteins into host cells, where they modulate crucial cellular processes for the pathogen's benefit. The mechanism of LCV formation appears to be evolutionarily conserved, and therefore, amoebae are not only ecologically significant niches for Legionella spp., but also useful cellular models for eukaryotic phagocytes. In particular, Acanthamoeba castellanii and Dictyostelium discoideum emerged over the last years as versatile and powerful models. Using genetic, biochemical and cell biological approaches, molecular interactions between amoebae and Legionella pneumophila have recently been investigated in detail with a focus on the role of phosphoinositide lipids, small and large GTPases, autophagy components and the retromer complex, as well as on bacterial effectors targeting these host factors.
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Affiliation(s)
- A Leoni Swart
- Institute of Medical Microbiology, Medical Faculty, University of Zurich, Zurich, Switzerland
| | - Christopher F Harrison
- Max von Pettenkofer Institute, Medical Faculty, Ludwig-Maximilians University Munich, Munich, Germany
| | - Ludwig Eichinger
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany
| | - Michael Steinert
- Department of Life Sciences, Institute of Microbiology, Technical University of Braunschweig, Braunschweig, Germany
| | - Hubert Hilbi
- Institute of Medical Microbiology, Medical Faculty, University of Zurich, Zurich, Switzerland
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Denoncourt AM, Paquet VE, Charette SJ. Packaging of Mycobacterium smegmatis bacteria into fecal pellets by the ciliate Tetrahymena pyriformis. FEMS Microbiol Lett 2017; 364:4597601. [PMID: 29126315 DOI: 10.1093/femsle/fnx237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/03/2017] [Indexed: 01/04/2023] Open
Abstract
Mycobacteria are widespread microorganisms that live in various environments, including man-made water systems where they cohabit with protozoa. Environmental mycobacterial species give rise to many opportunistic human infections and can infect phagocytic protozoa. Protozoa such as amoebae and ciliates feeding on bacteria can sometimes get rid of non-digestible or pathogenic material by packaging it into secreted fecal pellets. Usually, packaged bacteria are still viable and are protected against chemical and physical stresses. We report here that mycobacteria can be packaged into pellets by ciliates. The model bacterium Mycobacterium smegmatis survived digestion in food vacuoles of the ciliate Tetrahymena pyriformis and was included in expelled fecal pellets. LIVE/DEAD® staining confirmed that packaged M. smegmatis cells preserved their viability through the process. Scanning and transmission electron microscopy revealed that bacteria are packaged in undefined filamentous and/or laminar substances and that just a thin layer of material seemed to keep the pellet contents in a spherical shape. These results imply that packaging of bacteria is more common than expected, and merits further study to understand its role in persistence and dissemination of pathogens in the environment.
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Affiliation(s)
- Alix M Denoncourt
- Institut de Biologie Intégrative et des Systèmes, Pavillon Charles-Eugène-Marchand, Université Laval, Québec City, QC G1V 0A6, Canada.,Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Hôpital Laval, Québec City, QC G1V 4G5, Canada.,Département de Biochimie, de Microbiologie et de Bio-informatique, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada
| | - Valérie E Paquet
- Institut de Biologie Intégrative et des Systèmes, Pavillon Charles-Eugène-Marchand, Université Laval, Québec City, QC G1V 0A6, Canada.,Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Hôpital Laval, Québec City, QC G1V 4G5, Canada.,Département de Biochimie, de Microbiologie et de Bio-informatique, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada
| | - Steve J Charette
- Institut de Biologie Intégrative et des Systèmes, Pavillon Charles-Eugène-Marchand, Université Laval, Québec City, QC G1V 0A6, Canada.,Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Hôpital Laval, Québec City, QC G1V 4G5, Canada.,Département de Biochimie, de Microbiologie et de Bio-informatique, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada
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Ashbolt NJ. Environmental (Saprozoic) Pathogens of Engineered Water Systems: Understanding Their Ecology for Risk Assessment and Management. Pathogens 2015; 4:390-405. [PMID: 26102291 PMCID: PMC4493481 DOI: 10.3390/pathogens4020390] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/15/2015] [Accepted: 06/15/2015] [Indexed: 11/20/2022] Open
Abstract
Major waterborne (enteric) pathogens are relatively well understood and treatment controls are effective when well managed. However, water-based, saprozoic pathogens that grow within engineered water systems (primarily within biofilms/sediments) cannot be controlled by water treatment alone prior to entry into water distribution and other engineered water systems. Growth within biofilms or as in the case of Legionella pneumophila, primarily within free-living protozoa feeding on biofilms, results from competitive advantage. Meaning, to understand how to manage water-based pathogen diseases (a sub-set of saprozoses) we need to understand the microbial ecology of biofilms; with key factors including biofilm bacterial diversity that influence amoebae hosts and members antagonistic to water-based pathogens, along with impacts from biofilm substratum, water temperature, flow conditions and disinfectant residual—all control variables. Major saprozoic pathogens covering viruses, bacteria, fungi and free-living protozoa are listed, yet today most of the recognized health burden from drinking waters is driven by legionellae, non-tuberculous mycobacteria (NTM) and, to a lesser extent, Pseudomonas aeruginosa. In developing best management practices for engineered water systems based on hazard analysis critical control point (HACCP) or water safety plan (WSP) approaches, multi-factor control strategies, based on quantitative microbial risk assessments need to be developed, to reduce disease from largely opportunistic, water-based pathogens.
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Affiliation(s)
- Nicholas J Ashbolt
- School of Public Health, University of Alberta, Rm 3-57D South Academic Building, Edmonton, AB T6G 2G7, Canada.
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Hoffmann C, Harrison CF, Hilbi H. The natural alternative: protozoa as cellular models forLegionellainfection. Cell Microbiol 2013; 16:15-26. [DOI: 10.1111/cmi.12235] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/02/2013] [Accepted: 09/04/2013] [Indexed: 12/22/2022]
Affiliation(s)
- Christine Hoffmann
- Max von Pettenkofer Institute; Department of Medicine; Ludwig-Maximilians University Munich; 80336 Munich Germany
| | - Christopher F. Harrison
- Max von Pettenkofer Institute; Department of Medicine; Ludwig-Maximilians University Munich; 80336 Munich Germany
| | - Hubert Hilbi
- Max von Pettenkofer Institute; Department of Medicine; Ludwig-Maximilians University Munich; 80336 Munich Germany
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