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Barbosa A, Azevedo NF, Goeres DM, Cerqueira L. Ecology of Legionella pneumophila biofilms: The link between transcriptional activity and the biphasic cycle. Biofilm 2024; 7:100196. [PMID: 38601816 PMCID: PMC11004079 DOI: 10.1016/j.bioflm.2024.100196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 03/10/2024] [Accepted: 03/29/2024] [Indexed: 04/12/2024] Open
Abstract
There has been considerable discussion regarding the environmental life cycle of Legionella pneumophila and its virulence potential in natural and man-made water systems. On the other hand, the bacterium's morphogenetic mechanisms within host cells (amoeba and macrophages) have been well documented and are linked to its ability to transition from a non-virulent, replicative state to an infectious, transmissive state. Although the morphogenetic mechanisms associated with the formation and detachment of the L. pneumophila biofilm have also been described, the capacity of the bacteria to multiply extracellularly is not generally accepted. However, several studies have shown genetic pathways within the biofilm that resemble intracellular mechanisms. Understanding the functionality of L. pneumophila cells within a biofilm is fundamental for assessing the ecology and evaluating how the biofilm architecture influences L. pneumophila survival and persistence in water systems. This manuscript provides an overview of the biphasic cycle of L. pneumophila and its implications in associated intracellular mechanisms in amoeba. It also examines the molecular pathways and gene regulation involved in L. pneumophila biofilm formation and dissemination. A holistic analysis of the transcriptional activities in L. pneumophila biofilms is provided, combining the information of intracellular mechanisms in a comprehensive outline. Furthermore, this review discusses the techniques that can be used to study the morphogenetic states of the bacteria within biofilms, at the single cell and population levels.
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Affiliation(s)
- Ana Barbosa
- LEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
- ALiCE – Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
| | - Nuno F. Azevedo
- LEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
- ALiCE – Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
| | - Darla M. Goeres
- LEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
- ALiCE – Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
- The Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
| | - Laura Cerqueira
- LEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
- ALiCE – Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
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2
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Svetlicic E, Jaén-Luchoro D, Klobucar RS, Jers C, Kazazic S, Franjevic D, Klobucar G, Shelton BG, Mijakovic I. Genomic characterization and assessment of pathogenic potential of Legionella spp. isolates from environmental monitoring. Front Microbiol 2023; 13:1091964. [PMID: 36713227 PMCID: PMC9879626 DOI: 10.3389/fmicb.2022.1091964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/28/2022] [Indexed: 01/15/2023] Open
Abstract
Several species in the genus Legionella are known to cause an acute pneumonia when the aerosols containing the bacteria from man-made water systems are inhaled. The disease is usually caused by Legionella pneumophila, but other species have been implicated in the infection. The disease is frequently manifested as an outbreak, which means several people are affected when exposed to the common source of Legionella contamination. Therefor environmental surveillance which includes isolation and identification of Legionella is performed routinely. However, usually no molecular or genome-based methods are employed in further characterization of the isolates during routine environmental monitoring. During several years of such monitoring, isolates from different geographical locations were collected and 39 of them were sequenced by hybrid de novo approach utilizing short and long sequencing reads. In addition, the isolates were typed by standard culture and MALDI-TOF method. The sequencing reads were assembled and annotated to produce high-quality genomes. By employing discriminatory genome typing, four potential new species in the Legionella genus were identified, which are yet to be biochemically and morphologically characterized. Moreover, functional annotations concerning virulence and antimicrobial resistance were performed on the sequenced genomes. The study contributes to the knowledge on little-known non-pneumophila species present in man-made water systems and establishes support for future genetic relatedness studies as well as understanding of their pathogenic potential.
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Affiliation(s)
- Ema Svetlicic
- Novo Nordisk Foundation Center for Biosustainability, Kongens Lyngby, Denmark
| | - Daniel Jaén-Luchoro
- Department of Infectious Diseases (Sahlgrenska Academy) at the University of Gothenburg, Gothenburg, Sweden
| | | | - Carsten Jers
- Novo Nordisk Foundation Center for Biosustainability, Kongens Lyngby, Denmark
| | - Snjezana Kazazic
- Laboratory for Mass Spectrometry and Functional Proteomics, Ruder Boskovic Institute, Zagreb, Croatia
| | - Damjan Franjevic
- Division of Zoology, Department of Biology, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - Goran Klobucar
- Division of Zoology, Department of Biology, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | | | - Ivan Mijakovic
- Novo Nordisk Foundation Center for Biosustainability, Kongens Lyngby, Denmark,Systems and Synthetic Biology Division, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden,*Correspondence: Ivan Mijakovic,
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3
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Hochstrasser R, Michaelis S, Brülisauer S, Sura T, Fan M, Maaß S, Becher D, Hilbi H. Migration of Acanthamoeba through Legionella biofilms is regulated by the bacterial Lqs-LvbR network, effector proteins and the flagellum. Environ Microbiol 2022; 24:3672-3692. [PMID: 35415862 PMCID: PMC9544456 DOI: 10.1111/1462-2920.16008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/05/2022] [Accepted: 04/08/2022] [Indexed: 11/30/2022]
Abstract
The environmental bacterium Legionella pneumophila causes the pneumonia Legionnaires' disease. The opportunistic pathogen forms biofilms and employs the Icm/Dot type IV secretion system (T4SS) to replicate in amoebae and macrophages. A regulatory network comprising the Legionella quorum sensing (Lqs) system and the transcription factor LvbR controls bacterial motility, virulence and biofilm architecture. Here we show by comparative proteomics that in biofilms formed by the L. pneumophila ΔlqsR or ΔlvbR regulatory mutants the abundance of proteins encoded by a genomic ‘fitness island’, metabolic enzymes, effector proteins and flagellar components (e.g. FlaA) varies. ∆lqsR or ∆flaA mutants form ‘patchy’ biofilms like the parental strain JR32, while ∆lvbR forms a ‘mat‐like’ biofilm. Acanthamoeba castellanii amoebae migrated more slowly through biofilms of L. pneumophila lacking lqsR, lvbR, flaA, a functional Icm/Dot T4SS (∆icmT), or secreted effector proteins. Clusters of bacteria decorated amoebae in JR32, ∆lvbR or ∆icmT biofilms but not in ∆lqsR or ∆flaA biofilms. The amoeba‐adherent bacteria induced promoters implicated in motility (PflaA) or virulence (PsidC, PralF). Taken together, the Lqs‐LvbR network (quorum sensing), FlaA (motility) and the Icm/Dot T4SS (virulence) regulate migration of A. castellanii through L. pneumophila biofilms, and – apart from the T4SS – govern bacterial cluster formation on the amoebae.
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Affiliation(s)
- Ramon Hochstrasser
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland
| | - Sarah Michaelis
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland
| | - Sabrina Brülisauer
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland
| | - Thomas Sura
- Institute of Microbiology, University of Greifswald, Felix-Hausdorff-Strasse 8, 17489, Greifswald, Germany
| | - Mingzhen Fan
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland
| | - Sandra Maaß
- Institute of Microbiology, University of Greifswald, Felix-Hausdorff-Strasse 8, 17489, Greifswald, Germany
| | - Dörte Becher
- Institute of Microbiology, University of Greifswald, Felix-Hausdorff-Strasse 8, 17489, Greifswald, Germany
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland
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4
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Characterization of a Novel Regulator of Biofilm Formation in the Pathogen Legionella pneumophila. Biomolecules 2022; 12:biom12020225. [PMID: 35204726 PMCID: PMC8961574 DOI: 10.3390/biom12020225] [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: 12/31/2021] [Revised: 01/23/2022] [Accepted: 01/24/2022] [Indexed: 12/22/2022] Open
Abstract
Legionella pneumophila is a Gram-negative, facultative intracellular pathogen that causes severe pneumonia known as Legionnaires’ disease. The bacterium causes disease when contaminated water is aerosolized and subsequently inhaled by individuals, which allows the bacteria to gain access to the lungs, where they infect alveolar macrophages. L. pneumophila is ubiquitous in the environment, where it survives by growing in biofilms, intracellularly within protozoa, and planktonically. Biofilms are a major concern for public health because they provide a protective niche that allows for the continuous leaching of bacteria into the water supply. In addition, biofilms enhance the survival of the bacteria by increasing resistance to temperature fluctuations and antimicrobial agents. Currently, there is little known about biofilm formation and regulation by L. pneumophila. Here, we present evidence of a specific gene, bffA, which appears to be involved in the regulation of motility, biofilm formation, cellular replication, and virulence of L. pneumophila. A strain lacking bffA has an enhanced biofilm formation phenotype, forming biofilms that are both faster and thicker than wild type. Additionally, the knockout strain has significantly reduced motility, enhanced uptake into amoebae, and altered growth kinetics on solid media. Our data suggest a potential role for bffA in signaling pathways that govern changes in growth rate and motility in response to environmental conditions.
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Sciuto EL, Laganà P, Filice S, Scalese S, Libertino S, Corso D, Faro G, Coniglio MA. Environmental Management of Legionella in Domestic Water Systems: Consolidated and Innovative Approaches for Disinfection Methods and Risk Assessment. Microorganisms 2021; 9:577. [PMID: 33799845 PMCID: PMC8001549 DOI: 10.3390/microorganisms9030577] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 12/31/2022] Open
Abstract
Legionella is able to remain in water as free-living planktonic bacteria or to grow within biofilms that adhere to the pipes. It is also able to enter amoebas or to switch into a viable but not culturable (VBNC) state, which contributes to its resistance to harsh conditions and hinders its detection in water. Factors regulating Legionella growth, such as environmental conditions, type and concentration of available organic and inorganic nutrients, presence of protozoa, spatial location of microorganisms, metal plumbing components, and associated corrosion products are important for Legionella survival and growth. Finally, water treatment and distribution conditions may affect each of these factors. A deeper comprehension of Legionella interactions in water distribution systems with the environmental conditions is needed for better control of the colonization. To this purpose, the implementation of water management plans is the main prevention measure against Legionella. A water management program requires coordination among building managers, health care providers, and Public Health professionals. The review reports a comprehensive view of the state of the art and the promising perspectives of both monitoring and disinfection methods against Legionella in water, focusing on the main current challenges concerning the Public Health sector.
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Affiliation(s)
- Emanuele Luigi Sciuto
- Azienda Ospedaliero Universitaria Policlinico “G. Rodolico-San Marco”, Via Sofia 78, 95123 Catania, Italy;
| | - Pasqualina Laganà
- Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Messina, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Torre Biologica 3p, AOU ‘G. Martino, Via C. Valeria, s.n.c., 98125 Messina, Italy;
| | - Simona Filice
- Istituto per la Microelettronica e Microsistemi–Consiglio Nazionale delle Ricerche (CNR-IMM), Ottava Strada 5, 95121 Catania, Italy; (S.F.); (S.S.); (S.L.); (D.C.)
| | - Silvia Scalese
- Istituto per la Microelettronica e Microsistemi–Consiglio Nazionale delle Ricerche (CNR-IMM), Ottava Strada 5, 95121 Catania, Italy; (S.F.); (S.S.); (S.L.); (D.C.)
| | - Sebania Libertino
- Istituto per la Microelettronica e Microsistemi–Consiglio Nazionale delle Ricerche (CNR-IMM), Ottava Strada 5, 95121 Catania, Italy; (S.F.); (S.S.); (S.L.); (D.C.)
| | - Domenico Corso
- Istituto per la Microelettronica e Microsistemi–Consiglio Nazionale delle Ricerche (CNR-IMM), Ottava Strada 5, 95121 Catania, Italy; (S.F.); (S.S.); (S.L.); (D.C.)
| | - Giuseppina Faro
- Azienda Sanitaria Provinciale di Catania, Via S. Maria La Grande 5, 95124 Catania, Italy;
| | - Maria Anna Coniglio
- Azienda Ospedaliero Universitaria Policlinico “G. Rodolico-San Marco”, Via Sofia 78, 95123 Catania, Italy;
- Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Catania, Department of Medical and Surgical Sciences and Advanced Technologies “G.F. Ingrassia”, University of Catania, Via Sofia 87, 95123 Catania, Italy
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6
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Personnic N, Striednig B, Hilbi H. Quorum sensing controls persistence, resuscitation, and virulence of Legionella subpopulations in biofilms. ISME JOURNAL 2020; 15:196-210. [PMID: 32951019 DOI: 10.1038/s41396-020-00774-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 08/13/2020] [Accepted: 09/04/2020] [Indexed: 02/07/2023]
Abstract
The water-borne bacterium Legionella pneumophila is the causative agent of Legionnaires' disease. In the environment, the opportunistic pathogen colonizes different niches, including free-living protozoa and biofilms. The physiological state(s) of sessile Legionella in biofilms and their functional consequences are not well understood. Using single-cell techniques and fluorescent growth rate probes as well as promoter reporters, we show here that sessile L. pneumophila exhibits phenotypic heterogeneity and adopts growing and nongrowing ("dormant") states in biofilms and microcolonies. Phenotypic heterogeneity is controlled by the Legionella quorum sensing (Lqs) system, the transcription factor LvbR, and the temperature. The Lqs system and LvbR determine the ratio between growing and nongrowing sessile subpopulations, as well as the frequency of growth resumption ("resuscitation") and microcolony formation of individual bacteria. Nongrowing L. pneumophila cells are metabolically active, express virulence genes and show tolerance toward antibiotics. Therefore, these sessile nongrowers are persisters. Taken together, the Lqs system, LvbR and the temperature control the phenotypic heterogeneity of sessile L. pneumophila, and these factors regulate the formation of a distinct subpopulation of nongrowing, antibiotic tolerant, virulent persisters. Hence, the biofilm niche of L. pneumophila has a profound impact on the ecology and virulence of this opportunistic pathogen.
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Affiliation(s)
- Nicolas Personnic
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland.
| | - Bianca Striednig
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland.
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7
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Chatfield CH, Zaia J, Sauer C. Legionella pneumophila Attachment to Biofilms of an Acidovorax Isolate from a Drinking Water-Consortium Requires the Lcl-Adhesin Protein. Int Microbiol 2020; 23:597-605. [PMID: 32451737 DOI: 10.1007/s10123-020-00126-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/02/2020] [Accepted: 04/07/2020] [Indexed: 12/17/2022]
Abstract
Human infection by Legionella pneumophila (Lpn) only occurs via contaminated water from man-made sources, and eradication of these bacteria from man-made water systems is complicated by biofilm colonization. Using a continuously fed biofilm reactor model, we grew a biofilm consortium from potable water that was able to prolong recovery of Lpn CFU from biofilms. This effect was recreated using a subset of those species in a simplified consortium composed of eight bacterial isolates from the first biofilm reactor. In the reactor with the eight-species consortium, Lpn biofilm CFU was relatively stable over a 12-day trial. An isolate of Acidovorax from the consortium was, as a single species biofilm, able to promote Lpn surface attachment. Other isolates from the Pelomonas genus grew as equally robust biofilms alone, but did not promote surface attachment of Lpn. This attachment was disrupted by cationic polysaccharides and loss of the Lpn Lcl collagen-like adhesin protein. This work demonstrates that, while Lpn was fairly incompetent at attachment to surfaces to form a biofilm alone, pre-existing biofilms allowed attachment of Lpn as secondary colonizers. In addition, we demonstrate that initial attachment of Lpn to Acidovorax biofilms is likely via the Lcl-adhesin protein.
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Affiliation(s)
| | - Jenna Zaia
- Department of Biological Sciences, SUNY Cortland, Cortland, New York, USA
| | - Cassidy Sauer
- Department of Biological Sciences, SUNY Cortland, Cortland, New York, USA
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8
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Assaidi A, Ellouali M, Latrache H, Timinouni M, Zahir H, Karoumi A, Barguigua A, Mliji EM. Antimicrobial Susceptibility Patterns of Legionella spp. Strains Isolated from Water Systems in Morocco. Microb Drug Resist 2020; 26:991-996. [PMID: 32125920 DOI: 10.1089/mdr.2019.0218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Objective: Legionella is a waterborne pathogen that causes a severe form of pneumonia called Legionnaires' diseases, which is normally acquired by inhalation of aerosols containing Legionella originating from natural and man-made water systems. The aim of this study was to describe the level of antimicrobial susceptibility of environmental Legionella spp. strains to preferred and recommended therapeutic agents to treat Legionella disease. Methods: The minimum inhibitory concentrations (MICs) of 60 environmental Legionella spp. strains were tested using the broth dilution method. Susceptibility testing was performed for 12 antimicrobial agents: macrolides (erythromycin, azithromycin [AZI], and clarithromycin [CLA]), fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin, and gemifloxacin), a ketolide (telithromycin), cefotaxime (CEF), tigecycline (TIG), doxycycline (DOX), and rifampicin (RIF). Results: All tested strains of Legionella spp. were inhibited by low concentrations of fluoroquinolones and macrolides. Regarding the macrolides, CLA was the most active antibiotic, and AZI was the least active. RIF was the most effective antibiotic against the isolates in vitro. All isolates were inhibited by the following antibiotics (in decreasing order of their MICs): DOX>CEF>TIG. Conclusions: No resistance against these drugs was detected, and all isolates were inhibited by low concentrations of the tested antibiotics. Susceptibility testing of environmental Legionella spp. isolates must be monitored often to detect and evaluate the possible development of antibiotic resistance.
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Affiliation(s)
- Abdelwahid Assaidi
- Laboratory of Bioprocess and Biointerfaces, Life Sciences Department, Faculty of Sciences and Techniques, Sultan Moulay Slimane University, Beni Mellal, Morocco.,Laboratory of Water Microbiology and Environmental Hygiene, Food Safety & Environment Department, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Mostafa Ellouali
- Laboratory of Bioprocess and Biointerfaces, Life Sciences Department, Faculty of Sciences and Techniques, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Hassan Latrache
- Laboratory of Bioprocess and Biointerfaces, Life Sciences Department, Faculty of Sciences and Techniques, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Mohammed Timinouni
- Laboratory of Water Microbiology and Environmental Hygiene, Food Safety & Environment Department, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Hafida Zahir
- Laboratory of Bioprocess and Biointerfaces, Life Sciences Department, Faculty of Sciences and Techniques, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Abdelaziz Karoumi
- Laboratory of Water Microbiology and Environmental Hygiene, Food Safety & Environment Department, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Abouddihaj Barguigua
- Laboratory of Biotechnology and Sustainable Development of Natural Ressources, Life Sciences Department, Polydisciplinary Faculty, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - El Mostafa Mliji
- Laboratory of Water Microbiology and Environmental Hygiene, Food Safety & Environment Department, Institut Pasteur du Maroc, Casablanca, Morocco
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9
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Abstract
Biofilms form when bacteria adhere to a surface and secrete an extracellular polymeric substance. Bacteria embedded within a biofilm benefit from increased resistance to antibiotics, host immune responses, and harsh environmental factors. Nitric oxide (NO) is a signaling molecule that can modulate communal behavior, including biofilm formation, in many bacteria. In many cases, NO-induced biofilm dispersal is accomplished through signal transduction pathways that ultimately lead to a decrease in intracellular cyclic-di-GMP levels. H-NOX (heme nitric oxide/oxygen binding domain) proteins are the best characterized bacterial NO sensors and have been implicated in NO-mediated cyclic-di-GMP signaling, but we have recently discovered a second family of NO-sensitive proteins in bacteria named NosP (NO sensing protein); to date, a clear link between NosP signaling and cyclic-di-GMP metabolism has not been established. Here we present evidence that NosP (Lpg0279) binds to NO and directly affects cyclic-di-GMP production from two-component signaling proteins Lpg0278 and Lpg0277 encoded within the NosP operon. Lpg0278 and Lpg0277 are a histidine kinase and cyclic-di-GMP synthase/phosphodiesterase, respectively, that have already been established as being important in regulating Legionella pneumophila cyclic-di-GMP levels; NosP is thus implicated in regulating cyclic-di-GMP in L. pneumophila.
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Affiliation(s)
- Jonathan T Fischer
- Department of Chemistry and Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, New York 11794, United States
| | - Sajjad Hossain
- Department of Chemistry and Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, New York 11794, United States
| | - Elizabeth M Boon
- Department of Chemistry and Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, New York 11794, United States
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10
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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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11
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Hochstrasser R, Kessler A, Sahr T, Simon S, Schell U, Gomez-Valero L, Buchrieser C, Hilbi H. The pleiotropic Legionella transcription factor LvbR links the Lqs and c-di-GMP regulatory networks to control biofilm architecture and virulence. Environ Microbiol 2019; 21:1035-1053. [PMID: 30623561 DOI: 10.1111/1462-2920.14523] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 01/05/2019] [Indexed: 11/29/2022]
Abstract
The causative agent of Legionnaires' disease, Legionella pneumophila, colonizes amoebae and biofilms in the environment. The opportunistic pathogen employs the Lqs (Legionella quorum sensing) system and the signalling molecule LAI-1 (Legionella autoinducer-1) to regulate virulence, motility, natural competence and expression of a 133 kb genomic "fitness island", including a putative novel regulator. Here, we show that the regulator termed LvbR is an LqsS-regulated transcription factor that binds to the promoter of lpg1056/hnox1 (encoding an inhibitor of the diguanylate cyclase Lpg1057), and thus, regulates proteins involved in c-di-GMP metabolism. LvbR determines biofilm architecture, since L. pneumophila lacking lvbR accumulates less sessile biomass and forms homogeneous mat-like structures, while the parental strain develops more compact bacterial aggregates. Comparative transcriptomics of sessile and planktonic ΔlvbR or ΔlqsR mutant strains revealed concerted (virulence, fitness island, metabolism) and reciprocally (motility) regulated genes in biofilm and broth respectively. Moreover, ΔlvbR is hyper-competent for DNA uptake, defective for phagocyte infection, outcompeted by the parental strain in amoebae co-infections and impaired for cell migration inhibition. Taken together, our results indicate that L. pneumophila LvbR is a novel pleiotropic transcription factor, which links the Lqs and c-di-GMP regulatory networks to control biofilm architecture and pathogen-host cell interactions.
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Affiliation(s)
- Ramon Hochstrasser
- Institute of Medical Microbiology, Faculty of Medicine, University of Zürich, Gloriastrasse 30, 8006 Zürich, Switzerland
| | - Aline Kessler
- Max von Pettenkofer Institute, Faculty of Medicine, Ludwig-Maximilians University, Pettenkoferstrasse 9a, 80336 Munich, Germany
| | - Tobias Sahr
- Institut Pasteur, Unité de Biologie des Bactéries Intracellulaires, 28 Rue du Dr Roux, 75724 Paris, France.,CNRS UMR 3525, 28 Rue du Dr Roux, 75724 Paris, France
| | - Sylvia Simon
- Institute of Medical Microbiology, Faculty of Medicine, University of Zürich, Gloriastrasse 30, 8006 Zürich, Switzerland
| | - Ursula Schell
- Max von Pettenkofer Institute, Faculty of Medicine, Ludwig-Maximilians University, Pettenkoferstrasse 9a, 80336 Munich, Germany
| | - Laura Gomez-Valero
- Institut Pasteur, Unité de Biologie des Bactéries Intracellulaires, 28 Rue du Dr Roux, 75724 Paris, France.,CNRS UMR 3525, 28 Rue du Dr Roux, 75724 Paris, France
| | - Carmen Buchrieser
- Institut Pasteur, Unité de Biologie des Bactéries Intracellulaires, 28 Rue du Dr Roux, 75724 Paris, France.,CNRS UMR 3525, 28 Rue du Dr Roux, 75724 Paris, France
| | - Hubert Hilbi
- Institute of Medical Microbiology, Faculty of Medicine, University of Zürich, Gloriastrasse 30, 8006 Zürich, Switzerland
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12
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Abu Khweek A, Amer AO. Factors Mediating Environmental Biofilm Formation by Legionella pneumophila. Front Cell Infect Microbiol 2018. [PMID: 29535972 PMCID: PMC5835138 DOI: 10.3389/fcimb.2018.00038] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Legionella pneumophila (L. pneumophila) is an opportunistic waterborne pathogen and the causative agent for Legionnaires' disease, which is transmitted to humans via inhalation of contaminated water droplets. The bacterium is able to colonize a variety of man-made water systems such as cooling towers, spas, and dental lines and is widely distributed in multiple niches, including several species of protozoa In addition to survival in planktonic phase, L. pneumophila is able to survive and persist within multi-species biofilms that cover surfaces within water systems. Biofilm formation by L. pneumophila is advantageous for the pathogen as it leads to persistence, spread, resistance to treatments and an increase in virulence of this bacterium. Furthermore, Legionellosis outbreaks have been associated with the presence of L. pneumophila in biofilms, even after the extensive chemical and physical treatments. In the microbial consortium-containing L. pneumophila among other organisms, several factors either positively or negatively regulate the presence and persistence of L. pneumophila in this bacterial community. Biofilm-forming L. pneumophila is of a major importance to public health and have impact on the medical and industrial sectors. Indeed, prevention and removal protocols of L. pneumophila as well as diagnosis and hospitalization of patients infected with this bacteria cost governments billions of dollars. Therefore, understanding the biological and environmental factors that contribute to persistence and physiological adaptation in biofilms can be detrimental to eradicate and prevent the transmission of L. pneumophila. In this review, we focus on various factors that contribute to persistence of L. pneumophila within the biofilm consortium, the advantages that the bacteria gain from surviving in biofilms, genes and gene regulation during biofilm formation and finally challenges related to biofilm resistance to biocides and anti-Legionella treatments.
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Affiliation(s)
- Arwa Abu Khweek
- Department of Biology and Biochemistry, Birzeit University, West Bank, Palestine
| | - Amal O Amer
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, College of Medicine, Ohio State University, Columbus, OH, United States
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Peterson CP, Sauer C, Chatfield CH. The Extracellular Polymeric Substances of Legionella pneumophila Biofilms Contain Amyloid Structures. Curr Microbiol 2018; 75:736-744. [PMID: 29468303 DOI: 10.1007/s00284-018-1440-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 01/16/2018] [Indexed: 12/25/2022]
Abstract
Human infection by bacteria of the genus Legionella most often result in the pneumonia known as Legionnaires Disease. Legionella is found as a resident of adherent biofilms in man-made water systems. Disinfection efforts to prevent Legionella infections require a better understanding of the structures that promote Legionella surface attachment and biofilm colonization. Various enzymatic treatments, including multiple carbohydrate-targeting mixtures, failed to disrupt Legionella biofilms, despite the presence of carbohydrates in the biofilms as shown by biochemical methods and concanavalin-A lectin staining. Moreover, Legionella biofilms contained amyloids as detected by three microscopic staining methods (congo red, thioflavin T, and the amyloid-specific antibody WO2). Amyloid structures were seen in biofilms of both L. pneumophila and L. longbeachae, the two Legionella species most associated with human infection. Inhibition of amyloid assembly by congo red and thioflavin T limited both self-aggregation and surface attachment of L. pneumophila, indicating that functional amyloid structures have a key role in initial biofilm formation by these pathogenic bacteria.
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Affiliation(s)
- Casey P Peterson
- Department of Biological Sciences, SUNY Cortland, Cortland, NY, USA
| | - Cassidy Sauer
- Department of Biological Sciences, SUNY Cortland, Cortland, NY, USA
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Hochstrasser R, Hilbi H. Intra-Species and Inter-Kingdom Signaling of Legionella pneumophila. Front Microbiol 2017; 8:79. [PMID: 28217110 PMCID: PMC5289986 DOI: 10.3389/fmicb.2017.00079] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/11/2017] [Indexed: 12/24/2022] Open
Abstract
The ubiquitous Gram-negative bacterium Legionella pneumophila parasitizes environ mental amoebae and, upon inhalation, replicates in alveolar macrophages, thus causing a life-threatening pneumonia called “Legionnaires’ disease.” The opportunistic pathogen employs a bi-phasic life cycle, alternating between a replicative, non-virulent phase and a stationary, transmissive/virulent phase. L. pneumophila employs the Lqs (Legionella quorum sensing) system as a major regulator of the growth phase switch. The Lqs system comprises the autoinducer synthase LqsA, the homologous sensor kinases LqsS and LqsT, as well as a prototypic response regulator termed LqsR. These components produce, detect, and respond to the α-hydroxyketone signaling molecule LAI-1 (Legionella autoinducer-1, 3-hydroxypentadecane-4-one). LAI-1-mediated signal transduction through the sensor kinases converges on LqsR, which dimerizes upon phosphorylation. The Lqs system regulates the bacterial growth phase switch, pathogen-host cell interactions, motility, natural competence, filament production, and expression of a chromosomal “fitness island.” Yet, LAI-1 not only mediates bacterial intra-species signaling, but also modulates the motility of eukaryotic cells through the small GTPase Cdc42 and thus promotes inter-kingdom signaling. Taken together, the low molecular weight compound LAI-1 produced by L. pneumophila and sensed by the bacteria as well as by eukaryotic cells plays a major role in pathogen-host cell interactions.
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Affiliation(s)
- Ramon Hochstrasser
- Department of Medicine, Institute of Medical Microbiology, University of Zürich Zürich, Switzerland
| | - Hubert Hilbi
- Department of Medicine, Institute of Medical Microbiology, University of Zürich Zürich, Switzerland
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Portier E, Bertaux J, Labanowski J, Hechard Y. Iron Availability Modulates the Persistence of Legionella pneumophila in Complex Biofilms. Microbes Environ 2016; 31:387-394. [PMID: 27629106 PMCID: PMC5158110 DOI: 10.1264/jsme2.me16010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Legionella pneumophila is a pathogenic bacteria found in biofilms in freshwater. Iron is an essential nutrient for L. pneumophila growth. In this study, complex biofilms were developed using river water spiked with L. pneumophila, and the persistence of L. pneumophila in these complex biofilms was evaluated. In order to study the role of iron in the persistence of L. pneumophila, river water was supplied with either iron pyrophosphate or iron chelators (deferoxamine mesylate, DFX for ferric iron and dipyridyl, DIP for ferrous iron) to modulate iron availability. The addition of iron pyrophosphate and DFX did not markedly affect the persistence of L. pneumophila in the biofilms, whereas that of DIP had a beneficial effect. Since DIP specifically chelates ferrous iron, we hypothesized that DIP may protect L. pneumophila from the deleterious effects of ferrous iron. In conclusion, ferrous iron appears to be important for the persistence of L. pneumophila in complex biofilms. However, further studies are needed in order to obtain a better understanding of the role of ferrous iron in the behavior of this bacterium in the environment.
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Affiliation(s)
- Emilie Portier
- University of Poitiers, Laboratory of Ecology and Biology of Interactions, UMR CNRS 7267, Team of Microbiology of Water
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Pécastaings S, Allombert J, Lajoie B, Doublet P, Roques C, Vianney A. New insights into Legionella pneumophila biofilm regulation by c-di-GMP signaling. BIOFOULING 2016; 32:935-948. [PMID: 27494738 DOI: 10.1080/08927014.2016.1212988] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 07/07/2016] [Indexed: 06/06/2023]
Abstract
The waterborne pathogen Legionella pneumophila grows as a biofilm, freely or inside amoebae. Cyclic-di-GMP (c-di-GMP), a bacterial second messenger frequently implicated in biofilm formation, is synthesized and degraded by diguanylate cyclases (DGCs) and phosphodiesterases (PDEs), respectively. To characterize the c-di-GMP-metabolizing enzymes involved in L. pneumophila biofilm regulation, the consequences on biofilm formation and the c-di-GMP concentration of each corresponding gene inactivation were assessed in the Lens strain. The results showed that one DGC and two PDEs enhance different aspects of biofilm formation, while two proteins with dual activity (DGC/PDE) inhibit biofilm growth. Surprisingly, only two mutants exhibited a change in global c-di-GMP concentration. This study highlights that specific c-di-GMP pathways control L. pneumophila biofilm formation, most likely via temporary and/or local modulation of c-di-GMP concentration. Furthermore, Lpl1054 DGC is required to enable the formation a dense biofilm in response to nitric oxide, a signal for biofilm dispersion in many other species.
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Affiliation(s)
- Sophie Pécastaings
- a Laboratoire de Génie chimique UMR 5503 , UPS, Université de Toulouse , Toulouse , France
| | - Julie Allombert
- b CIRI, International Center for Infectiology Research , Legionella Pathogenesis Group, Université de Lyon , Lyon , France
- c Inserm , Lyon , France
- d Ecole Normale Supérieure de Lyon , Lyon , France
- e Université Lyon 1, CIRI, International Center for Infectiology Research , Lyon , France
- f CNRS , Lyon , France
| | - Barbora Lajoie
- a Laboratoire de Génie chimique UMR 5503 , UPS, Université de Toulouse , Toulouse , France
| | - Patricia Doublet
- b CIRI, International Center for Infectiology Research , Legionella Pathogenesis Group, Université de Lyon , Lyon , France
- c Inserm , Lyon , France
- d Ecole Normale Supérieure de Lyon , Lyon , France
- e Université Lyon 1, CIRI, International Center for Infectiology Research , Lyon , France
- f CNRS , Lyon , France
| | - Christine Roques
- a Laboratoire de Génie chimique UMR 5503 , UPS, Université de Toulouse , Toulouse , France
| | - Anne Vianney
- b CIRI, International Center for Infectiology Research , Legionella Pathogenesis Group, Université de Lyon , Lyon , France
- c Inserm , Lyon , France
- d Ecole Normale Supérieure de Lyon , Lyon , France
- e Université Lyon 1, CIRI, International Center for Infectiology Research , Lyon , France
- f CNRS , Lyon , France
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Andreozzi E, Barbieri F, Ottaviani MF, Giorgi L, Bruscolini F, Manti A, Battistelli M, Sabatini L, Pianetti A. Dendrimers and Polyamino-Phenolic Ligands: Activity of New Molecules Against Legionella pneumophila Biofilms. Front Microbiol 2016; 7:289. [PMID: 27014213 PMCID: PMC4783402 DOI: 10.3389/fmicb.2016.00289] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 02/23/2016] [Indexed: 12/01/2022] Open
Abstract
Legionnaires’ disease is a potentially fatal pneumonia caused by Legionella pneumophila, an aquatic bacterium often found within the biofilm niche. In man-made water systems microbial biofilms increase the resistance of legionella to disinfection, posing a significant threat to public health. Disinfection methods currently used in water systems have been shown to be ineffective against legionella over the long-term, allowing recolonization by the biofilm-protected microorganisms. In this study, the anti-biofilm activity of previously fabricated polyamino-phenolic ligands and polyamidoamine dendrimers was investigated against legionella mono-species and multi-species biofilms formed by L. pneumophila in association with other bacteria that can be found in tap water (Aeromonas hydrophila, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae). Bacterial ability to form biofilms was verified using a crystal violet colorimetric assay and testing cell viability by real-time quantitative PCR and Plate Count assay. The concentration of the chemicals tested as anti-biofilm agents was chosen based on cytotoxicity assays: the highest non-cytotoxic chemical concentration was used for biofilm inhibition assays, with dendrimer concentration 10-fold higher than polyamino-phenolic ligands. While Macrophen and Double Macrophen were the most active substances among polyamino-phenolic ligands, dendrimers were overall twofold more effective than all other compounds with a reduction up to 85 and 73% of legionella and multi-species biofilms, respectively. Chemical interaction with matrix molecules is hypothesized, based on SEM images and considering the low or absent anti-microbial activity on planktonic bacteria showed by flow cytometry. These data suggest that the studied compounds, especially dendrimers, could be considered as novel molecules in the design of research projects aimed at the development of efficacious anti-biofilm disinfection treatments of water systems in order to minimize legionellosis outbreaks.
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Affiliation(s)
- Elisa Andreozzi
- Department of Biomolecular Sciences, University of Urbino Carlo Bo Urbino, Italy
| | - Federica Barbieri
- Department of Biomolecular Sciences, University of Urbino Carlo Bo Urbino, Italy
| | - Maria F Ottaviani
- Department of Pure and Applied Sciences, University of Urbino Carlo Bo Urbino, Italy
| | - Luca Giorgi
- Department of Pure and Applied Sciences, University of Urbino Carlo Bo Urbino, Italy
| | - Francesca Bruscolini
- Department of Biomolecular Sciences, University of Urbino Carlo Bo Urbino, Italy
| | - Anita Manti
- Department of Biomolecular Sciences, University of Urbino Carlo Bo Urbino, Italy
| | - Michela Battistelli
- Department of Biomolecular Sciences, University of Urbino Carlo Bo Urbino, Italy
| | - Luigia Sabatini
- Department of Biomolecular Sciences, University of Urbino Carlo Bo Urbino, Italy
| | - Anna Pianetti
- Department of Biomolecular Sciences, University of Urbino Carlo Bo Urbino, Italy
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Loiseau C, Schlusselhuber M, Bigot R, Bertaux J, Berjeaud JM, Verdon J. Surfactin from Bacillus subtilis displays an unexpected anti-Legionella activity. Appl Microbiol Biotechnol 2015; 99:5083-93. [PMID: 25573468 DOI: 10.1007/s00253-014-6317-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 10/29/2014] [Accepted: 12/10/2014] [Indexed: 11/29/2022]
Abstract
A contaminant bacterial strain was found to exhibit an antagonistic activity against Legionella pneumophila, the causative agent of Legionnaires' disease. The bacterial strain was identified as a Bacillus subtilis and named B. subtilis AM1. PCR analysis revealed the presence of the sfp gene, involved in the biosynthesis of surfactin, a lipopeptide with versatile bioactive properties. The bioactive substances were extracted from AM1 cell-free supernatant with ethyl acetate and purified using reversed phase HPLC (RP-HPLC). Subsequent ESI-MS analyses indicated the presence of two active substances with protonated molecular ions at m/z 1008 and 1036 Da, corresponding to surfactin isoforms. Structures of lipopeptides were further determined by tandem mass spectrometry and compared to the spectra of a commercially available surfactin mixture. Surfactin displays an antibacterial spectrum almost restricted to the Legionella genus (MICs range 1-4 μg/mL) and also exhibits a weak activity toward the amoeba Acanthamoeba castellanii, known to be the natural reservoir of L. pneumophila. Anti-biofilm assays demonstrated that 66 μg/mL of surfactin successfully eliminated 90 % of a 6-day-old biofilm. In conclusion, this study reveals for the first time the potent activity of surfactin against Legionella sp. and preformed biofilms thus providing new directions toward the use and the development of lipopeptides for the control of Legionella spread in the environment.
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Affiliation(s)
- Clémence Loiseau
- Equipe Microbiologie de l'Eau, Université de Poitiers, Ecologie & Biologie des Interactions, UMR CNRS 7267, 1 Rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
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19
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Nomura H, Isshiki Y, Sakuda K, Sakuma K, Kondo S. Effects of oakmoss and its components on biofilm formation of Legionella pneumophila. Biol Pharm Bull 2014; 36:833-7. [PMID: 23649339 DOI: 10.1248/bpb.b12-01047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oakmoss and its components are known as antibacterial agents, specifically against Legionella pneumophila. In the present study, we investigated the effects of oakmoss and its components (phenol, didepside and isochromen derivatives) on L. pneumophila biofilm formation, with particular reference to the bactericidal activity (minimum bactericidal concentration; MBC) of these components against the bacterial cells in the biofilm. Of the 20 compounds tested, two didepside derivatives and four phenol derivatives reduced biofilm formation by more than 50% of that observed for the control at their respective minimum inhibitory concentrations (1/2×MIC). The inhibitory activities of these compounds were either equivalent to or greater than that of the clarithromycin reference. Isochromen derivatives had no effect on biofilm formation. Analysis of bactericidal activity of didepside and isochromen derivatives revealed that three of four didepside derivatives and one of four isochromen derivatives exhibited high bactericidal activity (MBC: 32.0-74.7 µg/mL) against the L. pneumophila in the biofilm after 24 h or 48 h of co-incubation; the antibacterial activities of these compounds were almost equivalent to clarithromycin and chlorhexidine gluconate (MBC: 42.7-64.0 µg/mL) that were used as references. Thus, based on their anti-biofilm forming and bactericidal activities, didepside derivatives are considered to be good candidates for disinfectants against L. pneumophila.
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Affiliation(s)
- Harue Nomura
- Department of Microbiology, School of Pharmaceutical Sciences, Josai University, Sakado, Saitama 350–0295, Japan.
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20
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Abdel-Nour M, Duncan C, Low DE, Guyard C. Biofilms: the stronghold of Legionella pneumophila. Int J Mol Sci 2013; 14:21660-75. [PMID: 24185913 PMCID: PMC3856027 DOI: 10.3390/ijms141121660] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/07/2013] [Accepted: 10/14/2013] [Indexed: 11/28/2022] Open
Abstract
Legionellosis is mostly caused by Legionella pneumophila and is defined as a severe respiratory illness with a case fatality rate ranging from 5% to 80%. L. pneumophila is ubiquitous in natural and anthropogenic water systems. L. pneumophila is transmitted by inhalation of contaminated aerosols produced by a variety of devices. While L. pneumophila replicates within environmental protozoa, colonization and persistence in its natural environment are also mediated by biofilm formation and colonization within multispecies microbial communities. There is now evidence that some legionellosis outbreaks are correlated with the presence of biofilms. Thus, preventing biofilm formation appears as one of the strategies to reduce water system contamination. However, we lack information about the chemical and biophysical conditions, as well as the molecular mechanisms that allow the production of biofilms by L. pneumophila. Here, we discuss the molecular basis of biofilm formation by L. pneumophila and the roles of other microbial species in L. pneumophila biofilm colonization. In addition, we discuss the protective roles of biofilms against current L. pneumophila sanitation strategies along with the initial data available on the regulation of L. pneumophila biofilm formation.
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Affiliation(s)
- Mena Abdel-Nour
- Ontario Agency for Health Protection and Promotion (OAHPP), Toronto, ON M9P 3T1, Canada; E-Mails: (M.A.-N.); (C.D.)
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Carla Duncan
- Ontario Agency for Health Protection and Promotion (OAHPP), Toronto, ON M9P 3T1, Canada; E-Mails: (M.A.-N.); (C.D.)
| | - Donald E. Low
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Cyril Guyard
- Ontario Agency for Health Protection and Promotion (OAHPP), Toronto, ON M9P 3T1, Canada; E-Mails: (M.A.-N.); (C.D.)
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-416-880-1339; Fax: +1-416-235-6281
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Bigot R, Bertaux J, Frere J, Berjeaud JM. Intra-amoeba multiplication induces chemotaxis and biofilm colonization and formation for Legionella. PLoS One 2013; 8:e77875. [PMID: 24205008 PMCID: PMC3812023 DOI: 10.1371/journal.pone.0077875] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 09/13/2013] [Indexed: 11/19/2022] Open
Abstract
Legionella pneumophila, a facultative intracellular bacterium, is the causative agent of legionellosis. In the environment this pathogenic bacterium colonizes the biofilms as well as amoebae, which provide a rich environment for the replication of Legionella. When seeded on pre-formed biofilms, L. pneumophila was able to establish and survive and was only found at the surface of the biofilms. Different phenotypes were observed when the L. pneumophila, used to implement pre-formed biofilms or to form mono-species biofilms, were cultivated in a laboratory culture broth or had grown intracellulary within the amoeba. Indeed, the bacteria, which developed within the amoeba, formed clusters when deposited on a solid surface. Moreover, our results demonstrate that multiplication inside the amoeba increased the capacity of L. pneumophila to produce polysaccharides and therefore enhanced its capacity to establish biofilms. Finally, it was shown that the clusters formed by L. pneumophila were probably related to the secretion of a chemotaxis molecular agent.
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Affiliation(s)
- Renaud Bigot
- Equipe Microbiologie de l’Eau, Ecologie & Biologie des Interactions, Centre national de la recherche scientifique UMR 7267, Université de Poitiers, Poitiers, France
| | - Joanne Bertaux
- Equipe Ecologie Evolution Symbiose, Ecologie and Biologie des Interactions, Centre national de la recherche scientifique UMR 7267, Université de Poitiers, Poitiers, France
| | - Jacques Frere
- Equipe Microbiologie de l’Eau, Ecologie & Biologie des Interactions, Centre national de la recherche scientifique UMR 7267, Université de Poitiers, Poitiers, France
| | - Jean-Marc Berjeaud
- Equipe Microbiologie de l’Eau, Ecologie & Biologie des Interactions, Centre national de la recherche scientifique UMR 7267, Université de Poitiers, Poitiers, France
- * E-mail:
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Abstract
Biofilm formation could be studied in various conditions. Most of the studies with Legionella pneumophila used monospecies biofilm in culture media. In some cases, it is important to study bacteria in conditions more close to environmental conditions. In this paper, we describe protocols to produce natural biofilms from river water that were spiked with L. pneumophila.
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Affiliation(s)
- Emilie Portier
- Faculté de Pharmacie, Laboratoire de Génie Chimique, BioSym Department, Université de Toulouse, Toulouse, France
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23
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Pécastaings S, Roques C. Production of L. pneumophila monospecies biofilms in a low-nutrient-concentration medium. Methods Mol Biol 2013; 954:219-224. [PMID: 23150398 DOI: 10.1007/978-1-62703-161-5_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In aquatic environments such as water distribution systems, Legionella pneumophila persistence is -correlated to the presence of a biofilm. The method described here permits the formation of a monospecies L. pneumophila biofilm in microplates, enabling the screening of multiple parameters. The culture medium used has a low nutrient concentration compared to the classical Buffered Yeast Extract culture medium. Hence, bacterial growth occurs in the sessile phase, allowing the formation of three-dimensional structures.
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Affiliation(s)
- Sophie Pécastaings
- Faculté de Pharmacie, Laboratoire de Génie Chimique, BioSym Department, Université de Toulouse, Toulouse, France.
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Hilbi H, Hoffmann C, Harrison CF. Legionella spp. outdoors: colonization, communication and persistence. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:286-296. [PMID: 23761274 DOI: 10.1111/j.1758-2229.2011.00247.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Bacteria of the genus Legionella persist in a wide range of environmental habitats, including biofilms, protozoa and nematodes. Legionellaceae are 'accidental' human pathogens that upon inhalation cause a severe pneumonia termed 'Legionnaires' disease'. The interactions of L. pneumophila with eukaryotic hosts are governed by the Icm/Dot type IV secretion system (T4SS) and more than 150 'effector proteins', which subvert signal transduction pathways and promote the formation of the replication-permissive 'Legionella-containing vacuole'. The Icm/Dot T4SS is essential to infect free-living protozoa, such as the amoeba Dictyostelium discoideum, as well as the nematode Caenorhabditis elegans, or mammalian macrophages. To adapt to different niches, L. pneumophila not only responds to exogenous cues, but also to endogenous signals, such as the α-hydroxyketone compound LAI-1 (Legionella autoinducer-1). The long-term adaptation of Legionella spp. is based on extensive horizontal DNA transfer. In fact, Legionella spp. have acquired canonical 'genomic islands' of prokaryotic origin, but also a number of eukaryotic genes. Since many aspects of Legionella virulence against environmental predators and immune phagocytes are similar, an understanding of Legionella ecology provides valuable insights into the pathogenesis of legionellaceae for humans.
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Affiliation(s)
- Hubert Hilbi
- Max von Pettenkofer Institute, Ludwig-Maximilian University Munich, Pettenkoferstrasse 9a, 80336 Munich, Germany
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