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Wang X, Chen C, Hu J, Liu C, Ning Y, Lu F. Current strategies for monitoring and controlling bacterial biofilm formation on medical surfaces. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 282:116709. [PMID: 39024943 DOI: 10.1016/j.ecoenv.2024.116709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 07/03/2024] [Accepted: 07/07/2024] [Indexed: 07/20/2024]
Abstract
Biofilms, intricate microbial communities that attach to surfaces, especially medical devices, form an exopolysaccharide matrix, which enables bacteria to resist environmental pressures and conventional antimicrobial agents, leading to the emergence of multi-drug resistance. Biofilm-related infections associated with medical devices are a significant public health threat, compromising device performance. Therefore, developing effective methods for supervising and managing biofilm growth is imperative. This in-depth review presents a systematic overview of strategies for monitoring and controlling bacterial biofilms. We first outline the biofilm creation process and its regulatory mechanisms. The discussion then progresses to advancements in biosensors for biofilm detection and diverse treatment strategies. Lastly, this review examines the obstacles and new perspectives associated with this domain to facilitate the advancement of innovative monitoring and control solutions. These advancements are vital in combating the spread of multi drug-resistant bacteria and mitigating public health risks associated with infections from biofilm formation on medical instruments.
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Affiliation(s)
- Xiaoqi Wang
- Department of integrated traditional Chinese and Western Medicine, The Medicine School of Hunan University of Chinese Medicine, Changsha, Hunan 410208, People's Republic of China
| | - Chunjing Chen
- Department of Microbiology, The Medicine School of Hunan University of Chinese Medicine, Changsha, Hunan 410208, People's Republic of China
| | - Jue Hu
- Department of Microbiology, The Medicine School of Hunan University of Chinese Medicine, Changsha, Hunan 410208, People's Republic of China
| | - Chang Liu
- Department of Microbiology, The Medicine School of Hunan University of Chinese Medicine, Changsha, Hunan 410208, People's Republic of China
| | - Yi Ning
- Department of Microbiology, The Medicine School of Hunan University of Chinese Medicine, Changsha, Hunan 410208, People's Republic of China.
| | - Fangguo Lu
- Department of Microbiology, The Medicine School of Hunan University of Chinese Medicine, Changsha, Hunan 410208, People's Republic of China.
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2
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Leistikow KR, May DS, Suh WS, Vargas Asensio G, Schaenzer AJ, Currie CR, Hristova KR. Bacillus subtilis-derived peptides disrupt quorum sensing and biofilm assembly in multidrug-resistant Staphylococcus aureus. mSystems 2024; 9:e0071224. [PMID: 38990088 PMCID: PMC11334493 DOI: 10.1128/msystems.00712-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 06/15/2024] [Indexed: 07/12/2024] Open
Abstract
Multidrug-resistant Staphylococcus aureus is one of the most clinically important pathogens in the world, with infections leading to high rates of morbidity and mortality in both humans and animals. The ability of S. aureus to form biofilms protects cells from antibiotics and promotes the transfer of antibiotic resistance genes; therefore, new strategies aimed at inhibiting biofilm growth are urgently needed. Probiotic species, including Bacillus subtilis, are gaining interest as potential therapies against S. aureus for their ability to reduce S. aureus colonization and virulence. Here, we search for strains and microbially derived compounds with strong antibiofilm activity against multidrug-resistant S. aureus by isolating and screening Bacillus strains from a variety of agricultural environments. From a total of 1,123 environmental isolates, we identify a single strain B. subtilis 6D1, with a potent ability to inhibit biofilm growth, disassemble mature biofilm, and improve antibiotic sensitivity of S. aureus biofilms through an Agr quorum sensing interference mechanism. Biochemical and molecular networking analysis of an active organic fraction revealed multiple surfactin isoforms, and an uncharacterized peptide was driving this antibiofilm activity. Compared with commercial high-performance liquid chromatography grade surfactin obtained from B. subtilis, we show these B. subtilis 6D1 peptides are significantly better at inhibiting biofilm formation in all four S. aureus Agr backgrounds and preventing S. aureus-induced cytotoxicity when applied to HT29 human intestinal cells. Our study illustrates the potential of exploring microbial strain diversity to discover novel antibiofilm agents that may help combat multidrug-resistant S. aureus infections and enhance antibiotic efficacy in clinical and veterinary settings. IMPORTANCE The formation of biofilms by multidrug-resistant bacterial pathogens, such as Staphylococcus aureus, increases these microorganisms' virulence and decreases the efficacy of common antibiotic regimens. Probiotics possess a variety of strain-specific strategies to reduce biofilm formation in competing organisms; however, the mechanisms and compounds responsible for these phenomena often go uncharacterized. In this study, we identified a mixture of small probiotic-derived peptides capable of Agr quorum sensing interference as one of the mechanisms driving antibiofilm activity against S. aureus. This collection of peptides also improved antibiotic killing and protected human gut epithelial cells from S. aureus-induced toxicity by stimulating an adaptive cytokine response. We conclude that purposeful strain screening and selection efforts can be used to identify unique probiotic strains that possess specially desired mechanisms of action. This information can be used to further improve our understanding of the ways in which probiotic and probiotic-derived compounds can be applied to prevent bacterial infections or improve bacterial sensitivity to antibiotics in clinical and agricultural settings.
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Affiliation(s)
- Kyle R. Leistikow
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Daniel S. May
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Chemistry, Washington College, Chestertown, Maryland, USA
| | - Won Se Suh
- Department of Biochemistry & Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | | | - Adam J. Schaenzer
- Department of Biochemistry & Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Cameron R. Currie
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Biochemistry & Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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3
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Mutlu A, Vanderpool EJ, Rumbaugh KP, Diggle SP, Griffin AS. Exploiting cooperative pathogen behaviour for enhanced antibiotic potency: A Trojan horse approach. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001454. [PMID: 38687006 PMCID: PMC11084615 DOI: 10.1099/mic.0.001454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 04/03/2024] [Indexed: 05/02/2024]
Abstract
Antimicrobial resistance poses an escalating global threat, rendering traditional drug development approaches increasingly ineffective. Thus, novel alternatives to antibiotic-based therapies are needed. Exploiting pathogen cooperation as a strategy for combating resistant infections has been proposed but lacks experimental validation. Empirical findings demonstrate the successful invasion of cooperating populations by non-cooperating cheats, effectively reducing virulence in vitro and in vivo. The idea of harnessing cooperative behaviours for therapeutic benefit involves exploitation of the invasive capabilities of cheats to drive medically beneficial traits into infecting populations of cells. In this study, we employed Pseudomonas aeruginosa quorum sensing cheats to drive antibiotic sensitivity into both in vitro and in vivo resistant populations. We demonstrated the successful invasion of cheats, followed by increased antibiotic effectiveness against cheat-invaded populations, thereby establishing an experimental proof of principle for the potential application of the Trojan strategy in fighting resistant infections.
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Affiliation(s)
- Alper Mutlu
- Department of Biology, University of Oxford, Oxford, UK
| | | | | | - Stephen P. Diggle
- Center for Microbial Dynamics and Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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4
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Dewar AE, Belcher LJ, Scott TW, West SA. Genes for cooperation are not more likely to be carried by plasmids. Proc Biol Sci 2024; 291:20232549. [PMID: 38412971 PMCID: PMC10898968 DOI: 10.1098/rspb.2023.2549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024] Open
Abstract
Cooperation is prevalent across bacteria, but risks being exploited by non-cooperative cheats. Horizontal gene transfer, particularly via plasmids, has been suggested as a mechanism to stabilize cooperation. A key prediction of this hypothesis is that genes which are more likely to be transferred, such as those on plasmids, should be more likely to code for cooperative traits. Testing this prediction requires identifying all genes for cooperation in bacterial genomes. However, previous studies used a method which likely misses some of these genes for cooperation. To solve this, we used a new genomics tool, SOCfinder, which uses three distinct modules to identify all kinds of genes for cooperation. We compared where these genes were located across 4648 genomes from 146 bacterial species. In contrast to the prediction of the hypothesis, we found no evidence that plasmid genes are more likely to code for cooperative traits. Instead, we found the opposite-that genes for cooperation were more likely to be carried on chromosomes. Overall, the vast majority of genes for cooperation are not located on plasmids, suggesting that the more general mechanism of kin selection is sufficient to explain the prevalence of cooperation across bacteria.
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Affiliation(s)
- Anna E Dewar
- Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
| | | | - Thomas W Scott
- Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
| | - Stuart A West
- Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
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5
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Mutlu A, Vanderpool E, Rumbaugh KP, Diggle SP, Griffin AS. Exploiting Cooperative Pathogen Behavior for Enhanced Antibiotic Potency: A Trojan Horse Approach. RESEARCH SQUARE 2023:rs.3.rs-3466639. [PMID: 37986882 PMCID: PMC10659551 DOI: 10.21203/rs.3.rs-3466639/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Antimicrobial resistance poses an escalating global threat, rendering traditional drug development approaches increasingly ineffective. Thus, novel alternatives to antibiotic-based therapies are needed. Exploiting pathogen cooperation as a strategy for combating resistant infections has been proposed but lacks experimental validation. Empirical findings demonstrate the successful invasion of cooperating populations by non-cooperating cheats, effectively reducing virulence in vitro and in vivo. The idea of harnessing cooperative behaviors for therapeutic benefit involves exploitation of the invasive capabilities of cheats to drive medically beneficial traits into infecting populations of cells. In this study, we employed Pseudomonas aeruginosa quorum sensing cheats to drive antibiotic sensitivity into both in vitro and in vivo resistant populations. We demonstrated the successful invasion of cheats, followed by increased antibiotic effectiveness against cheat-invaded populations, thereby establishing an experimental proof of principle for the potential application of the Trojan strategy in fighting resistant infections.
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Affiliation(s)
- Alper Mutlu
- Departmemt of Biology, University of Oxford, Oxford, United Kingdom
| | - Emily Vanderpool
- Texas Tech University Health Sciences Center, Lubbock, United States
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6
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Niggli S, Schwyter L, Poveda L, Grossmann J, Kümmerli R. Rapid and strain-specific resistance evolution of Staphylococcus aureus against inhibitory molecules secreted by Pseudomonas aeruginosa. mBio 2023; 14:e0315322. [PMID: 37646506 PMCID: PMC10653847 DOI: 10.1128/mbio.03153-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 06/30/2023] [Indexed: 09/01/2023] Open
Abstract
IMPORTANCE Polymicrobial infections are common. In chronic infections, the different pathogens may repeatedly interact, which could spur evolutionary dynamics with pathogens adapting to one another. Here, we explore the potential of Staphylococcus aureus to adapt to its competitor Pseudomonas aeruginosa. These two pathogens frequently co-occur, and P. aeruginosa is seen as the dominant species being able to displace S. aureus. We studied three different S. aureus strains and found that all became quickly resistant to inhibitory compounds secreted by P. aeruginosa. Our experimental evolution revealed strains-specific adaptations with three main factors contributing to resistance evolution: (i) overproduction of staphyloxanthin, a molecule protecting from oxidative stress; (ii) the formation of small colony variants also protecting from oxidative stress; and (iii) alterations of membrane transporters possibly reducing toxin uptake. Our results show that species interactions can change over time potentially favoring species co-existence, which in turn could affect disease progression and treatment options.
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Affiliation(s)
- Selina Niggli
- Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
| | - Lukas Schwyter
- Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
| | - Lucy Poveda
- Functional Genomics Center Zurich, ETH Zurich and University of Zurich, Winterthurerstrasse, Zurich, Switzerland
- Swiss Institute of Bioinformatics (SIB) Quartier Sorge-Batiment Amphipole, Lausanne, Switzerland
| | - Jonas Grossmann
- Functional Genomics Center Zurich, ETH Zurich and University of Zurich, Winterthurerstrasse, Zurich, Switzerland
- Swiss Institute of Bioinformatics (SIB) Quartier Sorge-Batiment Amphipole, Lausanne, Switzerland
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
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7
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Abstract
The first discovered and well-characterized bacterial quorum sensing (QS) system belongs to Vibrio fischeri, which uses N-acyl homo-serine lactones (AHLs) for cell-cell signaling. AHL QS cell-cell communication is often regarded as a cell density-dependent regulatory switch. Since the discovery of QS, it has been known that AHL concentration (which correlates imperfectly with cell density) is not necessarily the only QS trigger. Additionally, not all cells respond to a QS signal. Bacteria could, via QS, exhibit phenotypic heterogeneity, resulting in sub-populations with unique phenotypes. It is time to ascribe greater importance to QS-dependent phenotypic heterogeneity, and its potential purpose in natura, with emphasis on the division of labor, specialization, and "bet-hedging". We hope that this perspective article will stimulate the awareness that QS can be more than just a cell-density switch. This basic mechanism could result in "bacterial civilizations", thus forcing us to reconsider the way bacterial communities are envisioned in natura.
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Affiliation(s)
- Mihael Spacapan
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Cristina Bez
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Vittorio Venturi
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
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8
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Williams P, Hill P, Bonev B, Chan WC. Quorum-sensing, intra- and inter-species competition in the staphylococci. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001381. [PMID: 37578829 PMCID: PMC10482373 DOI: 10.1099/mic.0.001381] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/31/2023] [Indexed: 08/15/2023]
Abstract
In Gram-positive bacteria such as Staphylococcus aureus and the coagulase-negative staphylococci (CoNS), the accessory gene regulator (agr) is a highly conserved but polymorphic quorum-sensing system involved in colonization, virulence and biofilm development. Signalling via agr depends on the interaction of an autoinducing peptide (AIP) with AgrC, a transmembrane sensor kinase that, once phosphorylated activates the response regulator AgrA. This in turn autoinduces AIP biosynthesis and drives target gene expression directly via AgrA or via the post-transcriptional regulator, RNAIII. In this review we describe the molecular mechanisms underlying the agr-mediated generation of, and response to, AIPs and the molecular basis of AIP-dependent activation and inhibition of AgrC. How the environment impacts on agr functionality is considered and the consequences of agr dysfunction for infection explored. We also discuss the concept of AIP-driven competitive interference between S. aureus and the CoNS and its anti-infective potential.
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Affiliation(s)
- Paul Williams
- Biodiscovery Institute and School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Phil Hill
- School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
| | - Boyan Bonev
- Biodiscovery Institute and School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Weng C. Chan
- School of Pharmacy, Biodiscovery Institute, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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9
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He L, Lv H, Wang Y, Jiang F, Liu Q, Zhang F, Wang H, Shen H, Otto M, Li M. Antibiotic treatment can exacerbate biofilm-associated infection by promoting quorum cheater development. NPJ Biofilms Microbiomes 2023; 9:26. [PMID: 37202425 DOI: 10.1038/s41522-023-00394-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/27/2023] [Indexed: 05/20/2023] Open
Abstract
Quorum cheating, a socio-microbiological process that is based on mutations in cell density-sensing (quorum-sensing) systems, has emerged as an important contributor to biofilm-associated infection in the leading human pathogen Staphylococcus aureus. This is because inactivation of the staphylococcal Agr quorum-sensing system leads to pronounced biofilm formation, increasing resistance to antibiotics and immune defense mechanisms. Since biofilm infections in the clinic usually progress under antibiotic treatment, we here investigated whether such treatment promotes biofilm infection via the promotion of quorum cheating. Quorum cheater development was stimulated by several antibiotics used in the treatment of staphylococcal biofilm infections more strongly in biofilm than in the planktonic mode of growth. Sub-inhibitory concentrations of levofloxacin and vancomycin were investigated for their impact on biofilm-associated (subcutaneous catheter-associated and prosthetic joint-associated infection), where in contrast to a non-biofilm-associated subcutaneous skin infection model, a significant increase of the bacterial load and development of agr mutants was observed. Our results directly demonstrate the development of Agr dysfunctionality in animal biofilm-associated infection models and reveal that inappropriate antibiotic treatment can be counterproductive for such infections as it promotes quorum cheating and the associated development of biofilms.
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Affiliation(s)
- Lei He
- Department of Laboratory Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Shanghai, 200127, China
| | - Huiying Lv
- Department of Laboratory Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Shanghai, 200127, China
| | - Yanan Wang
- Department of Laboratory Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Shanghai, 200127, China
| | - Feng Jiang
- Department of Orthopedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai, 200233, China
| | - Qian Liu
- Department of Laboratory Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Shanghai, 200127, China
| | - Feiyang Zhang
- Department of Orthopedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai, 200233, China
| | - Hua Wang
- Department of Laboratory Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Shanghai, 200127, China
| | - Hao Shen
- Department of Orthopedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai, 200233, China
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, 50 South Drive, Bethesda, MD, 20814, USA.
| | - Min Li
- Department of Laboratory Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Shanghai, 200127, China.
- Faculty of Medical Laboratory Science, Shanghai Jiao Tong University School of Medicine, 227 South Chongqing Road, Shanghai, 200025, China.
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10
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Rodrigues Lopes I, Alcantara LM, Silva RJ, Josse J, Vega EP, Cabrerizo AM, Bonhomme M, Lopez D, Laurent F, Vandenesch F, Mano M, Eulalio A. Microscopy-based phenotypic profiling of infection by Staphylococcus aureus clinical isolates reveals intracellular lifestyle as a prevalent feature. Nat Commun 2022; 13:7174. [PMID: 36418309 PMCID: PMC9684519 DOI: 10.1038/s41467-022-34790-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/08/2022] [Indexed: 11/24/2022] Open
Abstract
Staphylococcus aureus is increasingly recognized as a facultative intracellular pathogen, although the significance and pervasiveness of its intracellular lifestyle remain controversial. Here, we applied fluorescence microscopy-based infection assays and automated image analysis to profile the interaction of 191 S. aureus isolates from patients with bone/joint infections, bacteremia, and infective endocarditis, with four host cell types, at five times post-infection. This multiparametric analysis revealed that almost all isolates are internalized and that a large fraction replicate and persist within host cells, presenting distinct infection profiles in non-professional vs. professional phagocytes. Phenotypic clustering highlighted interesting sub-groups, including one comprising isolates exhibiting high intracellular replication and inducing delayed host death in vitro and in vivo. These isolates are deficient for the cysteine protease staphopain A. This study establishes S. aureus intracellular lifestyle as a prevalent feature of infection, with potential implications for the effective treatment of staphylococcal infections.
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Affiliation(s)
- Ines Rodrigues Lopes
- grid.8051.c0000 0000 9511 4342RNA & Infection Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal ,grid.8051.c0000 0000 9511 4342Functional Genomics and RNA-based Therapeutics Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
| | - Laura Maria Alcantara
- grid.8051.c0000 0000 9511 4342RNA & Infection Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
| | - Ricardo Jorge Silva
- grid.8051.c0000 0000 9511 4342Functional Genomics and RNA-based Therapeutics Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
| | - Jerome Josse
- grid.15140.310000 0001 2175 9188Centre International de Recherche en Infectiologie (CIRI), Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
| | - Elena Pedrero Vega
- grid.4711.30000 0001 2183 4846National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, Spain
| | - Ana Marina Cabrerizo
- grid.4711.30000 0001 2183 4846National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, Spain
| | - Melanie Bonhomme
- grid.15140.310000 0001 2175 9188Centre International de Recherche en Infectiologie (CIRI), Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
| | - Daniel Lopez
- grid.4711.30000 0001 2183 4846National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, Spain
| | - Frederic Laurent
- grid.15140.310000 0001 2175 9188Centre International de Recherche en Infectiologie (CIRI), Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France ,grid.413852.90000 0001 2163 3825Centre National de Référence des Staphylocoques, Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France
| | - Francois Vandenesch
- grid.15140.310000 0001 2175 9188Centre International de Recherche en Infectiologie (CIRI), Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France ,grid.413852.90000 0001 2163 3825Centre National de Référence des Staphylocoques, Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France
| | - Miguel Mano
- grid.8051.c0000 0000 9511 4342Functional Genomics and RNA-based Therapeutics Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal ,grid.8051.c0000 0000 9511 4342Department of Life Sciences, University of Coimbra, Coimbra, Portugal ,grid.13097.3c0000 0001 2322 6764British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, King’s College London, London, United Kingdom
| | - Ana Eulalio
- grid.8051.c0000 0000 9511 4342RNA & Infection Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal ,grid.7311.40000000123236065Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal ,grid.7445.20000 0001 2113 8111Department of Life Sciences, Imperial College London, London, United Kingdom
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11
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Antibiotics Drive Expansion of Rare Pathogens in a Chronic Infection Microbiome Model. mSphere 2022; 7:e0031822. [PMID: 35972133 PMCID: PMC9599657 DOI: 10.1128/msphere.00318-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chronic (long-lasting) infections are globally a major and rising cause of morbidity and mortality. Unlike typical acute infections, chronic infections are ecologically diverse, characterized by the presence of a polymicrobial mix of opportunistic pathogens and human-associated commensals. To address the challenge of chronic infection microbiomes, we focus on a particularly well-characterized disease, cystic fibrosis (CF), where polymicrobial lung infections persist for decades despite frequent exposure to antibiotics. Epidemiological analyses point to conflicting results on the benefits of antibiotic treatment yet are confounded by the dependency of antibiotic exposures on prior pathogen presence, limiting their ability to draw causal inferences on the relationships between antibiotic exposure and pathogen dynamics. To address this limitation, we develop a synthetic infection microbiome model representing CF metacommunity diversity and benchmark on clinical data. We show that in the absence of antibiotics, replicate microbiome structures in a synthetic sputum medium are highly repeatable and dominated by oral commensals. In contrast, challenge with physiologically relevant antibiotic doses leads to substantial community perturbation characterized by multiple alternate pathogen-dominant states and enrichment of drug-resistant species. These results provide evidence that antibiotics can drive the expansion (via competitive release) of previously rare opportunistic pathogens and offer a path toward microbiome-informed conditional treatment strategies. IMPORTANCE We develop and clinically benchmark an experimental model of the cystic fibrosis (CF) lung infection microbiome to investigate the impacts of antibiotic exposures on chronic, polymicrobial infections. We show that a single experimental model defined by metacommunity data can partially recapitulate the diversity of individual microbiome states observed across a population of people with CF. In the absence of antibiotics, we see highly repeatable community structures, dominated by oral microbes. Under clinically relevant antibiotic exposures, we see diverse and frequently pathogen-dominated communities, and a nonevolutionary enrichment of antimicrobial resistance on the community scale, mediated by competitive release. The results highlight the potential importance of nonevolutionary (community-ecological) processes in driving the growing global crisis of increasing antibiotic resistance.
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12
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Reconstitution of the S. aureus agr quorum sensing pathway reveals a direct role for the integral membrane protease MroQ in pheromone biosynthesis. Proc Natl Acad Sci U S A 2022; 119:e2202661119. [PMID: 35939668 PMCID: PMC9388083 DOI: 10.1073/pnas.2202661119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Staphylococcus aureus, virulence is under the control of a quorum sensing (QS) circuit encoded in the accessory gene regulator (agr) genomic locus. Key to this pathogenic behavior is the production and signaling activity of a secreted pheromone, the autoinducing peptide (AIP), generated following the ribosomal synthesis and posttranslational modification of a precursor polypeptide, AgrD, through two discrete cleavage steps. The integral membrane protease AgrB is known to catalyze the first processing event, generating the AIP biosynthetic intermediate, AgrD (1-32) thiolactone. However, the identity of the second protease in this biosynthetic pathway, which removes an N-terminal leader sequence, has remained ambiguous. Here, we show that membrane protease regulator of agr QS (MroQ), an integral membrane protease recently implicated in the agr response, is directly involved in AIP production. Genetic complementation and biochemical experiments reveal that MroQ proteolytic activity is required for AIP biosynthesis in agr specificity group I and group II, but not group III. Notably, as part of this effort, the biosynthesis and AIP-sensing arms of the QS circuit were reconstituted together in vitro. Our experiments also reveal the molecular features guiding MroQ cleavage activity, a critical factor in defining agr specificity group identity. Collectively, our study adds to the molecular understanding of the agr response and Staphylococcus aureus virulence.
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13
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Demographic Expansions and the Emergence of Host Specialization in Genetically Distinct Ecotypes of the Tick-Transmitted Bacterium Anaplasma phagocytophilum. Appl Environ Microbiol 2022; 88:e0061722. [PMID: 35867580 PMCID: PMC9317897 DOI: 10.1128/aem.00617-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In Europe, genetically distinct ecotypes of the tick-vectored bacterium Anaplasma phagocytophilum circulate among mammals in three discrete enzootic cycles. To date, potential ecological factors that contributed to the emergence of these divergent ecotypes have been poorly studied. Here, we show that the ecotype that predominantly infects roe deer (Capreolus capreolus) is evolutionarily derived. Its divergence from a host generalist ancestor occurred after the last glacial maximum as mammal populations, including roe deer, recolonized the European mainland from southern refugia. We also provide evidence that this host specialist ecotype's effective population size (Ne) has tracked changes in the population of its roe deer host. Specifically, both host and bacterium have undergone substantial increases in Ne over the past 1,500 years. In contrast, we show that while it appears to have undergone a major population expansion starting ~3,500 years ago, in the past 500 years, the contemporary host generalist ecotype has experienced a substantial reduction in genetic diversity levels, possibly as a result of reduced opportunities for transmission between competent hosts. IMPORTANCE The findings of this study reveal specific events important for the evolution of host specialization in a naturally occurring, obligately intracellular bacterial pathogen. Specifically, they show that host range shifts and the emergence of host specialization may occur during periods of population growth in a generalist ancestor. Our results also demonstrate the close correlation between demographic patterns in host and pathogen for a specialist system. These findings have important relevance for understanding the evolution of host range diversity. They may inform future work on host range dynamics, and they provide insights for understanding the emergence of pathogens that have human and veterinary health implications.
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14
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Durand BARN, Pouget C, Magnan C, Molle V, Lavigne JP, Dunyach-Remy C. Bacterial Interactions in the Context of Chronic Wound Biofilm: A Review. Microorganisms 2022; 10:microorganisms10081500. [PMID: 35893558 PMCID: PMC9332326 DOI: 10.3390/microorganisms10081500] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/15/2022] [Accepted: 07/21/2022] [Indexed: 02/04/2023] Open
Abstract
Chronic wounds, defined by their resistance to care after four weeks, are a major concern, affecting millions of patients every year. They can be divided into three types of lesions: diabetic foot ulcers (DFU), pressure ulcers (PU), and venous/arterial ulcers. Once established, the classical treatment for chronic wounds includes tissue debridement at regular intervals to decrease biofilm mass constituted by microorganisms physiologically colonizing the wound. This particular niche hosts a dynamic bacterial population constituting the bed of interaction between the various microorganisms. The temporal reshuffle of biofilm relies on an organized architecture. Microbial community turnover is mainly associated with debridement (allowing transitioning from one major representant to another), but also with microbial competition and/or collaboration within wounds. This complex network of species and interactions has the potential, through diversity in antagonist and/or synergistic crosstalk, to accelerate, delay, or worsen wound healing. Understanding these interactions between microorganisms encountered in this clinical situation is essential to improve the management of chronic wounds.
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Affiliation(s)
- Benjamin A. R. N. Durand
- Bacterial Virulence and Chronic Infections, UMR 1047, Université Montpellier, INSERM, Service de Microbiologie et Hygiène Hospitalière, CHU Nîmes, 30908 Nîmes, France; (B.A.R.N.D.); (C.P.); (C.M.); (J.-P.L.)
| | - Cassandra Pouget
- Bacterial Virulence and Chronic Infections, UMR 1047, Université Montpellier, INSERM, Service de Microbiologie et Hygiène Hospitalière, CHU Nîmes, 30908 Nîmes, France; (B.A.R.N.D.); (C.P.); (C.M.); (J.-P.L.)
| | - Chloé Magnan
- Bacterial Virulence and Chronic Infections, UMR 1047, Université Montpellier, INSERM, Service de Microbiologie et Hygiène Hospitalière, CHU Nîmes, 30908 Nîmes, France; (B.A.R.N.D.); (C.P.); (C.M.); (J.-P.L.)
| | - Virginie Molle
- Laboratory of Pathogen Host Interactions, Université de Montpellier, CNRS, UMR 5235, 34000 Montpellier, France;
| | - Jean-Philippe Lavigne
- Bacterial Virulence and Chronic Infections, UMR 1047, Université Montpellier, INSERM, Service de Microbiologie et Hygiène Hospitalière, CHU Nîmes, 30908 Nîmes, France; (B.A.R.N.D.); (C.P.); (C.M.); (J.-P.L.)
| | - Catherine Dunyach-Remy
- Bacterial Virulence and Chronic Infections, UMR 1047, Université Montpellier, INSERM, Service de Microbiologie et Hygiène Hospitalière, CHU Nîmes, 30908 Nîmes, France; (B.A.R.N.D.); (C.P.); (C.M.); (J.-P.L.)
- Correspondence: ; Tel.: +33-466-683-202
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15
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Fan Q, Zuo J, Wang H, Grenier D, Yi L, Wang Y. Contribution of quorum sensing to virulence and antibiotic resistance in zoonotic bacteria. Biotechnol Adv 2022; 59:107965. [PMID: 35487393 DOI: 10.1016/j.biotechadv.2022.107965] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/15/2022] [Accepted: 04/21/2022] [Indexed: 11/02/2022]
Abstract
Quorum sensing (QS), which is a key part of cell/cell communication, is widely distributed in microorganisms, especially in bacteria. Bacteria can produce and detect the presence of QS signal molecule, perceive the composition and density of microorganisms in their complex habitat, and then dynamically regulate their own gene expression to adapt to their environment. Among the many traits controlled by QS in pathogenic bacteria is the expression of virulence factors and antibiotic resistance. Many pathogenic bacteria rely on QS to govern the production of virulence factors and express drug-resistance, especially in zoonotic bacteria. The threat of antibiotic resistant zoonotic bacteria has called for alternative antimicrobial strategies that would mitigate the increase of classical resistance mechanism. Targeting QS has proven to be a promising alternative to conventional antibiotic for controlling infections. Here we review the QS systems in common zoonotic pathogenic bacteria and outline how QS may control the virulence and antibiotic resistance of zoonotic bacteria.
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Affiliation(s)
- Qingying Fan
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, China; Key Laboratory of Molecular Pathogen and Immunology of Animal of Luoyang, Luoyang, China
| | - Jing Zuo
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, China; Key Laboratory of Molecular Pathogen and Immunology of Animal of Luoyang, Luoyang, China
| | - Haikun Wang
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, China; Key Laboratory of Molecular Pathogen and Immunology of Animal of Luoyang, Luoyang, China
| | - Daniel Grenier
- Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Canada
| | - Li Yi
- Key Laboratory of Molecular Pathogen and Immunology of Animal of Luoyang, Luoyang, China; College of Life Science, Luoyang Normal University, Luoyang, China.
| | - Yang Wang
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, China; Key Laboratory of Molecular Pathogen and Immunology of Animal of Luoyang, Luoyang, China.
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16
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Oberbach A, Schlichting N, Hagl C, Lehmann S, Kullnick Y, Friedrich M, Köhl U, Horn F, Kumbhari V, Löffler B, Schmidt F, Joskowiak D, Born F, Saha S, Bagaev E. Four decades of experience of prosthetic valve endocarditis reflect a high variety of diverse pathogens. Cardiovasc Res 2022; 119:410-428. [PMID: 35420122 DOI: 10.1093/cvr/cvac055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 03/04/2022] [Accepted: 03/23/2022] [Indexed: 01/18/2023] Open
Abstract
Prosthetic valve endocarditis (PVE) remains a serious condition with a high mortality rate. Precise identification of the PVE-associated pathogen/s and their virulence is essential for successful therapy, and patient survival. The commonly described PVE-associated pathogens are staphylococci, streptococci and enterococci, with Staphylococcus aureus being the most frequently diagnosed species. Furthermore, multi-drug resistance pathogens are increasing in prevalence, and continue to pose new challenges mandating a personalized approach. Blood cultures in combination with echocardiography are the most common methods to diagnose PVE, often being the only indication, it exists. In many cases, the diagnostic strategy recommended in the clinical guidelines does not identify the precise microbial agent and to frequently, false negative blood cultures are reported. Despite the fact that blood culture findings are not always a good indicator of the actual PVE agent in the valve tissue, only a minority of re-operated prostheses are subjected to microbiological diagnostic evaluation. In this review, we focus on the diversity and the complete spectrum of PVE-associated bacterial, fungal and viral pathogens in blood, and prosthetic heart valve, their possible virulence potential, and their challenges in making a microbial diagnosis. We are curious to understand if the unacceptable high mortality of PVE is associated with the high number of negative microbial findings in connection with a possible PVE. Herein, we discuss the possibilities and limits of the diagnostic methods conventionally used and make recommendations for enhanced pathogen identification. We also show possible virulence factors of the most common PVE-associated pathogens and their clinical effects. Based on blood culture, molecular biological diagnostics, and specific valve examination, better derivations for the antibiotic therapy as well as possible preventive intervention can be established in the future.
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Affiliation(s)
- Andreas Oberbach
- Department of Cardiac Surgery, Ludwig Maximilian University, Munich, Germany.,Fraunhofer Institute for Cell Therapy and Immunology, Department of Diagnostics, Leipzig, Germany
| | - Nadine Schlichting
- Fraunhofer Institute for Cell Therapy and Immunology, Department of Diagnostics, Leipzig, Germany.,Institute of Clinical Immunology, University of Leipzig, Leipzig, Germany
| | - Christian Hagl
- Department of Cardiac Surgery, Ludwig Maximilian University, Munich, Germany.,Munich Heart Alliance, Partner Site German Centre for Cardiovascular Disease (DZHK), Munich, Germany
| | - Stefanie Lehmann
- Fraunhofer Institute for Cell Therapy and Immunology, Department of Diagnostics, Leipzig, Germany.,Institute of Clinical Immunology, University of Leipzig, Leipzig, Germany
| | - Yvonne Kullnick
- Fraunhofer Institute for Cell Therapy and Immunology, Department of Diagnostics, Leipzig, Germany.,Institute of Clinical Immunology, University of Leipzig, Leipzig, Germany
| | - Maik Friedrich
- Fraunhofer Institute for Cell Therapy and Immunology, Department of Diagnostics, Leipzig, Germany.,Institute of Clinical Immunology, University of Leipzig, Leipzig, Germany
| | - Ulrike Köhl
- Fraunhofer Institute for Cell Therapy and Immunology, Department of Diagnostics, Leipzig, Germany.,Institute of Clinical Immunology, University of Leipzig, Leipzig, Germany
| | - Friedemann Horn
- Fraunhofer Institute for Cell Therapy and Immunology, Department of Diagnostics, Leipzig, Germany.,Institute of Clinical Immunology, University of Leipzig, Leipzig, Germany
| | - Vivek Kumbhari
- Department of Medicine, Division of Gastroenterology and Hepatology, Mayo Clinic, Florida, USA
| | - Bettina Löffler
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
| | - Frank Schmidt
- Proteomics Core, Weill Cornell Medical Centre Qatar, Doha, Qatar
| | - Dominik Joskowiak
- Department of Cardiac Surgery, Ludwig Maximilian University, Munich, Germany
| | - Frank Born
- Department of Cardiac Surgery, Ludwig Maximilian University, Munich, Germany
| | - Shekhar Saha
- Department of Cardiac Surgery, Ludwig Maximilian University, Munich, Germany
| | - Erik Bagaev
- Department of Cardiac Surgery, Ludwig Maximilian University, Munich, Germany
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17
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Kin selection for cooperation in natural bacterial populations. Proc Natl Acad Sci U S A 2022; 119:2119070119. [PMID: 35193981 PMCID: PMC8892524 DOI: 10.1073/pnas.2119070119] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2021] [Indexed: 01/03/2023] Open
Abstract
Bacteria secrete many molecules outside the cell, where they provide benefits to other cells. One potential reason for producing these “public goods” is that they benefit closely related cells that share the gene for cooperation (kin selection). While many laboratory studies have supported this hypothesis, there is a lack of evidence that kin selection favors cooperation in natural populations. We examined bacterial genomes from the environment and used population genetics theory to analyze the DNA sequences. Our analyses suggest that public goods cooperation has indeed been favored by kin selection in natural populations. Bacteria produce a range of molecules that are secreted from the cell and can provide a benefit to the local population of cells. Laboratory experiments have suggested that these “public goods” molecules represent a form of cooperation, favored because they benefit closely related cells (kin selection). However, there is a relative lack of data demonstrating kin selection for cooperation in natural populations of bacteria. We used molecular population genetics to test for signatures of kin selection at the genomic level in natural populations of the opportunistic pathogen Pseudomonas aeruginosa. We found consistent evidence from multiple traits that genes controlling putatively cooperative traits have higher polymorphism and greater divergence and are more likely to harbor deleterious mutations relative to genes controlling putatively private traits, which are expressed at similar rates. These patterns suggest that cooperative traits are controlled by kin selection, and we estimate that the relatedness for social interactions in P. aeruginosa is r = 0.84. More generally, our results demonstrate how molecular population genetics can be used to study the evolution of cooperation in natural populations.
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18
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Gurney J, Simonet C, Wollein Waldetoft K, Brown SP. Challenges and opportunities for cheat therapy in the control of bacterial infections. Nat Prod Rep 2021; 39:325-334. [PMID: 34913456 DOI: 10.1039/d1np00053e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: 1999 to 2021Bacterial pathogens can be highly social, communicating and cooperating within multi-cellular groups to make us sick. The requirement for collective action in pathogens presents novel therapeutic avenues that seek to undermine cooperative behavior, what we call here 'cheat therapies'. We review two broad avenues of cheat therapy: first, the introduction of genetically engineered 'cheat' strains (bio-control cheats), and second the chemical induction of 'cheat' behavior in the infecting pathogens (chemical-control cheats). Both genetically engineered and chemically induced cheats can socially exploit the cooperative wildtype infection, reducing pathogen burden and the severity of disease. We review the costs and benefits of cheat therapies, highlighting advantages of evolutionary robustness and also the challenges of low to moderate efficacy, compared to conventional antibiotic treatments. We end with a summary of what we see as the most valuable next steps, focusing on adjuvant treatments and use as alternate therapies for mild, self-resolving infections - allowing the reservation of current and highly effective antibiotics for more critical patient needs.
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Affiliation(s)
- James Gurney
- Center for Microbial Dynamics & Infection, Georgia Institute of Technology, Atlanta, 30332 GA, USA. .,School of Biological Sciences, Georgia Institute of Technology, Atlanta, 30332 GA, USA
| | - Camille Simonet
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Kristofer Wollein Waldetoft
- Center for Microbial Dynamics & Infection, Georgia Institute of Technology, Atlanta, 30332 GA, USA. .,School of Biological Sciences, Georgia Institute of Technology, Atlanta, 30332 GA, USA.,Torsby Hospital, Torsby, Sweden
| | - Sam P Brown
- Center for Microbial Dynamics & Infection, Georgia Institute of Technology, Atlanta, 30332 GA, USA. .,School of Biological Sciences, Georgia Institute of Technology, Atlanta, 30332 GA, USA
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19
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Cheung GYC, Bae JS, Otto M. Pathogenicity and virulence of Staphylococcus aureus. Virulence 2021; 12:547-569. [PMID: 33522395 PMCID: PMC7872022 DOI: 10.1080/21505594.2021.1878688] [Citation(s) in RCA: 457] [Impact Index Per Article: 152.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 12/15/2022] Open
Abstract
Staphylococcus aureus is one of the most frequent worldwide causes of morbidity and mortality due to an infectious agent. This pathogen can cause a wide variety of diseases, ranging from moderately severe skin infections to fatal pneumonia and sepsis. Treatment of S. aureus infections is complicated by antibiotic resistance and a working vaccine is not available. There has been ongoing and increasing interest in the extraordinarily high number of toxins and other virulence determinants that S. aureus produces and how they impact disease. In this review, we will give an overview of how S. aureus initiates and maintains infection and discuss the main determinants involved. A more in-depth understanding of the function and contribution of S. aureus virulence determinants to S. aureus infection will enable us to develop anti-virulence strategies to counteract the lack of an anti-S. aureus vaccine and the ever-increasing shortage of working antibiotics against this important pathogen.
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Affiliation(s)
- Gordon Y. C. Cheung
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
| | - Justin S. Bae
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
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20
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Kaur B, Gupta J, Sharma S, Sharma D, Sharma S. Focused review on dual inhibition of quorum sensing and efflux pumps: A potential way to combat multi drug resistant Staphylococcus aureus infections. Int J Biol Macromol 2021; 190:33-43. [PMID: 34480904 DOI: 10.1016/j.ijbiomac.2021.08.199] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/19/2022]
Abstract
Staphylococcus aureus is a common cause of skin infections, food poisoning and severe life-threatening infections. Methicillin-Resistant Staphylococcus aureus (MRSA) is known to cause chronic nosocomial infections by virtue of its multidrug resistance and biofilm formation mechanisms. The antimicrobial resistance owned by S. aureus is primarily due to efflux pumps and formation of microbial biofilms. These drug resistant, sessile and densely packed microbial communities possess various mechanisms including quorum sensing and drug efflux. Quorum sensing is a cooperative physiological process which is used by bacterial cells for social interaction and signal transduction in biofilm formation whereas efflux of drugs is derived by efflux pumps. Apart from their significant role in multidrug resistance, efflux pumps also contribute to transporting cell signalling molecules and due to their occurrence; we face the frightening possibility that we will enter the pre-antibiotic era soon. Compounds that modulate efflux pumps are also known as efflux pump inhibitors (EPI's) that act in a synergistic manner and potentiate the antibiotics efficacy which has been considered as a promising approach to encounter bacterial resistance. EPIs inhibit the mechanism of drug efflux s as well as transport of quorum sensing signalling molecules which are the supreme contributors of miscellaneous virulence factors. This review presents an accomplishments of the recent investigations allied to efflux pump inhibitors against S. aureus and also focus on related correspondence between quorum sensing system and efflux pump inhibitors in terms of S. aureus and MRSA biofilms that may open a new avenue for controlling MRSA infections.
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Affiliation(s)
- Bhawandeep Kaur
- Department of Medical Laboratory Sciences, Lovely Professional University, Phagwara, Punjab 144411, India
| | - Jeena Gupta
- Department of Biochemistry, Lovely Professional University, Phagwara, Punjab 144411, India
| | - Sarika Sharma
- Department of Life Sciences, Arni University, Indora, Kangra, H.P. 176402, India
| | - Divakar Sharma
- Department of Microbiology, Maulana Azad Medical College, New Delhi 110002, India.
| | - Sandeep Sharma
- Department of Medical Laboratory Sciences, Lovely Professional University, Phagwara, Punjab 144411, India.
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21
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West SA, Cooper GA, Ghoul MB, Griffin AS. Ten recent insights for our understanding of cooperation. Nat Ecol Evol 2021; 5:419-430. [PMID: 33510431 PMCID: PMC7612052 DOI: 10.1038/s41559-020-01384-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 12/11/2020] [Indexed: 01/29/2023]
Abstract
Since Hamilton published his seminal papers in 1964, our understanding of the importance of cooperation for life on Earth has evolved beyond recognition. Early research was focused on altruism in the social insects, where the problem of cooperation was easy to see. In more recent years, research into cooperation has expanded across the entire tree of life, and has been revolutionized by advances in genetic, microbiological and analytical techniques. We highlight ten insights that have arisen from these advances, which have illuminated generalizations across different taxa, making the world simpler to explain. Furthermore, progress in these areas has opened up numerous new problems to solve, suggesting exciting directions for future research.
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Affiliation(s)
- Stuart A West
- Department of Zoology, University of Oxford, Oxford, UK.
| | - Guy A Cooper
- Department of Zoology, University of Oxford, Oxford, UK
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22
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Staphylococcus aureus cell wall structure and dynamics during host-pathogen interaction. PLoS Pathog 2021; 17:e1009468. [PMID: 33788901 PMCID: PMC8041196 DOI: 10.1371/journal.ppat.1009468] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/12/2021] [Accepted: 03/12/2021] [Indexed: 01/09/2023] Open
Abstract
Peptidoglycan is the major structural component of the Staphylococcus aureus cell wall, in which it maintains cellular integrity, is the interface with the host, and its synthesis is targeted by some of the most crucial antibiotics developed. Despite this importance, and the wealth of data from in vitro studies, we do not understand the structure and dynamics of peptidoglycan during infection. In this study we have developed methods to harvest bacteria from an active infection in order to purify cell walls for biochemical analysis ex vivo. Isolated ex vivo bacterial cells are smaller than those actively growing in vitro, with thickened cell walls and reduced peptidoglycan crosslinking, similar to that of stationary phase cells. These features suggested a role for specific peptidoglycan homeostatic mechanisms in disease. As S. aureus missing penicillin binding protein 4 (PBP4) has reduced peptidoglycan crosslinking in vitro its role during infection was established. Loss of PBP4 resulted in an increased recovery of S. aureus from the livers of infected mice, which coincided with enhanced fitness within murine and human macrophages. Thicker cell walls correlate with reduced activity of peptidoglycan hydrolases. S. aureus has a family of 4 putative glucosaminidases, that are collectively crucial for growth. Loss of the major enzyme SagB, led to attenuation during murine infection and reduced survival in human macrophages. However, loss of the other three enzymes Atl, SagA and ScaH resulted in clustering dependent attenuation, in a zebrafish embryo, but not a murine, model of infection. A combination of pbp4 and sagB deficiencies resulted in a restoration of parental virulence. Our results, demonstrate the importance of appropriate cell wall structure and dynamics during pathogenesis, providing new insight to the mechanisms of disease. The prevalence of methicillin resistant Staphylococcus aureus (MRSA) in both hospitals and the wider community places a huge weight on healthcare providers. To discover new control regimes, it is therefore important to understand how the pathogen behaves within the relevant environment of the host. This is often hampered by the ability to obtain sufficient ex vivo pathogen samples for study. We have developed a method to isolate S. aureus from the infected host to be able to analyse cellular morphology and structure. S. aureus, isolated from an infected kidney abscess are smaller in size, with thicker cell walls than exponentially growing cells in vitro. Their cell wall peptidoglycan also is less crosslinked. These features suggested the role of components controlling cell wall homeostasis as being important for infections. We tested the role of PBP4, known to increase cell wall crosslinking and found a pbp4 mutant to have increased survival in macrophages and fitness within the murine host. Conversely the peptidoglycan hydrolase SagB, whose loss results in thinner cell walls was attenuated in the murine systemic model of infection, with concomitant loss of fitness within macrophages. Our study reveals an important adaptation to the host environment and the role of those components involved in cell wall homeostasis in vivo.
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23
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Penna B, Silva MB, Soares AER, Vasconcelos ATR, Ramundo MS, Ferreira FA, Silva-Carvalho MC, de Sousa VS, Rabello RF, Bandeira PT, de Souza VS, Planet PJ, Vieira-da-Motta O, Botelho AMN, Figueiredo AMS. Comparative genomics of MRSA strains from human and canine origins reveals similar virulence gene repertoire. Sci Rep 2021; 11:4724. [PMID: 33633263 PMCID: PMC7907190 DOI: 10.1038/s41598-021-83993-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 02/09/2021] [Indexed: 01/31/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen associated with a wide variety of infections in humans. The ability of MRSA to infect companion animals has gained increasing attention in the scientific literature. In this study, 334 dogs were screened for MRSA in two cities located in Rio de Janeiro State. The prevalence of MRSA in dogs was 2.7%. Genotyping revealed isolates from sequence types (ST) 1, 5, 30, and 239 either colonizing or infecting dogs. The genome of the canine ST5 MRSA (strain SA112) was compared with ST5 MRSA from humans-the main lineage found in Rio de Janeiro hospitals-to gain insights in the origin of this dog isolate. Phylogenetic analysis situated the canine genome and human strain CR14-035 in the same clade. Comparative genomics revealed similar virulence profiles for SA112 and CR14-035. Both genomes carry S. aureus genomic islands νSAα, νSAβ, and νSAγ. The virulence potential of the canine and human strains was similar in a Caenorhabditis elegans model. Together, these results suggest a potential of canine MRSA to infect humans and vice versa. The circulation in community settings of a MRSA lineage commonly found in hospitals is an additional challenge for public health surveillance authorities.
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Affiliation(s)
- Bruno Penna
- grid.411173.10000 0001 2184 6919Instituto Biomédico, Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil
| | - Marcella B. Silva
- grid.412331.60000 0000 9087 6639Laboratório de Sanidade Animal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - André E. R. Soares
- grid.452576.70000 0004 0602 9007Laboratório Nacional de Computação Científica, Petrópolis, Rio de Janeiro, Brazil
| | - Ana T. R. Vasconcelos
- grid.452576.70000 0004 0602 9007Laboratório Nacional de Computação Científica, Petrópolis, Rio de Janeiro, Brazil
| | - Mariana S. Ramundo
- grid.8536.80000 0001 2294 473XDepartment of Medical Microbiology, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabienne A. Ferreira
- grid.411237.20000 0001 2188 7235Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina Brazil
| | - Maria C. Silva-Carvalho
- grid.8536.80000 0001 2294 473XDepartment of Medical Microbiology, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Viviane S. de Sousa
- grid.8536.80000 0001 2294 473XDepartment of Medical Microbiology, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Renata F. Rabello
- grid.411173.10000 0001 2184 6919Instituto Biomédico, Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil
| | - Paula T. Bandeira
- grid.8536.80000 0001 2294 473XDepartment of Medical Microbiology, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil ,grid.8536.80000 0001 2294 473XInstituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Viviane S. de Souza
- grid.8536.80000 0001 2294 473XInstituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paul J. Planet
- grid.25879.310000 0004 1936 8972Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
| | - Olney Vieira-da-Motta
- grid.412331.60000 0000 9087 6639Laboratório de Sanidade Animal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Ana M. N. Botelho
- grid.411173.10000 0001 2184 6919Instituto Biomédico, Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil ,grid.8536.80000 0001 2294 473XDepartment of Medical Microbiology, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Agnes M. S. Figueiredo
- grid.8536.80000 0001 2294 473XDepartment of Medical Microbiology, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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24
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Menetrey Q, Dupont C, Chiron R, Jumas-Bilak E, Marchandin H. High Occurrence of Bacterial Competition Among Clinically Documented Opportunistic Pathogens Including Achromobacter xylosoxidans in Cystic Fibrosis. Front Microbiol 2020; 11:558160. [PMID: 33013789 PMCID: PMC7513574 DOI: 10.3389/fmicb.2020.558160] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 08/14/2020] [Indexed: 12/12/2022] Open
Abstract
Cystic Fibrosis (CF) airways favor abnormal microbial development. Infections are considered as polymicrobial and competition can be observed between microorganisms. The current literature on bacterial competition in CF mostly consists of studies with limited numbers of strains, mainly focused on the major pathogens Pseudomonas aeruginosa (Pa) and Staphylococcus aureus (Sa) and does not give a comprehensive overview of the overall importance of bacterial interactions or the behavior of less often encountered emerging bacteria such as Achromobacter. In this context, we screened a panel of 39 strains from six CF patients, of either clinical or domestic environmental origin, distinguished according to genotype and belonging to four opportunistic pathogens, Pa (n = 15), Sa (n = 3), Stenotrophomonas maltophilia (Sm, n = 10) and Achromobacter xylosoxidans (Ax, n = 11). We investigated their capacity to compete in terms of growth, motility, and pigment production on agar media through 203 crossing experiments. Eleven strains selected via the initial screening results were further studied for competitive growth in liquid medium and biofilm formation. Competition was noted for 33% (67/203) of the pairs of strains with 85 modifications observed between monocultures and co-cultures, impacting growth (23.6%), motility (13.8%), and/or pigment production (6.1%). Under all conditions of the study (clinical, environmental strains; intra-, inter-patients; intra-, inter-species levels), competition was significantly more frequent among pairs of strains with at least one clinical strain. While Pa mainly outcompeted other species, in one patient with chronic colonization by Ax and sporadic colonization by Pa, we showed that some Ax inhibited the growth and pigmentation of Pa whereas biofilm formation was drastically reduced. Enlarging the panel of strains tested in competition assays gave new perspectives on the complex interactions taking place among the CF airway community. Indeed, the frequent occurrence of varied, strain-dependent interactions is revealed here. We report the first results of competition assays for Ax with the ability of certain strains to outcompete Pa. Our results are linked to the patient’s colonization history and question the importance of bacterial competitiveness in the colonization pattern of CF airways.
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Affiliation(s)
- Quentin Menetrey
- HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Montpellier, France
| | - Chloé Dupont
- HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Montpellier, France.,HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Laboratoire d'Ecologie Microbienne Hospitalière, CHU Montpellier, Montpellier, France
| | - Raphaël Chiron
- HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Montpellier, France.,HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Centre de Ressources et de Compétences de la Mucoviscidose, CHU Montpellier, Montpellier, France
| | - Estelle Jumas-Bilak
- HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Montpellier, France.,HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Laboratoire d'Ecologie Microbienne Hospitalière, CHU Montpellier, Montpellier, France
| | - Hélène Marchandin
- HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Montpellier, France.,HydroSciences Montpellier, Univ Montpellier, CNRS, IRD, Département de Microbiologie, CHU Nîmes, Nîmes, France
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25
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Silence as a way of niche adaptation: mecC-MRSA with variations in the accessory gene regulator (agr) functionality express kaleidoscopic phenotypes. Sci Rep 2020; 10:14787. [PMID: 32901059 PMCID: PMC7479134 DOI: 10.1038/s41598-020-71640-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 08/19/2020] [Indexed: 11/09/2022] Open
Abstract
Functionality of the accessory gene regulator (agr) quorum sensing system is an important factor promoting either acute or chronic infections by the notorious opportunistic human and veterinary pathogen Staphylococcus aureus. Spontaneous alterations of the agr system are known to frequently occur in human healthcare-associated S. aureus lineages. However, data on agr integrity and function are sparse regarding other major clonal lineages. Here we report on the agr system functionality and activity level in mecC-carrying methicillin resistant S. aureus (MRSA) of various animal origins (n = 33) obtained in Europe as well as in closely related human isolates (n = 12). Whole genome analysis assigned all isolates to four clonal complexes (CC) with distinct agr types (CC599 agr I, CC49 agr II, CC130 agr III and CC1943 agr IV). Agr functionality was assessed by a combination of phenotypic assays and proteome analysis. In each CC, isolates with varying agr activity levels were detected, including the presence of completely non-functional variants. Genomic comparison of the agr I-IV encoding regions associated these phenotypic differences with variations in the agrA and agrC genes. The genomic changes were detected independently in divergent lineages, suggesting that agr variation might foster viability and adaptation of emerging MRSA lineages to distinct ecological niches.
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26
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Kramer J, López Carrasco MÁ, Kümmerli R. Positive linkage between bacterial social traits reveals that homogeneous rather than specialised behavioral repertoires prevail in natural Pseudomonas communities. FEMS Microbiol Ecol 2020; 96:5643885. [PMID: 31769782 DOI: 10.1093/femsec/fiz185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 11/22/2019] [Indexed: 12/27/2022] Open
Abstract
Bacteria frequently cooperate by sharing secreted metabolites such as enzymes and siderophores. The expression of such 'public good' traits can be interdependent, and studies on laboratory systems have shown that trait linkage affects eco-evolutionary dynamics within bacterial communities. Here, we examine whether linkage among social traits occurs in natural habitats by examining investment levels and correlations between five public goods (biosurfactants, biofilm components, proteases, pyoverdines and toxic compounds) in 315 Pseudomonas isolates from soil and freshwater communities. Our phenotypic assays revealed that (i) social trait expression profiles varied dramatically; (ii) correlations between traits were frequent, exclusively positive and sometimes habitat-specific; and (iii) heterogeneous (specialised) trait repertoires were rarer than homogeneous (unspecialised) repertoires. Our results show that most isolates lie on a continuum between a 'social' type producing multiple public goods, and an 'asocial' type showing low investment into social traits. This segregation could reflect local adaptation to different microhabitats, or emerge from interactions between different social strategies. In the latter case, our findings suggest that the scope for competition among unspecialised isolates exceeds the scope for mutualistic exchange of different public goods between specialised isolates. Overall, our results indicate that complex interdependencies among social traits shape microbial lifestyles in nature.
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Affiliation(s)
- Jos Kramer
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.,Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Miguel Ángel López Carrasco
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.,Departamento de Biología Celular, Genética y Fisiología, University of Málaga, Bulevar Louis Pasteur 31, 29010 Málaga, Spain
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.,Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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27
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Nakamura Y, Takahashi H, Takaya A, Inoue Y, Katayama Y, Kusuya Y, Shoji T, Takada S, Nakagawa S, Oguma R, Saito N, Ozawa N, Nakano T, Yamaide F, Dissanayake E, Suzuki S, Villaruz A, Varadarajan S, Matsumoto M, Kobayashi T, Kono M, Sato Y, Akiyama M, Otto M, Matsue H, Núñez G, Shimojo N. Staphylococcus Agr virulence is critical for epidermal colonization and associates with atopic dermatitis development. Sci Transl Med 2020; 12:eaay4068. [PMID: 32641488 PMCID: PMC7426015 DOI: 10.1126/scitranslmed.aay4068] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 06/12/2020] [Indexed: 01/07/2023]
Abstract
Atopic dermatitis (AD) is commonly associated with colonization by Staphylococcus aureus in the affected skin. To understand the role of S. aureus in the development of AD, we performed whole-genome sequencing of S. aureus strains isolated from the cheek skin of 268 Japanese infants 1 and 6 months after birth. About 45% of infants were colonized with S. aureus at 1 month regardless of AD outcome. In contrast, skin colonization by S. aureus at 6 months of age increased the risk of developing AD. Acquisition of dysfunctional mutations in the S. aureus Agr quorum-sensing (QS) system was primarily observed in strains from 6-month-old infants who did not develop AD. Expression of a functional Agr system in S. aureus was required for epidermal colonization and the induction of AD-like inflammation in mice. Thus, retention of functional S. aureus agr virulence during infancy is associated with pathogen skin colonization and the development of AD.
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Affiliation(s)
- Yuumi Nakamura
- Department of Dermatology, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan.
- Cutaneous Immunology, Immunology Frontier Research Center, Osaka University, Osaka 565-0871, Japan
| | - Hiroki Takahashi
- Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
- Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Akiko Takaya
- Laboratory of Microbiology and Immunology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Yuzaburo Inoue
- Department of Pediatrics, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Yuki Katayama
- Department of Dermatology, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Yoko Kusuya
- Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
| | - Tatsuma Shoji
- Laboratory of Microbiology and Immunology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Sanami Takada
- Department of Dermatology, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Seitaro Nakagawa
- Department of Dermatology, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Rena Oguma
- Department of Dermatology, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Nobuko Saito
- Department of Dermatology, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Naoko Ozawa
- Department of Pediatrics, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Taiji Nakano
- Department of Pediatrics, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Fumiya Yamaide
- Department of Pediatrics, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Eishika Dissanayake
- Department of Pediatrics, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
| | - Shuichi Suzuki
- Department of Pediatrics, Shimoshizu National Hospital, Chiba 284-0003, Japan
| | - Amer Villaruz
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Saranyaraajan Varadarajan
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Masanori Matsumoto
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Tomoko Kobayashi
- Department of Dermatology, Nagoya University Graduate School of Medicine, Aichi 466-8550, Japan
| | - Michihiro Kono
- Department of Dermatology, Nagoya University Graduate School of Medicine, Aichi 466-8550, Japan
| | - Yasunori Sato
- Department of Global Clinical Research, Chiba University Graduate School of Medicine, Chiba 260-0870, Japan
| | - Masashi Akiyama
- Department of Dermatology, Nagoya University Graduate School of Medicine, Aichi 466-8550, Japan
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hiroyuki Matsue
- Department of Dermatology, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
- Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
| | - Gabriel Núñez
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Naoki Shimojo
- Department of Pediatrics, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan
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28
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Gurney J, Azimi S, Brown SP, Diggle SP. Combinatorial quorum sensing in Pseudomonas aeruginosa allows for novel cheating strategies. MICROBIOLOGY-SGM 2020; 166:777-784. [PMID: 32511085 DOI: 10.1099/mic.0.000941] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing (QS) is a social trait that is exploitable by non-cooperating cheats. Previously it has been shown that by linking QS to the production of both public and private goods, cheats can be prevented from invading populations of cooperators and this was described by Dandekar et al. (Science 2012;338:264-266) as 'a metabolic incentive to cooperate'. We hypothesized that P. aeruginosa could evolve novel cheating strategies to circumvent private goods metabolism by rewiring its combinatorial response to two QS signals (3O-C12-HSL and C4-HSL). We performed a selection experiment that cycled P. aeruginosa between public and private goods growth media and evolved an isolate that rewired its control of cooperative protease expression from a synergistic (AND-gate) response to dual-signal input to a 3O-C12-HSL-only response. We show that this isolate circumvents metabolic incentives to cooperate and acts as a combinatorial signalling cheat, with higher fitness in competition with its ancestor. Our results show three important principles: first, combinatorial QS allows for diverse social strategies to emerge; second, restrictions levied by private goods are not sufficient to explain the maintenance of cooperation in natural populations; and third, modifying combinatorial QS responses could result in important physiological outcomes in bacterial populations.
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Affiliation(s)
- James Gurney
- School of Biological Sciences, Georgia Institute of Technology, Atlanta,, USA.,Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, USA
| | - Sheyda Azimi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta,, USA.,Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, USA
| | - Sam P Brown
- School of Biological Sciences, Georgia Institute of Technology, Atlanta,, USA.,Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, USA
| | - Stephen P Diggle
- School of Biological Sciences, Georgia Institute of Technology, Atlanta,, USA.,Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, USA
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29
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Optimal Response to Quorum-Sensing Signals Varies in Different Host Environments with Different Pathogen Group Size. mBio 2020; 11:mBio.00535-20. [PMID: 32487754 PMCID: PMC7267880 DOI: 10.1128/mbio.00535-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Quorum sensing describes the ability of microbes to alter gene regulation according to their local population size. Some successful theory suggests that this is a form of cooperation, namely, investment in shared products is only worthwhile if there are sufficient bacteria making the same product. This theory can explain the genetic diversity in these signaling systems in Gram-positive bacteria, such as Bacillus and Staphylococcus sp. The possible advantages gained by rare genotypes (which can exploit the products of their more common neighbors) could explain why different genotypes can coexist. We show that while these social interactions can occur in simple laboratory experiments, they do not occur in naturalistic infections using an invertebrate pathogen, Bacillus thuringiensis. Instead, our results suggest that different genotypes are adapted to differently sized hosts. Overall, social models are not easily applied to this system, implying that a different explanation for this form of quorum sensing is required. The persistence of genetic variation in master regulators of gene expression, such as quorum-sensing systems, is hard to explain. Here, we investigated two alternative hypotheses for the prevalence of polymorphic quorum sensing in Gram-positive bacteria, i.e., the use of different signal/receptor pairs (‘pherotypes’) to regulate the same functions. First, social interactions between pherotypes or ‘facultative cheating’ may favor rare variants that exploit the signals of others. Second, different pherotypes may increase fitness in different environments. We evaluated these hypotheses in the invertebrate pathogen Bacillus thuringiensis, using three pherotypes expressed in a common genetic background. Facultative cheating could occur in well-mixed host homogenates provided there was minimal cross talk between competing pherotypes. However, facultative cheating did not occur when spatial structure was increased in static cultures or in naturalistic oral infections, where common pherotypes had higher fitness. There was clear support for environment-dependent fitness; pherotypes varied in responsiveness to signals and in mean competitive fitness. Notably, competitive fitness varied with group size. In contrast to typical social evolution models of quorum sensing which predict higher response to signal at larger group size, the pherotype with highest responsiveness to signals performed best in smaller hosts where infections have a lower pathogen group size. In this system, low signal abundance appears to limit fitness in hosts, while the optimal level of response to signals varies in different host environments.
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30
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Small talk: chemical conversations with bacteria. CHEMTEXTS 2020. [DOI: 10.1007/s40828-020-0102-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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The Synergy of Ciprofloxacin and Carvedilol against Staphylococcus aureus-Prospects of a New Treatment Strategy? Molecules 2019; 24:molecules24224104. [PMID: 31739388 PMCID: PMC6891268 DOI: 10.3390/molecules24224104] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 11/11/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022] Open
Abstract
Staphylococcus aureus infections are common and difficult to treat. The increasing number of drug-resistant staphylococcal infections has created the need to develop new strategies for the treatment of these infections. The synergistic antimicrobial activity of different pharmaceuticals seems to be an interesting alternative. The aim of this study was to assess the synergistic activity of ciprofloxacin and carvedilol against S. aureus strains. The antibacterial potential of ciprofloxacin and carvedilol was evaluated according to the CLSI guidelines. The calcium content in S. aureus cells was measured using flow cytometry and atomic absorption spectroscopy. Moreover, confocal and scanning electron microscopy were used to determine the mechanism of antibacterial synergy of ciprofloxacin and carvedilol. The antibacterial effect of ciprofloxacin was higher in the presence of carvedilol than in S. aureus cultures containing the antibiotic only. A significant increase in S. aureus membrane permeability was also observed. The simultaneous administration of the tested compounds caused damage to S. aureus cells visualized by SEM. Enhancement of the antimicrobial action of ciprofloxacin by carvedilol was correlated with an increase in free calcium content in S. aureus cells, morphological changes to the cells, and a reduction in the ability to form bacterial aggregates.
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32
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George SE, Hrubesch J, Breuing I, Vetter N, Korn N, Hennemann K, Bleul L, Willmann M, Ebner P, Götz F, Wolz C. Oxidative stress drives the selection of quorum sensing mutants in the Staphylococcus aureus population. Proc Natl Acad Sci U S A 2019; 116:19145-19154. [PMID: 31488708 PMCID: PMC6754547 DOI: 10.1073/pnas.1902752116] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Quorum sensing (QS) is the central mechanism by which social interactions within the bacterial community control bacterial behavior. QS-negative cells benefit by exploiting public goods produced by the QS-proficient population. Mechanisms to keep the balance between producers and nonproducers within the population are expected but have not been elucidated for peptide-based QS systems in gram-positive pathogens. The Agr system of Staphylococcus aureus comprises the secretion and sensing of an autoinducing peptide to activate its own expression via the response regulator AgrA as well as the expression of a regulatory RNAIII and psmα/psmß coding for phenol-soluble modulins (PSMs). Agr mutants can be monitored on blood agar due to their nonhemolytic phenotype. In vitro evolution and competition experiments show that they readily accumulate in a process that is accelerated by ciprofloxacin, while the wild type (WT) is retained in the population at low numbers. However, agr mutants possess a fitness advantage only under aerobic conditions. Under hypoxia, Agr activity is increased but without the expected fitness cost. The Agr-imposed oxygen-dependent fitness cost is not due to a metabolic burden but due to the reactive oxygen species (ROS)-inducing capacity of the PSMs and RNAIII-regulated factors. Thus, selection of mutants is dictated by the QS system itself. Under aerobic conditions, emergence of agr-negative mutants may provide the population with a fitness advantage while hypoxia favors QS maintenance and even affords increased toxin production. The oxygen-driven tuning of the Agr system might be of importance to provide the pathogen with capabilities crucial for disease progression.
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Affiliation(s)
- Shilpa Elizabeth George
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Jennifer Hrubesch
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Inga Breuing
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Naisa Vetter
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Natalya Korn
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Katja Hennemann
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Lisa Bleul
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Matthias Willmann
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Patrick Ebner
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Friedrich Götz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
| | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen 72076, Germany
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33
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Analysis of the influence of cyclo (L-phenylalanine-L-proline) on the proteome of Staphylococcus aureus using iTRAQ. ANN MICROBIOL 2019. [DOI: 10.1007/s13213-019-01508-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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34
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Dynamics of cheater invasion in a cooperating population of Pseudomonas aeruginosa. Sci Rep 2019; 9:10190. [PMID: 31308401 PMCID: PMC6629668 DOI: 10.1038/s41598-019-46651-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 06/27/2019] [Indexed: 11/17/2022] Open
Abstract
Pseudomonas aeruginosa quorum sensing (QS) regulates expression of dozens of genes in a cell density-dependent manner. Many QS-regulated genes code for production of extracellular factors, “public goods” that can benefit the entire population. This cooperation encourages individuals to cheat by using but not producing public goods. QS also controls expression of a limited number of genes encoding “private” cellular enzymes like Nuh, an enzyme involved in adenosine catabolism. Growth of P. aeruginosa on casein requires QS-regulated production of an extracellular protease and is an example of cooperative behavior. When P. aeruginosa is transferred daily on casein, QS mutants emerge. These cheaters have mutations in lasR, which encodes the primary QS transcription factor. When growth is on casein and adenosine, cheater emergence is constrained. Here, we report the dynamics of LasR mutant invasion during growth on casein or casein plus adenosine. We show that LasR mutants have the greatest advantage during early to mid-logarithmic growth on casein. Addition of adenosine to casein medium constrains cheaters throughout growth. Our data support the view that co-regulation of the public protease and the private nucleosidase by QS stabilizes cooperation, and the data are not consistent with other proposed alternate hypotheses.
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Silva KPT, Boedicker JQ. A neural network model predicts community-level signaling states in a diverse microbial community. PLoS Comput Biol 2019; 15:e1007166. [PMID: 31233492 PMCID: PMC6611639 DOI: 10.1371/journal.pcbi.1007166] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 07/05/2019] [Accepted: 06/06/2019] [Indexed: 11/19/2022] Open
Abstract
Signal crosstalk within biological communication networks is common, and such crosstalk can have unexpected consequences for decision making in heterogeneous communities of cells. Here we examined crosstalk within a bacterial community composed of five strains of Bacillus subtilis, with each strain producing a variant of the quorum sensing peptide ComX. In isolation, each strain produced one variant of the ComX signal to induce expression of genes associated with bacterial competence. When strains were combined, a mixture of ComX variants was produced resulting in variable levels of gene expression. To examine gene regulation in mixed communities, we implemented a neural network model. Experimental quantification of asymmetric crosstalk between pairs of strains parametrized the model, enabling the accurate prediction of activity within the full five-strain network. Unlike the single strain system in which quorum sensing activated upon exceeding a threshold concentration of the signal, crosstalk within the five-strain community resulted in multiple community-level quorum sensing states, each with a unique combination of quorum sensing activation among the five strains. Quorum sensing activity of the strains within the community was influenced by the combination and ratio of strains as well as community dynamics. The community-level signaling state was altered through an external signal perturbation, and the output state depended on the timing of the perturbation. Given the ubiquity of signal crosstalk in diverse microbial communities, the application of such neural network models will increase accuracy of predicting activity within microbial consortia and enable new strategies for control and design of bacterial signaling networks.
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Affiliation(s)
- Kalinga Pavan T. Silva
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, United States of America
| | - James Q. Boedicker
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, United States of America
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
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36
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Abstract
Regulatory RNAs, present in many bacterial genomes and particularly in pathogenic bacteria such as Staphylococcus aureus, control the expression of genes encoding virulence factors or metabolic proteins. They are extremely diverse and include noncoding RNAs (sRNA), antisense RNAs, and some 5' or 3' untranslated regions of messenger RNAs that act as sensors for metabolites, tRNAs, or environmental conditions (e.g., temperature, pH). In this review we focus on specific examples of sRNAs of S. aureus that illustrate how numerous sRNAs and associated proteins are embedded in complex networks of regulation. In addition, we discuss the CRISPR-Cas systems defined as an RNA-interference-like mechanism, which also exist in staphylococcal strains.
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37
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Rezzoagli C, Granato ET, Kümmerli R. In-vivo microscopy reveals the impact of Pseudomonas aeruginosa social interactions on host colonization. ISME JOURNAL 2019; 13:2403-2414. [PMID: 31123320 DOI: 10.1038/s41396-019-0442-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 03/20/2019] [Accepted: 04/24/2019] [Indexed: 12/21/2022]
Abstract
Pathogenic bacteria engage in social interactions to colonize hosts, which include quorum-sensing-mediated communication and the secretion of virulence factors that can be shared as "public goods" between individuals. While in-vitro studies demonstrated that cooperative individuals can be displaced by "cheating" mutants freeriding on social acts, we know less about social interactions in infections. Here, we developed a live imaging system to track virulence factor expression and social strain interactions in the human pathogen Pseudomonas aeruginosa colonizing the gut of Caenorhabditis elegans. We found that shareable siderophores and quorum-sensing systems are expressed during infections, affect host gut colonization, and benefit non-producers. However, non-producers were unable to successfully cheat and outcompete producers. Our results indicate that the limited success of cheats is due to a combination of the down-regulation of virulence factors over the course of the infection, the fact that each virulence factor examined contributed to but was not essential for host colonization, and the potential for negative frequency-dependent selection. Our findings shed new light on bacterial social interactions in infections and reveal potential limits of therapeutic approaches that aim to capitalize on social dynamics between strains for infection control.
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Affiliation(s)
- Chiara Rezzoagli
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland. .,Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland.
| | | | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland. .,Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland.
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38
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Martinez MN, Watts JL, Gilbert JM. Questions associated with the development of novel drugs intended for the treatment of bacterial infections in veterinary species. Vet J 2019; 248:79-85. [PMID: 31113568 DOI: 10.1016/j.tvjl.2019.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 04/17/2019] [Accepted: 04/18/2019] [Indexed: 11/17/2022]
Abstract
The emergence of multi-drug resistant bacteria has limited therapeutic options for the treatment of bacterial diseases in both human and veterinary medicine. This has resulted in an urgent need for novel agents to treat infectious diseases. Veterinary medicine is further constrained by the need to ensure that our emerging therapeutics have minimal or no impact on resistance in human pathogens. Thus, there has recently been increased attention given to the development of alternative treatments for infectious disease in animals. The domain of alternative therapies, which includes antimicrobial peptides, bacteriophages, probiotics, and immunomodulators, provides a means to directly inhibit the ability of a pathogen to damage the host while optimally, not imposing a selective pressure favouring antibiotic resistance. However, it is recognized that bacterial pathogens have the capability of expressing a variety of virulence factors, necessitating a clear understanding of the specific target for that therapeutic intervention. This manuscript explores the various virulence mechanisms, the potential utility of developing novel anti-virulence agents for counteracting the expression of diseases associated with veterinary species, and some of the unique regulatory hurdles to be addressed within the framework of a new animal drug application. We conclude with the public health concerns to be considered as these agents are integrated into the veterinary therapeutic arsenal. Our hope is that this manuscript will provide a platform to stimulate discussions on the critical questions that need to be addressed.
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Affiliation(s)
- Marilyn N Martinez
- US FDA Center for Veterinary Medicine, Rockville, MD 20855, United States.
| | - Jeffrey L Watts
- Zoetis, Inc., 333 Portage Street, Kalamazoo, MI 49007, United States
| | - Jeffrey M Gilbert
- US FDA Center for Veterinary Medicine, Rockville, MD 20855, United States
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39
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Resistance to leukocytes ties benefits of quorum sensing dysfunctionality to biofilm infection. Nat Microbiol 2019; 4:1114-1119. [PMID: 30936487 PMCID: PMC6588452 DOI: 10.1038/s41564-019-0413-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 02/14/2019] [Indexed: 12/27/2022]
Abstract
Social interactions play an increasingly recognized key role in bacterial physiology1. One of the best studied is quorum sensing (QS), a mechanism by which bacteria sense and respond to the status of cell density2. While QS is generally deemed crucial for bacterial survival, QS-dysfunctional mutants frequently arise in in-vitro culture. This has been explained by the fitness cost an individual mutant, a “quorum cheater”, saves at the expense of the community3. QS mutants are also often isolated from biofilm-associated infections, including cystic fibrosis lung infection4, as well as medical device infection and associated bacteremia5–7. However, despite the frequently proposed use of QS blockers to control virulence8, the mechanisms underlying QS dysfunctionality during infection have remained poorly understood. Here we show that in the major human pathogen Staphylococcus aureus, QS-dysfunctional mutants arise exclusively in biofilm infection, while in non-biofilm-associated infection there is a high selective pressure to maintain QS control. We demonstrate that this infection-type dependence is due to QS-dysfunctional bacteria having a significant survival advantage in biofilm infection, because they form dense and enlarged biofilms that provide resistance to phagocyte attacks. Our results link the benefit of QS-dysfunctional mutants in vivo to biofilm-mediated immune evasion, thus to mechanisms that are specific to the in-vivo setting. Notably, our findings explain why QS mutants are frequently isolated from biofilm-associated infections and provide guidance for the therapeutic application of QS blockers.
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40
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Liu J, Cai M, Yan H, Fu J, Wu G, Zhao Z, Zhao Y, Wang Y, Sun Y, You Y, Lin L, Huang J, Huang R, Zeng J. Yunnan Baiyao reduces hospital-acquired pressure ulcers via suppressing virulence gene expression and biofilm formation of Staphylococcus aureus. Int J Med Sci 2019; 16:1078-1088. [PMID: 31523169 PMCID: PMC6743274 DOI: 10.7150/ijms.33723] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/17/2019] [Indexed: 01/28/2023] Open
Abstract
Yunnan Baiyao (YB) as a kind of famous Chinese herbal medicine, possessed hemostatic, invigorating the circulation of blood, and anti-inflammatory effects. Identifying strategies to protect patients at risk for hospital-acquired pressure ulcers (HAPU) is essential. Herein, our results showed that YB treatment can effectively reduce the acne wound area and improve efficacy in a comparative study of 60 cases HAPU patients with S. aureus positive of acne wound pathogens. Furthermore, YB inhibited HIa expression and suppressed accessory gene regulator (agr) system controlled by regulatory RNA II and RNA III molecule using pALC1740, pALC1742 and pALC1743 S. aureus strain linked to gfpuvr reporter gene. Moreover, YB downregulated cao mRNA expression and inhibited coagulase activity by RT-PCR, slide and tube coagulase test. Additionally, YB downregulated seb, sec, sed, and tsst-1 mRNA expression to suppress enterotoxin and tsst-1 secretion and adhesion function related genes sarA, icaA, and cidA mRNA expression. Taken together, the data suggest that YB may reduce HAPU via suppressing virulence gene expression and biofilm formation of S. aureus.
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Affiliation(s)
- Jun Liu
- Laboratory of Pathogenic Biology, Guangdong Medical University, Zhanjiang 524023, China.,Dongguan Key Laboratory of Medical Bioactive Molecular Developmental and Translational Research, Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Guangdong Medical University, Dongguan 523808, China
| | - Mufa Cai
- Department of Clinical Laboratory, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong 524001, China
| | - Huimin Yan
- Dongguan Key Laboratory of Medical Bioactive Molecular Developmental and Translational Research, Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Guangdong Medical University, Dongguan 523808, China
| | - Jiawu Fu
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Guocai Wu
- Department of Blood Internal Medicine, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Zuguo Zhao
- Laboratory of Pathogenic Biology, Guangdong Medical University, Zhanjiang 524023, China
| | - Yi Zhao
- Laboratory of Pathogenic Biology, Guangdong Medical University, Zhanjiang 524023, China
| | - Yan Wang
- Laboratory of Pathogenic Biology, Guangdong Medical University, Zhanjiang 524023, China
| | - Yuanming Sun
- Guangdong Provincial Key Laboratory of Food Quality and Safety, College of Food Science, South China Agricultural University, Guangzhou 510642, China
| | - Yongke You
- School of Chinese Medicine, The University of Hongkong, Pokfulam, Hongkong
| | - Liyao Lin
- Department of Cardiothoracic Surgery, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong 524001, China
| | - Juan Huang
- Dongguan Key Laboratory of Medical Bioactive Molecular Developmental and Translational Research, Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Guangdong Medical University, Dongguan 523808, China
| | - Riming Huang
- Guangdong Provincial Key Laboratory of Food Quality and Safety, College of Food Science, South China Agricultural University, Guangzhou 510642, China
| | - Jincheng Zeng
- Dongguan Key Laboratory of Medical Bioactive Molecular Developmental and Translational Research, Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Guangdong Medical University, Dongguan 523808, China
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41
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Trivedi U, Madsen JS, Everett J, Fell C, Russel J, Haaber J, Crosby HA, Horswill AR, Burmølle M, Rumbaugh KP, Sørensen SJ. Staphylococcus aureus coagulases are exploitable yet stable public goods in clinically relevant conditions. Proc Natl Acad Sci U S A 2018; 115:E11771-E11779. [PMID: 30463950 PMCID: PMC6294911 DOI: 10.1073/pnas.1804850115] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Coagulation is an innate defense mechanism intended to limit blood loss and trap invading pathogens during infection. However, Staphylococcus aureus has the ability to hijack the coagulation cascade and generate clots via secretion of coagulases. Although many S. aureus have this characteristic, some do not. The population dynamics regarding this defining trait have yet to be explored. We report here that coagulases are public goods that confer protection against antimicrobials and immune factors within a local population or community, thus promoting growth and virulence. By utilizing variants of a methicillin-resistant S. aureus we infer that the secretion of coagulases is a cooperative trait, which is subject to exploitation by invading mutants that do not produce the public goods themselves. However, overexploitation, "tragedy of the commons," does not occur at clinically relevant conditions. Our micrographs indicate this is due to spatial segregation and population viscosity. These findings emphasize the critical role of coagulases in a social evolution context and provide a possible explanation as to why the secretion of these public goods is maintained in mixed S. aureus communities.
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Affiliation(s)
- Urvish Trivedi
- Section of Microbiology, Department of Biology, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jonas S Madsen
- Section of Microbiology, Department of Biology, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jake Everett
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX 79430
| | - Cody Fell
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX 79430
| | - Jakob Russel
- Section of Microbiology, Department of Biology, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jakob Haaber
- Department of Veterinary and Animal Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, 1870 Copenhagen, Denmark
| | - Heidi A Crosby
- Department of Immunology and Microbiology, Anschutz Medical Campus, University of Colorado, Aurora, CO 80045
| | - Alexander R Horswill
- Department of Immunology and Microbiology, Anschutz Medical Campus, University of Colorado, Aurora, CO 80045
| | - Mette Burmølle
- Section of Microbiology, Department of Biology, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Kendra P Rumbaugh
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX 79430
| | - Søren J Sørensen
- Section of Microbiology, Department of Biology, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark;
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42
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Liu Y, Qin Q, Defoirdt T. Does quorum sensing interference affect the fitness of bacterial pathogens in the real world? Environ Microbiol 2018; 20:3918-3926. [DOI: 10.1111/1462-2920.14446] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/05/2018] [Accepted: 10/09/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Yiying Liu
- College of Marine Sciences, South China Agricultural University; Guangzhou China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University; Guangzhou China
| | - Tom Defoirdt
- Center for Microbial Ecology and Technology (CMET); Ghent University; Ghent Belgium
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43
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Granato ET, Ziegenhain C, Marvig RL, Kümmerli R. Low spatial structure and selection against secreted virulence factors attenuates pathogenicity in Pseudomonas aeruginosa. ISME JOURNAL 2018; 12:2907-2918. [PMID: 30065310 DOI: 10.1038/s41396-018-0231-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/14/2018] [Accepted: 06/19/2018] [Indexed: 02/01/2023]
Abstract
Bacterial opportunistic pathogens are feared for their difficult-to-treat nosocomial infections and for causing morbidity in immunocompromised patients. Here, we study how such a versatile opportunist, Pseudomonas aeruginosa, adapts to conditions inside and outside its model host Caenorhabditis elegans, and use phenotypic and genotypic screens to identify the mechanistic basis of virulence evolution. We found that virulence significantly dropped in unstructured environments both in the presence and absence of the host, but remained unchanged in spatially structured environments. Reduction of virulence was either driven by a substantial decline in the production of siderophores (in treatments without hosts) or toxins and proteases (in treatments with hosts). Whole-genome sequencing of evolved clones revealed positive selection and parallel evolution across replicates, and showed an accumulation of mutations in regulator genes controlling virulence factor expression. Our study identifies the spatial structure of the non-host environment as a key driver of virulence evolution in an opportunistic pathogen.
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Affiliation(s)
- Elisa T Granato
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland. .,Department of Zoology, University of Oxford, Oxford, United Kingdom.
| | - Christoph Ziegenhain
- Department Biology II, Ludwig-Maximilians-University, Munich, Germany.,Department of Cell and Molecular Biology, Karolinska Institutet, Solna, Sweden
| | - Rasmus L Marvig
- Center for Genomic Medicine, Rigshospitalet, Copenhagen, Denmark
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
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44
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Cooper GA, Levin SR, Wild G, West SA. Modeling relatedness and demography in social evolution. Evol Lett 2018. [DOI: 10.1002/evl3.69] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Guy A. Cooper
- Department of Zoology; University of Oxford; Oxford OX1 3PS United Kingdom
| | - Samuel R. Levin
- Department of Zoology; University of Oxford; Oxford OX1 3PS United Kingdom
| | - Geoff Wild
- Department of Applied Mathematics; University of Western Ontario; London Ontario N6A 3K7 Canada
| | - Stuart A. West
- Department of Zoology; University of Oxford; Oxford OX1 3PS United Kingdom
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45
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Oshri RD, Zrihen KS, Shner I, Omer Bendori S, Eldar A. Selection for increased quorum-sensing cooperation in Pseudomonas aeruginosa through the shut-down of a drug resistance pump. ISME JOURNAL 2018; 12:2458-2469. [PMID: 29925881 PMCID: PMC6154968 DOI: 10.1038/s41396-018-0205-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 05/10/2018] [Accepted: 05/15/2018] [Indexed: 01/24/2023]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa employs a hierarchical quorum-sensing network to regulate virulence factor production that cooperatively benefit the population at a cost to the individual. It has been argued that the evolution of a cooperative mutant in a quorum sensing-suppressed population would be hampered through its exploitation by neighboring non-mutant cells. It remains unclear whether mechanisms which overcome this exploitation exist. Here we investigate the regain of quorum-sensing cooperation by evolving a mutant of the lasR master quorum-sensing regulator. The mutant regained partial cooperative growth through null mutations in mexT, which codes for an activator of the MexEF-OprN multidrug-resistant pump. We find that these mutations enhance cooperative growth in both the lasR mutant and wild-type backgrounds through the activation of the RhlIR system. We show that the regain of cooperation in mexT mutants is mediated by the reduction in MexEF-OprN activity, whereas an additional source of private benefit is mostly mexEF-oprN-independent. Finally, we show that addition of antibiotics for which resistance is mediated by MexEF-OprN prevents the selection of increased cooperation at sub-MIC concentrations. MexT, therefore, not only links private and public goods, but also exposes conflicts between selection for antibiotic resistance and enhanced cooperation.
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Affiliation(s)
- Ron D Oshri
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Keren S Zrihen
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Itzhak Shner
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Shira Omer Bendori
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Avigdor Eldar
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.
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46
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Pollitt EJG, Szkuta PT, Burns N, Foster SJ. Staphylococcus aureus infection dynamics. PLoS Pathog 2018; 14:e1007112. [PMID: 29902272 PMCID: PMC6019756 DOI: 10.1371/journal.ppat.1007112] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 06/26/2018] [Accepted: 05/21/2018] [Indexed: 01/22/2023] Open
Abstract
Staphylococcus aureus is a human commensal that can also cause systemic infections. This transition requires evasion of the immune response and the ability to exploit different niches within the host. However, the disease mechanisms and the dominant immune mediators against infection are poorly understood. Previously it has been shown that the infecting S. aureus population goes through a population bottleneck, from which very few bacteria escape to establish the abscesses that are characteristic of many infections. Here we examine the host factors underlying the population bottleneck and subsequent clonal expansion in S. aureus infection models, to identify underpinning principles of infection. The bottleneck is a common feature between models and is independent of S. aureus strain. Interestingly, the high doses of S. aureus required for the widely used "survival" model results in a reduced population bottleneck, suggesting that host defences have been simply overloaded. This brings into question the applicability of the survival model. Depletion of immune mediators revealed key breakpoints and the dynamics of systemic infection. Loss of macrophages, including the liver Kupffer cells, led to increased sensitivity to infection as expected but also loss of the population bottleneck and the spread to other organs still occurred. Conversely, neutrophil depletion led to greater susceptibility to disease but with a concomitant maintenance of the bottleneck and lack of systemic spread. We also used a novel microscopy approach to examine abscess architecture and distribution within organs. From these observations we developed a conceptual model for S. aureus disease from initial infection to mature abscess. This work highlights the need to understand the complexities of the infectious process to be able to assign functions for host and bacterial components, and why S. aureus disease requires a seemingly high infectious dose and how interventions such as a vaccine may be more rationally developed.
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Affiliation(s)
- Eric J. G. Pollitt
- Department of Molecular Biology and Biotechnology, Firth Court, University of Sheffield, Western Bank, Sheffield, United Kingdom
| | - Piotr T. Szkuta
- Department of Molecular Biology and Biotechnology, Firth Court, University of Sheffield, Western Bank, Sheffield, United Kingdom
| | - Nicola Burns
- Department of Molecular Biology and Biotechnology, Firth Court, University of Sheffield, Western Bank, Sheffield, United Kingdom
| | - Simon J. Foster
- Department of Molecular Biology and Biotechnology, Firth Court, University of Sheffield, Western Bank, Sheffield, United Kingdom
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47
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Abstract
Many bacteria use a cell-cell communication system called quorum sensing to coordinate population density-dependent changes in behavior. Quorum sensing involves production of and response to diffusible or secreted signals, which can vary substantially across different types of bacteria. In many species, quorum sensing modulates virulence functions and is important for pathogenesis. Over the past half-century, there has been a significant accumulation of knowledge of the molecular mechanisms, signal structures, gene regulons, and behavioral responses associated with quorum-sensing systems in diverse bacteria. More recent studies have focused on understanding quorum sensing in the context of bacterial sociality. Studies of the role of quorum sensing in cooperative and competitive microbial interactions have revealed how quorum sensing coordinates interactions both within a species and between species. Such studies of quorum sensing as a social behavior have relied on the development of "synthetic ecological" models that use nonclonal bacterial populations. In this review, we discuss some of these models and recent advances in understanding how microbes might interact with one another using quorum sensing. The knowledge gained from these lines of investigation has the potential to guide studies of microbial sociality in natural settings and the design of new medicines and therapies to treat bacterial infections.
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48
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Yan H, Wang M, Sun F, Dandekar AA, Shen D, Li N. A Metabolic Trade-Off Modulates Policing of Social Cheaters in Populations of Pseudomonas aeruginosa. Front Microbiol 2018. [PMID: 29535700 PMCID: PMC5835063 DOI: 10.3389/fmicb.2018.00337] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa uses quorum sensing (QS) to regulate the production of public goods such as the secreted protease elastase. P. aeruginosa requires the LasI-LasR QS circuit to induce elastase and enable growth on casein as the sole carbon and energy source. The LasI-LasR system also induces a second QS circuit, the RhlI-RhlR system. During growth on casein, LasR-mutant social cheaters emerge, and this can lead to a population collapse. In a minimal medium containing ammonium sulfate as a nitrogen source, populations do not collapse, and cheaters and cooperators reach a stable equilibrium; however, without ammonium sulfate, cheaters overtake the cooperators and populations collapse. We show that ammonium sulfate enhances the activity of the RhlI-RhlR system in casein medium and this leads to increased production of cyanide, which serves to control levels of cheaters. This enhancement of cyanide production occurs because of a trade-off in the metabolism of glycine: exogenous ammonium ion inhibits the transformation of glycine to 5,10-methylenetetrahydrofolate through a reduction in the expression of the glycine cleavage genes gcvP1 and gcvP2, thereby increasing the availability of glycine as a substrate for RhlR-regulated hydrogen cyanide synthesis. Thus, environmental ammonia enhances cyanide production and stabilizes QS in populations of P. aeruginosa.
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Affiliation(s)
- Huicong Yan
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China
| | - Meizhen Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
| | - Feng Sun
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China
| | - Ajai A Dandekar
- Department of Microbiology, University of Washington, Seattle, WA, United States.,Department of Medicine, University of Washington, Seattle, WA, United States
| | - Dongsheng Shen
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
| | - Na Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
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49
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A common evolutionary pathway for maintaining quorum sensing in Pseudomonas aeruginosa. J Microbiol 2018; 56:83-89. [PMID: 29392560 DOI: 10.1007/s12275-018-7286-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 12/11/2017] [Accepted: 12/12/2017] [Indexed: 10/18/2022]
Abstract
In the bacterium Pseudomonas aeruginosa, the synthesis and secretion of extracellular protease is a typical cooperative behavior regulated by quorum sensing. However, this type of cooperative behavior is easily exploited by other individuals who do not synthesize public goods, which is known as the "tragedy of the commons". Here P. aeruginosa was inoculated into casein media with different nitrogen salts added. In casein broth, protease (a type of public good) is necessary for bacterial growth. After 30 days of sequential transfer, some groups propagated stably and avoided "tragedy of the commons". The evolved cooperators who continued to synthesize protease were isolated from these stable groups. By comparing the characteristics of quorum sensing in these cooperators, an identical evolutionary pattern was found. A variety of cooperative behaviors regulated by quorum sensing, such as the synthesis and secretion of protease and signals, were significantly reduced during the process of evolution. Such reductions improved the efficiency of cooperation, helping to prevent cheating. In addition, the production of pyocyanin, which is regulated by the RhlIR system, increased during the process of evolution, possibly due to its role in stabilizing the cooperation. This study contributes towards our understanding of the evolution of quorum sensing of P. aeruginosa.
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50
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Weigert M, Kümmerli R. The physical boundaries of public goods cooperation between surface-attached bacterial cells. Proc Biol Sci 2018; 284:rspb.2017.0631. [PMID: 28701557 DOI: 10.1098/rspb.2017.0631] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 06/02/2017] [Indexed: 01/17/2023] Open
Abstract
Bacteria secrete a variety of compounds important for nutrient scavenging, competition mediation and infection establishment. While there is a general consensus that secreted compounds can be shared and therefore have social consequences for the bacterial collective, we know little about the physical limits of such bacterial social interactions. Here, we address this issue by studying the sharing of iron-scavenging siderophores between surface-attached microcolonies of the bacterium Pseudomonas aeruginosa Using single-cell fluorescence microscopy, we show that siderophores, secreted by producers, quickly reach non-producers within a range of 100 µm, and significantly boost their fitness. Producers in turn respond to variation in sharing efficiency by adjusting their pyoverdine investment levels. These social effects wane with larger cell-to-cell distances and on hard surfaces. Thus, our findings reveal the boundaries of compound sharing, and show that sharing is particularly relevant between nearby yet physically separated bacteria on soft surfaces, matching realistic natural conditions such as those encountered in soft tissue infections.
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Affiliation(s)
- Michael Weigert
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland .,Department of Biology I, Division of Microbiology, Ludwig Maximilians University Munich, Grosshaderner Strasse 2-4, 82152 Martinsried, Germany
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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