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Saha S, Ghosh M. Computational exploration of natural compounds targeting Staphylococcus aureus: inhibiting AgrA promoter binding for antimicrobial intervention. J Biomol Struct Dyn 2024; 42:8256-8267. [PMID: 37578046 DOI: 10.1080/07391102.2023.2246566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 07/30/2023] [Indexed: 08/15/2023]
Abstract
Staphylococcus aureus is a highly virulent nosocomial pathogen that poses a significant threat to individuals exposed to healthcare settings. Due to its sophisticated machinery for producing virulence factors, S. aureus can cause severe and potentially fatal infections in humans. This study focuses on the response regulator AgrA, which plays a crucial role in regulating the production of virulence factors in S. aureus. The objective is to identify natural compounds that can inhibit the binding of AgrA to its promoter site, thus inhibiting the expression of virulence genes. To achieve this, a pharmacophore model was generated using known drugs and applied to screen the ZINC natural product database. The resulting compounds were subjected to molecular docking-based virtual screening against the C-terminal DNA binding domain of AgrA. Three compounds, namely ZINC000077269178, ZINC000051012304, and ZINC000004266026, were shortlisted based on their strong affinity for key residues involved in DNA binding and transcription initiation. Subsequently, the unbound and ligand-bound complexes were subjected to a 200 ns molecular dynamics simulation to assess their conformational stability. Various analyses, including RMSD, RMSF, Rg, SASA, Principal Component Analysis, and Gibbs free energy landscape, were conducted on the simulation trajectory. The RMSD profile indicated similar fluctuations in both bound and unbound structures, while the Rg profile demonstrated the compactness of the protein without any unfolding during the simulation. Furthermore, Principal component analysis revealed that ligand binding reduced the overall atomic motion of the protein whereas free energy landscape suggested the energy variations obtained in complexes.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Subhadip Saha
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, India
| | - Monidipa Ghosh
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, India
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2
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Manu P, Nketia PB, Osei-Poku P, Kwarteng A. Computational Mutagenesis and Inhibition of Staphylococcus aureus AgrA LytTR Domain Using Phenazine Scaffolds: Insight From a Biophysical Study. BIOMED RESEARCH INTERNATIONAL 2024; 2024:8843954. [PMID: 39328594 PMCID: PMC11424843 DOI: 10.1155/2024/8843954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Accepted: 08/29/2024] [Indexed: 09/28/2024]
Abstract
Biofilm formation by Staphylococcus aureus is a major challenge in clinical settings due to its role in persistent infections. The AgrA protein, a key regulator in biofilm development, is a promising target for therapeutic intervention. This study investigates the antibiofilm potential of halogenated phenazine compounds by targeting AgrA and explores their molecular interactions to provide insights for drug development. We employed molecular docking, molecular dynamics simulations, and computational mutagenesis to evaluate the binding of halogenated phenazine compounds (C1 to C7, HP, and HP-14) to AgrA. Binding free energy analysis was performed to assess the affinity of these compounds for the AgrA-DNA complex. Additionally, the impact of these compounds on AgrA's structural conformation and salt bridge interactions was examined. The binding-free energy analysis revealed that all compounds enhance binding affinity compared to the Apo form of AgrA, which has a ΔGbind of -80.75 kcal/mol. The strongest binding affinities were observed with compounds C7 (-113.84 kcal/mol), HP-14 (-115.23 kcal/mol), and HP (-112.28 kcal/mol), highlighting their effectiveness. Molecular dynamics simulations demonstrated that these compounds bind at the hydrophobic cleft of AgrA, disrupting essential salt bridge interactions between His174-Glu163 and His174-Glu226. This disruption led to structural conformational changes and reduced DNA binding affinity, aligning with experimental findings on biofilm inhibition. The halogenated phenazine compounds effectively inhibit biofilm formation by targeting AgrA, disrupting its DNA-binding function. The study supports the potential of these compounds as antibiofilm agents and provides a foundation for rational drug design targeting the AgrA-DNA interaction. Future research should focus on further optimizing these lead compounds and exploring additional active sites on AgrA to develop novel treatments for biofilm-associated infections.
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Affiliation(s)
- Prince Manu
- Department of ChemistryKwame Nkrumah University of Science and Technology, Kumasi, Ghana
- Kumasi Centre for Collaborative Research in Tropical MedicineKwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Prisca Baah Nketia
- Department of ChemistryKwame Nkrumah University of Science and Technology, Kumasi, Ghana
- Kumasi Centre for Collaborative Research in Tropical MedicineKwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Priscilla Osei-Poku
- Kumasi Centre for Collaborative Research in Tropical MedicineKwame Nkrumah University of Science and Technology, Kumasi, Ghana
- Department of Biochemistry and BiotechnologyKwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Alexander Kwarteng
- Kumasi Centre for Collaborative Research in Tropical MedicineKwame Nkrumah University of Science and Technology, Kumasi, Ghana
- Department of Biochemistry and BiotechnologyKwame Nkrumah University of Science and Technology, Kumasi, Ghana
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3
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Lee J, Carda-Diéguez M, Vreugde S, Cooksley C, Mashayamombe M, Dawson J, Fitridge R, Mira A, Zilm PS, Kidd SP. Characterising the role of enolase in a stable Small Colony Variant of Staphylococcus aureus isolated from a diabetic foot infection patient with osteomyelitis. Microb Pathog 2024; 196:106918. [PMID: 39243992 DOI: 10.1016/j.micpath.2024.106918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 09/01/2024] [Accepted: 09/04/2024] [Indexed: 09/09/2024]
Abstract
The switch to alternate cell types by Staphylococcus aureus creates sub-populations even within an active population, that are highly resilient, tolerant to antibiotics and lack clinical symptoms of infection. These cells present a challenge for clinical treatment where even after initial intervention has seemingly cleared the infection, these alternate cell types persist within tissue to revert and cause disease. Small colony variants (SCV) are a cell type which facilitate persistent infection but clinically isolated SCVs are often unstable in laboratory conditions. We have isolated a pair of S. aureus isolates from an individual patient with osteomyelitis presenting with heterogenous phenotypes; a stable SCV (sSCV) and a SCV that reverts upon laboratory culturing to the usual, active and non-SCV cell type. Thus we are able use this pair to investigate and compare the genetic mechanisms that underlie the clinical variatons of SCV phenotype. The switch to the sSCV phenotype was associated with frameshift mutations in the enolase eno and the histidine kinase arlS. The phenoptye of the sSCV was an impeded growth dependent on amino acid catabolism and modulated biofilm. These mutations present potentially a new molecular mechanism which confer persistence within osteomyelitis.
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Affiliation(s)
- James Lee
- Department of Molecular and Biomedical Sciences, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia; Australian Centre for Antimicrobial Resistance Ecology (ACARE), The University of Adelaide, Adelaide, South Australia, Australia; Research Centre for Infectious Diseases (RCID), The University of Adelaide, Adelaide, Australia
| | - Miguel Carda-Diéguez
- Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Institute, Province of Valencia, Valencia, Spain
| | - Sarah Vreugde
- Department of Otolaryngology, Head and Neck Surgery, Basil Hetzel Institute, South Australia, Adelaide, Australia
| | - Clare Cooksley
- Department of Otolaryngology, Head and Neck Surgery, Basil Hetzel Institute, South Australia, Adelaide, Australia
| | - Matipaishe Mashayamombe
- Department of Vascular and Endovascular Surgery, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Joseph Dawson
- Department of Vascular and Endovascular Surgery, Royal Adelaide Hospital, Adelaide, South Australia, Australia; Discipline of Surgery, The University of Adelaide, Adelaide, South Australia, Australia; Basil Hetzel Institute for Translational Health Research, The Queen Elizabeth Hospital, Woodville South, South Australia, Australia
| | - Robert Fitridge
- Department of Vascular and Endovascular Surgery, Royal Adelaide Hospital, Adelaide, South Australia, Australia; Discipline of Surgery, The University of Adelaide, Adelaide, South Australia, Australia; Basil Hetzel Institute for Translational Health Research, The Queen Elizabeth Hospital, Woodville South, South Australia, Australia
| | - Alex Mira
- Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Institute, Province of Valencia, Valencia, Spain
| | - Peter S Zilm
- Adelaide Dental School, The University of Adelaide, Adelaide, South Australia, Australia
| | - Stephen P Kidd
- Department of Molecular and Biomedical Sciences, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia; Australian Centre for Antimicrobial Resistance Ecology (ACARE), The University of Adelaide, Adelaide, South Australia, Australia; Research Centre for Infectious Diseases (RCID), The University of Adelaide, Adelaide, Australia.
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4
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Guan P, Fan S, Dong W, Wang X, Li Z, Song M, Suo B. Comparative genomic analysis and multilocus sequence typing of Staphylococcus aureus reveals candidate genes for low-temperature tolerance. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 923:171331. [PMID: 38428609 DOI: 10.1016/j.scitotenv.2024.171331] [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: 01/08/2024] [Revised: 02/23/2024] [Accepted: 02/26/2024] [Indexed: 03/03/2024]
Abstract
Staphylococcus aureus is one of the most frequently detected foodborne pathogens in cold chain foods. Worryingly, small colony variants (SCVs) can survive in cold environments for a long time and can revert to rapidly growing cells in suitable environments, causing serious food safety issues. This study investigated the underlying mechanism of SCV formation at low temperature (4 °C) via comparative genomics. Multilocus sequence typing (MLST) of 105 strains of S. aureus was divided into 9 sequence types. The ST352 strains exhibited the greatest tolerance to low temperature, with a mean reduction in survival rate of 10.34 % (p < 0.05). Comparative genomics revealed a total of 1941 core genes in the three S. aureus strains, and BB-1 had 468 specific genes, which were enriched mainly in translation, DNA recombination, DNA repair, metabolic pathways, two-component systems, and quorum sensing. Molecular docking analysis revealed that the binding of the RsbW protein to the SigB protein of BB-1 decreased due to base mutations in rsbW, while the binding to the RsbV protein was enhanced. In addition, the results of real-time quantitative PCR showed that the RsbV-RsbW/SigB system of BB-1 may play a role in the low-temperature survival of S. aureus and the formation of SCVs. These results suggest that genes specific to BB-1 may contribute to the mechanism of adaptation to low temperature and the formation of SCVs. This study helps elucidate the causes of SCV formation by S. aureus at low temperature at the molecular level and provides a basis for exploring the safety control of cold chain food environments.
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Affiliation(s)
- Peng Guan
- College of Food Science and Technology, Henan Agricultural University, Zhengzhou, China
| | - Shijia Fan
- College of Food Science and Technology, Henan Agricultural University, Zhengzhou, China
| | - Wenjing Dong
- College of Food Science and Technology, Henan Agricultural University, Zhengzhou, China
| | - Xiaojie Wang
- College of Food Science and Technology, Henan Agricultural University, Zhengzhou, China; Key Laboratory of Staple Grain Processing, Ministry of Agriculture and Rural Affairs, Zhengzhou, China; National R&D Center for Frozen Rice & Wheat Products Processing Technology, Henan Engineering Laboratory of Quick-Frozen Flour-Rice Food and Prepared Food, Henan Agricultural University, Zhengzhou, China
| | - Zhen Li
- College of Food Science and Technology, Henan Agricultural University, Zhengzhou, China; Key Laboratory of Staple Grain Processing, Ministry of Agriculture and Rural Affairs, Zhengzhou, China; National R&D Center for Frozen Rice & Wheat Products Processing Technology, Henan Engineering Laboratory of Quick-Frozen Flour-Rice Food and Prepared Food, Henan Agricultural University, Zhengzhou, China
| | - Miao Song
- College of Food Science and Technology, Henan Agricultural University, Zhengzhou, China; Key Laboratory of Staple Grain Processing, Ministry of Agriculture and Rural Affairs, Zhengzhou, China; National R&D Center for Frozen Rice & Wheat Products Processing Technology, Henan Engineering Laboratory of Quick-Frozen Flour-Rice Food and Prepared Food, Henan Agricultural University, Zhengzhou, China
| | - Biao Suo
- College of Food Science and Technology, Henan Agricultural University, Zhengzhou, China; Key Laboratory of Staple Grain Processing, Ministry of Agriculture and Rural Affairs, Zhengzhou, China; National R&D Center for Frozen Rice & Wheat Products Processing Technology, Henan Engineering Laboratory of Quick-Frozen Flour-Rice Food and Prepared Food, Henan Agricultural University, Zhengzhou, China.
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Doğan E, Sydow K, Heiden SE, Eger E, Wassilew G, Proctor RA, Bohnert JA, Idelevich EA, Schaufler K, Becker K. Klebsiella pneumoniae exhibiting a phenotypic hyper-splitting phenomenon including the formation of small colony variants. Front Cell Infect Microbiol 2024; 14:1372704. [PMID: 38601740 PMCID: PMC11004228 DOI: 10.3389/fcimb.2024.1372704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 03/07/2024] [Indexed: 04/12/2024] Open
Abstract
In this study, we characterized a Klebsiella pneumoniae strain in a patient with shrapnel hip injury, which resulted in multiple phenotypic changes, including the formation of a small colony variant (SCV) phenotype. Although already described since the 1960s, there is little knowledge about SCV phenotypes in Enterobacteriaceae. The formation of SCVs has been recognized as a bacterial strategy to evade host immune responses and compromise the efficacy of antimicrobial therapies, leading to persistent and recurrent courses of infections. In this case, 14 isolates with different resisto- and morpho-types were distinguished from the patient's urine and tissue samples. Whole genome sequencing revealed that all isolates were clonally identical belonging to the K. pneumoniae high-risk sequence type 147. Subculturing the SCV colonies consistently resulted in the reappearance of the initial SCV phenotype and three stable normal-sized phenotypes with distinct morphological characteristics. Additionally, an increase in resistance was observed over time in isolates that shared the same colony appearance. Our findings highlight the complexity of bacterial behavior by revealing a case of phenotypic "hyper-splitting" in a K. pneumoniae SCV and its potential clinical significance.
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Affiliation(s)
- Eyüp Doğan
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Katharina Sydow
- Department of Epidemiology and Ecology of Antimicrobial Resistance, Helmholtz Institute for One Health, Helmholtz Centre for Infection Research Helmholtz Center for Infection Research (HZI), Greifswald, Germany
| | - Stefan E. Heiden
- Department of Epidemiology and Ecology of Antimicrobial Resistance, Helmholtz Institute for One Health, Helmholtz Centre for Infection Research Helmholtz Center for Infection Research (HZI), Greifswald, Germany
| | - Elias Eger
- Department of Epidemiology and Ecology of Antimicrobial Resistance, Helmholtz Institute for One Health, Helmholtz Centre for Infection Research Helmholtz Center for Infection Research (HZI), Greifswald, Germany
| | - Georgi Wassilew
- Center for Orthopedics, Trauma Surgery and Rehabilitation Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Richard A. Proctor
- Departments of Medical Microbiology/Immunology and Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Jürgen A. Bohnert
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Evgeny A. Idelevich
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Katharina Schaufler
- Department of Epidemiology and Ecology of Antimicrobial Resistance, Helmholtz Institute for One Health, Helmholtz Centre for Infection Research Helmholtz Center for Infection Research (HZI), Greifswald, Germany
- University Medicine Greifswald, Greifswald, Germany
| | - Karsten Becker
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
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Gajewska J, Zakrzewski AJ, Chajęcka-Wierzchowska W, Zadernowska A. Impact of the Food-Related Stress Conditions on the Expression of Enterotoxin Genes among Staphylococcus aureus. Pathogens 2023; 12:954. [PMID: 37513801 PMCID: PMC10383469 DOI: 10.3390/pathogens12070954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/14/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
Staphylococcus aureus is one of the most important foodborne pathogens. S. aureus has the capability to produce a variety of toxins, including staphylococcal enterotoxins (SEs). The aim of this study was to evaluate the survival rate of S. aureus cells and analyze enterotoxins gene expression after exposure to osmotic stress and acidic/alkaline stress. To determine survival rates, the traditional plate counting method and flow cytometry were used. The expression levels of the enterotoxin genes were performed by quantitative reverse transcription PCR (RT-qPCR). Expression changes differed depending on the stressors chosen. The obtained results in this study showed the effect of critical food-related stress conditions on SE gene expression in S. aureus. The study showed different expression levels of the tested enterotoxins genes depending on the stress. The most tested enterotoxin genes (seg, sei, and selo) after exposure to pH = 4.5 stress have similar expression as in the optimal condition. After alkaline treatment (pH = 9.6), a similar expression gene value as for the optimal condition was observed. The analysis of gene expression in response to stress caused by NaCl, showed that the expression of selp decreased, whereas selu, selm, and selo genes increased. A significantly decreased expression of the sea gene was observed.
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Affiliation(s)
- Joanna Gajewska
- Department of Industrial and Food Microbiology, Faculty of Food Science, University of Warmia and Mazury in Olsztyn, 10-726 Olsztyn, Poland
| | - Arkadiusz Józef Zakrzewski
- Department of Industrial and Food Microbiology, Faculty of Food Science, University of Warmia and Mazury in Olsztyn, 10-726 Olsztyn, Poland
| | - Wioleta Chajęcka-Wierzchowska
- Department of Industrial and Food Microbiology, Faculty of Food Science, University of Warmia and Mazury in Olsztyn, 10-726 Olsztyn, Poland
| | - Anna Zadernowska
- Department of Industrial and Food Microbiology, Faculty of Food Science, University of Warmia and Mazury in Olsztyn, 10-726 Olsztyn, Poland
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Baran M, Feriotti C, McGinley A, Carlile SR, Jiang Z, Calderon-Gonzalez R, Dumigan A, Sá-Pessoa J, Sutton CE, Kearney J, McLoughlin RM, Mills KHG, Fitzgerald KA, Bengeochea JA, Bowie AG. PYHIN protein IFI207 regulates cytokine transcription and IRF7 and contributes to the establishment of K. pneumoniae infection. Cell Rep 2023; 42:112341. [PMID: 37018072 DOI: 10.1016/j.celrep.2023.112341] [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: 03/24/2022] [Revised: 02/02/2023] [Accepted: 03/20/2023] [Indexed: 04/06/2023] Open
Abstract
PYHIN proteins AIM2 and IFI204 sense pathogen DNA, while other PYHINs have been shown to regulate host gene expression through as-yet unclear mechanisms. We characterize mouse PYHIN IFI207, which we find is not involved in DNA sensing but rather is required for cytokine promoter induction in macrophages. IFI207 co-localizes with both active RNA polymerase II (RNA Pol II) and IRF7 in the nucleus and enhances IRF7-dependent gene promoter induction. Generation of Ifi207-/- mice shows no role for IFI207 in autoimmunity. Rather, IFI207 is required for the establishment of a Klebsiella pneumoniae lung infection and for Klebsiella macrophage phagocytosis. These insights into IFI207 function illustrate that PYHINs can have distinct roles in innate immunity independent of DNA sensing and highlight the need to better characterize the whole mouse locus, one gene at a time.
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Affiliation(s)
- Marcin Baran
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 Dublin, Ireland
| | - Claudia Feriotti
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queens University Belfast, 97 Lisburn Road, Belfast, UK
| | - Aoife McGinley
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 Dublin, Ireland
| | - Simon R Carlile
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 Dublin, Ireland
| | - Zhaozhao Jiang
- Division of Innate Immunity, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Ricardo Calderon-Gonzalez
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queens University Belfast, 97 Lisburn Road, Belfast, UK
| | - Amy Dumigan
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queens University Belfast, 97 Lisburn Road, Belfast, UK
| | - Joana Sá-Pessoa
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queens University Belfast, 97 Lisburn Road, Belfast, UK
| | - Caroline E Sutton
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 Dublin, Ireland
| | - Jay Kearney
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 Dublin, Ireland
| | - Rachel M McLoughlin
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 Dublin, Ireland
| | - Kingston H G Mills
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 Dublin, Ireland
| | - Katherine A Fitzgerald
- Division of Innate Immunity, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jose A Bengeochea
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queens University Belfast, 97 Lisburn Road, Belfast, UK
| | - Andrew G Bowie
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 Dublin, Ireland.
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Mashayamombe M, Carda-Diéguez M, Mira A, Fitridge R, Zilm PS, Kidd SP. Subpopulations in Strains of Staphylococcus aureus Provide Antibiotic Tolerance. Antibiotics (Basel) 2023; 12:antibiotics12020406. [PMID: 36830316 PMCID: PMC9952555 DOI: 10.3390/antibiotics12020406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/12/2023] [Accepted: 02/15/2023] [Indexed: 02/22/2023] Open
Abstract
The ability of Staphylococcus aureus to colonise different niches across the human body is linked to an adaptable metabolic capability, as well as its ability to persist within specific tissues despite adverse conditions. In many cases, as S. aureus proliferates within an anatomical niche, there is an associated pathology. The immune response, together with medical interventions such as antibiotics, often removes the S. aureus cells that are causing this disease. However, a common issue in S. aureus infections is a relapse of disease. Within infected tissue, S. aureus exists as a population of cells, and it adopts a diversity of cell types. In evolutionary biology, the concept of "bet-hedging" has established that even in positive conditions, there are members that arise within a population that would be present as non-beneficial, but if those conditions change, these traits could allow survival. For S. aureus, some of these cells within an infection have a reduced fitness, are not rapidly proliferating or are the cause of an active host response and disease, but these do remain even after the disease seems to have been cleared. This is true for persistence against immune responses but also as a continual presence in spite of antibiotic treatment. We propose that the constant arousal of suboptimal populations at any timepoint is a key strategy for S. aureus long-term infection and survival. Thus, understanding the molecular basis for this feature could be instrumental to combat persistent infections.
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Affiliation(s)
- Matipaishe Mashayamombe
- Department of Vascular Surgery, Royal Adelaide Hospital, Adelaide, SA 5000, Australia
- Discipline of Surgery, Adelaide Medical School, The University of Adelaide, Adelaide, SA 5000, Australia
- Basil Hetzel Institute for Translational Research, The Queen Elizabeth Hospital, Adelaide, SA 5000, Australia
| | - Miguel Carda-Diéguez
- Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Institute, 46020 Valencia, Spain
| | - Alex Mira
- Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Institute, 46020 Valencia, Spain
- School of Health and Welfare, Jönköping University, 551 11 Jönköping, Sweden
| | - Robert Fitridge
- Department of Vascular Surgery, Royal Adelaide Hospital, Adelaide, SA 5000, Australia
- Discipline of Surgery, Adelaide Medical School, The University of Adelaide, Adelaide, SA 5000, Australia
- Basil Hetzel Institute for Translational Research, The Queen Elizabeth Hospital, Adelaide, SA 5000, Australia
| | - Peter S. Zilm
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5000, Australia
| | - Stephen P. Kidd
- Department of Molecular and Biomedical Sciences, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
- Research Centre for Infectious Disease, The University of Adelaide, Adelaide, SA 5005, Australia
- Australian Centre for Antimicrobial Resistance Ecology (ACARE), The University of Adelaide, Adelaide, SA 5005, Australia
- Correspondence:
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9
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Functional mgrA Influences Genetic Changes within a Staphylococcus aureus Cell Population over Time. J Bacteriol 2022; 204:e0013822. [PMID: 36154359 DOI: 10.1128/jb.00138-22] [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: 11/20/2022] Open
Abstract
Prolonged survival in the host-bacteria microenvironment drives the selection of alternative cell types in Staphylococcus aureus, permitting quasi-dormant sub-populations to develop. These facilitate antibiotic tolerance, long-term growth, and relapse of infection. Small Colony Variants (SCV) are an important cell type associated with persistent infection but are difficult to study in vitro due to the instability of the phenotype and reversion to the normal cell type. We have previously reported that under conditions of growth in continuous culture over a prolonged culture time, SCVs dominated a heterogenous population of cell types and these SCVs harbored a mutation in the DNA binding domain of the gene for the transcription factor, mgrA. To investigate this specific cell type further, S. aureus WCH-SK2-ΔmgrA itself was assessed with continuous culture. Compared to the wild type, the mgrA mutant strain required fewer generations to select for SCVs. There was an increased rate of mutagenesis within the ΔmgrA strain compared to the wild type, which we postulate is the mechanism explaining the increased emergence of SCV selection. The mgrA derived SCVs had impeded metabolism, altered MIC to specific antibiotics and an increased biofilm formation compared to non-SCV strain. Whole genomic sequencing detected single nucleotide polymorphisms (SNP) in phosphoglucosamine mutase glmM and tyrosine recombinase xerC. In addition, several genomic rearrangements were detected which affected genes involved in important functions such as antibiotic and toxic metal resistance and pathogenicity. Thus, we propose a direct link between mgrA and the SCV phenotype. IMPORTANCE Within a bacterial population, a stochastically generated heterogeneity of phenotypes allows continual survival against current and future stressors. The generation of a sub-population of quasi-dormant Small Colony Variants (SCV) in Staphylococcus aureus is such a mechanism, allowing for persistent or relapse of infection despite initial intervention seemingly clearing the infection. The use of continuous culture under clinically relevant conditions has allowed us to introduce time to the growth system and selects SCV within the population. This study provides valuable insights into the generation of SCV which are not addressed in standard laboratory generated models and reveals new pathways for understanding persistent S. aureus infection which can potentially be targeted in future treatments of persistent S. aureus infection.
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Tan L, Huang Y, Shang W, Yang Y, Peng H, Hu Z, Wang Y, Rao Y, Hu Q, Rao X, Hu X, Li M, Chen K, Li S. Accessory Gene Regulator (agr) Allelic Variants in Cognate Staphylococcus aureus Strain Display Similar Phenotypes. Front Microbiol 2022; 13:700894. [PMID: 35295312 PMCID: PMC8919982 DOI: 10.3389/fmicb.2022.700894] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 01/14/2022] [Indexed: 11/13/2022] Open
Abstract
The accessory gene regulator (agr) quorum-sensing system is an important global regulatory system of Staphylococcus aureus and contributes to its pathogenicity. The S. aureus agr system is divided into four agr groups based on the amino acid polymorphisms of AgrB, AgrD, and AgrC. The agr activation is group-specific, resulting in variations in agr activity and pathogenicity among the four agr groups. Strains with divergent agr system always have different phenotypes. In the present report, we, respectively, exchanged the agr system of a certain S. aureus with other three agr alleles and assessed the corresponding phenotypes of these congenic strains. Replacement of the agr system led to significant variations in hemolytic activity, protein expression, and virulence gene expression comparing with that of the parental strain. Interestingly, we found that the biological characteristics of these agr congenic strains in the same strain background were highly similar to each other, and the allele-dependent differences of the agr systems were weakened. These findings indicate that the allele-dependent agr predilections of S. aureus are determined by some factors in addition to the polymorphisms of AgrB, AgrD, and AgrC. Future studies may reveal the novel mechanism to improve our understanding of the agr network.
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Affiliation(s)
- Li Tan
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yuyang Huang
- Queen Mary College, Nanchang University, Nanchang, China
| | - Weilong Shang
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yi Yang
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Huagang Peng
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Zhen Hu
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yuting Wang
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yifan Rao
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Qiwen Hu
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Xiancai Rao
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Xiaomei Hu
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Ming Li
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Kaisen Chen
- The First Affiliated Hospital of Nanchang University, Nanchang, China
- *Correspondence: Kaisen Chen,
| | - Shu Li
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
- Shu Li,
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11
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Abstract
We designed and synthesized antimicrobial compounds effective in killing pan-drug-resistant bacterial pathogens. These compounds have a large therapeutic window due to their low mammalian cell toxicity. A lead compound showed efficacy in treating murine model S. aureus and P. aeruginosa infections. In the case of the obligate respiratory bacterium P. aeruginosa we were unable to evolve strains resistant to these compounds. This paper points toward the potential of this type of compound to deal with the current threat of pan-resistant pathogens. For a myriad of different reasons most antimicrobial peptides (AMPs) have failed to reach clinical application. Different AMPs have different shortcomings including but not limited to toxicity issues, potency, limited spectrum of activity, or reduced activity in situ. We synthesized several cationic peptide mimics, main-chain cationic polyimidazoliums (PIMs), and discovered that, although select PIMs show little acute mammalian cell toxicity, they are potent broad-spectrum antibiotics with activity against even pan-antibiotic-resistant gram-positive and gram-negative bacteria, and mycobacteria. We selected PIM1, a particularly potent PIM, for mechanistic studies. Our experiments indicate PIM1 binds bacterial cell membranes by hydrophobic and electrostatic interactions, enters cells, and ultimately kills bacteria. Unlike cationic AMPs, such as colistin (CST), PIM1 does not permeabilize cell membranes. We show that a membrane electric potential is required for PIM1 activity. In laboratory evolution experiments with the gram-positive Staphylococcus aureus we obtained PIM1-resistant isolates most of which had menaquinone mutations, and we found that a site-directed menaquinone mutation also conferred PIM1 resistance. In similar experiments with the gram-negative pathogen Pseudomonas aeruginosa, PIM1-resistant mutants did not emerge. Although PIM1 was efficacious as a topical agent, intraperitoneal administration of PIM1 in mice showed some toxicity. We synthesized a PIM1 derivative, PIM1D, which is less hydrophobic than PIM1. PIM1D did not show evidence of toxicity but retained antibacterial activity and showed efficacy in murine sepsis infections. Our evidence indicates the PIMs have potential as candidates for development of new drugs for treatment of pan-resistant bacterial infections.
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12
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Ha KP, Clarke RS, Kim GL, Brittan JL, Rowley JE, Mavridou DAI, Parker D, Clarke TB, Nobbs AH, Edwards AM. Staphylococcal DNA Repair Is Required for Infection. mBio 2020; 11:e02288-20. [PMID: 33203752 PMCID: PMC7683395 DOI: 10.1128/mbio.02288-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/14/2020] [Indexed: 01/07/2023] Open
Abstract
To cause infection, Staphylococcus aureus must withstand damage caused by host immune defenses. However, the mechanisms by which staphylococcal DNA is damaged and repaired during infection are poorly understood. Using a panel of transposon mutants, we identified the rexBA operon as being important for the survival of Staphylococcus aureus in whole human blood. Mutants lacking rexB were also attenuated for virulence in murine models of both systemic and skin infections. We then demonstrated that RexAB is a member of the AddAB family of helicase/nuclease complexes responsible for initiating the repair of DNA double-strand breaks. Using a fluorescent reporter system, we were able to show that neutrophils cause staphylococcal DNA double-strand breaks through reactive oxygen species (ROS) generated by the respiratory burst, which are repaired by RexAB, leading to the induction of the mutagenic SOS response. We found that RexAB homologues in Enterococcus faecalis and Streptococcus gordonii also promoted the survival of these pathogens in human blood, suggesting that DNA double-strand break repair is required for Gram-positive bacteria to survive in host tissues. Together, these data demonstrate that DNA is a target of host immune cells, leading to double-strand breaks, and that the repair of this damage by an AddAB-family enzyme enables the survival of Gram-positive pathogens during infection.IMPORTANCE To cause infection, bacteria must survive attack by the host immune system. For many bacteria, including the major human pathogen Staphylococcus aureus, the greatest threat is posed by neutrophils. These immune cells ingest the invading organisms and try to kill them with a cocktail of chemicals that includes reactive oxygen species (ROS). The ability of S. aureus to survive this attack is crucial for the progression of infection. However, it was not clear how the ROS damaged S. aureus and how the bacterium repaired this damage. In this work, we show that ROS cause breaks in the staphylococcal DNA, which must be repaired by a two-protein complex known as RexAB; otherwise, the bacterium is killed, and it cannot sustain infection. This provides information on the type of damage that neutrophils cause S. aureus and the mechanism by which this damage is repaired, enabling infection.
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Affiliation(s)
- Kam Pou Ha
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Rebecca S Clarke
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Gyu-Lee Kim
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Jane L Brittan
- Bristol Dental School, University of Bristol, Bristol, United Kingdom
| | - Jessica E Rowley
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Despoina A I Mavridou
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
| | - Dane Parker
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Thomas B Clarke
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Angela H Nobbs
- Bristol Dental School, University of Bristol, Bristol, United Kingdom
| | - Andrew M Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
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13
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Lee J, Zilm PS, Kidd SP. Novel Research Models for Staphylococcus aureus Small Colony Variants (SCV) Development: Co-pathogenesis and Growth Rate. Front Microbiol 2020; 11:321. [PMID: 32184775 PMCID: PMC7058586 DOI: 10.3389/fmicb.2020.00321] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/13/2020] [Indexed: 01/08/2023] Open
Abstract
Staphylococcus aureus remains a great burden on the healthcare system. Despite prescribed treatments often seemingly to be successful, S. aureus can survive and cause a relapsing infection which cannot be cleared. These infections are in part due to quasi-dormant sub-population which is tolerant to antibiotics and able to evade the host immune response. These include Small Colony Variants (SCVs). Because SCVs readily revert to non-SCV cell types under laboratory conditions, the characterization of SCVs has been problematic. This mini-review covers the phenotypic and genetic changes in stable SCVs including the selection of SCVs by and interactions with other bacterial species.
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Affiliation(s)
- James Lee
- Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SA, Australia.,Research Centre for Infectious Diseases, Adelaide, SA, Australia.,Australian Centre for Antimicrobial Resistance Ecology, Adelaide, SA, Australia
| | - Peter S Zilm
- Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Stephen P Kidd
- Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SA, Australia.,Research Centre for Infectious Diseases, Adelaide, SA, Australia.,Australian Centre for Antimicrobial Resistance Ecology, Adelaide, SA, Australia
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14
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Magalhães AP, Jorge P, Pereira MO. Pseudomonas aeruginosa and Staphylococcus aureus communication in biofilm infections: insights through network and database construction. Crit Rev Microbiol 2019; 45:712-728. [DOI: 10.1080/1040841x.2019.1700209] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Andreia Patrícia Magalhães
- CEB - Centre of Biological Engineering, LIBRO - Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Braga, Portugal
| | - Paula Jorge
- CEB - Centre of Biological Engineering, LIBRO - Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Braga, Portugal
| | - Maria Olívia Pereira
- CEB - Centre of Biological Engineering, LIBRO - Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Braga, Portugal
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15
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Yang J, Qiu L, Huang Y, Chen Y, Rao S, Ruan W, Zhao G, Ye L. [The inhibition of accessory gene regulator C specific binding peptides on biofilm formation of Staphylococcus epidermidis on the surface of polyvinyl chloride in vitro]. ZHONGGUO XIU FU CHONG JIAN WAI KE ZA ZHI = ZHONGGUO XIUFU CHONGJIAN WAIKE ZAZHI = CHINESE JOURNAL OF REPARATIVE AND RECONSTRUCTIVE SURGERY 2019; 33:349-355. [PMID: 30874395 PMCID: PMC8337929 DOI: 10.7507/1002-1892.201806110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 01/15/2019] [Indexed: 11/03/2022]
Abstract
Objective To investigate the effect of accessory gene regulator C (agr C) specific binding peptides (named N1) on the biofilm formation of Staphylococcus epidermidis on the surface of polyvinyl chloride (PVC) materials in vitro. Methods Firstly, the two strains (ATCC35984, ATCC12228) were cultured with N1 at concentrations of 100, 200, 400, 800, and 1 600 μg/mL, respectively. The control group was cultured with agrC specific binding unrelated peptides (named N0) at the same concentrations and the absorbance ( A) value was measured after 24 hours to determine the optimal bacteriostatic concentration of N1. The two strains were cultured with N1 and N0 of the optimal concentration, respectively. The A values were measured at 6, 12, 18, 24, 30, and 48 hours to observe the effect of N1 on the biofilm formation ability of Staphylococcus epidermidis. On this basis, the surface structure of the biofilm on the surface of PVC material was observed by scanning electron microscopy after 6, 12, 18, 24, and 30 hours of incubation with PVC material sheet. The thickness of the biofilm was observed by laser confocal microscopy after 6, 12, 18, and 24 hours of incubation with ATCC35984 strain. Results The optimal bacteriostatic concentration of N1 was 800 μg/mL. ATCC 12228 strain did not form obvious biofilm after being cultured with N1 and N0. When ATCC35984 strain was cultured with N1 and N0 for 12 hours, the difference in biofilm formation ability between groups N1 and N0 was statistically significant ( P<0.05), but there was no significant difference at 6, 18, 24, 30, and 48 hours ( P>0.05). Scanning electron microscopy examination showed that mature biofilm structure was observed in ATCC35984 strain and was not observed in ATCC12228 strain. Laser confocal microscopy observation showed that the number of bacteria in the group N1 was significantly lower than that in the group N0 at 12 hours, and the most of bacteria were dead bacteria. There was no significant difference in the number of bacteria at 6, 18, and 24 hours, and the most of them were live bacteria. The biofilm thickness of group N1 was significantly lower than that of group N0 at 12 and 18 hours ( P<0.05). Conclusion The intensity of N1 inhibiting the formation of Staphylococcus epidermidis biofilm is dose-dependent. During the aggregation period, N1 can inhibit the biofilm formation by hindering the bacterial growth and aggregation. The inhibition effect on mature biofilm is not obvious.
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Affiliation(s)
- Jichen Yang
- Department of Thoracic Surgery, the Third Affiliated Hospital of Kunming Medical University, Tumor Hospital of Yunnan Province, Kunming Yunnan, 650118, P.R.China
| | - Liangting Qiu
- Department of Thoracic Surgery, the Third Affiliated Hospital of Kunming Medical University, Tumor Hospital of Yunnan Province, Kunming Yunnan, 650118, P.R.China
| | - Yunchao Huang
- Department of Thoracic Surgery, the Third Affiliated Hospital of Kunming Medical University, Tumor Hospital of Yunnan Province, Kunming Yunnan, 650118, P.R.China
| | - Ya Chen
- Department of Thoracic Surgery, the Third Affiliated Hospital of Kunming Medical University, Tumor Hospital of Yunnan Province, Kunming Yunnan, 650118, P.R.China
| | - Sunyin Rao
- Department of Thoracic Surgery, the Third Affiliated Hospital of Kunming Medical University, Tumor Hospital of Yunnan Province, Kunming Yunnan, 650118, P.R.China
| | - Wenpeng Ruan
- Department of Thoracic Surgery, the Third Affiliated Hospital of Kunming Medical University, Tumor Hospital of Yunnan Province, Kunming Yunnan, 650118, P.R.China
| | - Guangqiang Zhao
- Department of Thoracic Surgery, the Third Affiliated Hospital of Kunming Medical University, Tumor Hospital of Yunnan Province, Kunming Yunnan, 650118, P.R.China
| | - Lianhua Ye
- Department of Thoracic Surgery, the Third Affiliated Hospital of Kunming Medical University, Tumor Hospital of Yunnan Province, Kunming Yunnan, 650118,
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16
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Côté-Gravel J, Malouin F. Symposium review: Features of Staphylococcus aureus mastitis pathogenesis that guide vaccine development strategies. J Dairy Sci 2018; 102:4727-4740. [PMID: 30580940 DOI: 10.3168/jds.2018-15272] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 10/07/2018] [Indexed: 12/25/2022]
Abstract
Bovine mastitis affects animal health and welfare and milk production and quality, and it challenges the economic success of dairy farms. Staphylococcus aureus is one of the most commonly found pathogens in clinical mastitis but it also causes subclinical, persistent, and difficult-to-treat intramammary infections. Because of the failure of conventional antibiotic treatments and increasing pressure and concern from experts and consumers over the use of antibiotics in the dairy industry, many attempts have been made over the years to develop a vaccine for the prevention and control of Staph. aureus intramammary infections. Still, no commercially available vaccine formulation demonstrates sufficient protection and cost-effective potential. Multiple factors account for the lack of protection, including inadequate vaccine targets, high diversity among mastitis-provoking strains, cow-to-cow variation in immune response, and a failure to elicit an immune response that is appropriate for protection against a highly complex pathogen. The purpose of this review is to summarize key concepts related to the pathogenesis of Staph. aureus, and its interaction with the host, as well as to describe recent vaccine development strategies for prevention and control of Staph. aureus mastitis.
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Affiliation(s)
- Julie Côté-Gravel
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Canada, J1K 2R1
| | - François Malouin
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Canada, J1K 2R1.
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17
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Krishna A, Holden MTG, Peacock SJ, Edwards AM, Wigneshweraraj S. Naturally occurring polymorphisms in the virulence regulator Rsp modulate Staphylococcus aureus survival in blood and antibiotic susceptibility. MICROBIOLOGY (READING, ENGLAND) 2018; 164:1189-1195. [PMID: 30028663 PMCID: PMC6230762 DOI: 10.1099/mic.0.000695] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/03/2018] [Indexed: 01/20/2023]
Abstract
Nasal colonization by the pathogen Staphylococcus aureus is a risk factor for subsequent infection. Loss of function mutations in the gene encoding the virulence regulator Rsp are associated with the transition of S. aureus from a colonizing isolate to one that causes bacteraemia. Here, we report the identification of several novel activity-altering mutations in rsp detected in clinical isolates, including for the first time, mutations that enhance agr operon activity. We assessed how these mutations affected infection-relevant phenotypes and found loss and enhancement of function mutations to have contrasting effects on S. aureus survival in blood and antibiotic susceptibility. These findings add to the growing body of evidence that suggests S. aureus 'trades off' virulence for the acquisition of traits that benefit survival in the host, and indicates that infection severity and treatment options can be significantly affected by mutations in the virulence regulator rsp.
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Affiliation(s)
- Aishwarya Krishna
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| | - Matthew T. G. Holden
- Wellcome Trust Sanger Institute, Hinxton, UK
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Sharon J. Peacock
- Wellcome Trust Sanger Institute, Hinxton, UK
- London School of Hygiene and Tropical Medicine, London, UK
| | - Andrew M. Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
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18
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Intracellular Staphylococcus aureus Modulates Host Central Carbon Metabolism To Activate Autophagy. mSphere 2018; 3:3/4/e00374-18. [PMID: 30089650 PMCID: PMC6083095 DOI: 10.1128/msphere.00374-18] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Staphylococcus aureus is a facultative intracellular pathogen that invades and replicates within many types of phagocytic and nonphagocytic cells. During intracellular infection, S. aureus is capable of subverting xenophagy and escaping to the cytosol of the host cell. Furthermore, drug-induced autophagy facilitates the intracellular replication of S. aureus, but the reasons behind this are unclear. Here, we have studied the host central carbon metabolism during S. aureus intracellular infection. We found extensive metabolic rerouting and detected several distinct metabolic changes that suggested starvation-induced autophagic flux in infected cells. These changes included increased uptake but lower intracellular levels of glucose and low abundance of several essential amino acids, as well as markedly upregulated glutaminolysis. Furthermore, we show that AMP-activated protein kinase (AMPK) and extracellular signal-regulated kinase (ERK) phosphorylation levels are significantly increased in infected cells. Interestingly, while autophagy was activated in response to S. aureus invasion, most of the autophagosomes detected in infected cells did not contain bacteria, suggesting that S. aureus induces the autophagic flux during cell invasion for energy generation and nutrient scavenging. Accordingly, AMPK inhibition halted S. aureus intracellular proliferation.IMPORTANCEStaphylococcus aureus escapes from immune recognition by invading a wide range of human cells. Once the pathogen becomes intracellular, the most important last resort antibiotics are not effective. Therefore, novel anti-infective therapies against intracellular S. aureus are urgently needed. Here, we have studied the physiological changes induced in the host cells by S. aureus during its intracellular proliferation. This is important, because the pathogen exploits the host cell's metabolism for its own proliferation. We find that S. aureus severely depletes glucose and amino acid pools, which leads to increased breakdown of glutamine by the host cell in an attempt to meet its own metabolic needs. All of these metabolic changes activate autophagy in the host cell for nutrient scavenging and energy generation. The metabolic activation of autophagy could be used by the pathogen to sustain its own intracellular survival, making it an attractive target for novel anti-infectives.
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19
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Matias C, Serrano I, Van-Harten S, Mottola C, Mendes JJ, Tavares L, Oliveira M. Polymicrobial interactions influence the agr copy number in Staphylococcus aureus isolates from diabetic foot ulcers. Antonie van Leeuwenhoek 2018; 111:2225-2232. [PMID: 29796774 DOI: 10.1007/s10482-018-1103-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/18/2018] [Indexed: 01/07/2023]
Abstract
Diabetic foot ulcers are a major complication of diabetes and are often colonised by complex bacterial communities, where Staphylococcus aureus is frequently co-present with Pseudomonas aeruginosa. These bacteria interact through quorum sensing, encoded in S. aureus by the accessory gene regulator (agr). Typing and copy number of S. aureus agr were assessed here to give insights on strain variability and possible interspecies influence. As agr is classified in four genetic groups, agr-I, agr-II, agr-III and agr-IV, the agr type of 23 S. aureus diabetic foot ulcers isolates was evaluated by PCR and gene copy number determined by qPCR, including in S. aureus present in polymicrobial infections. agr-I and agr-II were found to be present in 52 and 39% of the isolates, respectively. In two isolates, no agr type was identified, and types III and IV were not detected. Interestingly, agr-II copy number was higher in dual suspensions than in S. aureus single suspension. We conclude that agr type I was the most frequent in clinical centers in Lisbon, and variations in agr-I and agr-II copy numbers were strain specific. Variations in agr copy number in dual suspensions suggests that P. aeruginosa may influence S. aureus agr-II gene regulation, confirming an interaction between these two bacteria. This is a first approach to characterise agr variation in S. aureus from diabetic foot ulcers in vitro.
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Affiliation(s)
- Carina Matias
- Interdisciplinary Centre of Research in Animal Health (CIISA)/Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal
| | - Isa Serrano
- Interdisciplinary Centre of Research in Animal Health (CIISA)/Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal.
| | - Sofia Van-Harten
- Interdisciplinary Centre of Research in Animal Health (CIISA)/Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal.,CBIOS-Research Centre for Biosciences and Health Technologies, Faculty of Veterinary Medicine, Lusófona University of Humanities and Technologies, Campo Grande 376, 1749-024, Lisbon, Portugal
| | - Carla Mottola
- Interdisciplinary Centre of Research in Animal Health (CIISA)/Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal
| | - João J Mendes
- Hospital Professor Doutor Fernando Fonseca, IC19, 2720-276, Amadora, Portugal.,Institute of Microbiology, Faculty of Medicine, University of Lisbon, Avenida Professor Egas Moniz MB, 1649-028, Lisbon, Portugal
| | - Luís Tavares
- Interdisciplinary Centre of Research in Animal Health (CIISA)/Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal
| | - Manuela Oliveira
- Interdisciplinary Centre of Research in Animal Health (CIISA)/Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal
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20
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Zeden MS, Schuster CF, Bowman L, Zhong Q, Williams HD, Gründling A. Cyclic di-adenosine monophosphate (c-di-AMP) is required for osmotic regulation in Staphylococcus aureus but dispensable for viability in anaerobic conditions. J Biol Chem 2018; 293:3180-3200. [PMID: 29326168 PMCID: PMC5836111 DOI: 10.1074/jbc.m117.818716] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 01/03/2018] [Indexed: 01/15/2023] Open
Abstract
Cyclic di-adenosine monophosphate (c-di-AMP) is a recently discovered signaling molecule important for the survival of Firmicutes, a large bacterial group that includes notable pathogens such as Staphylococcus aureus However, the exact role of this molecule has not been identified. dacA, the S. aureus gene encoding the diadenylate cyclase enzyme required for c-di-AMP production, cannot be deleted when bacterial cells are grown in rich medium, indicating that c-di-AMP is required for growth in this condition. Here, we report that an S. aureus dacA mutant can be generated in chemically defined medium. Consistent with previous findings, this mutant had a severe growth defect when cultured in rich medium. Using this growth defect in rich medium, we selected for suppressor strains with improved growth to identify c-di-AMP-requiring pathways. Mutations bypassing the essentiality of dacA were identified in alsT and opuD, encoding a predicted amino acid and osmolyte transporter, the latter of which we show here to be the main glycine betaine-uptake system in S. aureus. Inactivation of these transporters likely prevents the excessive osmolyte and amino acid accumulation in the cell, providing further evidence for a key role of c-di-AMP in osmotic regulation. Suppressor mutations were also obtained in hepS, hemB, ctaA, and qoxB, coding proteins required for respiration. Furthermore, we show that dacA is dispensable for growth in anaerobic conditions. Together, these findings reveal an essential role for the c-di-AMP signaling network in aerobic, but not anaerobic, respiration in S. aureus.
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Affiliation(s)
- Merve S Zeden
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
| | - Christopher F Schuster
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
| | - Lisa Bowman
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
| | - Qiyun Zhong
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
| | - Huw D Williams
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Angelika Gründling
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
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21
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The Electron Transport Chain Sensitizes Staphylococcus aureus and Enterococcus faecalis to the Oxidative Burst. Infect Immun 2017; 85:IAI.00659-17. [PMID: 28993457 DOI: 10.1128/iai.00659-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 09/28/2017] [Indexed: 12/16/2022] Open
Abstract
Small-colony variants (SCVs) of Staphylococcus aureus typically lack a functional electron transport chain and cannot produce virulence factors such as leukocidins, hemolysins, or the antioxidant staphyloxanthin. Despite this, SCVs are associated with persistent infections of the bloodstream, bones, and prosthetic devices. The survival of SCVs in the host has been ascribed to intracellular residency, biofilm formation, and resistance to antibiotics. However, the ability of SCVs to resist host defenses is largely uncharacterized. To address this, we measured the survival of wild-type and SCV S. aureus in whole human blood, which contains high numbers of neutrophils, the key defense against staphylococcal infection. Despite the loss of leukocidin production and staphyloxanthin biosynthesis, SCVs defective for heme or menaquinone biosynthesis were significantly more resistant to the oxidative burst than wild-type bacteria in human blood or the presence of purified neutrophils. Supplementation of the culture medium of the heme-auxotrophic SCV with heme, but not iron, restored growth, hemolysin and staphyloxanthin production, and sensitivity to the oxidative burst. Since Enterococcus faecalis is a natural heme auxotroph and cause of bloodstream infection, we explored whether restoration of the electron transport chain in this organism also affected survival in blood. Incubation of E. faecalis with heme increased growth and restored catalase activity but resulted in decreased survival in human blood via increased sensitivity to the oxidative burst. Therefore, the lack of functional electron transport chains in SCV S. aureus and wild-type E. faecalis results in reduced growth rate but provides resistance to a key immune defense mechanism.
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Pader V, Hakim S, Painter KL, Wigneshweraraj S, Clarke TB, Edwards AM. Staphylococcus aureus inactivates daptomycin by releasing membrane phospholipids. Nat Microbiol 2016; 2:16194. [PMID: 27775684 DOI: 10.1038/nmicrobiol.2016.194] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 09/07/2016] [Indexed: 01/27/2023]
Abstract
Daptomycin is a bactericidal antibiotic of last resort for serious infections caused by methicillin-resistant Staphylococcus aureus (MRSA)1,2. Although resistance is rare, treatment failure can occur in more than 20% of cases3,4 and so there is a pressing need to identify and mitigate factors that contribute to poor therapeutic outcomes. Here, we show that loss of the Agr quorum-sensing system, which frequently occurs in clinical isolates, enhances S. aureus survival during daptomycin treatment. Wild-type S. aureus was killed rapidly by daptomycin, but Agr-defective mutants survived antibiotic exposure by releasing membrane phospholipids, which bound and inactivated the antibiotic. Although wild-type bacteria also released phospholipid in response to daptomycin, Agr-triggered secretion of small cytolytic toxins, known as phenol soluble modulins, prevented antibiotic inactivation. Phospholipid shedding by S. aureus occurred via an active process and was inhibited by the β-lactam antibiotic oxacillin, which slowed inactivation of daptomycin and enhanced bacterial killing. In conclusion, S. aureus possesses a transient defence mechanism that protects against daptomycin, which can be compromised by Agr-triggered toxin production or an existing therapeutic antibiotic.
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Affiliation(s)
- Vera Pader
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
| | - Sanika Hakim
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
| | - Kimberley L Painter
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
| | - Sivaramesh Wigneshweraraj
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
| | - Thomas B Clarke
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
| | - Andrew M Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
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Clinical Significance and Pathogenesis of Staphylococcal Small Colony Variants in Persistent Infections. Clin Microbiol Rev 2016; 29:401-27. [PMID: 26960941 DOI: 10.1128/cmr.00069-15] [Citation(s) in RCA: 217] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Small colony variants (SCVs) were first described more than 100 years ago for Staphylococcus aureus and various coagulase-negative staphylococci. Two decades ago, an association between chronic staphylococcal infections and the presence of SCVs was observed. Since then, many clinical studies and observations have been published which tie recurrent, persistent staphylococcal infections, including device-associated infections, bone and tissue infections, and airway infections of cystic fibrosis patients, to this special phenotype. By their intracellular lifestyle, SCVs exhibit so-called phenotypic (or functional) resistance beyond the classical resistance mechanisms, and they can often be retrieved from therapy-refractory courses of infection. In this review, the various clinical infections where SCVs can be expected and isolated, diagnostic procedures for optimized species confirmation, and the pathogenesis of SCVs, including defined underlying molecular mechanisms and the phenotype switch phenomenon, are presented. Moreover, relevant animal models and suggested treatment regimens, as well as the requirements for future research areas, are highlighted.
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Staphylococcus aureus adapts to oxidative stress by producing H2O2-resistant small-colony variants via the SOS response. Infect Immun 2015; 83:1830-44. [PMID: 25690100 PMCID: PMC4399076 DOI: 10.1128/iai.03016-14] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/10/2015] [Indexed: 12/30/2022] Open
Abstract
The development of chronic and recurrent Staphylococcus aureus infections is associated with the emergence of slow-growing mutants known as small-colony variants (SCVs), which are highly tolerant of antibiotics and can survive inside host cells. However, the host and bacterial factors which underpin SCV emergence during infection are poorly understood. Here, we demonstrate that exposure of S. aureus to sublethal concentrations of H2O2 leads to a specific, dose-dependent increase in the population frequency of gentamicin-resistant SCVs. Time course analyses revealed that H2O2 exposure caused bacteriostasis in wild-type cells during which time SCVs appeared spontaneously within the S. aureus population. This occurred via a mutagenic DNA repair pathway that included DNA double-strand break repair proteins RexAB, recombinase A, and polymerase V. In addition to triggering SCV emergence by increasing the mutation rate, H2O2 also selected for the SCV phenotype, leading to increased phenotypic stability and further enhancing the size of the SCV subpopulation by reducing the rate of SCV reversion to the wild type. Subsequent analyses revealed that SCVs were significantly more resistant to the toxic effects of H2O2 than wild-type bacteria. With the exception of heme auxotrophs, gentamicin-resistant SCVs displayed greater catalase activity than wild-type bacteria, which contributed to their resistance to H2O2. Taken together, these data reveal a mechanism by which S. aureus adapts to oxidative stress via the production of a subpopulation of H2O2-resistant SCVs with enhanced catalase production.
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Prolonged growth of a clinical Staphylococcus aureus strain selects for a stable small-colony-variant cell type. Infect Immun 2014; 83:470-81. [PMID: 25385795 DOI: 10.1128/iai.02702-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An undetermined feature of Staphylococcus aureus pathogenesis is its persistence and then relapse of disease. This has been explained by its switch to alternative lifestyles, mainly as biofilm or small-colony variants (SCVs). Studying the native characteristics of SCVs has been problematic due to their reversion to the parental lifestyle. We have observed that for a number of S. aureus strains as they switch to an SCV lifestyle, there is the formation of an extracellular matrix. We focused our analysis on one strain, WCH-SK2. For bacterial survival in the host, the combination of low nutrients and the prolonged time frame forms a stress that selects for a specific cell type from the population. In this context, we used steady-state growth conditions with low nutrients and a controlled low growth rate for a prolonged time and with methylglyoxal. These conditions induced S. aureus WCH-SK2 into a stable SCV cell type; the cells did not revert after subculturing. Analysis revealed these cells possessed a metabolic and surface profile that was different from those of previously described SCVs or biofilm cells. The extracellular matrix was protein and extracellular DNA but not polysaccharide. The SCV cells induced expression of certain surface proteins (such as Ebh) and synthesis of lantibiotics while downregulating factors that stimulate the immune response (leucocidin, capsule, and carotenoid). Our data reveal cell heterogeneity within an S. aureus population and under conditions that resemble long-term survival in the host have identified a previously unnoticed S. aureus cell type with a distinctive metabolic and molecular profile.
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Painter KL, Krishna A, Wigneshweraraj S, Edwards AM. What role does the quorum-sensing accessory gene regulator system play during Staphylococcus aureus bacteremia? Trends Microbiol 2014; 22:676-85. [PMID: 25300477 DOI: 10.1016/j.tim.2014.09.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 09/10/2014] [Accepted: 09/12/2014] [Indexed: 11/18/2022]
Abstract
Staphylococcus aureus is a major cause of bacteremia, which frequently results in serious secondary infections such as infective endocarditis, osteomyelitis, and septic arthritis. The ability of S. aureus to cause such a wide range of infections has been ascribed to its huge armoury of different virulence factors, many of which are under the control of the quorum-sensing accessory gene regulator (Agr) system. However, a significant fraction of S. aureus bacteremia cases are caused by agr-defective isolates, calling into question the role of Agr in invasive staphylococcal infections. This review draws on recent work to define the role of Agr during bacteremia and explain why the loss of this major virulence regulator is sometimes a price worth paying for S. aureus.
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Affiliation(s)
- Kimberley L Painter
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College, Armstrong Road, London SW7 2AZ, UK
| | - Aishwarya Krishna
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College, Armstrong Road, London SW7 2AZ, UK
| | - Sivaramesh Wigneshweraraj
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College, Armstrong Road, London SW7 2AZ, UK
| | - Andrew M Edwards
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College, Armstrong Road, London SW7 2AZ, UK.
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