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Voth K, Pasricha S, Chung IYW, Wibawa RR, Zainudin ENHE, Hartland EL, Cygler M. Structural and Functional Characterization of Legionella pneumophila Effector MavL. Biomolecules 2021; 11:biom11121802. [PMID: 34944446 PMCID: PMC8699189 DOI: 10.3390/biom11121802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/25/2021] [Accepted: 11/27/2021] [Indexed: 11/23/2022] Open
Abstract
Legionella pneumophila is a Gram-negative intracellular pathogen that causes Legionnaires’ disease in elderly or immunocompromised individuals. This bacterium relies on the Dot/Icm (Defective in organelle trafficking/Intracellular multiplication) Type IV Secretion System (T4SS) and a large (>330) set of effector proteins to colonize the host cell. The structural variability of these effectors allows them to disrupt many host processes. Herein, we report the crystal structure of MavL to 2.65 Å resolution. MavL adopts an ADP-ribosyltransferase (ART) fold and contains the distinctive ligand-binding cleft of ART proteins. Indeed, MavL binds ADP-ribose with Kd of 13 µM. Structural overlay of MavL with poly-(ADP-ribose) glycohydrolases (PARGs) revealed a pair of aspartate residues in MavL that align with the catalytic glutamates in PARGs. MavL also aligns with ADP-ribose “reader” proteins (proteins that recognize ADP-ribose). Since no glycohydrolase activity was observed when incubated in the presence of ADP-ribosylated PARP1, MavL may play a role as a signaling protein that binds ADP-ribose. An interaction between MavL and the mammalian ubiquitin-conjugating enzyme UBE2Q1 was revealed by yeast two-hybrid and co-immunoprecipitation experiments. This work provides structural and molecular insights to guide biochemical studies aimed at elucidating the function of MavL. Our findings support the notion that ubiquitination and ADP-ribosylation are global modifications exploited by L. pneumophila.
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Affiliation(s)
- Kevin Voth
- Department of Biochemistry, Microbiology & Immunology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada; (K.V.); (I.Y.W.C.)
| | - Shivani Pasricha
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton 3168, Australia; (S.P.); (R.R.W.)
| | - Ivy Yeuk Wah Chung
- Department of Biochemistry, Microbiology & Immunology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada; (K.V.); (I.Y.W.C.)
| | - Rachelia R. Wibawa
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton 3168, Australia; (S.P.); (R.R.W.)
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne 3000, Australia;
| | - Engku Nuraishah Huda E. Zainudin
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne 3000, Australia;
| | - Elizabeth L. Hartland
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton 3168, Australia; (S.P.); (R.R.W.)
- Department of Molecular and Translational Science, Monash University, Clayton 3168, Australia
- Correspondence: (E.L.H.); (M.C.)
| | - Miroslaw Cygler
- Department of Biochemistry, Microbiology & Immunology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada; (K.V.); (I.Y.W.C.)
- Correspondence: (E.L.H.); (M.C.)
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Hsieh TS, Lopez VA, Black MH, Osinski A, Pawłowski K, Tomchick DR, Liou J, Tagliabracci VS. Dynamic remodeling of host membranes by self-organizing bacterial effectors. Science 2021; 372:935-941. [PMID: 33927055 PMCID: PMC8543759 DOI: 10.1126/science.aay8118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 02/17/2021] [Accepted: 04/14/2021] [Indexed: 01/09/2023]
Abstract
During infection, intracellular bacterial pathogens translocate a variety of effectors into host cells that modify host membrane trafficking for their benefit. We found a self-organizing system consisting of a bacterial phosphoinositide kinase and its opposing phosphatase that formed spatiotemporal patterns, including traveling waves, to remodel host cellular membranes. The Legionella effector MavQ, a phosphatidylinositol (PI) 3-kinase, was targeted to the endoplasmic reticulum (ER). MavQ and the Legionella PI 3-phosphatase SidP, even in the absence of other bacterial components, drove rapid PI 3-phosphate turnover on the ER and spontaneously formed traveling waves that spread along ER subdomains inducing vesicle and tubule budding. Thus, bacteria can exploit a self-organizing membrane-targeting mechanism to hijack host cellular structures for survival.
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Affiliation(s)
- Ting-Sung Hsieh
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Victor A Lopez
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Miles H Black
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Adam Osinski
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Krzysztof Pawłowski
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Biochemistry and Microbiology, Institute of Biology, Warsaw University of Life Sciences, Warsaw 02-776, Poland
| | - Diana R Tomchick
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jen Liou
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vincent S Tagliabracci
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Kim RQ, Misra M, Gonzalez A, Tomašković I, Shin D, Schindelin H, Filippov DV, Ovaa H, Đikić I, van der Heden van Noort GJ. Development of ADPribosyl Ubiquitin Analogues to Study Enzymes Involved in Legionella Infection. Chemistry 2021; 27:2506-2512. [PMID: 33075184 PMCID: PMC7898697 DOI: 10.1002/chem.202004590] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Indexed: 11/18/2022]
Abstract
Legionnaires' disease is caused by infection with the intracellularly replicating Gram-negative bacterium Legionella pneumophila. This pathogen uses an unconventional way of ubiquitinating host proteins by generating a phosphoribosyl linkage between substrate proteins and ubiquitin by making use of an ADPribosylated ubiquitin (UbADPr ) intermediate. The family of SidE effector enzymes that catalyze this reaction is counteracted by Legionella hydrolases, which are called Dups. This unusual ubiquitination process is important for Legionella proliferation and understanding these processes on a molecular level might prove invaluable in finding new treatments. Herein, a modular approach is used for the synthesis of triazole-linked UbADPr , and analogues thereof, and their affinity towards the hydrolase DupA is determined and hydrolysis rates are compared to natively linked UbADPr . The inhibitory effects of modified Ub on the canonical eukaryotic E1-enzyme Uba1 are investigated and rationalized in the context of a high-resolution crystal structure reported herein. Finally, it is shown that synthetic UbADPr analogues can be used to effectively pull-down overexpressed DupA from cell lysate.
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Affiliation(s)
- Robbert Q. Kim
- Oncode Institute and Department of Cell and Chemical BiologyLeiden University Medical CentreEinthovenweg 202333 ZCLeidenThe Netherlands
| | - Mohit Misra
- Institute of Biochemistry IIGoethe University Faculty of MedicineTheodor-Stern-Kai 760590Frankfurt am MainGermany
- Buchmann Institute for Molecular Life SciencesGoethe University Frankfurt, Riedberg CampusMax-von-Laue-Strasse 1560438Frankfurt am MainGermany
- Rudolf Virchow Center for Integrative and Translational BioimagingUniversity of WürzburgJosef-Schneider-Strasse 297080WürzburgGermany
| | - Alexis Gonzalez
- Institute of Biochemistry IIGoethe University Faculty of MedicineTheodor-Stern-Kai 760590Frankfurt am MainGermany
- Buchmann Institute for Molecular Life SciencesGoethe University Frankfurt, Riedberg CampusMax-von-Laue-Strasse 1560438Frankfurt am MainGermany
| | - Ines Tomašković
- Institute of Biochemistry IIGoethe University Faculty of MedicineTheodor-Stern-Kai 760590Frankfurt am MainGermany
- Buchmann Institute for Molecular Life SciencesGoethe University Frankfurt, Riedberg CampusMax-von-Laue-Strasse 1560438Frankfurt am MainGermany
| | - Donghyuk Shin
- Institute of Biochemistry IIGoethe University Faculty of MedicineTheodor-Stern-Kai 760590Frankfurt am MainGermany
- Buchmann Institute for Molecular Life SciencesGoethe University Frankfurt, Riedberg CampusMax-von-Laue-Strasse 1560438Frankfurt am MainGermany
- Current Address: Department of Nano-BioengineeringIncheon National UniversityAcademyro 11922012IncheonSouth Korea
| | - Hermann Schindelin
- Rudolf Virchow Center for Integrative and Translational BioimagingUniversity of WürzburgJosef-Schneider-Strasse 297080WürzburgGermany
| | - Dmitri V. Filippov
- Leiden Institute of ChemistryLeiden UniversityEinsteinweg 552333 CCLeidenThe Netherlands
| | - Huib Ovaa
- Oncode Institute and Department of Cell and Chemical BiologyLeiden University Medical CentreEinthovenweg 202333 ZCLeidenThe Netherlands
| | - Ivan Đikić
- Institute of Biochemistry IIGoethe University Faculty of MedicineTheodor-Stern-Kai 760590Frankfurt am MainGermany
- Buchmann Institute for Molecular Life SciencesGoethe University Frankfurt, Riedberg CampusMax-von-Laue-Strasse 1560438Frankfurt am MainGermany
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Lesar A, Mušković M, Begić G, Lončarić M, Tomić Linšak D, Malatesti N, Gobin I. Cationic Porphyrins as Effective Agents in Photodynamic Inactivation of Opportunistic Plumbing Pathogen Legionella pneumophila. Int J Mol Sci 2020; 21:ijms21155367. [PMID: 32731616 PMCID: PMC7432253 DOI: 10.3390/ijms21155367] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/23/2020] [Accepted: 07/24/2020] [Indexed: 02/02/2023] Open
Abstract
Legionella pneumophila is an environmental bacterium, an opportunistic premise plumbing pathogen that causes the Legionnaires’ disease. L. pneumophila presents a serious health hazard in building water systems, due to its high resistance to standard water disinfection methods. Our aim was to study the use of photodynamic inactivation (PDI) against Legionella. We investigated and compared the photobactericidal potential of five cationic dyes. We tested toluidine blue (TBO) and methylene blue (MB), and three 3-N-methylpyridylporphyrins, one tetra-cationic and two tri-cationic, one with a short (CH3) and the other with a long (C17H35) alkyl chain, against L. pneumophila in tap water and after irradiation with violet light. All tested dyes demonstrated a certain dark toxicity against L. pneumophila; porphyrins with lower minimal effective concentration (MEC) values than TBO and MB. Nanomolar MEC values, significantly lower than with TBO and MB, were obtained with all three porphyrins in PDI experiments, with amphiphilic porphyrin demonstrating the highest PDI activity. All tested dyes showed increasing PDI with longer irradiation (0–108 J/cm2), especially the two hydrophilic porphyrins. All three porphyrins caused significant changes in cell membrane permeability after irradiation and L. pneumophila, co-cultivated with Acanthamoeba castellanii after treatment with all three porphyrins and irradiation, did not recover in amoeba. We believe our results indicate the considerable potential of cationic porphyrins as effective anti-Legionella agents.
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Affiliation(s)
- Andrija Lesar
- Bioinstitut d.o.o., R. Steinera 7, 40000 Čakovec, Croatia;
| | - Martina Mušković
- Department of Biotechnology, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia;
| | - Gabrijela Begić
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia; (G.B.); (I.G.)
| | - Martin Lončarić
- Photonics and Quantum Optics Unit, Center of Excellence for Advanced Materials and Sensing Devices, Ruđer Bošković Institute, Bijenička cesta 54, 10002 Zagreb, Croatia;
| | - Dijana Tomić Linšak
- Department for Health Ecology, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia;
| | - Nela Malatesti
- Department of Biotechnology, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia;
- Correspondence: ; Tel.: +385-51-584-585; Fax: +385-51-584-599
| | - Ivana Gobin
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia; (G.B.); (I.G.)
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Yang C, McDermot DS, Pasricha S, Brown AS, Bedoui S, Lenz LL, van Driel IR, Hartland EL. IFNγ receptor down-regulation facilitates Legionella survival in alveolar macrophages. J Leukoc Biol 2020; 107:273-284. [PMID: 31793076 PMCID: PMC8015206 DOI: 10.1002/jlb.4ma1019-152r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 10/10/2019] [Accepted: 10/30/2019] [Indexed: 12/17/2022] Open
Abstract
Legionella pneumophila is an opportunistic human pathogen and causative agent of the acute pneumonia known as Legionnaire's disease. Upon inhalation, the bacteria replicate in alveolar macrophages (AM), within an intracellular vacuole termed the Legionella-containing vacuole. We recently found that, in vivo, IFNγ was required for optimal clearance of intracellular L. pneumophila by monocyte-derived cells (MC), but the cytokine did not appear to influence clearance by AM. Here, we report that during L. pneumophila lung infection, expression of the IFNγ receptor subunit 1 (IFNGR1) is down-regulated in AM and neutrophils, but not MC, offering a possible explanation for why AM are unable to effectively restrict L. pneumophila replication in vivo. To test this, we used mice that constitutively express IFNGR1 in AM and found that prevention of IFNGR1 down-regulation enhanced the ability of AM to restrict L. pneumophila intracellular replication. IFNGR1 down-regulation was independent of the type IV Dot/Icm secretion system of L. pneumophila indicating that bacterial effector proteins were not involved. In contrast to previous work, we found that signaling via type I IFN receptors was not required for IFNGR1 down-regulation in macrophages but rather that MyD88- or Trif- mediated NF-κB activation was required. This work has uncovered an alternative signaling pathway responsible for IFNGR1 down-regulation in macrophages during bacterial infection.
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Affiliation(s)
- Chao Yang
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Daniel S McDermot
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Denver, Colorado, USA
| | - Shivani Pasricha
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Australia
| | - Andrew S Brown
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Sammy Bedoui
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Laurel L Lenz
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Denver, Colorado, USA
| | - Ian R van Driel
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Elizabeth L Hartland
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Australia
- Department of Molecular and Translational Science, Monash University, Melbourne, Victoria, Australia
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Oder M, Koklič T, Umek P, Podlipec R, Štrancar J, Dobeic M. Photocatalytic biocidal effect of copper doped TiO2 nanotube coated surfaces under laminar flow, illuminated with UVA light on Legionella pneumophila. PLoS One 2020; 15:e0227574. [PMID: 31940328 PMCID: PMC6961935 DOI: 10.1371/journal.pone.0227574] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 12/20/2019] [Indexed: 11/18/2022] Open
Abstract
Legionella pneumophila can cause a potentially fatal form of humane pneumonia (Legionnaires' disease), which is most problematic in immunocompromised and in elderly people. Legionella species is present at low concentrations in soil, natural and artificial aquatic systems and is therefore constantly entering man-made water systems. The environment temperature for it's ideal growth range is between 32 and 42°C, thus hot water pipes represent ideal environment for spread of Legionella. The bacteria are dormant below 20°C and do not survive above 60°C. The primary method used to control the risk from Legionella is therefore water temperature control. There are several other effective treatments to prevent growth of Legionella in water systems, however current disinfection methods can be applied only intermittently thus allowing Legionella to grow in between treatments. Here we present an alternative disinfection method based on antibacterial coatings with Cu-TiO2 nanotubes deposited on preformed surfaces. In the experiment the microbiocidal efficiency of submicron coatings on polystyrene to the bacterium of the genus Legionella pneumophila with a potential use in a water supply system was tested. The treatment thus constantly prevents growth of Legionella pneumophila in presence of water at room temperature. Here we show that 24-hour illumination with low power UVA light source (15 W/m2 UVA illumination) of copper doped TiO2 nanotube coated surfaces is effective in preventing growth of Legionella pneumophila. Microbiocidal effects of Cu-TiO2 nanotube coatings were dependent on the flow of the medium and the intensity of UV-A light. It was determined that tested submicron coatings have microbiocidal effects specially in a non-flow or low-flow conditions, as in higher flow rates, probably to a greater possibility of Legionella pneumophila sedimentation on the coated polystyrene surfaces, meanwhile no significant differences among bacteria reduction was noted regarding to non or low flow of medium.
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Affiliation(s)
- Martina Oder
- Department of Sanitary Engineering, University of Ljubljana, Faculty of Health Sciences, Ljubljana, Slovenia
| | - Tilen Koklič
- Laboratory of Biophysics, “Jožef Stefan” Institute, Ljubljana, Slovenia
| | - Polona Umek
- Laboratory of Biophysics, “Jožef Stefan” Institute, Ljubljana, Slovenia
| | - Rok Podlipec
- Laboratory of Biophysics, “Jožef Stefan” Institute, Ljubljana, Slovenia
- Helmholz Zentrum Dresden Rossendorf, Ion Beam Center, Dresden, Germany
| | - Janez Štrancar
- Laboratory of Biophysics, “Jožef Stefan” Institute, Ljubljana, Slovenia
| | - Martin Dobeic
- Institute of Food Safety Feed and Environment, University of Ljubljana, Veterinary Faculty, Ljubljana, Slovenia
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Zeng LZ, Liao HY, Luo LZ, He SS, Qin T, Zhou HJ, Li HX, Chen DL, Chen JP. An Investigation on the Molecular Characteristics and Intracellular Growth Ability among Environmental and Clinical Isolates of Legionella pneumophila in Sichuan Province, China. Biomed Environ Sci 2019; 32:520-530. [PMID: 31331436 DOI: 10.3967/bes2019.069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 06/03/2019] [Indexed: 06/10/2023]
Abstract
OBJECTIVE To investigate the molecular characteristics and intracellular growth ability of Legionella pneumophila (L. pneumophila) strains from 1989 to 2016 in Sichuan Province, China. METHODS Seventy-nine isolates of L. pneumophila were collected from environmental and clinical sources, including cooling towers, hot springs, bath water, fountains, and patients, and identified with 16S rRNA gene analysis and serum agglutination assay. The isolates were then typed by Sequence-Based Typing (SBT), and Genotyping of forty-two LP1 strains were analyzed by means of multiple-locus VNTR analysis with 8 loci (MLVA-8). All strains were further analyzed for two virulence genes: Legionella vir homologue (lvh) and repeats in structural toxin (rtxA). The intracellular growth ability of 33 selected isolates was determined by examining their interaction with J774 cells. RESULTS All isolates were identified to L. pneumophila including 11 serogroups, among which the main serogroup were LP1, accounting for 54.43%. Thirty-three different sequence types (STs) from five main clonal groups and five singletons were identified, along with 8 different MLVA patterns. Both the lvh and rtxA loci were found in all 79 strains. Thirty isolates showed high intracellular growth ability in J774 cells. CONCLUSION L. pneumophila is a potential threat to public health, and effective control and prevention strategies are urgently needed.
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Affiliation(s)
- Lin Zi Zeng
- Department of Parasitology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China; Sichuan Center for Disease Control and Prevention, Chengdu 610041, Sichuan, China
| | - Hong Yu Liao
- Sichuan Center for Disease Control and Prevention, Chengdu 610041, Sichuan, China
| | - Long Ze Luo
- Sichuan Center for Disease Control and Prevention, Chengdu 610041, Sichuan, China
| | - Shu Sen He
- Sichuan Center for Disease Control and Prevention, Chengdu 610041, Sichuan, China
| | - Tian Qin
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Hai Jian Zhou
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Hong Xia Li
- Chengdu first people's Hospital, Chengdu 610041, Sichuan, China
| | - Da Li Chen
- Department of Parasitology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Jian Ping Chen
- Department of Parasitology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
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Okubo T, Matsushita M, Nakamura S, Matsuo J, Nagai H, Yamaguchi H. Acanthamoeba S13WT relies on its bacterial endosymbiont to backpack human pathogenic bacteria and resist Legionella infection on solid media. Environ Microbiol Rep 2018; 10:344-354. [PMID: 29611898 DOI: 10.1111/1758-2229.12645] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 03/22/2018] [Indexed: 06/08/2023]
Abstract
Soil-borne amoeba Acanthamoeba S13WT has an endosymbiotic relationship with an environmental Neochlamydia bacterial strain. However, regardless of extensive experiments in liquid media, the biological advantage of the symbiosis remained elusive. We therefore explored the role of the endosymbiont in predator-prey interactions on solid media. A mixed culture of the symbiotic or aposymbiotic amoebae and GFP-expressing Escherichia coli or Salmonella Enteritidis was spotted onto the centre of a LB or B-CYE agar plate preinoculated with a ring of mCherry-expressing Legionella pneumophila (Legionella 'wall'). The spread of the amoebae on the plate was assessed using a fluorescence imaging system or scanning electron microscopy. As a result, in contrast to the aposymbiotic amoebae, the symbiotic amoebae backpacked these GFP-expressing bacteria and formed flower-like fluorescence patterns in an anticlockwise direction. Other bacteria (Pseudomonas aeruginosa and Stenotrophomonas maltophilia), but not Staphylococcus aureus, were also backpacked by the symbiotic amoebae on LB agar, although lacked the movement to anticlockwise direction. Furthermore, in contrast to the aposymbiotic amoebae, the symbiotic amoebae backpacking the E. coli broke through the Legionella 'wall' on B-CYE agar plates. Thus, we concluded that Acanthamoeba S13WT required the Neochlamydia endosymbiont to backpack human pathogenic bacteria and resist Legionella infection on solid agar.
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Affiliation(s)
- Torahiko Okubo
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, North-12, West-5, Kita-ku, Sapporo 060-0812, Japan
| | - Mizue Matsushita
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, North-12, West-5, Kita-ku, Sapporo 060-0812, Japan
| | - Shinji Nakamura
- Division of Biomedical Imaging Research, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Junji Matsuo
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, North-12, West-5, Kita-ku, Sapporo 060-0812, Japan
| | - Hiroki Nagai
- Department of Microbiology, Gifu University School of Medicine, Yanagido 1-1, Gifu, Gifu 501-1194, Japan
| | - Hiroyuki Yamaguchi
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, North-12, West-5, Kita-ku, Sapporo 060-0812, Japan
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Ji P, Rhoads WJ, Edwards MA, Pruden A. Effect of heat shock on hot water plumbing microbiota and Legionella pneumophila control. Microbiome 2018; 6:30. [PMID: 29426363 PMCID: PMC5807837 DOI: 10.1186/s40168-018-0406-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 01/18/2018] [Indexed: 05/25/2023]
Abstract
BACKGROUND Heat shock is a potential control strategy for Legionella pneumophila in hot water plumbing systems. However, it is not consistently effective, with little understanding of its influence on the broader plumbing microbiome. Here, we employed a lab-scale recirculating hot water plumbing rig to compare the pre- and post-"heat shock" (i.e., 40 → 60 → 40 °C) microbiota at distal taps. In addition, we used a second plumbing rig to represent a well-managed system at 60 °C and conducted a "control" sampling at 60 °C, subsequently reducing the temperature to 40 °C to observe the effects on Legionella and the microbiota under a simulated "thermal disruption" scenario. RESULTS According to 16S rRNA gene amplicon sequencing, in the heat shock scenario, there was no significant difference or statistically significant, but small, difference in the microbial community composition at the distal taps pre- versus post-heat shock (both biofilm and water; weighted and unweighted UniFrac distance matrices). While heat shock did lead to decreased total bacteria numbers at distal taps, it did not measurably alter the richness or evenness of the microbiota. Quantitative PCR measurements demonstrated that L. pneumophila relative abundance at distal taps also was not significantly different at 2-month post-heat shock relative to the pre-heat shock condition, while relative abundance of Vermamoeba vermiformis, a known Legionella host, did increase. In the thermal disruption scenario, relative abundance of planktonic L. pneumophila (quantitative PCR data) increased to levels comparable to those observed in the heat shock scenario within 2 months of switching long-term operation at 60 to 40 °C. Overall, water use frequency and water heater temperature set point exhibited a stronger effect than one-time heat shock on the microbial composition and Legionella levels at distal taps. CONCLUSIONS While heat shock may be effective for instantaneous Legionella control and reduction in total bacteria numbers, water heater temperature set point and water use frequency are more promising factors for long-term Legionella and microbial community control, illustrating the importance of maintaining consistent elevated temperatures in the system relative to short-term heat shock.
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Affiliation(s)
- Pan Ji
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
| | - William J Rhoads
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Marc A Edwards
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Amy Pruden
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA.
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Veenendaal HR, Brouwer-Hanzens AJ, van der Kooij D. Incubation of premise plumbing water samples on Buffered Charcoal Yeast Extract agar at elevated temperature and pH selects for Legionella pneumophila. Water Res 2017; 123:439-447. [PMID: 28689128 DOI: 10.1016/j.watres.2017.06.077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 05/30/2017] [Accepted: 06/26/2017] [Indexed: 06/07/2023]
Abstract
Worldwide, over 90% of the notified cases of Legionnaires' disease are caused by Legionella pneumophila. However, the standard culture medium for the detection of Legionella in environmental water samples, Buffered Charcoal Yeast Extract (BCYE) agar of pH 6.9 ± 0.4 with or without antimicrobial agents incubated at 36 ± 1 °C, supports the growth of a large diversity of Legionella species. BCYE agar of elevated pH or/and incubation at elevated temperature gave strongly reduced recoveries of most of 26 L. non-pneumophila spp. tested, but not of L. pneumophila. BCYE agar of pH 7.3 ± 0.1, incubated at 40 ± 0.5 °C (BCYE pH 7.3/40 °C) was tested for selective enumeration of L. pneumophila. Of the L. non-pneumophila spp. tested, only L. adelaidensis and L. londiniensis multiplied under these conditions. The colony counts on BCYE pH 7.3/40 °C of a L. pneumophila serogroup 1 strain cultured in tap water did not differ significantly from those on BCYE pH 6.9/36 °C when directly plated and after membrane filtration and showed repeatability's of 13-14%. By using membrane filtration L. pneumophila was detected in 58 (54%) of 107 Legionella-positive water samples from premise plumbing systems under one or both of these culture conditions. The L. pneumophila colony counts (log-transformed) on BCYE pH 7.3/40 °C were strongly related (r2 = 0.87) to those on BCYE pH 6.9/36 °C, but differed significantly (p < 0.05) by a mean of - 0.12 ± 0.30 logs. L. non-pneumophila spp. were detected only on BCYE pH 6.9/36 °C in 49 (46%) of the samples. Hence, BCYE pH 7.3/40 °C can facilitate the enumeration of L. pneumophila and their isolation from premise plumbing systems with culturable L. non-pneumophila spp., some of which, e.g. L. anisa, can be present in high numbers.
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Affiliation(s)
- Harm R Veenendaal
- KWR Watercycle Research Institute, PO Box 1072, 3430 BB, Nieuwegein, The Netherlands
| | | | - Dick van der Kooij
- KWR Watercycle Research Institute, PO Box 1072, 3430 BB, Nieuwegein, The Netherlands.
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Proctor CR, Dai D, Edwards MA, Pruden A. Interactive effects of temperature, organic carbon, and pipe material on microbiota composition and Legionella pneumophila in hot water plumbing systems. Microbiome 2017; 5:130. [PMID: 28978350 PMCID: PMC5628487 DOI: 10.1186/s40168-017-0348-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 09/20/2017] [Indexed: 05/22/2023]
Abstract
BACKGROUND Several biotic and abiotic factors have been reported to influence the proliferation of microbes, including Legionella pneumophila, in hot water premise plumbing systems, but their combined effects have not been systematically evaluated. Here, we utilize simulated household water heaters to examine the effects of stepwise increases in temperature (32-53 °C), pipe material (copper vs. cross-linked polyethylene (PEX)), and influent assimilable organic carbon (0-700 μg/L) on opportunistic pathogen gene copy numbers and the microbiota composition, as determined by quantitative polymerase chain reaction and 16S rRNA gene amplicon sequencing. RESULTS Temperature had an overarching influence on both the microbiota composition and L. pneumophila numbers. L. pneumophila peaked at 41 °C in the presence of PEX (1.58 × 105 gene copies/mL). At 53 °C, L. pneumophila was not detected. Several operational taxonomic units (OTUs) persisted across all conditions, accounting for 50% of the microbiota composition from 32 to 49 °C and 20% at 53 °C. Pipe material most strongly influenced microbiota composition at lower temperatures, driven by five to six OTUs enriched with each material. Copper pipes supported less L. pneumophila than PEX pipes (mean 2.5 log10 lower) at temperatures ≤ 41 °C, but showed no difference in total bacterial numbers. Differences between pipe materials diminished with elevated temperature, probably resulting from decreased release of copper ions. At temperatures ≤ 45 °C, influent assimilable organic carbon correlated well with total bacterial numbers, but not with L. pneumophila numbers. At 53 °C, PEX pipes leached organic carbon, reducing the importance of dosed organic carbon. L. pneumophila numbers correlated with a Legionella OTU and a Methylophilus OTU identified by amplicon sequencing. CONCLUSIONS Temperature was the most effective factor for the control of L. pneumophila, while microbiota composition shifted with each stepwise temperature increase. While copper pipe may also help shape the microbiota composition and limit L. pneumophila proliferation, its benefits might be constrained at higher temperatures. Influent assimilable organic carbon affected total bacterial numbers, but had minimal influence on opportunistic pathogen gene numbers or microbiota composition. These findings provide guidance among multiple control measures for the growth of opportunistic pathogens in hot water plumbing and insight into the mediating role of microbial ecological factors.
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Affiliation(s)
- Caitlin R. Proctor
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, 24061 USA
- EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Überlandstr 133, CH-8600 Duebendorf, Switzerland
| | - Dongjuan Dai
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, 24061 USA
| | - Marc A. Edwards
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, 24061 USA
| | - Amy Pruden
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, 24061 USA
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Jwanoswki K, Wells C, Bruce T, Rutt J, Banks T, McNealy TL. The Legionella pneumophila GIG operon responds to gold and copper in planktonic and biofilm cultures. PLoS One 2017; 12:e0174245. [PMID: 28463986 PMCID: PMC5413113 DOI: 10.1371/journal.pone.0174245] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Accepted: 03/06/2017] [Indexed: 11/18/2022] Open
Abstract
Legionella pneumophila contaminates man-made water systems and creates numerous exposure risks for Legionnaires’ Disease. Because copper/silver ionization is commonly used to control L. pneumophila, its mechanisms of metal response and detoxification are of significant interest. Here we describe an L. pneumophila operon with significant similarity to the GIG operon of Cupriavidus metallidurans. The Legionella GIG operon is present in a subset of strains and has been acquired as part of the ICE-βox 65-kB integrative conjugative element. We assessed GIG promoter activity following exposure of L. pneumophila to multiple concentrations of HAuCl4, CuSO4 and AgNO3. At 37°C, control stationary phase cultures exhibited GIG promoter activity. This activity increased significantly in response to 20 and 50uM HAuCl4 and CuSO4 but not in response to AgNO3. Conversely, at 26°C, cultures exhibited decreased promoter response to copper. GIG promoter activity was also induced by HAuCl4 or CuSO4 during early biofilm establishment at both temperatures. When an L. pneumophila GIG promoter construct was transformed into E. coli DH5α, cultures showed baseline expression levels that did not increase following metal addition. Analysis of L. pneumophila transcriptional regulatory mutants suggested that GIG up-regulation in the presence of metal ions may be influenced by the stationary phase sigma factor, RpoS.
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Affiliation(s)
- Kathleen Jwanoswki
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Christina Wells
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Terri Bruce
- Clemson Light Imaging Facility, Clemson University, Clemson, South Carolina, United States of America
| | - Jennifer Rutt
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Tabitha Banks
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Tamara L. McNealy
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
- * E-mail:
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Rhoads WJ, Ji P, Pruden A, Edwards MA. Water heater temperature set point and water use patterns influence Legionella pneumophila and associated microorganisms at the tap. Microbiome 2015; 3:67. [PMID: 26627188 PMCID: PMC4666224 DOI: 10.1186/s40168-015-0134-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/17/2015] [Indexed: 05/22/2023]
Abstract
BACKGROUND Lowering water heater temperature set points and using less drinking water are common approaches to conserving water and energy; yet, there are discrepancies in past literature regarding the effects of water heater temperature and water use patterns on the occurrence of opportunistic pathogens, in particular Legionella pneumophila. Our objective was to conduct a controlled, replicated pilot-scale investigation to address this knowledge gap using continuously recirculating water heaters to examine five water heater set points (39-58 °C) under three water use conditions. We hypothesized that L. pneumophila levels at the tap depend on the collective influence of water heater temperature, flow frequency, and the resident plumbing ecology. RESULTS We confirmed temperature setting to be a critical factor in suppressing L. pneumophila growth both in continuously recirculating hot water lines and at distal taps. For example, at 51 °C, planktonic L. pneumophila in recirculating lines was reduced by a factor of 28.7 compared to 39 °C and was prevented from re-colonizing biofilm. However, L. pneumophila still persisted up to 58 °C, with evidence that it was growing under the conditions of this study. Further, exposure to 51 °C water in a low-use tap appeared to optimally select for L. pneumophila (e.g., 125 times greater numbers than in high-use taps). We subsequently explored relationships among L. pneumophila and other ecologically relevant microbes, noting that elevated temperature did not have a general disinfecting effect in terms of total bacterial numbers. We documented the relationship between L. pneumophila and Legionella spp., and noted several instances of correlations with Vermamoeba vermiformis, and generally found that there is a dynamic relationship with this amoeba host over the range of temperatures and water use frequencies examined. CONCLUSIONS Our study provides a new window of understanding into the microbial ecology of potable hot water systems and helps to resolve past discrepancies in the literature regarding the influence of water temperature and stagnation on L. pneumophila, which is the cause of a growing number of outbreaks. This work is especially timely, given society's movement towards "green" buildings and the need to reconcile innovations in building design with public health.
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Affiliation(s)
- William J Rhoads
- Charles E. Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Pan Ji
- Charles E. Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Amy Pruden
- Charles E. Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Marc A Edwards
- Charles E. Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
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Mendis N, McBride P, Faucher SP. Short-Term and Long-Term Survival and Virulence of Legionella pneumophila in the Defined Freshwater Medium Fraquil. PLoS One 2015; 10:e0139277. [PMID: 26406895 PMCID: PMC4583229 DOI: 10.1371/journal.pone.0139277] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 09/09/2015] [Indexed: 12/03/2022] Open
Abstract
Legionella pneumophila (Lp) is the etiological agent responsible for Legionnaires’ disease, a potentially fatal pulmonary infection. Lp lives and multiplies inside protozoa in a variety of natural and man-made water systems prior to human infection. Fraquil, a defined freshwater medium, was used as a highly reproducible medium to study the behaviour of Lp in water. Adopting a reductionist approach, Fraquil was used to study the impact of temperature, pH and trace metal levels on the survival and subsequent intracellular multiplication of Lp in Acanthamoeba castellanii, a freshwater protozoan and a natural host of Legionella. We show that temperature has a significant impact on the short- and long-term survival of Lp, but that the bacterium retains intracellular multiplication potential for over six months in Fraquil. Moreover, incubation in Fraquil at pH 4.0 resulted in a rapid decline in colony forming units, but was not detrimental to intracellular multiplication. In contrast, variations in trace metal concentrations had no impact on either survival or intracellular multiplication in amoeba. Our data show that Lp is a resilient bacterium in the water environment, remaining infectious to host cells after six months under the nutrient-deprived conditions of Fraquil.
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Affiliation(s)
- Nilmini Mendis
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Peter McBride
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Sébastien P. Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
- * E-mail:
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Tartakovsky IS, Karpoval TI, Gruzdeva OA, Marinenko OV, Dronina YE. [EFFECT OF TEMPERATURE ON THE VIABILITY OF PLANKTON CELLS AND MODEL LEGIONELLA PNEUMOPHILA BIOFILMS IN WATER]. Zh Mikrobiol Epidemiol Immunobiol 2015:7-12. [PMID: 26829847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
AIM Study the effect of water temperature from 40 to 70 degrees C on viability of plankton forms and model Legionella pneumophila under experimental conditions. MATERIALS AND METHODS Monospecies legionella biofilms, obtained in plates for enzyme immunoassay during 96 hours at 28 degrees C, and water suspension of BCYE agar cultivated cells of L. pneumophila at a concentration of 10(3) - 10(5) CFU per liter were used in the study for evaluation of bactericidal effect of temperature on various legionella forms. RESULTS Analysis of effects of various temperature regimens on plankton forms and model legionella biofilms has shown that at a temperature range from 50 to 60 degrees C a significant reduction of quantity of viable legionella cells occurs. Model legionella biofilms have partially conserved viability at a temperature of 60 degrees C and only exposition to a temperature of 70 degrees C resulted in death of legionella biofilms and plankton forms of bacteria. A dependence of viability conservation of legionella from the initial concentration of the causative agent in water and duration of exposition at varying temperature was shown. CONCLUSION Short-term heating at a temperature of at least 70 degrees C has the most pronounced bactericidal effect on plankton forms and model L. pneumophila biofilms under experimental conditions. Such temperature regimen could be used as one of the prophylaxis approaches during maintenance of especially dangerous water system and, fist of all, systems of hot water supply.
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Rodríguez-Martínez S, Sharaby Y, Pecellín M, Brettar I, Höfle M, Halpern M. Spatial distribution of Legionella pneumophila MLVA-genotypes in a drinking water system. Water Res 2015; 77:119-132. [PMID: 25864003 DOI: 10.1016/j.watres.2015.03.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 03/10/2015] [Accepted: 03/12/2015] [Indexed: 06/04/2023]
Abstract
Bacteria of the genus Legionella cause water-based infections, resulting in severe pneumonia. To improve our knowledge about Legionella spp. ecology, its prevalence and its relationships with environmental factors were studied. Seasonal samples were taken from both water and biofilm at seven sampling points of a small drinking water distribution system in Israel. Representative isolates were obtained from each sample and identified to the species level. Legionella pneumophila was further determined to the serotype and genotype level. High resolution genotyping of L. pneumophila isolates was achieved by Multiple-Locus Variable number of tandem repeat Analysis (MLVA). Within the studied water system, Legionella plate counts were higher in summer and highly variable even between adjacent sampling points. Legionella was present in six out of the seven selected sampling points, with counts ranging from 1.0 × 10(1) to 5.8 × 10(3) cfu/l. Water counts were significantly higher in points where Legionella was present in biofilms. The main fraction of the isolated Legionella was L. pneumophila serogroup 1. Serogroup 3 and Legionella sainthelensis were also isolated. Legionella counts were positively correlated with heterotrophic plate counts at 37 °C and negatively correlated with chlorine. Five MLVA-genotypes of L. pneumophila were identified at different buildings of the sampled area. The presence of a specific genotype, "MLVA-genotype 4", consistently co-occurred with high Legionella counts and seemed to "trigger" high Legionella counts in cold water. Our hypothesis is that both the presence of L. pneumophila in biofilm and the presence of specific genotypes, may indicate and/or even lead to high Legionella concentration in water. This observation deserves further studies in a broad range of drinking water systems to assess its potential for general use in drinking water monitoring and management.
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Affiliation(s)
- Sarah Rodríguez-Martínez
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Yehonatan Sharaby
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Marina Pecellín
- Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Ingrid Brettar
- Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Manfred Höfle
- Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Malka Halpern
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel; Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa, Oranim, Tivon, Israel.
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20
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Oder M, Kompare B, Bohinc K, Torkar KG. The impact of material surface roughness and temperature on the adhesion of Legionella pneumophila to contact surfaces. Int J Environ Health Res 2014; 25:469-479. [PMID: 25307889 DOI: 10.1080/09603123.2014.963035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 08/03/2014] [Indexed: 06/04/2023]
Abstract
The adhesion of bacterial cells to various surfaces is based on physical and chemical interactions between the micro-organisms and the surfaces. The main purpose of this research is to determine the effect of material roughness and incubation temperature on the adhesion of bacteria. To determine the adhesion of the bacterial strain of Legionella pneumophila ATCC 33153 to the glass coupons, a spectrophotometric method of measuring the optical density of crystal violet dye that is released from pre-stained bacterial cells attached to the test surface was used. The intensity of adhesion is in positive correlation to the increase in surface roughness (p < 0.05). The adhesion is the greatest at an optimal temperature of 36 °C, whereas the temperature of 15 °C has a bacteriostatic effect and the temperature of 55 °C a bactericidal effect.
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Affiliation(s)
- Martina Oder
- a Faculty of Health Sciences , University of Ljubljana , Ljubljana , Slovenia
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Fonseca MV, Sauer JD, Crepin S, Byrne B, Swanson MS. The phtC-phtD locus equips Legionella pneumophila for thymidine salvage and replication in macrophages. Infect Immun 2014; 82:720-30. [PMID: 24478086 PMCID: PMC3911408 DOI: 10.1128/iai.01043-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/24/2013] [Indexed: 11/20/2022] Open
Abstract
The phagosomal transporter (Pht) family of the major facilitator superfamily (MFS) is encoded by phylogenetically related intracellular gammaproteobacteria, including the opportunistic pathogen Legionella pneumophila. The location of the pht genes between the putative thymidine kinase (tdk) and phosphopentomutase (deoB) genes suggested that the phtC and phtD loci contribute to thymidine salvage in L. pneumophila. Indeed, a phtC(+) allele in trans restored pyrimidine uptake to an Escherichia coli mutant that lacked all known nucleoside transporters, whereas a phtD(+) allele did not. The results of phenotypic analyses of L. pneumophila strains lacking phtC or phtD strongly indicate that L. pneumophila requires PhtC and PhtD function under conditions where sustained dTMP synthesis is compromised. First, in broth cultures that mimicked thymidine limitation or starvation, L. pneumophila exhibited a marked requirement for PhtC function. Conversely, mutation of phtD conferred a survival advantage. Second, in medium that lacked thymidine, multicopy phtC(+) or phtD(+) alleles enhanced the survival of L. pneumophila thymidylate synthase (thyA)-deficient strains, which cannot synthesize dTMP endogenously. Third, under conditions in which transport of the pyrimidine nucleoside analog 5-fluorodeoxyuridine (FUdR) would inhibit growth, PhtC and PhtD conferred a growth advantage to L. pneumophila thyA(+) strains. Finally, when cultured in macrophages, L. pneumophila required the phtC-phtD locus to replicate. Accordingly, we propose that PhtC and PhtD contribute to protect L. pneumophila from dTMP starvation during its intracellular life cycle.
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Affiliation(s)
- Maris V Fonseca
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
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22
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Ducret A, Chabalier M, Dukan S. Characterization and resuscitation of 'non-culturable' cells of Legionella pneumophila. BMC Microbiol 2014; 14:3. [PMID: 24383402 PMCID: PMC3882098 DOI: 10.1186/1471-2180-14-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 12/02/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Legionella pneumophila is a waterborne pathogen responsible for Legionnaires' disease, an infection which can lead to potentially fatal pneumonia. After disinfection, L. pneumophila has been detected, like many other bacteria, in a "viable but non culturable" state (VBNC). The physiological significance of the VBNC state is unclear and controversial: it could be an adaptive response favoring long-term survival; or the consequence of cellular deterioration which, despite maintenance of certain features of viable cells, leads to death; or an injured state leading to an artificial loss of culturability during the plating procedure. VBNC cells have been found to be resuscitated by contact with amoebae. RESULTS We used quantitative microscopic analysis, to investigate this "resuscitation" phenomenon in L. pneumophila in a model involving amending solid plating media with ROS scavengers (pyruvate or glutamate), and co-culture with amoebae. Our results suggest that the restoration observed in the presence of pyruvate and glutamate may be mostly due to the capacity of these molecules to help the injured cells to recover after a stress. We report evidence that this extracellular signal leads to a transition from a not-culturable form to a culturable form of L. pneumophila, providing a technique for recovering virulent and previously uncultivated forms of L. pneumophila. CONCLUSION These new media could be used to reduce the risk of underestimation of counts of virulent of L. pneumophila cells in environmental samples.
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Affiliation(s)
- Adrien Ducret
- Aix Marseille Université, Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée - CNRS, 31, Chemin Joseph Aiguier, 13402 Marseille, France
- Present address: Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405 USA
| | - Maïalène Chabalier
- Aix Marseille Université, Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée - CNRS, 31, Chemin Joseph Aiguier, 13402 Marseille, France
| | - Sam Dukan
- Aix Marseille Université, Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée - CNRS, 31, Chemin Joseph Aiguier, 13402 Marseille, France
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Akamine M, Higa F, Haranaga S, Tateyama M, Mori N, Heuner K, Fujita J. Interferon-Gamma Reverses the Evasion ofBirc1e/Naip5Gene Mediated Murine Macrophage Immunity byLegionella pneumophilaMutant Lacking Flagellin. Microbiol Immunol 2013; 51:279-87. [PMID: 17380047 DOI: 10.1111/j.1348-0421.2007.tb03909.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Legionella pneumophila is the etiologic agent of Legionnaires' disease. This bacterium contains a single monopolar flagellum, of which the FlaA subunit is a major protein constituent. The murine macrophage resistance against this bacterium is controlled by the Birc1e/Naip5 gene, which belongs to the NOD family. We evaluated the intracellular growth of the flaA mutant bacteria as well as another aflagellated fliA mutant, within bone marrow-derived macrophages from mice with an intact (C57BL/6, BALB/c) or mutated (A/J) Birc1e/Naip5 gene. The flaA mutant L. pneumophila multiplied within C57BL/6 and BALB/c macrophages while the wild-type strain did not. Cell viability was not impaired until 3 days after infection when the flaA mutant bacteria replicated 10(2-3)-fold in macrophages, implying that L. pneumophila inhibited host cell death during the early phase of intracellular replication. The addition of recombinant interferon-gamma (IFN-gamma) to the infected macrophages restricted replication of the flaA mutant within macrophages; these treated cells also showed enhanced nitric oxide production, although inhibition of nitric oxide production did not affect the IFN-gamma induced inhibition of Legionella replication. These findings suggested that IFN-gamma activated macrophages to restrict the intracellular growth of the L. pneumophila flaA mutant by a NO independent pathway.
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Affiliation(s)
- Morikazu Akamine
- Department of Medicine and Therapeutics, Control and Prevention of Infectious Diseases, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan.
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24
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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25
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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26
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Buse HY, Donohue MJ, Ashbolt NJ. Hartmannella vermiformis inhibition of Legionella pneumophila cultivability. Microb Ecol 2013; 66:715-726. [PMID: 23764733 DOI: 10.1007/s00248-013-0250-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/27/2013] [Indexed: 06/02/2023]
Abstract
Hartmannella vermiformis and Acanthamoeba polyphaga are frequently isolated from drinking water and permissive to Legionella pneumophila parasitization. In this study, extracellular factor(s) produced by H. vermiformis and A. polyphaga were assessed for their effects on cultivability of L. pneumophila. Page's amoeba saline (PAS) was used as an encystment medium for H. vermiformis and A. polyphaga monolayers, and the culture supernatants (HvS and ApS, respectively) were assessed against L. pneumophila growth. Compared to PAS and ApS, HvS significantly inhibited L. pneumophila strain Philadelphia-1 (Ph-1) cultivability by 3 log(10) colony forming unit (CFU) mL(-1) after 3 days of exposure compared to <0.5 log(10) CFU mL(-1) reduction of strain Lp02 (P < 0.001). Flow cytometric analysis revealed changes in the percentage and cultivability of three bacterial subpopulations: intact/slightly damaged membrane (ISM), undefined membrane status (UD), and mixed type (MT). After 3 days of HvS exposure, the MT subpopulation decreased significantly (31.6 vs 67.2 %, respectively, P < 0.001), while the ISM and UD subpopulations increased (+26.7 and +6.9 %, respectively) with the ISM subpopulation appearing as viable but nonculturable (VBNC) cells. HvS was separated into two fractions based on molecular weight, with more than 99 % of the L. pneumophila inhibition arising from the <5 kDa fraction (P < 0.001). Liquid chromatography indicated the inhibitory molecule(s) are likely polar and elute from a Novapak C18 column between 6 and 15 min. These results demonstrate that H. vermiformis is capable of extracellular modulation of L. pneumophila cultivability and probably promote the VBNC state for this bacterium.
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Affiliation(s)
- Helen Y Buse
- Dynamac c/o US Environmental Protection Agency, 26 W Martin Luther King Dr, Cincinnati, OH, 45268, USA,
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27
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Harrison CF, Kicka S, Trofimov V, Berschl K, Ouertatani-Sakouhi H, Ackermann N, Hedberg C, Cosson P, Soldati T, Hilbi H. Exploring anti-bacterial compounds against intracellular Legionella. PLoS One 2013; 8:e74813. [PMID: 24058631 PMCID: PMC3772892 DOI: 10.1371/journal.pone.0074813] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Accepted: 08/06/2013] [Indexed: 01/10/2023] Open
Abstract
Legionella pneumophila is a ubiquitous fresh-water bacterium which reproduces within its erstwhile predators, environmental amoeba, by subverting the normal pathway of phagocytosis and degradation. The molecular mechanisms which confer resistance to amoeba are apparently conserved and also allow replication within macrophages. Thus, L. pneumophila can act as an 'accidental' human pathogen and cause a severe pneumonia known as Legionnaires' disease. The intracellular localisation of L. pneumophila protects it from some antibiotics, and this fact must be taken into account to develop new anti-bacterial compounds. In addition, the intracellular lifestyle of L. pneumophila may render the bacteria susceptible to compounds diminishing bacterial virulence and decreasing intracellular survival and replication of this pathogen. The development of a single infection cycle intracellular replication assay using GFP-producing L. pneumophila and Acanthamoebacastellanii amoeba is reported here. This fluorescence-based assay allows for continuous monitoring of intracellular replication rates, revealing the effect of bacterial gene deletions or drug treatment. To examine how perturbations of the host cell affect L. pneumophila replication, several known host-targeting compounds were tested, including modulators of cytoskeletal dynamics, vesicle scission and Ras GTPase localisation. Our results reveal a hitherto unrealized potential antibiotic property of the β-lactone-based Ras depalmitoylation inhibitor palmostatin M, but not the closely related inhibitor palmostatin B. Further characterisation indicated that this compound caused specific growth inhibition of Legionella and Mycobacterium species, suggesting that it may act on a common bacterial target.
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Affiliation(s)
| | - Sébastien Kicka
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Valentin Trofimov
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Kathrin Berschl
- Max von Pettenkofer Institute, Ludwig-Maximilians University, Munich, Germany
| | | | - Nikolaus Ackermann
- Max von Pettenkofer Institute, Ludwig-Maximilians University, Munich, Germany
| | | | - Pierre Cosson
- Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Thierry Soldati
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Hubert Hilbi
- Max von Pettenkofer Institute, Ludwig-Maximilians University, Munich, Germany
- * E-mail:
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28
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Gómez-Lus ML, Corcuera MT, Gómez-Lus R, Sánchez-Serrano C, Gómez-Aguado F, Alonso MJ, Prieto J. [Structural dynamics of Legionella pneumophila and Legionella bozemanii colony/biofilm]. Rev Esp Quimioter 2013; 26:214-219. [PMID: 24080887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
OBJECTIVES The genus Legionella includes very pleomorphic species responsible for disease outbreaks in humans. The appearance of such has great importance to develop artificial biofilms in aquatic ecosystems. The aim of this work was to study the dynamics of growth and evolution of the internal structure of colonies of representative species of the genus as static biofilm model. METHODS Isolated colonies of Legionella pneumophila and Legionella bozemanii grown in specific media for three and fifteen days were processed for histological methods and embedded in paraffin and epoxy resin for analysis by light microscopy, electron microscopy and image analysis. RESULTS. In colonies of both species were observed and defined specific architectural patterns, based on stratification and evolve over time. The strata differ in the amount of extracellular matrix, the morphology and population density and the proportion of dead cells. The internal structure of three days colonies showed large differences between L. pneumophila (two layers) and L. bozemanii (four layers). However, in the fifteen days colonies of both species evolved towards a common unique pattern formed by three layers. In both species the growth was also found within the culture medium, although this phenomenon was more intense in L. bozemanii with unique, central and larger invasions. CONCLUSIONS Our results demonstrate that Legionella colonies on solid culture media are a good model of static biofilm with a complex structural dynamics characterized by the presence of morphological and functional subpopulations. We bring here an histological approach model, allowing, in further research, detailed studies in evolutionary adaptations in multicellular communities to adverse media and to antimicrobials in Legionella species of clinical interest.
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Affiliation(s)
- María Luisa Gómez-Lus
- María Luisa Gómez-Lus, Departamento de Medicina, Área de Microbiología, Facultad de Medicina, Universidad Complutense de Madrid, Avda Complutense s/n 28040, Madrid, Spain.
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29
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Khan MA, Knox N, Prashar A, Alexander D, Abdel-Nour M, Duncan C, Tang P, Amatullah H, Dos Santos CC, Tijet N, Low DE, Pourcel C, Van Domselaar G, Terebiznik M, Ensminger AW, Guyard C. Comparative Genomics Reveal That Host-Innate Immune Responses Influence the Clinical Prevalence of Legionella pneumophila Serogroups. PLoS One 2013; 8:e67298. [PMID: 23826259 PMCID: PMC3694923 DOI: 10.1371/journal.pone.0067298] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 05/16/2013] [Indexed: 11/19/2022] Open
Abstract
Legionella pneumophila is the primary etiologic agent of legionellosis, a potentially fatal respiratory illness. Amongst the sixteen described L. pneumophila serogroups, a majority of the clinical infections diagnosed using standard methods are serogroup 1 (Sg1). This high clinical prevalence of Sg1 is hypothesized to be linked to environmental specific advantages and/or to increased virulence of strains belonging to Sg1. The genetic determinants for this prevalence remain unknown primarily due to the limited genomic information available for non-Sg1 clinical strains. Through a systematic attempt to culture Legionella from patient respiratory samples, we have previously reported that 34% of all culture confirmed legionellosis cases in Ontario (n = 351) are caused by non-Sg1 Legionella. Phylogenetic analysis combining multiple-locus variable number tandem repeat analysis and sequence based typing profiles of all non-Sg1 identified that L. pneumophila clinical strains (n = 73) belonging to the two most prevalent molecular types were Sg6. We conducted whole genome sequencing of two strains representative of these sequence types and one distant neighbour. Comparative genomics of the three L. pneumophila Sg6 genomes reported here with published L. pneumophila serogroup 1 genomes identified genetic differences in the O-antigen biosynthetic cluster. Comparative optical mapping analysis between Sg6 and Sg1 further corroborated this finding. We confirmed an altered O-antigen profile of Sg6, and tested its possible effects on growth and replication in in vitro biological models and experimental murine infections. Our data indicates that while clinical Sg1 might not be better suited than Sg6 in colonizing environmental niches, increased bloodstream dissemination through resistance to the alternative pathway of complement mediated killing in the human host may explain its higher prevalence.
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Affiliation(s)
- Mohammad Adil Khan
- Public Health Ontario, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Natalie Knox
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Akriti Prashar
- Cell and Systems Biology and Biological Sciences, University of Toronto at Scarborough, Scarborough, Ontario, Canada
| | - David Alexander
- Public Health Ontario, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Mena Abdel-Nour
- Public Health Ontario, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | | | | | - Hajera Amatullah
- The Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Claudia C. Dos Santos
- The Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | | | - Donald E. Low
- Public Health Ontario, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Christine Pourcel
- Institut de Génétique et Microbiologie, Université Paris-Sud, Paris, France
| | - Gary Van Domselaar
- Cell and Systems Biology and Biological Sciences, University of Toronto at Scarborough, Scarborough, Ontario, Canada
| | - Mauricio Terebiznik
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Alexander W. Ensminger
- Public Health Ontario, Toronto, Ontario, Canada
- Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Cyril Guyard
- Public Health Ontario, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
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30
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Messi P, Bargellini A, Anacarso I, Marchesi I, de Niederhäusern S, Bondi M. Protozoa and human macrophages infection by Legionella pneumophila environmental strains belonging to different serogroups. Arch Microbiol 2013; 195:89-96. [PMID: 23135482 DOI: 10.1007/s00203-012-0851-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 10/11/2012] [Accepted: 10/29/2012] [Indexed: 12/01/2022]
Abstract
Three Legionella pneumophila strains isolated from municipal hot tap water during a multicentric Italian survey and belonging to serogroups 1, 6, 9 and the reference strain Philadelphia-1 were studied to determine the intracellular replication capability and the cytopathogenicity in human monocyte cell line U937 and in an Acanthamoeba polyphaga strain. Our results show that both serogroups 1 and Philadelphia-1 were able to multiply into macrophages inducing cytopathogenicity, while serogroup 6 and ever more serogroup 9 were less efficient in leading to death of the infected macrophages. Both serogroups 1 and 6 displayed a quite good capability of intracellular replication in A. polyphaga, although serogroup 1 was less cytopathogenic than serogroup 6. Serogroup 9, like Philadelphia-1 strain, showed a reduced efficiency of infection and replication and a low cytopathogenicity towards the protozoan. Our study suggests that bacterial pathogenesis is linked to the difference in the virulence expression of L. pneumophila serogroups in both hosts, as demonstrated by the fact that only L. pneumophila serogroup 1 shows the contextual expression of the two virulence traits. Serogroup 6 proves to be a good candidate as pathogen since it shows a good capacity for intracellular replication in protozoan.
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Affiliation(s)
- Patrizia Messi
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy.
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31
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Raftery TD, Lindler H, McNealy TL. Altered host cell-bacteria interaction due to nanoparticle interaction with a bacterial biofilm. Microb Ecol 2013; 65:496-503. [PMID: 23052925 DOI: 10.1007/s00248-012-0128-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 09/15/2012] [Indexed: 06/01/2023]
Abstract
Nanoparticle (NP) use in everyday applications creates the potential for NPs to enter the environment where, in aquatic systems, they are likely to settle on substrates and interact with microbial communities. Legionella pneumophila biofilms are found as part of microbial communities in both natural and man-made environments, especially in man-made cooling systems. The bacterium is the causative agent of Legionnaires' disease. Legionella requires a host cell for replication in the environment, and amoebae commonly serve as this host cell. Our previous work demonstrated significant changes in Legionella biofilm morphology after exposure to 0.7 μg/L gold NPs (AuNPs). Here, we investigate how these morphology changes alter host-bacteria interactions using Acanthamoeba polyphaga as a model. Host-bacteria-NP interactions are affected by NP characteristics. Biofilms exposed to 4- and 18-nm, citrate-capped, spherical AuNPs significantly altered the grazing ability of A. polyphaga, which was not observed in biofilms exposed to 24-nm polystyrene beads. Uptake and replication of NP-exposed planktonic L. pneumophila within A. polyphaga were not altered regardless of NP size or core chemistry. Nanomaterial effects on the interaction of benthic organisms and bacteria may be directly or, as shown here, indirectly dependent on bacterial morphology. NP contamination therefore may alter interactions in a normal ecosystem function.
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Affiliation(s)
- Tara D Raftery
- Institute of Environmental Toxicology (CU-ENTOX), Clemson University, Clemson, SC 29634, USA.
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Abstract
Caspase-1 is a critical factor in the innate immune response to Legionella pneumophila. The development of methods for analyzing caspase-1 activation pathways and downstream caspase-1-associated activities has helped in understanding the regulation of this protease and the signaling components involved. Here we outline methods for directly detecting active caspase-1, measuring caspase-1 activities and analyzing components involved in the regulation of caspase-1 during L. pneumophila infection in macrophages.
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Affiliation(s)
- Christopher L Case
- Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, CT, USA
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Abstract
This chapter describes methods for culturing Legionella pneumophila in both complex and defined media. The first protocol describes the use of buffered charcoal yeast extract (BCYE) agar, the solid medium that is most commonly used for culturing L. pneumophila. The next procedure details the cultivation of L. pneumophila in buffered yeast extract (BYE) broth, i.e., the liquid medium version of BCYE agar. We describe how culturing in BYE broth can also be used for investigating proteins that are secreted by the type II secretion system of L. pneumophila. The next part of the chapter explains the cultivation of L. pneumophila in a chemically defined liquid media (CDM). CDM contains a mixture of amino acids, metals, α-ketoglutarate, and pyruvate. Because of its defined nature, CDM provides a simple means for controlling the concentration of nutrients and thereby allows for investigations of physiology and metabolism. To illustrate this point, the use of deferrated CDM for the purpose of assessing Legionella siderophore production is outlined. Finally, the chapter ends with a brief discussion of the storage and shipping of L. pneumophila.
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Affiliation(s)
- Christa H Chatfield
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, IL, USA
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Abstract
The production of outer membrane vesicles (OMVs) is a widespread phenomenon employed by bacteria to secrete cell envelope components into the environment. A contribution of Legionella pneumophila OMVs to the pathogenesis of Legionnaires' disease is likely due to the high number of virulence-related proteins in the vesicles. OMVs are isolated from the supernatant of liquid cultures of L. pneumophila. After low-speed centrifugation, residual bacteria and cell fragments are eliminated by passing the supernatant through a filter. OMVs are pelleted by ultracentrifugation and resuspended in buffer. The isolated OMVs can be analyzed for their molecular components and their interactions with host structures, bacterial cells, or surfaces.
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Affiliation(s)
- Jens Jäger
- Institut für Mikrobiologie, Technische Universität Braunschweig, Braunschweig, Germany
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Chien SH, Chowdhury I, Hsieh MK, Li H, Dzombak DA, Vidic RD. Control of biological growth in recirculating cooling systems using treated secondary effluent as makeup water with monochloramine. Water Res 2012; 46:6508-6518. [PMID: 23063442 DOI: 10.1016/j.watres.2012.09.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 09/07/2012] [Accepted: 09/11/2012] [Indexed: 06/01/2023]
Abstract
Secondary-treated municipal wastewater, an abundant and widely distributed impaired water source, is a promising alternative water source for thermoelectric power plant cooling. However, excessive biological growth is a major challenge associated with wastewater reuse in cooling systems as it can interfere with normal system operation as well as enhance corrosion and scaling problems. Furthermore, possible emission of biological aerosols (e.g., Legionella pneumophila) with the cooling tower drift can lead to public health concerns within the zone of aerosol deposition. In this study, the effectiveness of pre-formed and in-situ-formed monochloramine was evaluated for its ability to control biological growth in recirculating cooling systems using secondary-treated municipal wastewater as the only makeup water source. Bench-scale studies were compared with pilot-scale studies for their ability to predict system behavior under realistic process conditions. Effectiveness of the continuous addition of pre-formed monochloramine and monochloramine formed in-situ through the reaction of free chlorine with ammonia in the incoming water was evaluated in terms of biocide residual and its ability to control both planktonic and sessile microbial populations. Results revealed that monochloramine can effectively control biofouling in cooling systems employing secondary-treated municipal wastewater and has advantages relative to use of free chlorine, but that bench-scale studies seriously underestimate biocide dose and residual requirements for proper control of biological growth in full-scale systems. Pre-formed monochloramine offered longer residence time and more reliable performance than in-situ-formed monochloramine due to highly variable ammonia concentration in the recirculating water caused by ammonia stripping in the cooling tower. Pilot-scale tests revealed that much lower dosing rate was required to maintain similar total chlorine residual when pre-formed monochloramine was used as compared to in-situ-formed monochloramine. Adjustment of biocide dose to maintain monochloramine residual above 3mg/L is needed to achieve successful biological growth control in recirculating cooling systems using secondary-treated municipal effluent as the only source of makeup water.
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Affiliation(s)
- Shih-Hsiang Chien
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
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Stewart CR, Muthye V, Cianciotto NP. Legionella pneumophila persists within biofilms formed by Klebsiella pneumoniae, Flavobacterium sp., and Pseudomonas fluorescens under dynamic flow conditions. PLoS One 2012; 7:e50560. [PMID: 23185637 PMCID: PMC3503961 DOI: 10.1371/journal.pone.0050560] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 10/23/2012] [Indexed: 11/18/2022] Open
Abstract
Legionella pneumophila, the agent of Legionnaires' disease pneumonia, is transmitted to humans following the inhalation of contaminated water droplets. In aquatic systems, L. pneumophila survives much of time within multi-organismal biofilms. Therefore, we examined the ability of L. pneumophila (clinical isolate 130 b) to persist within biofilms formed by various types of aquatic bacteria, using a bioreactor with flow, steel surfaces, and low-nutrient conditions. L. pneumophila was able to intercalate into and persist within a biofilm formed by Klebsiella pneumoniae, Flavobacterium sp. or Pseudomonas fluorescens. The levels of L. pneumophila within these biofilms were as much as 4 × 10(4) CFU per cm(2) of steel coupon and lasted for at least 12 days. These data document that K. pneumoniae, Flavobacterium sp., and P. fluorescens can promote the presence of L. pneumophila in dynamic biofilms. In contrast to these results, L. pneumophila 130 b did not persist within a biofilm formed by Pseudomonas aeruginosa, confirming that some bacteria are permissive for Legionella colonization whereas others are antagonistic. In addition to colonizing certain mono-species biofilms, L. pneumophila 130 b persisted within a two-species biofilm formed by K. pneumoniae and Flavobacterium sp. Interestingly, the legionellae were also able to colonize a two-species biofilm formed by K. pneumoniae and P. aeruginosa, demonstrating that a species that is permissive for L. pneumophila can override the inhibitory effect(s) of a non-permissive species.
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Affiliation(s)
- Catherine R. Stewart
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, Illinois, United States of America
| | - Viraj Muthye
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, Illinois, United States of America
| | - Nicholas P. Cianciotto
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, Illinois, United States of America
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Mallegol J, Duncan C, Prashar A, So J, Low DE, Terebeznik M, Guyard C. Essential roles and regulation of the Legionella pneumophila collagen-like adhesin during biofilm formation. PLoS One 2012; 7:e46462. [PMID: 23029523 PMCID: PMC3460888 DOI: 10.1371/journal.pone.0046462] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 08/31/2012] [Indexed: 11/19/2022] Open
Abstract
Legionellosis is mostly caused by Legionella pneumophila (Lp) and is defined by a severe respiratory illness with a case fatality rate ranging from 5 to 80%. In a previous study, we showed that a glycosaminoglycan (GAG)-binding adhesin of Lp, named Lcl, is produced during legionellosis and is unique to the L. pneumophila species. Importantly, a mutant depleted in Lcl (Δlpg2644) is impaired in adhesion to GAGs and epithelial cells and in biofilm formation. Here, we examine the molecular function(s) of Lcl and the transcriptional regulation of its encoding gene during different stages of the biofilm development. We show that the collagen repeats and the C-terminal domains of Lcl are crucial for the production of biofilm. We present evidence that Lcl is involved in the early step of surface attachment but also in intercellular interactions. Furthermore, we address the relationship between Lcl gene regulation during biofilm formation and quorum sensing (QS). In a static biofilm assay, we show that Lcl is differentially regulated during growth phases and biofilm formation. Moreover, we show that the transcriptional regulation of lpg2644, mediated by a prototype of QS signaling homoserine lactone (3OC12-HSL), may play a role during the biofilm development. Thus, transcriptional down-regulation of lpg2644 may facilitate the dispersion of Lp to reinitiate biofilm colonization on a distal surface.
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Affiliation(s)
- Julia Mallegol
- Ontario Agency for Health Protection and Promotion (OAHPP), Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Carla Duncan
- Ontario Agency for Health Protection and Promotion (OAHPP), Toronto, Ontario, Canada
| | - Akriti Prashar
- Cells and System Biology and Department of Biological Sciences, University of Toronto at Scarborough, Toronto, Ontario, Canada
| | - Jannice So
- Ontario Agency for Health Protection and Promotion (OAHPP), Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Donald E. Low
- Ontario Agency for Health Protection and Promotion (OAHPP), Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Mauricio Terebeznik
- Cells and System Biology and Department of Biological Sciences, University of Toronto at Scarborough, Toronto, Ontario, Canada
| | - Cyril Guyard
- Ontario Agency for Health Protection and Promotion (OAHPP), Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
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Dronina IE, Karpova TI, Sadretdinova OV, Didenko LV, Tartakovskiĭ IS. [Features of legionella biofilm formation in artificial and natural water systems]. Zh Mikrobiol Epidemiol Immunobiol 2012:76-80. [PMID: 22937712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
AIM Study the ability to form monospecies and associative biofilms as a characteristic oflegionella strains and features of organization of natural legionella biofilms in potentially dangerous water systems. MATERIALS AND METHODS Comparative evaluation ofthe ability of 28 strains of Legionella spp. to form biofilms was determined in water according to previously developed procedure. Samples from biofilm of industrial enterprise coolers and systems of hot water supply of public buildings (hotels, trade centers, hospitals) were studied. Biofilms were studied by scanning and transmission electron microscopy methods. RESULTS Legionella strains are divided into 3 groups by the ability to form biofilms. L. pneumophila BLR-05 strain that has the most pronounced ability to form monospecies biofilm and persistence in association with Pseudomonas aeruginosa was detected. Formation of massive legionella biofilm in association with bacteria of other taxonomic groups was detected on protective antibacterial filters in the system of hot water supply of a department of a therapeutic prophylaxis institution in the course of 2-3 weeks. Legionella biofilms on the surface of coolers resemble an aggregate of fungi, bacteria and blue-green algae enclosed into matrix. CONCLUSION The ability to form artificial monospecies and associative biofilm may be a useful characteristic of legionella strains for evaluation of their adhesion and be used to evaluate epidemiological significance of the isolated strains. Prevention of formation of natural legionella biofilms in potentially dangerous water systems is necessary as an essential component of modern strategy of legionellosis prophylaxis.
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Zhang Q, Chen R, Xiao Y, Liu B, Qin T, Shao ZJ, Zhou WJ. [Contamination status and molecular biological characteristics of Legionella in cooling water samples from different places in Wuxi city]. Zhonghua Yu Fang Yi Xue Za Zhi 2012; 46:264-268. [PMID: 22800600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
OBJECTIVE To investigate the contamination state of Legionella in cooling water samples from different places in Wuxi city and reveal the molecular biological characteristics of Legionella strains. METHODS 112 parallel water samples (500 ml each) were collected from 56 sites in Wuxi city during year 2009 - 2010. The samples were used for Legionella test and quantitative culture. The isolated Legionella strains were used for serotyping, pulsed-field gel electrophoresis (PFGE), sequence-based typing (SBT), and intracellular growth were tested. RESULTS The positive proportion of Legionella was 39. 3% (22/56) among all sampling sites. A total of 29 Legionella strains were isolated, and the serotypes include LP1, LP3, LP5 and LP6. LP1 serotype was the major one with a proportion of 65.5% (19/29). 29 Legionella strains got 17 PFGE types. There were 10 SBT types among 10 Legionella strains with different PFGE types. Comparing to LP1 strain (ATCC 33152), WX2011062 (LP6) and WX2011067 (LP5) had strong intracellular growth ability in mouse peritoneal macrophages J774 cell line (the amount of intracellular bacteria on day 0 after infection were (5.5 +/- 1.32) x 10(5), (3.9 +/- 0.60) x 10(5), (7.8 +/- 0.76) x 10(5) CFU/ml, respectively; the amount of intracellular bacteria on day 3 after infection were (58.3 +/- 1.61) x 10(5), (2700.0 +/- 655.74) x 10(5), (3066.7 +/- 208.17) x 10(5) CFU/ml, respectively). CONCLUSION The Legionella contamination existed in cooling water samples from different places in Wuxi city. Legionella strains isolated showed high genetic variation. Some Legionella strains had vigorous intracellular growth ability.
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Affiliation(s)
- Qi Zhang
- Wuxi Center for Disease Control and Prevention, Wuxi 214023, China
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Rakić A, Perić J, Foglar L. Influence of temperature, chlorine residual and heavy metals on the presence of Legionella pneumophila in hot water distribution systems. Ann Agric Environ Med 2012; 19:431-436. [PMID: 23020035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The microbiological colonisation of buildings and man-made structures often occurs on the walls of plumbing systems; therefore, monitoring of opportunistic pathogens such as Legionella pneumophila (L. pneumophila), both in water distribution mains and in consumers' plumbing systems, is an important issue according to the international and national guidelines that regulate the quality of drinking water. This paper investigates the presence of L. pneumophila in the Dalmatian County of Croatia and the relationship between L. pneumophila presence and heavy metals concentrations, free residual chlorine and water temperature in hot water distribution systems (WDS). Investigations were performed on a large number of hot water samples taken from taps in kitchens and bathrooms in hotels and homes for the elderly and disabled in the Split region. Of the 127 hot water samples examined, 12 (9.4%) were positive for Legionella spp. with median values concentration of 450 cfu × L(-1). Among positive isolates, 10 (83.3%) were L. pneumophila sg 1, and two of them (16.6%) belonged to the genera L. pneumophila sg 2-14. The positive correlation between the water temperature, iron and manganese concentrations, and L. pneumophila contamination was proved by statistical analysis of the experimental data. On the contrary, zinc and free residual chlorine had no observed influence on the presence of L. pneumophila. The presence of heavy metals in water samples confirms the corrosion of distribution system pipes and fittings, and suggests that metal plumbing components and associated corrosion products are important factors in the survival and growth of L. pneumophila in WDS.
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Yao Y, Kubota Y, Murakami T, Ochiai T, Ishiguro H, Nakata K, Fujishima A. Electrochemical inactivation kinetics of boron-doped diamond electrode on waterborne pathogens. J Water Health 2011; 9:534-543. [PMID: 21976200 DOI: 10.2166/wh.2011.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A boron-doped diamond (BDD) electrode was constructed as a water disinfector for the inactivation of water borne pathogens. The bactericidal effect of the disinfector was evaluated on artificially contaminated waters containing, respectively, Escherichia coli, Pseudomonas aeruginosa and Legionella pneumophila at high density. By treating the bacterial suspensions with 4 V of constant voltage between the BDD and the counter-electrode for 50 min, the population of E. coli and P. aeruginosa decreased from (10E + 7-8 colony-forming unit mL(-1)) to below the detection limits of the colony-formation method. Meanwhile, L. pneumophila were reduced to virtually zero when analyzed by fluorescence-based staining. The influences of production parameters (voltage, NaCl concentration and flow rate) on the disinfection kinetics of the BDD disinfector were examined with respect to operational conditions. Voltage was the most significant factor for adjusting the extent of electrolysis, followed by NaCl concentration and flow rate, to influence the disinfection efficiency. The disinfection of natural river water samples containing numerous microbes was performed for a practicability investigation of the BDD electrode. Approximately 99.99% bactericidal efficiency was confirmed by viability detection for E. coli and common germs in treated water. The results showed that the BDD electrode is a promising tool for various wastewater disinfections to combat waterborne diseases.
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Affiliation(s)
- Yanyan Yao
- Kanagawa Academy of Science and Technology, KSP Bldg. West 6F, 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa 213-0012, Japan
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Abstract
UNLABELLED Legionella pneumophila, aerosolized from numerous indoor facilities (e.g., shower heads, hot tubs, spas), may cause Pontiac fever (PF) and lethal pneumonia named Legionnaires' disease (LD) in humans. Reliable methods on quantitative exposure assessment of this bioaerosol are essential for the prevention of PF and LD. Coupled with culture, ethidium monoazide with qPCR, and qPCR assays, the collection efficiency for culturable, viable, and total L. pneumophila was assessed by means of filtration sampling (IOM with gelatin filter and cassette with polycarbonate filter) and liquid-based sampling methods (BioSampler, AGI-30, MAS-100 sampler with Tween mixture and deionized water (DW)). Results show IOM/gelatin filter was comparable to cassette/polycarbonate filter (P = 0.33) and performed greater than all of tested liquid-based methods for total cell collection. On the other hand, IOM/gelatin filter obtained greater efficiencies than cassette/polycarbonate filter by a factor of 3.8-8.6 for viable cells (P = 0.0006) and two orders of magnitude for culturable cells (P = 0.00002). Further comparison between liquid impingement and filtration methods indicates the sampling by IOM/gelatin filter, AGI-30, and BioSampler with DW were the most appropriate for viable cells, while culturable cells were collected most efficiently by BioSampler/DW with periodical replenishment during the sampling. PRACTICAL IMPLICATIONS This study recommends the most suitable methodologies for quantifying culturable, viable, and total Legionella pneumophila in indoor air. By using appropriate sampling and analytical methods, the residents and building owners are able to obtain the reliable data and further characterize the exposure risk and/or intervention efficacy against L. pneumophila. Moreover, the adoption of suitable monitoring methods also assists the investigators to explore the sources linked to PF and LD during the outbreaks. Considering reliable microbial monitoring is fundamental for epidemiological survey and risk assessment, the present information should be taken into account in assessing L. pneumophila indoors.
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Affiliation(s)
- C-W Chang
- Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Republic of China.
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Gião MS, Azevedo NF, Wilks SA, Vieira MJ, Keevil CW. Interaction of Legionella pneumophila and Helicobacter pylori with bacterial species isolated from drinking water biofilms. BMC Microbiol 2011; 11:57. [PMID: 21418578 PMCID: PMC3068934 DOI: 10.1186/1471-2180-11-57] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 03/18/2011] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND It is well established that Legionella pneumophila is a waterborne pathogen; by contrast, the mode of Helicobacter pylori transmission remains unknown but water seems to play an important role. This work aims to study the influence of five microorganisms isolated from drinking water biofilms on the survival and integration of both of these pathogens into biofilms. RESULTS Firstly, both pathogens were studied for auto- and co-aggregation with the species isolated from drinking water; subsequently the formation of mono and dual-species biofilms by L. pneumophila or H. pylori with the same microorganisms was investigated. Neither auto- nor co-aggregation was observed between the microorganisms tested. For biofilm studies, sessile cells were quantified in terms of total cells by SYTO 9 staining, viable L. pneumophila or H. pylori cells were quantified using 16 S rRNA-specific peptide nucleic acid (PNA) probes and cultivable cells by standard culture techniques. Acidovorax sp. and Sphingomonas sp. appeared to have an antagonistic effect on L. pneumophila cultivability but not on the viability (as assessed by rRNA content using the PNA probe), possibly leading to the formation of viable but noncultivable (VBNC) cells, whereas Mycobacterium chelonae increased the cultivability of this pathogen. The results obtained for H. pylori showed that M. chelonae and Sphingomonas sp. help this pathogen to maintain cultivability for at least 24 hours. CONCLUSIONS It appears that M. chelonae may have an important role in the survival of both pathogens in drinking water. This work also suggests that the presence of some microorganisms can decrease the cultivability of L. pneumophila but not the viability which indicates that the presence of autochthonous microorganisms can lead to misleading results when the safety of water is assessed by cultivable methods alone.
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Affiliation(s)
- Maria S Gião
- School of Biological Sciences, Life Sciences Building, Highfield Campus, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar 4710-057, Braga, Portugal
| | - Nuno F Azevedo
- School of Biological Sciences, Life Sciences Building, Highfield Campus, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar 4710-057, Braga, Portugal
- LEPAE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
| | - Sandra A Wilks
- School of Biological Sciences, Life Sciences Building, Highfield Campus, University of Southampton, Southampton SO17 1BJ, UK
| | - Maria J Vieira
- Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar 4710-057, Braga, Portugal
| | - Charles W Keevil
- School of Biological Sciences, Life Sciences Building, Highfield Campus, University of Southampton, Southampton SO17 1BJ, UK
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Weissenmayer BA, Prendergast JGD, Lohan AJ, Loftus BJ. Sequencing illustrates the transcriptional response of Legionella pneumophila during infection and identifies seventy novel small non-coding RNAs. PLoS One 2011; 6:e17570. [PMID: 21408607 PMCID: PMC3048289 DOI: 10.1371/journal.pone.0017570] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Accepted: 02/03/2011] [Indexed: 11/18/2022] Open
Abstract
Second generation sequencing has prompted a number of groups to re-interrogate the transcriptomes of several bacterial and archaeal species. One of the central findings has been the identification of complex networks of small non-coding RNAs that play central roles in transcriptional regulation in all growth conditions and for the pathogen's interaction with and survival within host cells. Legionella pneumophila is a Gram-negative facultative intracellular human pathogen with a distinct biphasic lifestyle. One of its primary environmental hosts in the free-living amoeba Acanthamoeba castellanii and its infection by L. pneumophila mimics that seen in human macrophages. Here we present analysis of strand specific sequencing of the transcriptional response of L. pneumophila during exponential and post-exponential broth growth and during the replicative and transmissive phase of infection inside A. castellanii. We extend previous microarray based studies as well as uncovering evidence of a complex regulatory architecture underpinned by numerous non-coding RNAs. Over seventy new non-coding RNAs could be identified; many of them appear to be strain specific and in configurations not previously reported. We discover a family of non-coding RNAs preferentially expressed during infection conditions and identify a second copy of 6S RNA in L. pneumophila. We show that the newly discovered putative 6S RNA as well as a number of other non-coding RNAs show evidence for antisense transcription. The nature and extent of the non-coding RNAs and their expression patterns suggests that these may well play central roles in the regulation of Legionella spp. specific traits and offer clues as to how L. pneumophila adapts to its intracellular niche. The expression profiles outlined in the study have been deposited into Genbank's Gene Expression Omnibus (GEO) database under the series accession GSE27232.
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Affiliation(s)
| | | | - Amanda J. Lohan
- UCD Conway Institute for Biomolecular and Biomedical Research, Dublin, Ireland
| | - Brendan J. Loftus
- UCD Conway Institute for Biomolecular and Biomedical Research, Dublin, Ireland
- * E-mail:
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Shkarin VV, Blagonravova AS, Chubukova OA, Korotaeva SV. [Contamination of health care institutions environmental objects by Legionella pneumophila]. Zh Mikrobiol Epidemiol Immunobiol 2011:75-78. [PMID: 21598621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
UNLABELLED AIM. The extent of environmental objects contamination by Legionella pneumophila in Nizhny Novgorod and Nizhny Novgorod region hospitals evaluation, and detection of potentially hazardous objects. MATERIALS AND METHODS 433 swabs of environmental objects, and 43 hot water supply and pool water samples from various departments of 4 multi-disciplinary hospitals were studies. DNA from environmental samples was detected by using real time PCR. RESULTS L. pneumophila DNA was detected in 41 (9,47%) samples from environmental objects and in 2 (4,65%) samples from hot water supply. These bacteria were more frequently detected in environmental samples from physiotherapy departments. Repeated detection of legionellae from the same objects was registered. CONCLUSION Circulation of legionellae in multidisciplinary hospitals was determined. Circulation high risk departments and risk objects--reservoirs of L. pneumophila in health care institutions were determined.
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Moritz MM, Flemming HC, Wingender J. Integration of Pseudomonas aeruginosa and Legionella pneumophila in drinking water biofilms grown on domestic plumbing materials. Int J Hyg Environ Health 2010; 213:190-7. [PMID: 20556878 DOI: 10.1016/j.ijheh.2010.05.003] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Drinking water biofilms were grown on coupons of plumbing materials, including ethylene-propylene-diene-monomer (EPDM) rubber, silane cross-linked polyethylene (PE-X b), electron-ray cross-linked PE (PE-X c) and copper under constant flow-through of cold tap water. After 14 days, the biofilms were spiked with Pseudomonas aeruginosa, Legionella pneumophila and Enterobacter nimipressuralis (10(6) cells/mL each). The test bacteria were environmental isolates from contamination events in drinking water systems. After static incubation for 24 h, water flow was resumed and continued for 4 weeks. Total cell count and heterotrophic plate count (HPC) of biofilms were monitored, and P. aeruginosa, L. pneumophila and E. nimipressuralis were quantified, using standard culture-based methods or culture-independent fluorescence in situ hybridization (FISH). After 14 days total cell counts and HPC values were highest on EPDM followed by the plastic materials and copper. P. aeruginosa and L. pneumophila became incorporated into drinking water biofilms and were capable to persist in biofilms on EPDM and PE-X materials for several weeks, while copper biofilms were colonized only by L. pneumophila in low culturable numbers. E. nimipressuralis was not detected in any of the biofilms. Application of the FISH method often yielded orders of magnitude higher levels of P. aeruginosa and L. pneumophila than culture methods. These observations indicate that drinking water biofilms grown under cold water conditions on domestic plumbing materials, especially EPDM and PE-X in the present study, can be a reservoir for P. aeruginosa and L. pneumophila that persist in these habitats mostly in a viable but non-culturable state.
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Affiliation(s)
- Miriam M Moritz
- Biofilm Centre, Department of Aquatic Microbiology, Faculty of Chemistry, University of Duisburg-Essen, D-47057 Duisburg, Germany
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Olsen JS, Aarskaug T, Thrane I, Pourcel C, Ask E, Johansen G, Waagen V, Blatny JM. Alternative routes for dissemination of Legionella pneumophila causing three outbreaks in Norway. Environ Sci Technol 2010; 44:8712-8717. [PMID: 20949911 DOI: 10.1021/es1007774] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Three outbreaks of Legionnaires' disease were reported in the Fredrikstad/Sarpsborg community, Norway, in 2005 and 2008 caused by the L. pneumophila ST15 and ST462 strains determined by sequence based typing. In this retrospective study, we suggest that the aeration ponds, a part of the biological treatment plant at Borregaard Ind. Ltd., are the main amplifiers and primary disseminators of the outbreak L. pneumophila strains. This result is supported by the finding that the ST15 and ST462 strains were not able to survive in air scrubber liquid media more than two days of incubation at the scrubber's operating conditions during the 2005 and 2008 outbreaks. In 2008, >10¹⁰ CFU/L of L. pneumophila ST462 were detected in the aeration ponds. ST15 and ST462 were also detected in the river Glomma in 2005 and 2008, respectively, downstream of the wastewater outlet from the treatment plant (10⁵CFU/L). These findings strongly suggest that the presence of L. pneumophila in the river is due to the release of wastewater from the industrial aeration ponds, demonstrating that the river Glomma may be an additional disseminator of L. pneumophila during the outbreaks. This work emphasizes the need for preventive actions against the release of wastewater containing human pathogens to the environment.
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Cazalet C, Gomez-Valero L, Rusniok C, Lomma M, Dervins-Ravault D, Newton HJ, Sansom FM, Jarraud S, Zidane N, Ma L, Bouchier C, Etienne J, Hartland EL, Buchrieser C. Analysis of the Legionella longbeachae genome and transcriptome uncovers unique strategies to cause Legionnaires' disease. PLoS Genet 2010; 6:e1000851. [PMID: 20174605 PMCID: PMC2824747 DOI: 10.1371/journal.pgen.1000851] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 01/20/2010] [Indexed: 12/15/2022] Open
Abstract
Legionella pneumophila and L. longbeachae are two species of a large genus of bacteria that are ubiquitous in nature. L. pneumophila is mainly found in natural and artificial water circuits while L. longbeachae is mainly present in soil. Under the appropriate conditions both species are human pathogens, capable of causing a severe form of pneumonia termed Legionnaires' disease. Here we report the sequencing and analysis of four L. longbeachae genomes, one complete genome sequence of L. longbeachae strain NSW150 serogroup (Sg) 1, and three draft genome sequences another belonging to Sg1 and two to Sg2. The genome organization and gene content of the four L. longbeachae genomes are highly conserved, indicating strong pressure for niche adaptation. Analysis and comparison of L. longbeachae strain NSW150 with L. pneumophila revealed common but also unexpected features specific to this pathogen. The interaction with host cells shows distinct features from L. pneumophila, as L. longbeachae possesses a unique repertoire of putative Dot/Icm type IV secretion system substrates, eukaryotic-like and eukaryotic domain proteins, and encodes additional secretion systems. However, analysis of the ability of a dotA mutant of L. longbeachae NSW150 to replicate in the Acanthamoeba castellanii and in a mouse lung infection model showed that the Dot/Icm type IV secretion system is also essential for the virulence of L. longbeachae. In contrast to L. pneumophila, L. longbeachae does not encode flagella, thereby providing a possible explanation for differences in mouse susceptibility to infection between the two pathogens. Furthermore, transcriptome analysis revealed that L. longbeachae has a less pronounced biphasic life cycle as compared to L. pneumophila, and genome analysis and electron microscopy suggested that L. longbeachae is encapsulated. These species-specific differences may account for the different environmental niches and disease epidemiology of these two Legionella species.
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Affiliation(s)
- Christel Cazalet
- Institut Pasteur, Biologie des Bactéries Intracellulaires, CNRS URA 2171, Paris, France
| | - Laura Gomez-Valero
- Institut Pasteur, Biologie des Bactéries Intracellulaires, CNRS URA 2171, Paris, France
| | - Christophe Rusniok
- Institut Pasteur, Biologie des Bactéries Intracellulaires, CNRS URA 2171, Paris, France
| | - Mariella Lomma
- Institut Pasteur, Biologie des Bactéries Intracellulaires, CNRS URA 2171, Paris, France
| | | | - Hayley J. Newton
- Department of Microbiology and Immunology, University of Melbourne, Victoria, Australia
| | - Fiona M. Sansom
- Department of Microbiology and Immunology, University of Melbourne, Victoria, Australia
| | - Sophie Jarraud
- Centre National de Référence des Legionella, Université de Lyon, INSERM U851, Faculté de Médecine, IFR 128, Lyon, France
| | - Nora Zidane
- Institut Pasteur, Plate-forme Génomique, Pasteur Génopole Ile de France, Paris, France
| | - Laurence Ma
- Institut Pasteur, Plate-forme Génomique, Pasteur Génopole Ile de France, Paris, France
| | - Christiane Bouchier
- Institut Pasteur, Plate-forme Génomique, Pasteur Génopole Ile de France, Paris, France
| | - Jerôme Etienne
- Centre National de Référence des Legionella, Université de Lyon, INSERM U851, Faculté de Médecine, IFR 128, Lyon, France
| | - Elizabeth L. Hartland
- Department of Microbiology and Immunology, University of Melbourne, Victoria, Australia
| | - Carmen Buchrieser
- Institut Pasteur, Biologie des Bactéries Intracellulaires, CNRS URA 2171, Paris, France
- * E-mail:
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Declerck P, Vanysacker L, Hulsmans A, Lambert N, Liers S, Ollevier F. Evaluation of power ultrasound for disinfection of both Legionella pneumophila and its environmental host Acanthamoeba castellanii. Water Res 2010; 44:703-710. [PMID: 19854466 DOI: 10.1016/j.watres.2009.09.062] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 09/29/2009] [Accepted: 09/30/2009] [Indexed: 05/28/2023]
Abstract
The objectives of this study were to (1) examine the effect of power ultrasound on the viability of both Legionella pneumophila and Acanthamoeba castellanii trophozoites and cysts, (2) investigate if intracellular Legionella replication in trophozoites positively affects bacterial resistance to ultrasound and (3) study if Legionella renders viable but non-culturable (VBNC) due to ultrasound treatments. Using laboratory scale experiments, microorganisms were exposed for various time periods to power ultrasound at a frequency of 36 kHz and an ultrasound power setting of 50 and 100%. Due to a fast destruction, trophozoite hosts were not able to protect intracellular Legionella from eradication by ultrasound, in contrast to cysts. No significant effects of ultrasound on cyst viability could be detected and power settings of 100% for 30 min only made intracellular Legionella concentrations decrease with 1.3 log units. Due to intracellular replication of Legionella in trophozoites, ultrasound no longer affected bacterial viability. Concerning the VBNC state, ultrasound treatments using a power setting of 50% partly induced Legionella (+/-7%) to transform into VBNC bacteria, in contrast to power settings of 100%. Promising results obtained in this study indicate the possible application of power ultrasound in the control of both Legionella and Acanthamoeba concentrations in anthropogenic water systems.
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Affiliation(s)
- Priscilla Declerck
- Laboratory of Aquatic Ecology and Evolutionary Biology, Zoological Institute, K.U.Leuven, Ch. Deberiotstraat 32, 3000 Leuven, Belgium.
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Napoli C, Iatta R, Fasano F, Marsico T, Montagna MT. Variable bacterial load of Legionella spp. in a hospital water system. Sci Total Environ 2009; 408:242-244. [PMID: 19836825 DOI: 10.1016/j.scitotenv.2009.09.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 09/16/2009] [Accepted: 09/24/2009] [Indexed: 05/28/2023]
Abstract
Several approved protocols for the prevention of Legionella pneumonia base the type of intervention (to disinfect or not) on the level of contamination found (cfu/L). However, if the level of contamination by Legionella spp. of a water system fluctuates in a short period of time, inadequate sampling could lead to different decisions being made. To determine if there are significant variations in the bacterial count of Legionella spp., water samples were taken at different times from the same sites. Eight wards were selected from a large hospital in Southern Italy and a water sample was taken from 21 taps in each ward at the same time each day for 5 consecutive days. A Freidman test detected statistically significant differences in average Legionella spp. load over the 5 sampling days (p value<0.001). This fluctuating load can have practical implications: the Italian Guidelines recommend disinfection only for a Legionella count>10,000 cfu/L in hospitals without documented cases of disease. In the present study, the daily average loads varied, during the 5-day sampling period, above and below this cut-off (10,000 cfu/L). This means that the decision to disinfect or not would be different depending on which day the sampling was carried out. Our data suggest that, especially in health-care facilities, a single sampling would not give a realistic estimation of risk; therefore, even at lower levels of bacterial load, measures should be taken to reduce it further.
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Affiliation(s)
- Christian Napoli
- Department of Biomedical Science - Hygiene Section, University of Bari, Bari, Italy.
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