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Xiong YQ, Li Y, Goncheva MI, Elsayed AM, Zhu F, Li L, Abdelhady W, Flannagan RS, Yeaman MR, Bayer AS, Heinrichs DE. The Purine Biosynthesis Repressor, PurR, Contributes to Vancomycin Susceptibility of Methicillin-resistant Staphylococcus aureus in Experimental Endocarditis. J Infect Dis 2024; 229:1648-1657. [PMID: 38297970 PMCID: PMC11175694 DOI: 10.1093/infdis/jiad577] [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: 07/27/2023] [Indexed: 02/02/2024] Open
Abstract
BACKGROUND Staphylococcus aureus is the most common cause of life-threatening endovascular infections, including infective endocarditis (IE). These infections, especially when caused by methicillin-resistant strains (MRSA), feature limited therapeutic options and high morbidity and mortality rates. METHODS Herein, we investigated the role of the purine biosynthesis repressor, PurR, in virulence factor expression and vancomycin (VAN) treatment outcomes in experimental IE due to MRSA. RESULTS The PurR-mediated repression of purine biosynthesis was confirmed by enhanced purF expression and production of an intermediate purine metabolite in purR mutant strain. In addition, enhanced expression of the transcriptional regulators, sigB and sarA, and their key downstream virulence genes (eg, fnbA, and hla) was demonstrated in the purR mutant in vitro and within infected cardiac vegetations. Furthermore, purR deficiency enhanced fnbA/fnbB transcription, translating to increased fibronectin adhesion versus the wild type and purR-complemented strains. Notably, the purR mutant was refractory to significant reduction in target tissues MRSA burden following VAN treatment in the IE model. CONCLUSIONS These findings suggest that the purine biosynthetic pathway intersects the coordination of virulence factor expression and in vivo persistence during VAN treatment, and may represent an avenue for novel antimicrobial development targeting MRSA.
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Affiliation(s)
- Yan Q Xiong
- The Lundquist Institute for Biomedical Innovation, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Yi Li
- The Lundquist Institute for Biomedical Innovation, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
| | - Mariya I Goncheva
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Ahmed M Elsayed
- The Lundquist Institute for Biomedical Innovation, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
| | - Fengli Zhu
- The Lundquist Institute for Biomedical Innovation, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
| | - Liang Li
- The Lundquist Institute for Biomedical Innovation, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
| | - Wessam Abdelhady
- The Lundquist Institute for Biomedical Innovation, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
| | - Ronald S Flannagan
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Michael R Yeaman
- The Lundquist Institute for Biomedical Innovation, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
- Department of Medicine, Division of Molecular Medicine, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
| | - Arnold S Bayer
- The Lundquist Institute for Biomedical Innovation, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - David E Heinrichs
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
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Yamaguchi J, Manome T, Hara Y, Yamazaki Y, Nakamura Y, Ishibashi M, Takaya A. Physalin H, physalin B, and isophysalin B suppress the quorum-sensing function of Staphylococcus aureus by binding to AgrA. Front Pharmacol 2024; 15:1365815. [PMID: 38659576 PMCID: PMC11039898 DOI: 10.3389/fphar.2024.1365815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 03/25/2024] [Indexed: 04/26/2024] Open
Abstract
The virulence of Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), depends on the expression of toxins and virulence factors controlled by the quorum-sensing (QS) system, encoded on the virulence accessory gene regulator (agr) locus. The aim of this study was to identify a phytochemical that inhibits Agr-QS function and to elucidate its mechanism. We screened 577 compounds and identified physalin H, physalin B, and isophysalin B--phytochemicals belonging to physalins found in plants of the Solanaceae family--as novel Agr-QS modulators. Biological analyses and in vitro protein-DNA binding assays suggested that these physalins suppress gene expression related to the Agr-QS system by inhibiting binding of the key response regulator AgrA to the agr promoters, reducing the function of hemolytic toxins downstream of these genes in MRSA. Furthermore, although physalin F suppressed gene expression in the Agr-QS system, its anti-hemolytic activity was lower than that of physalins H, B, and isophysalin B. Conversely, five physalins isolated from the same plant with the ability to suppress Agr-QS did not reduce bacterial Agr-QS activity but inhibited AgrA binding to DNA in vitro. A docking simulation revealed that physalin interacts with the DNA-binding site of AgrA in three docking states. The carbonyl oxygens at C-1 and C-18 of physalins, which can suppress Agr-QS, were directed to residues N201 and R198 of AgrA, respectively, whereas these carbonyl oxygens of physalins, without Agr-QS suppression activity, were oriented in different directions. Next, 100-ns molecular dynamics simulations revealed that the hydrogen bond formed between the carbonyl oxygen at C-15 of physalins and L186 of AgrA functions as an anchor, sustaining the interaction between the carbonyl oxygen at C-1 of physalins and N201 of AgrA. Thus, these results suggest that physalin H, physalin B, and isophysalin B inhibit the interaction of AgrA with the agr promoters by binding to the DNA-binding site of AgrA, suppressing the Agr-QS function of S. aureus. Physalins that suppress the Agr-QS function are proposed as potential lead compounds in the anti-virulence strategy for MRSA infections.
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Affiliation(s)
- Junpei Yamaguchi
- Department of Infection Control Science, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Teruhisa Manome
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
- Laboratory of Natural Products Chemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Yasumasa Hara
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
- Faculty of Agriculture, Kagawa University, Takamatsu, Japan
| | - Yuriko Yamazaki
- Cutaneous Allergy and Host Defense, Immunology Frontier Research Center, Osaka University, Osaka, Japan
- Department of Dermatology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yuumi Nakamura
- Cutaneous Allergy and Host Defense, Immunology Frontier Research Center, Osaka University, Osaka, Japan
- Department of Dermatology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Masami Ishibashi
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
- School of Pharmacy at Fukuoka, International University of Health and Welfare, Okawa, Japan
| | - Akiko Takaya
- Department of Infection Control Science, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
- Medical Mycology Research Center, Chiba University, Chiba, Japan
- Plant Molecular Science Center, Chiba University, Chiba, Japan
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3
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Jiang JH, Cameron DR, Nethercott C, Aires-de-Sousa M, Peleg AY. Virulence attributes of successful methicillin-resistant Staphylococcus aureus lineages. Clin Microbiol Rev 2023; 36:e0014822. [PMID: 37982596 PMCID: PMC10732075 DOI: 10.1128/cmr.00148-22] [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] [Indexed: 11/21/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of severe and often fatal infections. MRSA epidemics have occurred in waves, whereby a previously successful lineage has been replaced by a more fit and better adapted lineage. Selection pressures in both hospital and community settings are not uniform across the globe, which has resulted in geographically distinct epidemiology. This review focuses on the mechanisms that trigger the establishment and maintenance of current, dominant MRSA lineages across the globe. While the important role of antibiotic resistance will be mentioned throughout, factors which influence the capacity of S. aureus to colonize and cause disease within a host will be the primary focus of this review. We show that while MRSA possesses a diverse arsenal of toxins including alpha-toxin, the success of a lineage involves more than just producing toxins that damage the host. Success is often attributed to the acquisition or loss of genetic elements involved in colonization and niche adaptation such as the arginine catabolic mobile element, as well as the activity of regulatory systems, and shift metabolism accordingly (e.g., the accessory genome regulator, agr). Understanding exactly how specific MRSA clones cause prolonged epidemics may reveal targets for therapies, whereby both core (e.g., the alpha toxin) and acquired virulence factors (e.g., the Panton-Valentine leukocidin) may be nullified using anti-virulence strategies.
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Affiliation(s)
- Jhih-Hang Jiang
- Department of Microbiology, Infection Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Infectious Diseases, The Alfred Hospital and Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - David R. Cameron
- Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Cara Nethercott
- Department of Microbiology, Infection Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Marta Aires-de-Sousa
- Laboratory of Molecular Genetics, Institutode Tecnologia Químicae Biológica António Xavier (ITQB-NOVA), Universidade Nova de Lisboa, Oeiras, Portugal
- Escola Superior de Saúde da Cruz Vermelha Portuguesa-Lisboa (ESSCVP-Lisboa), Lisbon, Portugal
| | - Anton Y. Peleg
- Department of Microbiology, Infection Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Infectious Diseases, The Alfred Hospital and Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Centre to Impact Antimicrobial Resistance, Monash University, Clayton, Melbourne, Victoria, Australia
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Li Y, Zhu F, Manna AC, Chen L, Jiang J, Hong JI, Proctor RA, Bayer AS, Cheung AL, Xiong YQ. Gp05, a Prophage-Encoded Virulence Factor, Contributes to Persistent Methicillin-Resistant Staphylococcus aureus Endovascular Infection. Microbiol Spectr 2023; 11:e0060023. [PMID: 37358448 PMCID: PMC10434118 DOI: 10.1128/spectrum.00600-23] [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: 02/08/2023] [Accepted: 05/24/2023] [Indexed: 06/27/2023] Open
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections represent a serious public health threat. We recently demonstrated that the presence of a novel prophage ϕSA169 was associated with vancomycin (VAN) treatment failure in experimental MRSA endocarditis. In this study, we assessed the role of a ϕSA169 gene, ϕ80α_gp05 (gp05), in VAN-persistent outcome using gp05 isogenic MRSA strain sets. Of note, Gp05 significantly influences the intersection of MRSA virulence factors, host immune responses, and antibiotic treatment efficacy, including the following: (i) activity of the significant energy-yielding metabolic pathway (e.g., tricarboxylic acid cycle); (ii) carotenoid pigment production; (iii) (p)ppGpp (guanosine tetra- and pentaphosphate) production, which activates the stringent response and subsequent downstream functional factors (e.g., phenol-soluble modulins and polymorphonuclear neutrophil bactericidal activity); and (iv) persistence to VAN treatment in an experimental infective endocarditis model. These data suggest that Gp05 is a significant virulence factor which contributes to the persistent outcomes in MRSA endovascular infection by multiple pathways. IMPORTANCE Persistent endovascular infections are often caused by MRSA strains that are susceptible to anti-MRSA antibiotics in vitro by CLSI breakpoints. Thus, the persistent outcome represents a unique variant of traditional antibiotic resistance mechanisms and a significant therapeutic challenge. Prophage, a critical mobile genetic element carried by most MRSA isolates, provides their bacterial host with metabolic advantages and resistance mechanisms. However, how prophage-encoded virulence factors interact with the host defense system and antibiotics, driving the persistent outcome, is not well known. In the current study, we demonstrated that a novel prophage gene, gp05, significantly impacts tricarboxylic acid cycle activity, stringent response, and pigmentation, as well as vancomycin treatment outcome in an experimental endocarditis model using isogenic gp05 overexpression and chromosomal deletion mutant MRSA strain sets. The findings significantly advance our understanding of the role of Gp05 in persistent MRSA endovascular infection and provide a potential target for development of novel drugs against these life-threatening infections.
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Affiliation(s)
- Yi Li
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Fengli Zhu
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Adhar C. Manna
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Liang Chen
- Center for Discovery and Innovation, Nutley, New Jersey, USA
| | - Jason Jiang
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Jong-In Hong
- Department of Chemistry, Seoul National University, Seoul, South Korea
| | - Richard A. Proctor
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Arnold S. Bayer
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Ambrose L. Cheung
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Yan Q. Xiong
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- David Geffen School of Medicine at UCLA, Los Angeles, California, USA
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5
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MRSA Isolates from Patients with Persistent Bacteremia Generate Nonstable Small Colony Variants In Vitro within Macrophages and Endothelial Cells during Prolonged Vancomycin Exposure. Infect Immun 2023; 91:e0042322. [PMID: 36602380 PMCID: PMC9872686 DOI: 10.1128/iai.00423-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Staphylococcus aureus (especially methicillin-resistant S. aureus [MRSA]) is frequently associated with persistent bacteremia (PB) during vancomycin therapy despite consistent susceptibility in vitro. Strategic comparisons of PB strains versus those from vancomycin-resolving bacteremia (RB) would yield important mechanistic insights into PB outcomes. Clinical PB versus RB isolates were assessed in vitro for intracellular replication and small colony variant (SCV) formation within macrophages and endothelial cells (ECs) in the presence or absence of exogenous vancomycin. In both macrophages and ECs, PB and RB isolates replicated within lysosome-associated membrane protein-1 (LAMP-1)-positive compartments. PB isolates formed nonstable small colony variants (nsSCVs) in vancomycin-exposed host cells at a significantly higher frequency than matched RB isolates (in granulocyte-macrophage colony-stimulating factor [GM-CSF], human macrophages PB versus RB, P < 0.0001 at 48 h; in ECs, PB versus RB, P < 0.0001 at 24 h). This phenotype could represent one potential basis for the unique ability of PB isolates to adaptively resist vancomycin therapy and cause PB in humans. Elucidating the molecular mechanism(s) by which PB strains form nsSCVs could facilitate the discovery of novel treatment strategies to mitigate PB due to MRSA.
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6
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Transcriptome Analyses of Prophage in Mediating Persistent Methicillin-Resistant Staphylococcus aureus Endovascular Infection. Genes (Basel) 2022; 13:genes13091527. [PMID: 36140695 PMCID: PMC9498598 DOI: 10.3390/genes13091527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/23/2022] [Accepted: 08/23/2022] [Indexed: 12/24/2022] Open
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections represent a significant subset of S. aureus infections and correlate with exceptionally high mortality. We have recently demonstrated that the lysogenization of prophage ϕSA169 from a clinical persistent MRSA bacteremia isolate (300-169) into a clinical resolving bacteremia MRSA isolate (301-188) resulted in the acquisition of well-defined in vitro and in vivo phenotypic and genotypic profiles related to persistent outcome. However, the underlying mechanism(s) of this impact is unknown. In the current study, we explored the genetic mechanism that may contribute to the ϕSA169-correlated persistence using RNA sequencing. Transcriptomic analyses revealed that the most significant impacts of ϕSA169 were: (i) the enhancement of fatty acid biosynthesis and purine and pyrimidine metabolic pathways; (ii) the repression of galactose metabolism and phosphotransferase system (PTS); and (iii) the down-regulation of the mutual prophage genes in both 300-169 and 301-188 strains. In addition, the influence of different genetic backgrounds between 300-169 and 301-188 might also be involved in the persistent outcome. These findings may provide targets for future studies on the persistence of MRSA.
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Kinney KJ, Stach JM, Kulhankova K, Brown M, Salgado-Pabón W. Vegetation Formation in Staphylococcus Aureus Endocarditis Inversely Correlates With RNAIII and sarA Expression in Invasive Clonal Complex 5 Isolates. Front Cell Infect Microbiol 2022; 12:925914. [PMID: 35860377 PMCID: PMC9289551 DOI: 10.3389/fcimb.2022.925914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/14/2022] [Indexed: 01/29/2023] Open
Abstract
Infective endocarditis (IE) is one of the most feared and lethal diseases caused by Staphylococcus aureus. Once established, the infection is fast-progressing and tissue destructive. S. aureus of the clonal complex 5 (CC5) commonly cause IE yet are severely understudied. IE results from bacterial colonization and formation of tissue biofilms (known as vegetations) on injured or inflamed cardiac endothelium. S. aureus IE is promoted by adhesins, coagulases, and superantigens, with the exotoxins and exoenzymes likely contributing to tissue destruction and dissemination. Expression of the large repertoire of virulence factors required for IE and sequelae is controlled by complex regulatory networks. We investigated the temporal expression of the global regulators agr (RNAIII), rot, sarS, sarA, sigB, and mgrA in 8 invasive CC5 isolates and established intrinsic expression patterns associated with IE outcomes. We show that vegetation formation, as tested in the rabbit model of IE, inversely correlates with RNAIII and sarA expression during growth in Todd-Hewitt broth (TH). Large vegetations with severe sequelae arise from strains with high-level expression of colonization factors but slower transition towards expression of the exotoxins. Overall, strains proficient in vegetation formation, a hallmark of IE, exhibit lower expression of RNAIII and sarA. Simultaneous high expression of RNAIII, sarA, sigB, and mgrA is the one phenotype assessed in this study that fails to promote IE. Thus, RNAIII and sarA expression that provides for rheostat control of colonization and virulence genes, rather than an on and off switch, promote both vegetation formation and lethal sepsis.
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Affiliation(s)
- Kyle J. Kinney
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Jessica M. Stach
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Katarina Kulhankova
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Matthew Brown
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Wilmara Salgado-Pabón
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, United States
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, United States
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Qiu Y, Chu AJ, Tsang TF, Zheng Y, Lam NM, Li KSL, Ip M, Yang X, Ma C. Synthesis and biological evaluation of nusbiarylin derivatives as bacterial rRNA synthesis inhibitor with potent antimicrobial activity against MRSA and VRSA. Bioorg Chem 2022; 124:105863. [DOI: 10.1016/j.bioorg.2022.105863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/09/2022] [Accepted: 05/06/2022] [Indexed: 11/25/2022]
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New Mechanistic Insights into Purine Biosynthesis with Second Messenger c-di-AMP in Relation to Biofilm-Related Persistent Methicillin-Resistant Staphylococcus aureus Infections. mBio 2021; 12:e0208121. [PMID: 34724823 PMCID: PMC8561390 DOI: 10.1128/mbio.02081-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections represent a significant clinically challenging subset of invasive, life-threatening S. aureus infections. We have recently demonstrated that purine biosynthesis plays an important role in such persistent infections. Cyclic di-AMP (c-di-AMP) is an essential and ubiquitous second messenger that regulates many cellular pathways in bacteria. However, whether there is a regulatory connection between the purine biosynthesis pathway and c-di-AMP impacting persistent outcomes was not known. Here, we demonstrated that the purine biosynthesis mutant MRSA strain, the ΔpurF strain (compared to its isogenic parental strain), exhibited the following significant differences in vitro: (i) lower ADP, ATP, and c-di-AMP levels; (ii) less biofilm formation with decreased extracellular DNA (eDNA) levels and Triton X-100-induced autolysis paralleling enhanced expressions of the biofilm formation-related two-component regulatory system lytSR and its downstream gene lrgB; (iii) increased vancomycin (VAN)-binding and VAN-induced lysis; and (iv) decreased wall teichoic acid (WTA) levels and expression of the WTA biosynthesis-related gene, tarH. Substantiating these data, the dacA (encoding diadenylate cyclase enzyme required for c-di-AMP synthesis) mutant strain (dacAG206S strain versus its isogenic wild-type MRSA and dacA-complemented strains) showed significantly decreased c-di-AMP levels, similar in vitro effects as seen above for the purF mutant and hypersusceptible to VAN treatment in an experimental biofilm-related MRSA endovascular infection model. These results reveal an important intersection between purine biosynthesis and c-di-AMP that contributes to biofilm-associated persistence in MRSA endovascular infections. This signaling pathway represents a logical therapeutic target against persistent MRSA infections.
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Impact of Bicarbonate-β-Lactam Exposures on Methicillin-Resistant Staphylococcus aureus (MRSA) Gene Expression in Bicarbonate-β-Lactam-Responsive vs. Non-Responsive Strains. Genes (Basel) 2021; 12:genes12111650. [PMID: 34828256 PMCID: PMC8619011 DOI: 10.3390/genes12111650] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 01/11/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infections represent a difficult clinical treatment issue. Recently, a novel phenotype was discovered amongst selected MRSA which exhibited enhanced β-lactam susceptibility in vitro in the presence of NaHCO3 (termed ‘NaHCO3-responsiveness’). This increased β-lactam susceptibility phenotype has been verified in both ex vivo and in vivo models. Mechanistic studies to-date have implicated NaHCO3-mediated repression of genes involved in the production, as well as maturation, of the alternative penicillin-binding protein (PBP) 2a, a necessary component of MRSA β-lactam resistance. Herein, we utilized RNA-sequencing (RNA-seq) to identify genes that were differentially expressed in NaHCO3-responsive (MRSA 11/11) vs. non-responsive (COL) strains, in the presence vs. absence of NaHCO3-β-lactam co-exposures. These investigations revealed that NaHCO3 selectively repressed the expression of a cadre of genes in strain 11/11 known to be a part of the sigB-sarA-agr regulon, as well as a number of genes involved in the anchoring of cell wall proteins in MRSA. Moreover, several genes related to autolysis, cell division, and cell wall biosynthesis/remodeling, were also selectively impacted by NaHCO3-OXA exposure in the NaHCO3-responsive strain MRSA 11/11. These outcomes provide an important framework for further studies to mechanistically verify the functional relevance of these genetic perturbations to the NaHCO3-responsiveness phenotype in MRSA.
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11
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Dehbashi S, Tahmasebi H, Zeyni B, Arabestani MR. Regulation of virulence and β-lactamase gene expression in Staphylococcus aureus isolates: cooperation of two-component systems in bloodstream superbugs. BMC Microbiol 2021; 21:192. [PMID: 34172010 PMCID: PMC8228909 DOI: 10.1186/s12866-021-02257-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/13/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA)-bloodstream infections (BSI) are predominantly seen in the hospital or healthcare-associated host. Nevertheless, the interactions of virulence factor (VFs) regulators and β-lactam resistance in MRSA-BSI are unclear. This study aims to characterize the molecular relationship of two-component systems of VFs and the expression of the β-lactamase gene in MRSA-BSI isolates. In this study, 639 samples were collected from BSI and identified by phenotypic methods. We performed extensive molecular characterization, including SCCmec type, agr type, VFs gene profiles determinations, and MLST on isolates. Also, a quantitative real-time PCR (q-RT PCR) assay was developed for identifying the gene expressions. RESULTS Ninety-one (91) S. aureus and 61 MRSA (67.0%) strains were detected in BSI samples. The presence of VFs and SCCmec genes in MRSA isolates were as follows: tst (31.4%), etA (18.0%), etB (8.19%), lukS-PVL (31.4%), lukF-PV (18.0%), lukE-lukD (16.3%), edin (3.2%), hla (16.3%), hlb (18.0%), hld (14.7%), hlg (22.9%), SCCmecI (16.3%), SCCmecII (22.9%), SCCmecIII (36.0%), SCCmecIV (21.3%), and SCCmecV (16.3%). Quantitative real-time PCR showed overexpression of mecRI and mecI in the toxigenic isolates. Moreover, RNAIII and sarA genes were the highest expressions of MRSA strains. The multi-locus sequence typing data confirmed a high prevalence of CC5, CC8, and CC30. However, ST30, ST22, and ST5 were the most prevalent in the resistant and toxigenic strains. CONCLUSION We demonstrated that although regulation of β-lactamase gene expressions is a significant contributor to resistance development, two-component systems also influence antibiotic resistance development in MRSA-BSI isolates. This indicates that resistant strains might have pathogenic potential. We also confirmed that some MLST types are more successful colonizers with a potential for MRSA-BSI.
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Affiliation(s)
- Sanaz Dehbashi
- Microbiology Department, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Hamed Tahmasebi
- School of Medicine, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Behrouz Zeyni
- Microbiology Department, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Reza Arabestani
- Microbiology Department, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran. .,Nutrition health Research center, Hamadan University of Medical Sciences, Hamadan, Iran.
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12
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Impact of Bicarbonate on PBP2a Production, Maturation, and Functionality in Methicillin-Resistant Staphylococcus aureus (MRSA). Antimicrob Agents Chemother 2021; 65:AAC.02621-20. [PMID: 33649115 PMCID: PMC8092911 DOI: 10.1128/aac.02621-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Certain methicillin-resistant Staphylococcus aureus (MRSA) strains exhibit β-lactam-susceptibility in vitro, ex vivo and in vivo in the presence of NaHCO3 (NaHCO3-responsive MRSA). Herein, we investigate the impact of NaHCO3 on factors required for PBP2a functionality. Prototype NaHCO3-responsive and -nonresponsive MRSA strains (as defined in vitro) were assessed for the impact of NaHCO3 on: expression of genes involved in PBP2a production-maturation pathways (mecA, blaZ, pbp4, vraSR, prsA, sigB, and floA); membrane PBP2a and PrsA protein content; and membrane carotenoid content. Following NaHCO3 exposure in NaHCO3-responsive (vs - nonresponsive) MRSA, there was significantly reduced expression of: i) mecA and blaZ; ii) the vraSR-prsA gene axis; and iii) pbp4 Carotenoid production was reduced, while floA expression was increased by NaHCO3 exposure in all MRSA strains. This work underscores the distinct regulatory impact of NaHCO3 on a cadre of genes encoding factors required for maintenance of the MRSA phenotype through PBP2a functionality and maturation.
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Li L, Bayer AS, Cheung A, Lu L, Abdelhady W, Donegan NP, Hong JI, Yeaman MR, Xiong YQ. The Stringent Response Contributes to Persistent Methicillin-Resistant Staphylococcus aureus Endovascular Infection Through the Purine Biosynthetic Pathway. J Infect Dis 2021; 222:1188-1198. [PMID: 32333768 DOI: 10.1093/infdis/jiaa202] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 04/21/2020] [Indexed: 02/02/2023] Open
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections represent a significant clinical-therapeutic challenge. Of particular concern is antibiotic treatment failure in infections caused by MRSA that are "susceptible" to antibiotic in vitro. In the current study, we investigate specific purine biosynthetic pathways and stringent response mechanism(s) related to this life-threatening syndrome using genetic matched persistent and resolving MRSA clinical bacteremia isolates (PB and RB, respectively), and isogenic MRSA strain sets. We demonstrate that PB isolates (vs RB isolates) have significantly higher (p)ppGpp production, phenol-soluble-modulin expression, polymorphonuclear leukocyte lysis and survival, fibronectin/endothelial cell (EC) adherence, and EC damage. Importantly, an isogenic strain set, including JE2 parental, relP-mutant and relP-complemented strains, translated the above findings into significant outcome differences in an experimental endocarditis model. These observations indicate a significant regulation of purine biosynthesis on stringent response, and suggest the existence of a previously unknown adaptive genetic mechanism in persistent MRSA infection.
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Affiliation(s)
- Liang Li
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Arnold S Bayer
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA.,Division of Infectious Diseases, Department of Medicine, Harbor-UCLA Medical Center, Torrance, California, USA.,David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Ambrose Cheung
- Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Lou Lu
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA.,Division of Infectious Diseases, Department of Medicine, Harbor-UCLA Medical Center, Torrance, California, USA.,Division of Molecular Medicine, Department of Medicine, Harbor-UCLA Medical Center, Torrance, California, USA
| | - Wessam Abdelhady
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Niles P Donegan
- Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jong-In Hong
- Department of Chemistry, Seoul National University, Seoul, Korea
| | - Michael R Yeaman
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA.,Division of Infectious Diseases, Department of Medicine, Harbor-UCLA Medical Center, Torrance, California, USA.,David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Division of Molecular Medicine, Department of Medicine, Harbor-UCLA Medical Center, Torrance, California, USA
| | - Yan Q Xiong
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA.,Division of Infectious Diseases, Department of Medicine, Harbor-UCLA Medical Center, Torrance, California, USA.,David Geffen School of Medicine at UCLA, Los Angeles, California, USA
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14
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Rossato AM, Primon-Barros M, Dias CAG, d'Azevedo PA. Vancomycin MIC and agr dysfunction in invasive MRSA infections in southern Brazil. Braz J Microbiol 2020; 51:1819-1823. [PMID: 33074551 DOI: 10.1007/s42770-020-00384-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/14/2020] [Indexed: 10/23/2022] Open
Abstract
In methicillin-resistant Staphylococcus aureus (MRSA) treatment, the vancomycin minimum inhibitory concentration (MIC) increase, vancomycin heteroresistance (hVISA) presence, and accessory gene regulator (agr) dysfunction are predictors of vancomycin therapy failure. This study evaluated the association between vancomycin MIC (≥ 1.0 μg/mL) and agr dysfunction in invasive MRSA isolates. Vancomycin MIC, hVISA phenotype, agr group, and function were determined in 171 MRSA isolates obtained between 2014 and 2019 from hospitals in Porto Alegre, Brazil. All MRSA were susceptible to vancomycin; 16.4% of these had MIC ≥ 1.0 μg/mL. Seventeen MRSA isolates expressed the hVISA phenotype; 35.3% of them had MIC of 1.5 μg/mL. agr groups I (40.9%) and II (47.1%) were the most found groups for MRSA and hVISA isolates, respectively. The proportion of MRSA with vancomycin MIC ≥ 1.0 μg/mL in agr group II was significantly higher than in agr groups I and III (p = 0.002). agr dysfunction was observed in 4.7% (8/171) of MRSA, especially those with vancomycin MIC ≥ 1.0 μg/mL (p < 0.001). In addition, six isolates (35.3%; 6/17) with hVISA phenotype presented agr dysfunction, which was significantly higher than that in non-hVISA phenotype (p < 0.001). In conclusion, agr dysfunction in MRSA is associated with vancomycin MIC ≥ 1.0 μg/mL and hVISA phenotype, which suggests that agr dysfunction might confer potential advantages on MRSA to survive in invasive infections.
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Affiliation(s)
- Adriana Medianeira Rossato
- Basic Health Department, Postgraduate Program in Health Sciences of Porto Alegre (PPGCS), Federal University of Health Science of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil.
| | - Muriel Primon-Barros
- Basic Health Department, Postgraduate Program in Health Sciences of Porto Alegre (PPGCS), Federal University of Health Science of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil
| | - Cícero Armídio Gomes Dias
- Basic Health Department, Postgraduate Program in Health Sciences of Porto Alegre (PPGCS), Federal University of Health Science of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil
| | - Pedro Alves d'Azevedo
- Basic Health Department, Postgraduate Program in Health Sciences of Porto Alegre (PPGCS), Federal University of Health Science of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil
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15
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Chu AJ, Qiu Y, Harper R, Lin L, Ma C, Yang X. Nusbiarylins Inhibit Transcription and Target Virulence Factors in Bacterial Pathogen Staphylococcus aureus. Int J Mol Sci 2020; 21:ijms21165772. [PMID: 32796751 PMCID: PMC7461214 DOI: 10.3390/ijms21165772] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/02/2020] [Accepted: 08/07/2020] [Indexed: 12/29/2022] Open
Abstract
The emergence of multidrug resistance in the clinically significant pathogen Staphylococcus aureus is a global health burden, compounded by a diminishing drug development pipeline, and a lack of approved novel antimicrobials. Our previously reported first-in-class bacterial transcription inhibitors “nusbiarylins” presented a promising prospect towards the discovery of novel antimicrobial agents with a novel mechanism. Here we investigated and characterised the lead nusbiarylin compound, MC4, and several of its chemical derivatives in both methicillin-resistant S. aureus (MRSA) and the S. aureus type strains, demonstrating their capacity for the arrest of growth and cellular respiration, impairment of RNA and intracellular protein levels at subinhibitory concentrations. In some instances, derivatives of MC4 were also shown to attenuate the production of staphylococcal virulence factors in vitro, such as the exoproteins α-toxin and Panton–Valentine Leukocidin (PVL). Trends observed from quantitative PCR assays suggested that nusbiarylins elicited these effects possibly by acting via but not limited to the modulation of global regulatory pathways, such as the agr regulon, which coordinates the expression of S. aureus genes associated with virulence. Our findings encourage the continued development of more potent compounds within this novel family of bacterial transcription inhibitors.
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Affiliation(s)
- Adrian Jun Chu
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; (A.J.C.); (R.H.); (L.L.)
| | - Yangyi Qiu
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong;
| | - Rachel Harper
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; (A.J.C.); (R.H.); (L.L.)
| | - Lin Lin
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; (A.J.C.); (R.H.); (L.L.)
| | - Cong Ma
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong;
- Correspondence: (C.M.); (X.Y.)
| | - Xiao Yang
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; (A.J.C.); (R.H.); (L.L.)
- Correspondence: (C.M.); (X.Y.)
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16
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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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17
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Li L, Wang G, Li Y, Francois P, Bayer AS, Chen L, Seidl K, Cheung A, Xiong YQ. Impact of the Novel Prophage ϕSA169 on Persistent Methicillin-Resistant Staphylococcus aureus Endovascular Infection. mSystems 2020; 5:e00178-20. [PMID: 32606024 PMCID: PMC7329321 DOI: 10.1128/msystems.00178-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/16/2020] [Indexed: 12/26/2022] Open
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections are life-threatening syndromes with few therapeutic options. The potential impact of bacteriophages on the persistent outcome has not been well studied. In this study, we investigated the role of a novel prophage (ϕSA169) in MRSA persistence by using a lysogen-free clinically resolving bacteremia (RB) isolate and comparing it to a derivative which was obtained by infecting the RB strain with ϕSA169, which has been lysogenized in a clinical persistent MRSA bacteremia (PB) isolate. Similar to the PB isolate, the ϕSA169-lysogenized RB strain exhibited well-defined in vitro and in vivo phenotypic and genotypic signatures related to the persistent outcome, including earlier activation of global regulators (i.e., sigB, sarA, agr RNAIII, and sae); higher expression of a critical purine biosynthesis gene, purF; and higher growth rates accompanied by lower ATP levels and vancomycin (VAN) susceptibility and stronger δ-hemolysin and biofilm formation versus its isogenic parental RB isolate. Notably, the contribution of ϕSA169 in persistent outcome with VAN treatment was confirmed in an experimental infective endocarditis model. Taken together, these results indicate the critical role of the prophage ϕSA169 in persistent MRSA endovascular infections. Further studies are needed to identify the mechanisms of ϕSA169 in mediating the persistence, as well as establishing the scope of impact, of this prophage in other PB strains.IMPORTANCE Bacteriophages are viruses that invade the bacterial host, disrupt bacterial metabolism, and cause the bacterium to lyse. Because of its remarkable antibacterial activity and unique advantages over antibiotics, for instance, bacteriophage is specific for one species of bacteria and resistance to phage is less common than resistance to antibiotics. Indeed, bacteriophage therapy for treating infections due to multidrug-resistant pathogens in humans has become a research hot spot. However, it is also worth considering that bacteriophages are transferable and could cotransfer host chromosomal genes, e.g., virulence and antimicrobial resistance genes, while lysogenizing and integrating into the bacterial chromosome (prophage), thus playing a role in bacterial evolution and virulence. In the current study, we identified a novel prophage, ϕSA169, from a clinical persistent MRSA bacteremia isolate, and we determined that ϕSA169 mediated well-defined in vitro and in vivo phenotypic and genotypic signatures related to the persistent outcome, which may represent a unique and important persistent mechanism(s).
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Affiliation(s)
- Liang Li
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Genzhu Wang
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Yi Li
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | | | - Arnold S Bayer
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA
| | - Liang Chen
- Center for Discovery and Innovation, Nutley, New Jersey, USA
| | - Kati Seidl
- University Hospital of Zurich, Zurich, Switzerland
| | | | - Yan Q Xiong
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA
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18
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Li L, Wang G, Cheung A, Abdelhady W, Seidl K, Xiong YQ. MgrA Governs Adherence, Host Cell Interaction, and Virulence in a Murine Model of Bacteremia Due to Staphylococcus aureus. J Infect Dis 2020; 220:1019-1028. [PMID: 31177268 DOI: 10.1093/infdis/jiz219] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 04/26/2019] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND MgrA is an important global virulence gene regulator in Staphylococcus aureus. In the present study, the role of mgrA in host-pathogen interactions related to virulence was explored in both methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) strains. METHODS In vitro susceptibilities to human defense peptides (HDPs), adherence to fibronectin (Fn) and endothelial cells (ECs), EC damage, α-toxin production, expression of global regulator (eg, agr RNAIII) and its downstream effectors (eg, α-toxin [hla] and Fn binding protein A [fnbA]), MgrA binding to fnbA promoter, and the effect on HDP-induced mprF and dltA expression were analyzed. The impact of mgrA on virulence was evaluated using a mouse bacteremia model. RESULTS mgrA mutants displayed significantly higher susceptibility to HDPs, which might be related to the decreased HDP-induced mprF and dltA expression but decreased Fn and EC adherence, EC damage, α-toxin production, agr RNAIII, hla and fnbA expression, and attenuated virulence in the bacteremia model as compared to their respective parental and mgrA-complemented strains. Importantly, direct binding of MgrA to the fnbA promoter was observed. CONCLUSIONS These results suggest that mgrA mediates host-pathogen interactions and virulence and may provide a novel therapeutic target for invasive S. aureus infections.
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Affiliation(s)
- Liang Li
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance
| | - Genzhu Wang
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance
| | | | - Wessam Abdelhady
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance
| | - Kati Seidl
- University Hospital of Zurich, Switzerland
| | - Yan Q Xiong
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance.,David Geffen School of Medicine at UCLA, Los Angeles, California
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19
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Yolmeh M, Khomeiri M, Ghaemi E. High-efficiency anti-enterotoxigenic activity of Lactobacillus on staphylococcal enterotoxins biosynthesis. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Wang G, Li L, Wang X, Li X, Zhang Y, Yu J, Jiang J, You X, Xiong YQ. Hypericin enhances β-lactam antibiotics activity by inhibiting sarA expression in methicillin-resistant Staphylococcus aureus. Acta Pharm Sin B 2019; 9:1174-1182. [PMID: 31867163 PMCID: PMC6900551 DOI: 10.1016/j.apsb.2019.05.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 05/11/2019] [Accepted: 05/20/2019] [Indexed: 01/11/2023] Open
Abstract
Bacteremia is a life-threating syndrome often caused by methicillin-resistant Staphylococcus aureus (MRSA). Thus, there is an urgent need to develop novel approaches to successfully treat this infection. Staphylococcal accessory regulator A (SarA), a global virulence regulator, plays a critical role in pathogenesis and β-lactam antibiotic resistance in Staphylococcus aureus. Hypericin is believed to act as an antibiotic, antidepressant, antiviral and non-specific kinase inhibitor. In the current study, we investigated the impact of hypericin on β-lactam antibiotics susceptibility and mechanism(s) of its activity. We demonstrated that hypericin significantly decreased the minimum inhibitory concentrations of β-lactam antibiotics (e.g., oxacillin, cefazolin and nafcillin), biofilm formation and fibronectin binding in MRSA strain JE2. In addition, hypericin significantly reduced sarA expression, and subsequently decreased mecA, and virulence-related regulators (e.g., agr RNAⅢ) and genes (e.g., fnbA and hla) expression in the studied MRSA strain. Importantly, the in vitro synergistic effect of hypericin with β-lactam antibiotic (e.g., oxacillin) translated into in vivo therapeutic outcome in a murine MRSA bacteremia model. These findings suggest that hypericin plays an important role in abrogation of β-lactam resistance against MRSA through sarA inhibition, and may allow us to repurpose the use of β-lactam antibiotics, which are normally ineffective in the treatment of MRSA infections (e.g., oxacillin).
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Affiliation(s)
- Genzhu Wang
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Liang Li
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA
| | - Xiukun Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xue Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Youwen Zhang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Jie Yu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Jiandong Jiang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xuefu You
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
- Corresponding authors. Tel.: +86 10 67061033, fax: +86 10 67017302 (Xuefu You); Tel.: +1 310 2223545 (Yan Q. Xiong).
| | - Yan Q. Xiong
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA
- Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Corresponding authors. Tel.: +86 10 67061033, fax: +86 10 67017302 (Xuefu You); Tel.: +1 310 2223545 (Yan Q. Xiong).
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21
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Phenotypic and Genotypic Characteristics of Methicillin-Resistant Staphylococcus aureus (MRSA) Related to Persistent Endovascular Infection. Antibiotics (Basel) 2019; 8:antibiotics8020071. [PMID: 31146412 PMCID: PMC6627527 DOI: 10.3390/antibiotics8020071] [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: 05/01/2019] [Revised: 05/22/2019] [Accepted: 05/24/2019] [Indexed: 12/03/2022] Open
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (PB) represents an important subset of S. aureus infection and correlates with poor clinical outcomes. MRSA isolates from patients with PB differ significantly from those of resolving bacteremia (RB) with regard to several in vitro phenotypic and genotypic profiles. For instance, PB strains exhibit less susceptibility to cationic host defense peptides and vancomycin (VAN) killing under in vivo-like conditions, greater damage to endothelial cells, thicker biofilm formation, altered growth rates, early activation of many global virulence regulons (e.g., sigB, sarA, sae and agr) and higher expression of purine biosynthesis genes (e.g., purF) than RB strains. Importantly, PB strains are significantly more resistant to VAN treatment in experimental infective endocarditis as compared to RB strains, despite similar VAN minimum inhibitory concentrations (MICs) in vitro. Here, we review relevant phenotypic and genotypic characteristics related to the PB outcome. These and future insights may improve our understanding of the specific mechanism(s) contributing to the PB outcome, and aid in the development of novel therapeutic and preventative measures against this life-threatening infection.
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Li L, Abdelhady W, Donegan NP, Seidl K, Cheung A, Zhou YF, Yeaman MR, Bayer AS, Xiong YQ. Role of Purine Biosynthesis in Persistent Methicillin-Resistant Staphylococcus aureus Infection. J Infect Dis 2018; 218:1367-1377. [PMID: 29868791 PMCID: PMC6151072 DOI: 10.1093/infdis/jiy340] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 06/01/2018] [Indexed: 11/13/2022] Open
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (PB) represents an important subset of S. aureus endovascular infections. In this study, we investigated potential genetic mechanisms underlying the persistent outcomes. Compared with resolving bacteremia (RB) isolates (defined as isolates associated with negative results of blood cultures 2-4 days after initiation of therapy), PB strains (defined as isolates associated with positive results of blood cultures ≥7 days after initiation of therapy) had significantly earlier onset activation of key virulence regulons and structural genes (eg, sigB, sarA, sae, and cap5), higher expression of purine biosynthesis genes (eg, purF), and faster growth rates, with earlier entrance into stationary phase. Importantly, an isogenic strain set featuring a wild-type MRSA isolate, a purF mutant strain, and a purF-complemented strain and use of strategic purine biosynthesis inhibitors implicated a causal relationship between purine biosynthesis and the in vivo persistent outcomes. These observations suggest that purine biosynthesis plays a key role in the outcome of PB and may represent a new target for enhanced efficacy in treating life-threatening MRSA infections.
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Affiliation(s)
- Liang Li
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance
| | - Wessam Abdelhady
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance
| | | | - Kati Seidl
- University Hospital of Zurich, Switzerland
| | | | - Yu-Feng Zhou
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance
- South China Agricultural University, Guangzhou
| | - Michael R Yeaman
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance
- David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Arnold S Bayer
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance
- David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Yan Q Xiong
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance
- David Geffen School of Medicine at UCLA, Los Angeles, California
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23
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Viedma E, Pérez-Montarelo D, Villa J, Muñoz-Gallego I, Larrosa N, Fernández-Hidalgo N, Gavaldà J, Almirante B, Chaves F. Sub-inhibitory concentrations of oxacillin modify the expression of agr locus in Staphylococcus aureus clinical strains belonging to different clonal complexes. BMC Infect Dis 2018; 18:177. [PMID: 29661157 PMCID: PMC5902860 DOI: 10.1186/s12879-018-3088-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 04/05/2018] [Indexed: 02/08/2023] Open
Abstract
Background The ability of Staphylococcus aureus to invade tissues and cause an infectious disease is the result of a multi-factorial process supported by the huge number of virulence factors inherent to this microorganism tightly regulated by the accessory gene regulator (agr). During antimicrobial therapy bacteria may be exposed to sub-inhibitory concentrations (subMICs) of antibiotics that may trigger transcriptional changes that may have an impact on the pathogenesis of infection. The objective of this study was to investigate the effect of oxacillin sub-MICs on agr system expression as the key component in the regulation of virulence in methicillin-susceptible (MSSA) and -resistant S. aureus (MRSA) strains. Furthermore, we studied the genetic basis of the agr locus and their potential association with the expression levels. Methods We have examined the expression of RNAIII and agrA mRNA as biomarkers for agr expression in the presence and absence of oxacillin subMICs in 10 MSSA and 4 MRSA clinical strains belonging to 5 clonal complexes (CC45-agrI, CC8-agrI, CC5-agrII, CC15-agrII and CC30-agrIII) causing endovascular complications. The DNA sequences of agr locus were obtained by whole genome sequencing. Results Our results revealed that exposure to subMICs of oxacillin had an impact on agr locus expression modifying the relative levels of expression with increases in 11 strains and with decreases in 3 strains. Thereby, the exposure to subMICs of oxacillin resulted in higher levels of expression of agr in CC15 and CC45 and lower levels in CC30. We also observed the presence of mutations in agrC and agrA in 13/14 strains with similar mutation profiles among strains within individual CCs except for strains of CC5. Although, agr expression levels differed among strains within CCs, the presence of these mutations was associated with differences in agr expression levels in most cases. Conclusions Changes in agr expression induced by exposure to oxacillin subMICs should be considered because they could lead to changes in the virulence modulation and have an adverse effect on the course of infection, especially in certain clonal complexes. Electronic supplementary material The online version of this article (10.1186/s12879-018-3088-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Esther Viedma
- Department of Microbiology, Hospital Universitario 12 de Octubre, Madrid, Spain.
| | | | - Jennifer Villa
- Department of Microbiology, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Irene Muñoz-Gallego
- Department of Microbiology, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Nieves Larrosa
- Department of Infectious Diseases, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | | | - Joan Gavaldà
- Department of Infectious Diseases, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Benito Almirante
- Department of Infectious Diseases, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Fernando Chaves
- Department of Microbiology, Hospital Universitario 12 de Octubre, Madrid, Spain
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Rose WE, Shukla SK, Berti AD, Hayney MS, Henriquez KM, Ranzoni A, Cooper MA, Proctor RA, Nizet V, Sakoulas G. Increased Endovascular Staphylococcus aureus Inoculum Is the Link Between Elevated Serum Interleukin 10 Concentrations and Mortality in Patients With Bacteremia. Clin Infect Dis 2018; 64:1406-1412. [PMID: 28205673 DOI: 10.1093/cid/cix157] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 02/15/2017] [Indexed: 12/12/2022] Open
Abstract
Background Cell wall peptidoglycan stimulates interleukin 10 (IL-10) production in Staphylococcus aureus bacteremia (SaB) animal models, but clinical data are not available. This study evaluates the impact of intravascular bacterial cell numbers (ie, the level of bacteremia), in patients at the time of clinical presentation on IL-10 production and its association with S. aureus bacteremia (SaB) mortality. Methods Blood and isolates were collected in 133 consecutive SaB patients. Serum IL-10 was quantified by an electrochemoluminescence assay. Bacterial inoculum was measured in patient sera with elevated (n = 8) or low (n = 8) IL-10 using a magnetic bacterial capture assay. Staphylococcus aureus from these 2 groups were introduced into whole blood ex vivo to determine IL-10 production with variable inocula. Results IL-10 serum concentration was higher in SaB patient mortality (n = 27) vs survival (n = 106) (median, 36.0 pg/mL vs 10.4 pg/mL, respectively, P < .001). Patients with elevated IL-10 more often had endovascular SaB sources. The inoculum level of SaB was higher in patients with elevated serum IL-10 vs patients with low IL-10 (35.5 vs 0.5 median CFU/mL; P = .044). Ex vivo studies showed that 108 CFU/mL yielded greater IL-10 than did 103 CFU/mL (4.4 ± 1.8 vs 1.0 ± 0.6 pg/mL; P < .01). Conclusions Elevated IL-10 serum concentrations at clinical presentation of SaB were highly associated with mortality. High intravascular peptidoglycan concentration, driven by a higher level of bacteremia, is a key mediator of IL-10 anti-inflammatory response that portends poor clinical outcome. Using IL-10 as an initial biomarker, clinicians may consider more aggressive antimicrobials for rapid bacterial load reduction in high-risk SaB patients.
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Affiliation(s)
- Warren E Rose
- School of Pharmacy, University of Wisconsin-Madison, and
| | | | - Andrew D Berti
- School of Pharmacy, University of Wisconsin-Madison, and
| | - Mary S Hayney
- School of Pharmacy, University of Wisconsin-Madison, and
| | | | - Andrea Ranzoni
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Matthew A Cooper
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Richard A Proctor
- Departments of Medicine and Medical Microbiology/Immunology, University of Wisconsin School of Medicine and Public Health, Madison, and
| | - Victor Nizet
- Department of Pediatrics, University of California, San Diego School of Medicine, La Jolla
| | - George Sakoulas
- Department of Pediatrics, University of California, San Diego School of Medicine, La Jolla
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25
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Fernández-Hidalgo N, Ribera A, Larrosa MN, Viedma E, Origüen J, de Alarcón A, Fariñas MC, Sáez C, Peña C, Múñez E, García López MV, Gavaldà J, Pérez-Montarelo D, Chaves F, Almirante B. Impact of Staphylococcus aureus phenotype and genotype on the clinical characteristics and outcome of infective endocarditis. A multicentre, longitudinal, prospective, observational study. Clin Microbiol Infect 2017; 24:985-991. [PMID: 29269091 DOI: 10.1016/j.cmi.2017.12.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 12/10/2017] [Accepted: 12/11/2017] [Indexed: 12/11/2022]
Abstract
OBJECTIVE We aimed to evaluate the impact of Staphylococcus aureus phenotype (vancomycin MIC) and genotype (agr group, clonal complex CC) on the prognosis and clinical characteristics of infective endocarditis (IE). METHODS We performed a multicentre, longitudinal, prospective, observational study (June 2013 to March 2016) in 15 Spanish hospitals. Two hundred and thirteen consecutive adults (≥18 years) with a definite diagnosis of S. aureus IE were included. Primary outcome was death during hospital stay. Main secondary end points were persistent bacteraemia, sepsis/septic shock, peripheral embolism and osteoarticular involvement. RESULTS Overall in-hospital mortality was 37% (n = 72). Independent risk factors for death were age-adjusted Charlson co-morbidity index (OR 1.20; 95% CI 1.08-1.34), congestive heart failure (OR 3.60; 95% CI 1.72-7.50), symptomatic central nervous system complication (OR 3.17; 95% CI 1.41-7.11) and severe sepsis/septic shock (OR 4.41; 95% CI 2.18-8.96). In the subgroup of methicillin-susceptible S. aureus IE (n = 173), independent risk factors for death were the age-adjusted Charlson co-morbidity index (OR 1.17; 95% CI 1.03-1.31), congestive heart failure (OR 3.39; 95% CI 1.51-7.64), new conduction abnormality (OR 4.42; 95% CI 1.27-15.34), severe sepsis/septic shock (OR 5.76; 95% CI 2.57-12.89) and agr group III (OR 0.27; 0.10-0.75). Vancomycin MIC ≥1.5 mg/L was not independently associated with death during hospital nor was it related to secondary end points. No other genotype variables were independently associated with in-hospital death. CONCLUSIONS This is the first prospective study to assess the impact of S. aureus phenotype and genotype. Phenotype and genotype provided no additional predictive value beyond conventional clinical characteristics. No evidence was found to justify therapeutic decisions based on vancomycin MIC for either methicillin-resistant or methicillin-susceptible S. aureus.
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Affiliation(s)
- N Fernández-Hidalgo
- Servei de Malalties Infeccioses, Hospital Universitari Vall d'Hebron, Barcelona, Spain; Universitat Autonoma de Barcelona, Barcelona, Spain; Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain.
| | - A Ribera
- Cardiovascular Epidemiology Unit, Cardiology Department, Vall d'Hebron University Hospital, CIBERESP, Barcelona, Spain
| | - M N Larrosa
- Universitat Autonoma de Barcelona, Barcelona, Spain; Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Servei de Microbiologia, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - E Viedma
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Servicio de Microbiologia, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - J Origüen
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Unit of Infectious Diseases, Hospital Universitario 12 de Octubre, Instituto de Investigacion Hospital 12 de Octubre (i+12), School of Medicine, Universidad Complutense, Madrid, Spain
| | - A de Alarcón
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Clinical Unit of Infectious Diseases, Microbiology, and Preventive Medicine, Infectious Diseases Research Group, Institute of Biomedicine of Seville, University of Seville/CSIC/University Hospital Virgen del Rocio, Seville, Spain
| | - M C Fariñas
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Infectious Diseases Unit, Hospital Universitario Marques de Valdecilla, University of Cantabria, Santander, Spain
| | - C Sáez
- Unidad de Infecciosas, Hospital de la Princesa, Instituto de Investigacion, Madrid, Spain
| | - C Peña
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Servei de Malalties Infeccioses, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat, Spain; Servei de Medicina Interna, Hospital Mare de Deu dels Lliris, Alcoi, Spain
| | - E Múñez
- Unidad de Enfermedades Infecciosas, Servicio de Medicina Interna, Hospital Universitario Puerta de Hierro, Majadahonda, Spain
| | - M V García López
- Servicio de Microbiologia, Hospital Universitario Virgen de la Victoria, Instituto de Investigacion Biomedica, Malaga, Spain
| | - J Gavaldà
- Servei de Malalties Infeccioses, Hospital Universitari Vall d'Hebron, Barcelona, Spain; Universitat Autonoma de Barcelona, Barcelona, Spain; Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain
| | - D Pérez-Montarelo
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Servicio de Microbiologia, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - F Chaves
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Servicio de Microbiologia, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - B Almirante
- Servei de Malalties Infeccioses, Hospital Universitari Vall d'Hebron, Barcelona, Spain; Universitat Autonoma de Barcelona, Barcelona, Spain; Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain
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26
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A Human Biofilm-Disrupting Monoclonal Antibody Potentiates Antibiotic Efficacy in Rodent Models of both Staphylococcus aureus and Acinetobacter baumannii Infections. Antimicrob Agents Chemother 2017; 61:AAC.00904-17. [PMID: 28717038 DOI: 10.1128/aac.00904-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/11/2017] [Indexed: 12/22/2022] Open
Abstract
Many serious bacterial infections are antibiotic refractory due to biofilm formation. A key structural component of biofilm is extracellular DNA, which is stabilized by bacterial proteins, including those from the DNABII family. TRL1068 is a high-affinity human monoclonal antibody against a DNABII epitope conserved across both Gram-positive and Gram-negative bacterial species. In the present study, the efficacy of TRL1068 for the disruption of biofilm was demonstrated in vitro in the absence of antibiotics by scanning electron microscopy. The in vivo efficacy of this antibody was investigated in a well-characterized catheter-induced aortic valve infective endocarditis model in rats infected with a methicillin-resistant Staphylococcus aureus (MRSA) strain with the ability to form thick biofilms, obtained from the blood of a patient with persistent clinical infection. Animals were treated with vancomycin alone or in combination with TRL1068. MRSA burdens in cardiac vegetations and within intracardiac catheters, kidneys, spleen, and liver showed significant reductions in the combination arm versus vancomycin alone (P < 0.001). A trend toward mortality reduction was also observed (P = 0.09). In parallel, the in vivo efficacy of TRL1068 against a multidrug-resistant clinical Acinetobacter baumannii isolate was explored by using an established mouse model of skin and soft tissue catheter-related biofilm infection. Catheter segments infected with A. baumannii were implanted subcutaneously into mice; animals were treated with imipenem alone or in combination with TRL1068. The combination showed a significant reduction of catheter-adherent bacteria versus the antibiotic alone (P < 0.001). TRL1068 shows excellent promise as an adjunct to standard-of-care antibiotics for a broad range of difficult-to-treat bacterial infections.
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27
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The Effect of Adding Blood on the Virulence Genes Expression of Staphylococcus aureus in Exponential and Stationary Growth Phase. Jundishapur J Microbiol 2017. [DOI: 10.5812/jjm.14380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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28
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Pérez-Montarelo D, Viedma E, Murcia M, Muñoz-Gallego I, Larrosa N, Brañas P, Fernández-Hidalgo N, Gavaldà J, Almirante B, Chaves F. Pathogenic Characteristics of Staphylococcus aureus Endovascular Infection Isolates from Different Clonal Complexes. Front Microbiol 2017; 8:917. [PMID: 28579985 PMCID: PMC5437158 DOI: 10.3389/fmicb.2017.00917] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 05/04/2017] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus is a major cause of bacteremia and, even with appropriate clinical management, causes high morbidity, and mortality due to its involvement in endovascular complications and metastatic infections. Through different pathogenic in vivo and in vitro models we investigated the behavior of S. aureus most relevant clonal complexes (CCs) causing endovascular complications. We analyzed 14 S. aureus strains representing CC5, CC8, CC15, CC30, and CC45 that caused endovascular complications, including methicillin susceptible and resistant isolates and strains with different functionality of the agr global regulator. Their adherence to collagen, interaction with the endothelium, resistance to immune attack, capacity to form biofilm and virulence in the Galleria mellonella model were analyzed. CC30 and CC45 showed greater adhesion to collagen and CC8 showed a trend towards higher rate of intracellular persistence in endothelial cells. All CCs exhibited similar tolerance to neutrophil antimicrobial peptide hNP-1 and were capable of forming biofilms under static conditions. The virulence assay in the G. mellonella model demonstrated that CC15 and CC30 were the most and least virulent, respectively. The analysis of the genomic sequences of the most relevant virulence genes identified some CC15 specific gene patterns (absence of enterotoxins and sak gene) and variants (mainly in leucocidins and proteases), but did not reveal any gene or variant that could be responsible for the increased virulence detected for CC15 strains. Even though all the CCs were capable of causing endovascular complications, our results showed that different CCs are likely to produce these complications through different mechanisms which, if confirmed in more sophisticated models, would indicate the need to more specific management and therapeutic approaches.
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Affiliation(s)
- Dafne Pérez-Montarelo
- Department of Microbiology, Instituto de Investigación Hospital de OctubreMadrid, Spain
| | - Esther Viedma
- Department of Microbiology, Instituto de Investigación Hospital de OctubreMadrid, Spain
| | - Mercedes Murcia
- Department of Microbiology, Instituto de Investigación Hospital de OctubreMadrid, Spain
| | - Irene Muñoz-Gallego
- Department of Microbiology, Instituto de Investigación Hospital de OctubreMadrid, Spain
| | - Nieves Larrosa
- Department of Microbiology, Hospital Universitari Vall d'hebron, Universitat Autónoma de BarcelonaBarcelona, Spain
| | - Patricia Brañas
- Department of Microbiology, Instituto de Investigación Hospital de OctubreMadrid, Spain
| | - Nuria Fernández-Hidalgo
- Department of Infectious Diseases, Hospital Universitari Vall d'hebron, Universitat Autónoma de BarcelonaBarcelona, Spain
| | - Joan Gavaldà
- Department of Infectious Diseases, Hospital Universitari Vall d'hebron, Universitat Autónoma de BarcelonaBarcelona, Spain
| | - Benito Almirante
- Department of Infectious Diseases, Hospital Universitari Vall d'hebron, Universitat Autónoma de BarcelonaBarcelona, Spain
| | - Fernando Chaves
- Department of Microbiology, Instituto de Investigación Hospital de OctubreMadrid, Spain
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29
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San-Juan R, Pérez-Montarelo D, Viedma E, Lalueza A, Fortún J, Loza E, Pujol M, Ardanuy C, Morales I, de Cueto M, Resino-Foz E, Morales-Cartagena MA, Fernández-Ruiz M, Rico A, Romero MP, Fernández de Mera M, López-Medrano F, Orellana MÁ, Aguado JM, Chaves F. Pathogen-related factors affecting outcome of catheter-related bacteremia due to methicillin-susceptible Staphylococcus aureus in a Spanish multicenter study. Eur J Clin Microbiol Infect Dis 2017; 36:1757-1765. [PMID: 28477236 DOI: 10.1007/s10096-017-2989-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 04/13/2017] [Indexed: 11/24/2022]
Abstract
Even with appropriate clinical management, complicated methicillin-susceptible Staphylococcus aureus (MSSA) catheter-related bacteremia (CRB) is frequent. We investigated the influence of molecular characteristics of MSSA strains on the risk of complicated bacteremia (CB) in MSSA-CRB. A multicenter prospective study was conducted in Spain between 2011 and 2014 on MSSA-CRB. Optimized protocol-guided clinical management was required. CB included endocarditis, septic thrombophlebitis, persistent bacteremia and/or end-organ hematogenous spread. Molecular typing, agr functionality and DNA microarray analysis of virulence factors were performed in all MSSA isolates. Out of 83 MSSA-CRB episodes included, 26 (31.3%) developed CB. MSSA isolates belonged to 16 clonal complexes (CCs), with CC30 (32.5%), CC5 (15.7%) and CC45 (13.3) being the most common. Comparison between MSSA isolates in episodes with or without CB revealed no differences regarding agr type and functionality. However, our results showed that CC15 and the presence of genes like cna, chp and cap8 were associated with the development of CB. The multivariate analysis highlighted that the presence of cna (Hazard ratio 2.9; 95% CI 1.14-7.6) was associated with the development of CB. Our results suggest that particular CCs and specific genes may influence the outcome of MSSA-CRB.
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Affiliation(s)
- R San-Juan
- Unit of Infectious Diseases, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Avenida de Córsoba, s/n, 28041, Madrid, Spain.
| | - D Pérez-Montarelo
- Department of Microbiology, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Madrid, Spain
| | - E Viedma
- Department of Microbiology, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Madrid, Spain
| | - A Lalueza
- Unit of Infectious Diseases, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Avenida de Córsoba, s/n, 28041, Madrid, Spain
| | - J Fortún
- Department of Infectious Diseases, University Hospital Ramón y Cajal, Madrid, Spain
| | - E Loza
- Department of Microbiology, University Hospital Ramón y Cajal, Madrid, Spain
| | - M Pujol
- Department of Infectious Diseases, University Hospital Bellvitge, Universidad de Barcelona-IDIBELL, Barcelona, Spain
| | - C Ardanuy
- Department of Microbiology, University Hospital Bellvitge, Universidad de Barcelona-IDIBELL, Barcelona, Spain
| | - I Morales
- Department of Infectious Diseases, University Hospital Virgen de la Macarena, Seville, Spain
| | - M de Cueto
- Department of Microbiology, University Hospital Virgen de la Macarena, Seville, Spain
| | - E Resino-Foz
- Unit of Infectious Diseases, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Avenida de Córsoba, s/n, 28041, Madrid, Spain
| | - M A Morales-Cartagena
- Unit of Infectious Diseases, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Avenida de Córsoba, s/n, 28041, Madrid, Spain
| | - M Fernández-Ruiz
- Unit of Infectious Diseases, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Avenida de Córsoba, s/n, 28041, Madrid, Spain
| | - A Rico
- Unit of Infectious Diseases, University Hospital La Paz, Madrid, Spain
| | - M P Romero
- Department of Microbiology, University Hospital La Paz, Madrid, Spain
| | - M Fernández de Mera
- Department of Microbiology, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Madrid, Spain
| | - F López-Medrano
- Unit of Infectious Diseases, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Avenida de Córsoba, s/n, 28041, Madrid, Spain
| | - M Á Orellana
- Department of Microbiology, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Madrid, Spain
| | - J M Aguado
- Unit of Infectious Diseases, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Avenida de Córsoba, s/n, 28041, Madrid, Spain
| | - F Chaves
- Department of Microbiology, University Hospital 12 de Octubre, Instituto de Investigación Hospital "12 de Octubre" (i+12), Universidad Complutense, Madrid, Spain
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30
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Gomes-Fernandes M, Laabei M, Pagan N, Hidalgo J, Molinos S, Villar Hernandez R, Domínguez-Villanueva D, Jenkins ATA, Lacoma A, Prat C. Accessory gene regulator (Agr) functionality in Staphylococcus aureus derived from lower respiratory tract infections. PLoS One 2017; 12:e0175552. [PMID: 28410390 PMCID: PMC5391941 DOI: 10.1371/journal.pone.0175552] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 03/28/2017] [Indexed: 01/09/2023] Open
Abstract
Objective Characterization of Staphylococcus aureus clinical isolates derived from lower respiratory tract infections (LRTIs), and correlation between the functionality of the accessory gene regulator (Agr) and genotypic and phenotypic characteristics, clinical variables and clinical outcome. Methods S aureus isolates derived from LRTIs and control groups (nasal carriage and bacteraemia) were genotyped using StaphyType DNA microarray. Agr activity was evaluated using the CAMP synergistic haemolysis assay and the Vesicle Lysis Test (VLT). Discordant strains were analysed by quantitative reverse-transcriptase real-time PCR (qRT-PCR). Results Agr was functional in 79.7% and 84.5% of strains according to the CAMP and VLT assays respectively. Higher concordance with RNAIII expression measured by qRT-PCR was observed with the VLT assay (76.2%) compared with the CAMP assay (23.8%). No statistically significant differences were observed in Agr functionality between the study groups, nor the phenotypical/genotypical bacterial characteristics. No association between increased mortality/respiratory complications and Agr function was observed. Conclusions Agr activity was high (82.2%) in isolates from LRTIs suggesting the importance of this global regulator in lower respiratory tract colonisation and infection. However, equally high Agr activity was observed in isolates derived from nasal carriage and bacteraemia, contradictory to previous observations. Agr functionality measured by the VLT assay was superior to CAMP assay.
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Affiliation(s)
- Meissiner Gomes-Fernandes
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
- CAPES Foundation, Ministry of Education of Brazil, Brasília, Brazil
| | - Maisem Laabei
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Natalia Pagan
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
| | - Jessica Hidalgo
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
| | - Sònia Molinos
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
| | - Raquel Villar Hernandez
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
| | - Dídac Domínguez-Villanueva
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
| | | | - Alicia Lacoma
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
- CIBER Enfermedades Respiratorias, CIBER, Instituto de Salud Carlos III, Badalona, Spain
| | - Cristina Prat
- Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d’ Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain
- CIBER Enfermedades Respiratorias, CIBER, Instituto de Salud Carlos III, Badalona, Spain
- * E-mail:
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Telavancin Is Active against Experimental Aortic Valve Endocarditis Caused by Daptomycin- and Methicillin-Resistant Staphylococcus aureus Strains. Antimicrob Agents Chemother 2017; 61:AAC.01877-16. [PMID: 27872064 DOI: 10.1128/aac.01877-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/06/2016] [Indexed: 11/20/2022] Open
Abstract
We compared the efficacy of telavancin (TLV) and daptomycin (DAP) in an experimental rabbit endocarditis model caused by two clinically derived daptomycin-resistant (DAPr) methicillin-resistant Staphylococcus aureus (MRSA) strains. TLV treatment significantly reduced MRSA densities in all target tissues and increased the percentage of these organs rendered culture negative compared to those with the untreated control or DAP-treated animals. These results demonstrate that TLV has potent in vivo efficacy against DAPr MRSA isolates in this invasive endovascular infection model.
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Seidl K, Leemann M, Palheiros Marques M, Rachmühl C, Leimer N, Andreoni F, Achermann Y, Zinkernagel AS. High level methicillin resistance correlates with reduced Staphylococcus aureus endothelial cell damage. Int J Med Microbiol 2016; 307:11-20. [PMID: 27955998 DOI: 10.1016/j.ijmm.2016.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/29/2016] [Accepted: 11/27/2016] [Indexed: 11/17/2022] Open
Abstract
There has been controversy about the intrinsic virulence of methicillin-resistant Staphylococcus aureus (MRSA) as compared to methicillin-susceptible S. aureus (MSSA). To address this discrepancy, the intrinsic virulence of 42 MRSA and 40 MSSA clinical isolates was assessed by testing endothelial cell (EC) damage, a surrogate marker for virulence in blood stream infections. Since these clinical isolates represent a heterogeneous group, well characterized S. aureus laboratory strains with SCCmec loss- and gain-of-function mutations were used in addition. The clinical MRSA isolates carrying typical hospital acquired SCCmec types (I, II or III) induced significantly less damage (47.8%) as compared to isolates with other SCCmec types (62.3%, p=0.03) and MSSA isolates (64.2%, p<0.01). There was a strong inverse correlation between high-level oxacillin resistance and low EC damage induction (R2=0.4464, p<0.001). High-level oxacillin resistant strains (MIC >32μ/ml) grew significantly slower as compared to isolates with low-level resistance (p=0.047). The level of EC damage positively correlated with α- and δ-toxin production (p<0.0001 and p<0.05, respectively) but not with β-toxin production. Invasive MRSA isolates (n=21, 56.3%) were significantly less cytotoxic as compared to invasive MSSA isolates (n=20, 68.0%, p<0.05). There was no difference between EC damage induced by superficial versus invasive isolates in either MRSA or MSSA strains. Our data suggest that the intrinsic virulence of MRSA is similar or even reduced as compared to MSSA strains but is linked to the level of methicillin resistance.
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Affiliation(s)
- Kati Seidl
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
| | - Michèle Leemann
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Miguel Palheiros Marques
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Carole Rachmühl
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Nadja Leimer
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Federica Andreoni
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Yvonne Achermann
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Annelies S Zinkernagel
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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33
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Li L, Cheung A, Bayer AS, Chen L, Abdelhady W, Kreiswirth BN, Yeaman MR, Xiong YQ. The Global Regulon sarA Regulates β-Lactam Antibiotic Resistance in Methicillin-Resistant Staphylococcus aureus In Vitro and in Endovascular Infections. J Infect Dis 2016; 214:1421-1429. [PMID: 27543672 DOI: 10.1093/infdis/jiw386] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 08/11/2016] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The global regulator sarA modulates virulence of methicillin-resistant Staphylococcus aureus (MRSA) via regulation of principal virulence factors (eg, adhesins and toxins) and biofilm formation. Resistance of S. aureus strains to β-lactam antibiotics (eg, oxacillin) depends on the production of penicillin-binding protein 2a (PBP2a), encoded by mecA METHODS: In the present study, we investigated the impact of sarA on the phenotypic and genotypic characteristics of oxacillin resistance both in vitro and in an experimental endocarditis model, using prototypic healthcare- and community-associated MRSA parental and their respective sarA mutant strain sets. RESULTS All sarA mutants (vs respective MRSA parental controls) displayed significant reductions in oxacillin resistance and biofilm formation in vitro and oxacillin persistence in an experimental endocarditis model in vivo. These phenotypes corresponded to reduced mecA expression and PBP2a production and an interdependency of sarA and sigB regulators. Moreover, RNA sequencing analyses showed that sarA mutants exhibited significantly increased levels of primary extracellular proteases and suppressed pyrimidine biosynthetic pathway, argininosuccinate lyase-encoding, and ABC transporter-related genes as compared to the parental strain. CONCLUSIONS These results suggested that sarA regulates oxacillin resistance in mecA-positive MRSA. Thus, abrogation of this regulator represents an attractive and novel drug target to potentiate efficacy of existing antibiotic for MRSA therapy.
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Affiliation(s)
- Liang Li
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center
| | | | - Arnold S Bayer
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Liang Chen
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark
| | - Wessam Abdelhady
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center
| | - Barry N Kreiswirth
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark
| | - Michael R Yeaman
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,Division of Molecular Medicine, Los Angeles County-Harbor-UCLA Medical Center, Torrance.,David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Yan Q Xiong
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,David Geffen School of Medicine at UCLA, Los Angeles, California
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34
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Xiong YQ, Abdelhady W, Tang C'G, Bayer AS. Comparative efficacy of telavancin and daptomycin in experimental endocarditis due to multi-clonotype MRSA strains. J Antimicrob Chemother 2016; 71:2890-4. [PMID: 27353467 DOI: 10.1093/jac/dkw249] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 05/24/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND MRSA strains of clonal complexes (CCs) 5, 8, 30 and 45 are leading causes of complicated endovascular infections associated with suboptimal clinical outcomes. Telavancin is a novel anti-MRSA agent that both inhibits bacterial cell wall synthesis and disrupts membranes by depolarization. METHODS In this study, we compared the in vitro susceptibility and in vivo efficacy of telavancin versus daptomycin in an experimental rabbit infective endocarditis (IE) model caused by four MRSA strains representing each of the above CC types. RESULTS All study strains were susceptible to telavancin (MICs of ≤0.12 mg/L) and daptomycin (MICs of ≤0.5 mg/L). In vitro time-kill analyses revealed that supra-MIC levels of telavancin were effective at preventing regrowth at 24 h of incubation. In the IE animal model for all CC types, treatment with telavancin produced significantly greater reductions in MRSA counts as compared with daptomycin-treated animals in all target tissues. Moreover, telavancin-treated animals had a significantly higher percentage of sterile tissue cultures versus daptomycin-treated animals (e.g. 78%-100% versus 0% sterile vegetations and 100% versus 0%-11% sterile kidneys and spleen, in the telavancin- and daptomycin-treated animals, respectively). CONCLUSIONS These results suggest that telavancin exhibits significantly greater efficacies versus daptomycin in treating experimental IE caused by MRSA clinical isolates across four common CC types.
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Affiliation(s)
- Yan Q Xiong
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Wessam Abdelhady
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Chieh 'Genna' Tang
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Arnold S Bayer
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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35
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Gharsa H, Ben Slama K, Gómez-Sanz E, Lozano C, Zarazaga M, Messadi L, Boudabous A, Torres C. Molecular characterization of Staphylococcus aureus from nasal samples of healthy farm animals and pets in Tunisia. Vector Borne Zoonotic Dis 2016; 15:109-15. [PMID: 25700041 DOI: 10.1089/vbz.2014.1655] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A total of 261 healthy farm and pet animals (75 cattle, 52 goats, 100 dogs, and 34 cats) from different regions of Tunisia were screened for Staphylococcus aureus nasal carriage. Molecular typing of isolates (by spa- and multilocus sequence-typing) was performed, and their antimicrobial resistance and virulence genotypes were determined by PCR and sequencing. S. aureus isolates were detected in 17 of 261 tested samples (6.5%). All S. aureus isolates recovered were methicillin-susceptible (MSSA), and one isolate/sample was further studied. Eight different spa types were detected (t189, t279, t582, t701, t1166, t1268, t1534, and t1773), and eight different sequence types were identified (ST6, ST15, ST45, ST133, ST188, ST700 [clonal complex CC130], ST2057, and a new ST2121). MSSA from pets (six isolates) showed resistance to (number of isolates, resistance gene): penicillin (six, blaZ), tetracycline (one, tet[M]), erythromycin one, erm[A]), streptomycin (one, ant[6]-Ia), and ciprofloxacin (one). All isolates from farm animals showed susceptibility to the tested antimicrobials, except for two penicillin-resistant isolates. Five S. aureus isolates from goats and cats harbored the lukF/lukS-PV genes, encoding the Panton-Valentine leukocidin, and six isolates from goats harbored the tst virulence gene. In addition, diverse combinations of enterotoxin genes were detected, including two variants of the egc cluster. Goats and cats could represent a reservoir of important toxin genes, with potential implications in animal and human health.
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Affiliation(s)
- Haythem Gharsa
- 1 Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université Tunis-El Manar , Tunis, Tunisia
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A novel nitro-dexamethasone inhibits agr system activity and improves therapeutic effects in MRSA sepsis models without antibiotics. Sci Rep 2016; 6:20307. [PMID: 26839286 PMCID: PMC4738243 DOI: 10.1038/srep20307] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/30/2015] [Indexed: 12/13/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) sepsis is a life-threatening medical condition that involves systemic inflammation throughout the body. Glucocorticoids are widely used in combination with antibiotics in the treatment of MRSA sepsis to fight the overwhelming inflammation. Here, we describe the improved anti-inflammatory properties of a nitric oxide (NO)-releasing derivative of dexamethasone, ND8008. ND8008 affected MRSA biofilm formation, caused biofilm cell death, and reduced the effects of virulence factors, such as α-toxin, by inhibiting the activity of the Staphylococcus aureus accessory gene regulator (agr) system. Dosing of mice with ND8008 (127.4 nmol/kg, i.p.) alone greatly reduced the inflammatory response caused by MRSA blood stream infection and considerably increased the survival rate of septic mice. These findings suggest that this novel NO-releasing derivative of dexamethasone ND8008 could be helpful in the treatment of MRSA sepsis.
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37
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Endovascular infections caused by methicillin-resistant Staphylococcus aureus are linked to clonal complex-specific alterations in binding and invasion domains of fibronectin-binding protein A as well as the occurrence of fnbB. Infect Immun 2015; 83:4772-80. [PMID: 26416903 DOI: 10.1128/iai.01074-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 09/21/2015] [Indexed: 11/20/2022] Open
Abstract
Endovascular infections caused by Staphylococcus aureus involve interactions with fibronectin present as extracellular matrix or surface ligand on host cells. We examined the expression, structure, and binding activity of the two major S. aureus fibronectin-binding proteins (FnBPA, FnBPB) in 10 distinct, methicillin-resistant clinical isolates from patients with either persistent or resolving bacteremia. The persistent bacteremia isolates (n = 5) formed significantly stronger bonds with immobilized fibronectin as determined by dynamic binding measurements performed with atomic force microscopy. Several notable differences were also observed when the results were grouped by clonal complex 5 (CC5) strains (n = 5) versus CC45 strains (n = 5). Fibronectin-binding receptors on CC5 formed stronger bonds with immobilized fibronectin (P < 0.001). The fnbA gene was expressed at higher levels in CC45, whereas fnbB was found in only CC5 isolates. The fnbB gene was not sequenced because all CC45 isolates lacked this gene. Instead, comparisons were made for fnbA, which was present in all 10 isolates. Sequencing of fnbA revealed discrete differences within high-affinity, fibronectin-binding repeats (FnBRs) of FnBPA that included (i) 5-amino-acid polymorphisms in FnBR-9, FnBR-10, and FnBR-11 involving charged or polar side chains, (ii) an extra, 38-amino-acid repeat inserted between FnBR-9 and FnBR-10 exclusively seen in CC45 isolates, and (iii) CC5 isolates had the SVDFEED epitope in FnBR-11 (a sequence shown to be essential for fibronectin binding), while this sequence was replaced in all CC45 isolates with GIDFVED (a motif known to favor host cell invasion at the cost of reduced fibronectin binding). These complementary sequence and binding data suggest that differences in fnbA and fnbB, particularly polymorphisms and duplications in FnBPA, give S. aureus two distinct advantages in human endovascular infections: (i) FnBPs similar to that of CC5 enhance ligand binding and foster initiation of disease, and (ii) CC45-like FnBPs promote cell invasion, a key attribute in persistent endovascular infections.
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38
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Phloretin derived from apple can reduce alpha-hemolysin expression in methicillin-resistant Staphylococcus aureus USA300. World J Microbiol Biotechnol 2015; 31:1259-65. [PMID: 26026280 DOI: 10.1007/s11274-015-1879-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Accepted: 05/25/2015] [Indexed: 01/04/2023]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly important because it is the most common cause of hospital-acquired infections, which have become globally epidemic. Our study specifically focused on the MRSA strain USA300, which was shown in 2014 to be responsible for the most current pandemic of highly virulent MRSA in the United States. We aimed to evaluate the in vitro effect of phloretin on USA300. Susceptibility testing, western blotting assays, hemolysis assays and real-time RT-PCR were employed to examine the in vitro effects of phloretin on alpha-hemolysin (Hla) production when the bacterium was co-cultured with phloretin. The protective effect of phloretin against the USA300-mediated injury of human alveolar epithelial cells (A549) was tested using the live/dead analysis and cytotoxicity assays. We showed that sub-inhibitory concentrations of phloretin have no effect on bacterial viability; however, they can markedly inhibit the production of Hla in culture supernatants and the transcriptional levels of hla (the gene encoding Hla) and agrA (the accessory gene regulator). Phloretin, at a final concentration of 16 µg/ml, could protect A549 cells from injury caused by USA300 in the co-culture system. Our study suggests that phloretin might have a potential application in the development of treatment for MRSA infections.
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Abdelhady W, Chen L, Bayer AS, Seidl K, Yeaman MR, Kreiswirth BN, Xiong YQ. Early agr activation correlates with vancomycin treatment failure in multi-clonotype MRSA endovascular infections. J Antimicrob Chemother 2015; 70:1443-52. [PMID: 25564565 DOI: 10.1093/jac/dku547] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 12/03/2014] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVES Persistent MRSA infections are especially relevant to endovascular infections and correlate with suboptimal outcomes. However, the virulence signatures of Staphylococcus aureus that drive such persistence outcomes are not well defined. In the current study, we investigated correlations between accessory gene regulator (agr) activation and the outcome of vancomycin treatment in an experimental model of infective endocarditis (IE) due to MRSA strains with different agr and clonal complex (CC) types. METHODS Twelve isolates with the four most common MRSA CC and agr types (CC5-agr II, CC8-agr I, CC30-agr III and CC45-agr I) were evaluated for heterogeneous vancomycin-intermediate S. aureus (hVISA), agr function, agrA and RNAIII transcription, agr locus sequences, virulence and response to vancomycin in the IE model. RESULTS Early agr RNAIII activation (beginning at 2 h of growth) in parallel with strong δ-haemolysin production correlated with persistent outcomes in the IE model following vancomycin therapy. Importantly, such treatment failures occurred across the range of CC/agr types studied. In addition, these MRSA strains: (i) were vancomycin susceptible in vitro; (ii) were not hVISA or vancomycin tolerant; and (iii) did not evolve hVISA phenotypes or perturbed δ-haemolysin activity in vivo following vancomycin therapy. Moreover, agr locus sequence analyses revealed no common point mutations that correlated with either temporal RNAIII transcription or vancomycin treatment outcomes, encompassing different CC and agr types. CONCLUSIONS These data suggest that temporal agr RNAIII activation and agr functional profiles may be useful biomarkers to predict the in vivo persistence of endovascular MRSA infections despite vancomycin therapy.
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Affiliation(s)
- Wessam Abdelhady
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Liang Chen
- Public Health Research Institute, NJMS-Rutgers University, Newark, NJ, USA
| | - Arnold S Bayer
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Kati Seidl
- University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Michael R Yeaman
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Barry N Kreiswirth
- Public Health Research Institute, NJMS-Rutgers University, Newark, NJ, USA
| | - Yan Q Xiong
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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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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41
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Genome Sequences of Sequence Type 45 (ST45) Persistent Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteremia Strain 300-169 and ST45 Resolving MRSA Bacteremia Strain 301-188. GENOME ANNOUNCEMENTS 2014; 2:2/2/e00174-14. [PMID: 24625873 PMCID: PMC3953194 DOI: 10.1128/genomea.00174-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (positive blood cultures after ≥7 days) represents a challenging subset of invasive MRSA infections. The comparison of genome sequences of persistent (300-169) and resolving (301-188) MRSA bacteremia isolates with similar genetic background (sequence type 45 [ST45]) will help us to better understand underlying mechanisms of persistent MRSA bacteremia.
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Abdelhady W, Bayer AS, Seidl K, Moormeier DE, Bayles KW, Cheung A, Yeaman MR, Xiong YQ. Impact of vancomycin on sarA-mediated biofilm formation: role in persistent endovascular infections due to methicillin-resistant Staphylococcus aureus. J Infect Dis 2014; 209:1231-40. [PMID: 24403556 DOI: 10.1093/infdis/jiu007] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Staphylococcus aureus is the most common cause of endovascular infections. The staphylococcal accessory regulator A locus (sarA) is a major virulence determinant that may potentially impact methicillin-resistant S. aureus (MRSA) persistence in such infections via its influence on biofilm formation. METHODS Two healthcare-associated MRSA isolates from patients with persistent bacteremia and 2 prototypical community-acquired MRSA strains, as well as their respective isogenic sarA mutants, were studied for in vitro biofilm formation, fibronectin-binding capacity, autolysis, and protease and nuclease activities. These assays were done in the presence or absence of sub-minimum inhibitory concentrations (MICs) of vancomycin. In addition, these strain pairs were compared for intrinsic virulence and responses to vancomycin therapy in experimental infective endocarditis, a prototypical biofilm model. RESULTS All sarA mutants displayed significantly reduced biofilm formation and binding to fibronectin but increased protease production in vitro, compared with their respective parental strains. Interestingly, exposure to sub-MICs of vancomycin significantly promoted biofilm formation and fibronectin-binding in parental strains but not in sarA mutants. In addition, all sarA mutants became exquisitely susceptible to vancomycin therapy, compared with their respective parental strains, in the infective endocarditis model. CONCLUSIONS These observations suggest that sarA activation is important in persistent MRSA endovascular infection, potentially in the setting of biofilm formation.
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Affiliation(s)
- Wessam Abdelhady
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance
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43
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Viedma E, Sanz F, Orellana MA, San Juan R, Aguado JM, Otero JR, Chaves F. Relationship between agr dysfunction and reduced vancomycin susceptibility in methicillin-susceptible Staphylococcus aureus causing bacteraemia. J Antimicrob Chemother 2014; 69:51-8. [DOI: 10.1093/jac/dkt337] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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44
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Nakamura Y, Oscherwitz J, Cease KB, Chan SM, Muñoz-Planillo R, Hasegawa M, Villaruz AE, Cheung GYC, McGavin MJ, Travers JB, Otto M, Inohara N, Núñez G. Staphylococcus δ-toxin induces allergic skin disease by activating mast cells. Nature 2013; 503:397-401. [PMID: 24172897 PMCID: PMC4090780 DOI: 10.1038/nature12655] [Citation(s) in RCA: 377] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 09/12/2013] [Indexed: 12/14/2022]
Abstract
Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects 15 to 30% of children and ~5% of adults in industrialized countries1. Although the pathogenesis of AD is not fully understood, the disease is mediated by an abnormal immunoglobulin E (IgE) immune response in the setting of skin barrier dysfunction2. Mast cells (MCs) contribute to IgE-mediated allergic disorders including AD3. Upon activation, MCs release their membrane-bound cytosolic granules leading to the release of multiple molecules that are important in the pathogenesis of AD and host defense4. More than 90% of AD patients are colonized with Staphylococcus aureus in the lesional skin whereas most healthy individuals do not harbor the pathogen5. Several Staphylococcal exotoxins (SEs) can act as superantigens and/or antigens in models of AD6. However, the role of these SEs in disease pathogenesis remains unclear. Here, we report that culture supernatants of S. aureus contain potent MC degranulation activity. Biochemical analysis identified δ-toxin as the MC degranulation-inducing factor produced by S. aureus. MC degranulation induced by δ-toxin depended on phosphoinositide 3-kinase (PI3K) and calcium (Ca2+) influx, but unlike that mediated by IgE crosslinking, it did not require the spleen tyrosine kinase (Syk). In addition, IgE enhanced δ-toxin-induced MC degranulation in the absence of antigen. Furthermore, S. aureus isolates recovered from AD patients produced high levels of δ-toxin. Importantly, skin colonization with S. aureus, but not a mutant deficient in δ-toxin, promoted IgE and IL-4 production, as well as inflammatory skin disease. Furthermore, enhancement of IgE production and dermatitis by δ-toxin was abrogated in KitW-sh/W-sh MC-deficient mice and restored by MC reconstitution. These studies identify δ-toxin as a potent inducer of MC degranulation and suggest a mechanistic link between S. aureus colonization and allergic skin disease.
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Affiliation(s)
- Yuumi Nakamura
- Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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Grinholc M, Nakonieczna J, Negri A, Rapacka-Zdonczyk A, Motyka A, Fila G, Kurlenda J, Leibner-Ciszak J, Otto M, Bielawski KP. The agr function and polymorphism: impact on Staphylococcus aureus susceptibility to photoinactivation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2013; 129:100-7. [PMID: 24211295 DOI: 10.1016/j.jphotobiol.2013.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/07/2013] [Accepted: 10/10/2013] [Indexed: 11/18/2022]
Abstract
Staphylococcus aureus is an important human pathogen that causes healthcare-associated and community-acquired infections. Moreover, the growing prevalence of multiresistant strains requires the development of alternative methods to antibiotic therapy. One effective therapeutic option may be antimicrobial photodynamic inactivation (aPDI). Recently, S. aureus strain-dependent response to PDI was demonstrated, although the mechanism underlying this phenomenon remains unexplained. The aim of the current study was to investigate statistically relevant correlations between the functionality and polymorphisms of agr gene determined for 750 methicillin-susceptible and methicillin-resistant S. aureus strains and their responses to photodynamic inactivation using protoporphyrin IX. An AluI and RsaI digestion of the agr gene PCR product revealed existing correlations between the determined digestion profiles (designations used for the first time) and the PDI response. Moreover, the functionality of the agr system affected S. aureus susceptibility to PDI. Based on our results, we conclude that the agr gene may be a genetic factor affecting the strain dependent response to PDI.
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Affiliation(s)
- Mariusz Grinholc
- Laboratory of Molecular Diagnostics, Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Kladki 24, 80-822 Gdansk, Poland.
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Arya R, Princy SA. An insight into pleiotropic regulators Agr and Sar: molecular probes paving the new way for antivirulent therapy. Future Microbiol 2013; 8:1339-53. [DOI: 10.2217/fmb.13.92] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Staphylococcus aureus pathogenesis is an intricate process involving a diverse array of extracellular proteins, biofilm and cell wall components that are coordinately expressed in different stages of infection. The expression of two divergent loci, agr and sar, is increasingly recognized as a key regulator of virulence in S. aureus, and there is mounting evidence for the role of these loci in staphylococcal infections. The functional agr regulon is critical for the production of virulence factors, including α, β and δ hemolysins. The sar locus encodes SarA protein, which regulates the expression of cell wall-associated and certain extracellular proteins in agr-dependent and agr-independent pathways. Multidrug-resistant S. aureus is a leading cause of morbidity and mortality in the world and its management, especially in community-acquired methicillin-resistant S. aureus infections, has evolved comparatively little. In particular, no novel targets have been incorporated into its treatment to date. Hence, these loci appear to be the most significant and are currently at the attention of intense investigation regarding their therapeutic prospects.
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Affiliation(s)
- Rekha Arya
- Quorum Sensing Laboratory, SASTRA‘s Hub for Research & Innovation (SHRI), School of Chemical & Biotechnology, SASTRA University, Tirumalaisamudrum 613401, Thanjavur, Tamil Nadu, India
| | - S Adline Princy
- Quorum Sensing Laboratory, SASTRA‘s Hub for Research & Innovation (SHRI), School of Chemical & Biotechnology, SASTRA University, Tirumalaisamudrum 613401, Thanjavur, Tamil Nadu, India
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Impact of reduced vancomycin MIC on clinical outcomes of methicillin-resistant Staphylococcus aureus bacteremia. Antimicrob Agents Chemother 2013; 57:5536-42. [PMID: 23979741 DOI: 10.1128/aac.01137-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Vancomycin has been a key antibiotic agent for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. However, little is known about the relationship between vancomycin MIC values at the higher end of the susceptibility range and clinical outcomes. The aim of this study was to determine the impact of MRSA bacteremia on clinical outcomes in patients with a vancomycin MIC near the upper limit of the susceptible range. Patients with MRSA bacteremia were divided into a high-vancomycin-MIC group (2 μg/ml) and a low-vancomycin-MIC group (≤1.0 μg/ml). We examined the relationship between MIC, genotype, primary source of bacteremia, and mortality. Ninety-four patients with MRSA bacteremia, including 31 with a high vancomycin MIC and 63 with a low MIC were analyzed. There was no significant difference between the presence of agr dysfunction and SCCmec type between the two groups. A higher vancomycin MIC was not found to be associated with mortality. In contrast, high-risk bloodstream infection sources (hazard ratio [HR], 4.63; 95% confidence interval [CI] = 1.24 to 17.33) and bacterial eradication after treatment (HR, 0.06; 95% CI = 0.02 to 0.17), irrespective of vancomycin MIC, were predictors of all-cause 30-day mortality. Our study suggests that a high-risk source of bacteremia is likely to be associated with unfavorable clinical outcomes, but a high vancomycin MIC in a susceptible range, as well as genotype characteristics, are not associated with mortality.
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Lebeaux D, Chauhan A, Rendueles O, Beloin C. From in vitro to in vivo Models of Bacterial Biofilm-Related Infections. Pathogens 2013; 2:288-356. [PMID: 25437038 PMCID: PMC4235718 DOI: 10.3390/pathogens2020288] [Citation(s) in RCA: 308] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 05/01/2013] [Accepted: 05/08/2013] [Indexed: 12/13/2022] Open
Abstract
The influence of microorganisms growing as sessile communities in a large number of human infections has been extensively studied and recognized for 30–40 years, therefore warranting intense scientific and medical research. Nonetheless, mimicking the biofilm-life style of bacteria and biofilm-related infections has been an arduous task. Models used to study biofilms range from simple in vitro to complex in vivo models of tissues or device-related infections. These different models have progressively contributed to the current knowledge of biofilm physiology within the host context. While far from a complete understanding of the multiple elements controlling the dynamic interactions between the host and biofilms, we are nowadays witnessing the emergence of promising preventive or curative strategies to fight biofilm-related infections. This review undertakes a comprehensive analysis of the literature from a historic perspective commenting on the contribution of the different models and discussing future venues and new approaches that can be merged with more traditional techniques in order to model biofilm-infections and efficiently fight them.
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Affiliation(s)
- David Lebeaux
- Institut Pasteur, Unité de Génétique des Biofilms, 25 rue du Dr. Roux, 75724 Paris cedex 15, France.
| | - Ashwini Chauhan
- Institut Pasteur, Unité de Génétique des Biofilms, 25 rue du Dr. Roux, 75724 Paris cedex 15, France.
| | - Olaya Rendueles
- Institut Pasteur, Unité de Génétique des Biofilms, 25 rue du Dr. Roux, 75724 Paris cedex 15, France.
| | - Christophe Beloin
- Institut Pasteur, Unité de Génétique des Biofilms, 25 rue du Dr. Roux, 75724 Paris cedex 15, France.
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Quiblier C, Seidl K, Roschitzki B, Zinkernagel AS, Berger-Bächi B, Senn MM. Secretome analysis defines the major role of SecDF in Staphylococcus aureus virulence. PLoS One 2013; 8:e63513. [PMID: 23658837 PMCID: PMC3643904 DOI: 10.1371/journal.pone.0063513] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 04/02/2013] [Indexed: 01/27/2023] Open
Abstract
The Sec pathway plays a prominent role in protein export and membrane insertion, including the secretion of major bacterial virulence determinants. The accessory Sec constituent SecDF has been proposed to contribute to protein export. Deletion of Staphylococcus aureus secDF has previously been shown to reduce resistance, to alter cell separation, and to change the expression of certain virulence factors. To analyse the impact of the secDF deletion in S. aureus on protein secretion, a quantitative secretome analysis was performed. Numerous Sec signal containing proteins involved in virulence were found to be decreased in the supernatant of the secDF mutant. However, two Sec-dependent hydrolases were increased in comparison to the wild type, suggesting additional indirect, regulatory effects to occur upon deletion of secDF. Adhesion, invasion, and cytotoxicity of the secDF mutant were reduced in human umbilical vein endothelial cells. Virulence was significantly reduced using a Galleria mellonella insect model. Altogether, SecDF is a promising therapeutic target for controlling S. aureus infections.
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Affiliation(s)
- Chantal Quiblier
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Kati Seidl
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Bernd Roschitzki
- Functional Genomics Center Zurich, Swiss Federal Institute of Technology and University of Zurich, Zurich, Switzerland
| | - Annelies S. Zinkernagel
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | | | - Maria M. Senn
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
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Reduced vancomycin susceptibility in an in vitro catheter-related biofilm model correlates with poor therapeutic outcomes in experimental endocarditis due to methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2013; 57:1447-54. [PMID: 23295925 DOI: 10.1128/aac.02073-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is the most common cause of endovascular infections, including catheter sepsis and infective endocarditis (IE). Vancomycin (VAN) is the primary choice for treatment of methicillin-resistant S. aureus (MRSA) infections. However, high rates of VAN treatment failure in MRSA infections caused by VAN-susceptible strains have been increasingly reported. Biofilm-associated MRSA infections are especially prone to clinical antibiotic failure. The present studies examined potential relationships between MRSA susceptibility to VAN in biofilms in vitro and nonsusceptibility to VAN in endovascular infection in vivo. Using 10 "VAN-susceptible" MRSA bloodstream isolates previously investigated for VAN responsiveness in experimental IE, we studied the mechanism(s) of such in vivo VAN resistance, including: (i) VAN binding to MRSA organisms; (ii) the impact of VAN on biofilm formation and biofilm composition; (iii) VAN efficacy in an in vitro catheter-related biofilm model; (iv) effects on cell wall thickness. As a group, the five strains previously categorized as VAN nonresponders (non-Rsp) in the experimental IE model differed from the five responders (Rsp) in terms of lower VAN binding, increased biofilm formation, higher survival in the presence of VAN within biofilms in the presence or absence of catheters, and greater biofilm reduction upon proteinase K treatment. Interestingly, sub-MICs of VAN significantly promoted biofilm formation only in the non-Rsp isolates. Cell wall thickness was similar among all MRSA strains. These results suggest that sublethal VAN levels that induce biofilm formation and reduce efficacy of VAN in the in vitro catheter-associated biofilms may contribute to suboptimal treatment outcomes for endovascular infections caused by "VAN-susceptible" MRSA strains.
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