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Nygaard TK, Borgogna TR, Pallister KB, Predtechenskaya M, Burroughs OS, Gao A, Lubick EG, Voyich JM. The Relative Importance of Cytotoxins Produced by Methicillin-Resistant Staphylococcus aureus Strain USA300 for Causing Human PMN Destruction. Microorganisms 2024; 12:1782. [PMID: 39338457 PMCID: PMC11434515 DOI: 10.3390/microorganisms12091782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2024] [Revised: 08/20/2024] [Accepted: 08/22/2024] [Indexed: 09/30/2024] Open
Abstract
Staphylococcus aureus (S. aureus) is a prominent Gram-positive bacterial pathogen that expresses numerous cytotoxins known to target human polymorphonuclear leukocytes (PMNs or neutrophils). These include leukocidin G/H (LukGH, also known as LukAB), the Panton-Valentine leukocidin (PVL), γ-hemolysin A/B (HlgAB), γ-hemolysin B/C (HlgBC), leukocidin E/D (LukED), α-hemolysin (Hla), and the phenol-soluble modulin-α peptides (PSMα). However, the relative contribution of each of these cytotoxins in causing human PMN lysis is not clear. In this study, we used a library of cytotoxin deletion mutants in the clinically relevant methicillin-resistant S. aureus (MRSA) isolate LAC (strain ST8:USA300) to determine the relative importance of each for causing human PMN lysis upon exposure to extracellular components as well as following phagocytosis. Using flow cytometry to examine plasma membrane permeability and assays quantifying lactose dehydrogenase release, we found that PVL was the dominant extracellular factor causing human PMN lysis produced by USA300. In contrast, LukGH was the most important cytotoxin causing human PMN lysis immediately following phagocytosis with contributions from the other bicomponent leukocidins only observed at later time points. These results not only clarify the relative importance of different USA300 cytotoxins for causing human PMN destruction but also demonstrate how two apparently redundant virulence factors play distinctive roles in promoting S. aureus pathogenesis.
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Affiliation(s)
- Tyler K Nygaard
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Timothy R Borgogna
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Kyler B Pallister
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Maria Predtechenskaya
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Owen S Burroughs
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Annika Gao
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Evan G Lubick
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Jovanka M Voyich
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
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Nygaard TK, Borgogna TR, Sward EW, Guerra FE, Dankoff JG, Collins MM, Pallister KB, Chen L, Kreiswirth BN, Voyich JM. Aspartic Acid Residue 51 of SaeR Is Essential for Staphylococcus aureus Virulence. Front Microbiol 2018; 9:3085. [PMID: 30619166 PMCID: PMC6302044 DOI: 10.3389/fmicb.2018.03085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 11/29/2018] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus is a common Gram-positive bacteria that is a major cause of human morbidity and mortality. The SaeR/S two-component sensory system of S. aureus is important for virulence gene transcription and pathogenesis. However, the influence of SaeR phosphorylation on virulence gene transcription is not clear. To determine the importance of potential SaeR phosphorylation sites for S. aureus virulence, we generated genomic alanine substitutions at conserved aspartic acid residues in the receiver domain of the SaeR response regulator in clinically significant S. aureus pulsed-field gel electrophoresis (PFGE) type USA300. Transcriptional analysis demonstrated a dramatic reduction in the transcript abundance of various toxins, adhesins, and immunomodulatory proteins for SaeR with an aspartic acid to alanine substitution at residue 51. These findings corresponded to a significant decrease in cytotoxicity against human erythrocytes and polymorphonuclear leukocytes, the ability to block human myeloperoxidase activity, and pathogenesis during murine soft-tissue infection. Analysis of SaeR sequences from over 8,000 draft S. aureus genomes revealed that aspartic acid residue 51 is 100% conserved. Collectively, these results demonstrate that aspartic acid residue 51 of SaeR is essential for S. aureus virulence and underscore a conserved target for novel antimicrobial strategies that treat infection caused by this pathogen.
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Affiliation(s)
- Tyler K Nygaard
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Timothy R Borgogna
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Eli W Sward
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Fermin E Guerra
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Jennifer G Dankoff
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Madison M Collins
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Kyler B Pallister
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Liang Chen
- Public Health Research Institute Tuberculosis Center, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Barry N Kreiswirth
- Public Health Research Institute Tuberculosis Center, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Jovanka M Voyich
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
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3
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Kloppot P, Selle M, Kohler C, Stentzel S, Fuchs S, Liebscher V, Müller E, Kale D, Ohlsen K, Bröker BM, Zipfel PF, Kahl BC, Ehricht R, Hecker M, Engelmann S. Microarray-based identification of human antibodies against Staphylococcus aureus antigens. Proteomics Clin Appl 2015; 9:1003-11. [PMID: 25676254 DOI: 10.1002/prca.201400123] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 01/06/2015] [Accepted: 02/05/2015] [Indexed: 02/03/2023]
Abstract
PURPOSE The mortality rate of patients with Staphylococcus aureus infections is alarming and urgently demands new strategies to attenuate the course of these infections or to detect them at earlier stages. EXPERIMENTAL DESIGN To study the adaptive immune response to S. aureus antigens in healthy human volunteers, a protein microarray containing 44 S. aureus proteins was developed using the ArrayStrip platform technology. RESULTS Testing plasma samples from 15 S. aureus carriers and 15 noncarriers 21 immunogenic S. aureus antigens have been identified. Seven antigens were recognized by antibodies present in at least 60% of the samples, representing the core S. aureus immunome of healthy individuals. S. aureus-specific serum immunoglobulin G (IgG) levels were significantly lower in noncarriers than in carriers specifically anti-IsaA, anti-SACOL0479, and anti-SACOL0480 IgGs were found at lower frequencies and quantities. Twenty-two antigens present on the microarray were encoded by all S. aureus carrier isolates. Nevertheless, the immune system of the carriers was responsive to only eight of them and with different intensities. CONCLUSION AND CLINICAL RELEVANCE The established protein microarray allows a broad profiling of the S. aureus-specific antibody response and can be used to identify S. aureus antigens that might serve as vaccines or diagnostic markers.
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Affiliation(s)
- Peggy Kloppot
- Institut für Mikrobiologie, Universität Greifswald, Greifswald, Germany
| | - Martina Selle
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Würzburg, Germany
| | - Christian Kohler
- Institut für Mikrobiologie, Universität Greifswald, Greifswald, Germany
| | - Sebastian Stentzel
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Stephan Fuchs
- Institut für Mikrobiologie, Universität Greifswald, Greifswald, Germany
| | - Volkmar Liebscher
- Institut für Mathematik und Informatik, Universität Greifswald, Greifswald, Germany
| | | | - Devika Kale
- Institut für Medizinische Mikrobiologie, Universitätsklinikum Münster, Münster, Germany
| | - Knut Ohlsen
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Würzburg, Germany
| | - Barbara M Bröker
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Peter F Zipfel
- Infektionsbiologie, Hans-Knöll-Institut Jena, Münster, Germany.,Friedrich Schiller Universität, Jena, Germany
| | - Barbara C Kahl
- Institut für Medizinische Mikrobiologie, Universitätsklinikum Münster, Münster, Germany
| | | | - Michael Hecker
- Institut für Mikrobiologie, Universität Greifswald, Greifswald, Germany
| | - Susanne Engelmann
- Institut für Mikrobiologie, Universität Greifswald, Greifswald, Germany.,Institut für Mikrobiologie, TU Braunschweig, Braunschweig, Germany.,Mikrobielle Proteomik, Helmholtzzentrum für Infektionsforschung, Braunschweig, Germany
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Differential regulation of staphylococcal virulence by the sensor kinase SaeS in response to neutrophil-derived stimuli. Proc Natl Acad Sci U S A 2014; 111:E2037-45. [PMID: 24782537 DOI: 10.1073/pnas.1322125111] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Two-component systems (TCSs) are highly conserved across bacteria and are used to rapidly sense and respond to changing environmental conditions. The human pathogen Staphylococcus aureus uses the S. aureus exoprotein expression (sae) TCS to sense host signals and activate transcription of virulence factors essential to pathogenesis. Despite its importance, the mechanism by which the histidine kinase SaeS recognizes specific host stimuli is unknown. After mutagenizing the predicted extracellular loop of SaeS, we discovered one methionine residue (M31) was essential for the ability of S. aureus to transcribe sae target genes, including hla, lukAB/lukGH, and hlgA. This single M31A mutation also significantly reduced cytotoxicity in human neutrophils to levels observed in cells following interaction with ΔsaeS. Another important discovery was that mutation of two aromatic anchor residues (W32A and F33A) disrupted the normal basal signaling of SaeS in the absence of inducing signals, yet both mutant kinases had appropriate activation of effector genes following exposure to neutrophils. Although the transcriptional profile of aromatic mutation W32A was consistent with that of WT in response to human α-defensin 1, mutant kinase F33A did not properly transcribe the γ-toxin genes in response to this stimulus. Taken together, our results provide molecular evidence for how SaeS recognizes host signals and triggers activation of select virulence factors to facilitate evasion of innate immunity. These findings have important implications for signal transduction in prokaryotes and eukaryotes due to conservation of aromatic anchor residues across both of these domains and the important role they play in sensor protein structure and function.
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Role of antibodies in protection elicited by active vaccination with genetically inactivated alpha hemolysin in a mouse model of staphylococcus aureus skin and soft tissue infections. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:622-7. [PMID: 24574539 DOI: 10.1128/cvi.00051-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Due to the emergence of highly virulent community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections, S. aureus has become a major threat to public health. A majority of CA-MRSA skin and soft tissue infections in the United States are caused by S. aureus USA300 strains that are known to produce high levels of alpha hemolysin (Hla). Therefore, vaccines that contain inactivated forms of this toxin are currently being developed. In this study, we sought to determine the immune mechanisms of protection for this antigen using a vaccine composed of a genetically inactivated form of Hla (HlaH35L). Using a murine model of skin and soft tissue infections (SSTI), we found that BALB/c mice were protected by vaccination with HlaH35L; however, Jh mice, which are deficient in mature B lymphocytes and lack IgM and IgG in their serum, were not protected. Passive immunization with anti-HlaH35L antibodies conferred protection against bacterial colonization. Moreover, we found a positive correlation between the total antibody concentration induced by active vaccination and reduced bacterial levels. Animals that developed detectable neutralizing antibody titers after active vaccination were significantly protected from infection. These data demonstrate that antibodies to Hla represent the major mechanism of protection afforded by active vaccination with inactivated Hla in this murine model of SSTI, and in this disease model, antibody levels correlate with protection. These results provide important information for the future development and evaluation of S. aureus vaccines.
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Nygaard TK, Pallister KB, Zurek OW, Voyich JM. The impact of α-toxin on host cell plasma membrane permeability and cytokine expression during human blood infection by CA-MRSA USA300. J Leukoc Biol 2013; 94:971-9. [PMID: 24026286 DOI: 10.1189/jlb.0213080] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This investigation examines the influence of α-toxin (Hla) expression by CA-MRSA on host immune cell integrity and cytokine expression during infection of human blood. Flow cytometry analysis of human blood infected by Staphylococcus aureus PFGE type USA300 or a USA300Δhla demonstrated that Hla expression significantly increased plasma membrane permeability of human CD14(+) monocytes. The increased susceptibility of human CD14(+) monocytes to Hla toxicity paralleled the high cell-surface expression on these cell types of ADAM10. USA300 rapidly associated with PMNs and monocytes but not T cells following inoculation of human blood. Transcription analysis indicated a strong up-regulation of proinflammatory cytokine transcription following infection of human blood by USA300 and USA300Δhla. CBAs and ELISAs determined that IL-6, IL-10, TNF-α, IFN-γ, IL-1β, IL-8, and IL-4 are significantly up-regulated during the initial phases of human blood infection by USA300 relative to mock-infected blood but failed to distinguish any significant differences in secreted cytokine protein concentrations during infection by USA300Δhla relative to USA300. Collectively, these findings demonstrate that expression of Hla by USA300 has a significant impact on human CD14(+) monocyte plasma membrane integrity but is not exclusively responsible for the proinflammatory cytokine profile induced by USA300 during the initial stages of human blood infection.
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Affiliation(s)
- Tyler K Nygaard
- 1.Lewis Hall, Montana State University, Bozeman, MT 59717, USA.
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Staphylococcus aureus elaborates leukocidin AB to mediate escape from within human neutrophils. Infect Immun 2013; 81:1830-41. [PMID: 23509138 DOI: 10.1128/iai.00095-13] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) strains of the pulsed-field type USA300 are primarily responsible for the current community-associated epidemic of MRSA infections in the United States. The success of USA300 is partly attributed to the ability of the pathogen to avoid destruction by human neutrophils (polymorphonuclear leukocytes [PMNs]), which are crucial to the host immune response to S. aureus infection. In this work, we investigated the contribution of bicomponent pore-forming toxins to the ability of USA300 to withstand attack from primary human PMNs. We demonstrate that in vitro growth conditions influence the expression, production, and availability of leukotoxins by USA300, which in turn impact the cytotoxic potential of this clone toward PMNs. Interestingly, we also found that upon exposure to PMNs, USA300 preferentially activates the promoter of the lukAB operon, which encodes the recently identified leukocidin AB (LukAB). LukAB elaborated by extracellular S. aureus forms pores in the plasma membrane of PMNs, leading to PMN lysis, highlighting a contribution of LukAB to USA300 virulence. We now show that LukAB also facilitates the escape of bacteria engulfed within PMNs, in turn enabling the replication and outgrowth of S. aureus. Together, these results suggest that upon encountering PMNs S. aureus induces the production of LukAB, which serves as an extra- and intracellular weapon to protect the bacterium from destruction by human PMNs.
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18β-Glycyrrhetinic acid inhibits methicillin-resistant Staphylococcus aureus survival and attenuates virulence gene expression. Antimicrob Agents Chemother 2012; 57:241-7. [PMID: 23114775 DOI: 10.1128/aac.01023-12] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) has become a major source of infection in hospitals and in the community. Increasing antibiotic resistance in S. aureus strains has created a need for alternative therapies to treat disease. A component of the licorice root Glycyrrhiza spp., 18β-glycyrrhetinic acid (GRA), has been shown to have antiviral, antitumor, and antibacterial activity. This investigation explores the in vitro and in vivo effects of GRA on MRSA pulsed-field gel electrophoresis (PFGE) type USA300. GRA exhibited bactericidal activity at concentrations exceeding 0.223 μM. Upon exposure of S. aureus to sublytic concentrations of GRA, we observed a reduction in expression of key virulence genes, including saeR and hla. In murine models of skin and soft tissue infection, topical GRA treatment significantly reduced skin lesion size and decreased the expression of saeR and hla genes. Our investigation demonstrates that at high concentrations GRA is bactericidal to MRSA and at sublethal doses it reduces virulence gene expression in S. aureus both in vitro and in vivo.
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Luhachack LG, Visvikis O, Wollenberg AC, Lacy-Hulbert A, Stuart LM, Irazoqui JE. EGL-9 controls C. elegans host defense specificity through prolyl hydroxylation-dependent and -independent HIF-1 pathways. PLoS Pathog 2012; 8:e1002798. [PMID: 22792069 PMCID: PMC3390412 DOI: 10.1371/journal.ppat.1002798] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 05/29/2012] [Indexed: 12/28/2022] Open
Abstract
Understanding host defense against microbes is key to developing new and more effective therapies for infection and inflammatory disease. However, how animals integrate multiple environmental signals and discriminate between different pathogens to mount specific and tailored responses remains poorly understood. Using the genetically tractable model host Caenorhabditis elegans and pathogenic bacterium Staphylococcus aureus, we describe an important role for hypoxia-inducible factor (HIF) in defining the specificity of the host response in the intestine. We demonstrate that loss of egl-9, a negative regulator of HIF, confers HIF-dependent enhanced susceptibility to S. aureus while increasing resistance to Pseudomonas aeruginosa. In our attempt to understand how HIF could have these apparently dichotomous roles in host defense, we find that distinct pathways separately regulate two opposing functions of HIF: the canonical pathway is important for blocking expression of a set of HIF-induced defense genes, whereas a less well understood noncanonical pathway appears to be important for allowing the expression of another distinct set of HIF-repressed defense genes. Thus, HIF can function either as a gene-specific inducer or repressor of host defense, providing a molecular mechanism by which HIF can have apparently opposing roles in defense and inflammation. Together, our observations show that HIF can set the balance between alternative pathogen-specific host responses, potentially acting as an evolutionarily conserved specificity switch in the host innate immune response. Understanding how animals detect infection and mount appropriate responses is key to treating infection and inflammatory disease. We use the tractable model Caenorhabditis elegans to study mechanisms of host defense against pathogenic bacteria. Here we show that hypoxia-inducible factor (HIF) is important for ensuring that the intestinal host response to infection has the appropriate specificity. HIF acts as an inducer and a repressor of host genes in the intestine, and regulation of these opposing activities is genetically separable. One well-understood regulatory pathway requires EGL-9 and VHL-1, negative regulators of HIF, to prevent constitutive expression of host defense genes. Noncanonical pathways are less understood; a recently identified noncanonical pathway requires EGL-9 and SWAN-1. This pathway appears to be more important for lifting the repression of defense genes by HIF-1. Mutants defective in EGL-9 are more susceptible to S. aureus but more resistant to the distinct pathogen P. aeruginosa, indicating that the defense role of HIF-1 is pathogen-specific. These studies are relevant to mammalian defense because mutations in hif-1, egl-9, and vhl-1 homologs in mice have similar effects on intestinal inflammation as in worms, and provide a framework to further explore the role of noncanonical HIF signaling in human infection and inflammatory disease.
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Affiliation(s)
- Lyly G. Luhachack
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Orane Visvikis
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Amanda C. Wollenberg
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Adam Lacy-Hulbert
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lynda M. Stuart
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Javier E. Irazoqui
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Nygaard TK, Pallister KB, DuMont AL, DeWald M, Watkins RL, Pallister EQ, Malone C, Griffith S, Horswill AR, Torres VJ, Voyich JM. Alpha-toxin induces programmed cell death of human T cells, B cells, and monocytes during USA300 infection. PLoS One 2012; 7:e36532. [PMID: 22574180 PMCID: PMC3344897 DOI: 10.1371/journal.pone.0036532] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 04/03/2012] [Indexed: 11/19/2022] Open
Abstract
This investigation examines the influence of alpha-toxin (Hla) during USA300 infection of human leukocytes. Survival of an USA300 isogenic deletion mutant of hla (USA300Δhla) in human blood was comparable to the parental wild-type strain and polymorphonuclear leukocyte (PMN) plasma membrane permeability caused by USA300 did not require Hla. Flow cytometry analysis of peripheral blood mononuclear cells (PBMCs) following infection by USA300, USA300Δhla, and USA300Δhla transformed with a plasmid over-expressing Hla (USA300Δhla Comp) demonstrated this toxin plays a significant role inducing plasma membrane permeability of CD14+, CD3+, and CD19+ PBMCs. Rapid plasma membrane permeability independent of Hla was observed for PMNs, CD14+ and CD19+ PBMCs following intoxication with USA300 supernatant while the majority of CD3+ PBMC plasma membrane permeability induced by USA300 required Hla. Addition of recombinant Hla to USA300Δhla supernatant rescued CD3+ and CD19+ PBMC plasma membrane permeability generated by USA300 supernatant. An observed delay in plasma membrane permeability caused by Hla in conjunction with Annexin V binding and ApoBrdU Tunel assays examining PBMCs intoxicated with recombinant Hla or infected with USA300, USA300Δhla, USA300Δhla Comp, and USA300ΔsaeR/S suggest Hla induces programmed cell death of monocytes, B cells, and T cells that results in plasma membrane permeability. Together these findings underscore the importance of Hla during S. aureus infection of human tissue and specifically demonstrate Hla activity during USA300 infection triggers programmed cell death of human monocytes, T cells and B cells that leads to plasma membrane permeability.
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Affiliation(s)
- Tyler K. Nygaard
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Kyler B. Pallister
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Ashley L. DuMont
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Mark DeWald
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Robert L. Watkins
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Erik Q. Pallister
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Cheryl Malone
- Department of Microbiology University of Iowa, Iowa City, Iowa, United States of America
| | - Shannon Griffith
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
| | - Alexander R. Horswill
- Department of Microbiology University of Iowa, Iowa City, Iowa, United States of America
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Jovanka M. Voyich
- Department of Immunology and Infectious Diseases, Montana State University – Bozeman, Montana, United States of America
- * E-mail:
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Abstract
Children with infectious diseases are commonly encountered in primary care settings. Identification of the subset of patients with bacterial infections is key in guiding the best possible management. Clinicians frequently care for children with infections of the upper respiratory tract, including acute otitis media, otitis externa, sinusitis, and pharyngitis. Conjunctivitis is not an uncommon reason for office visits. Bacterial pneumonia, urinary tract infections, and gastroenteritis are regularly seen. Over the last decade, a growing number of children have had infections of the skin and soft tissue, driven by the increased prevalence of infections caused by methicillin-resistant Staphylococcus aureus. The following review addresses the epidemiology and risk factors for specific infections and examines the clinical presentation and selection of appropriate diagnostic methods in such conditions. Methods to prevent these bacterial infections and recommendations for follow-up are suggested. Management of these infections requires that antimicrobial agents be used in a judicious manner in the outpatient setting. Such antibiotic therapy is recommended using both available clinical evidence and review of disease-specific treatment guidelines.
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Spentzas T, Shapley RKH, Aguirre CA, Meals E, Lazar L, Rayburn MS, Walker BS, English BK. Ketamine inhibits tumor necrosis factor secretion by RAW264.7 murine macrophages stimulated with antibiotic-exposed strains of community-associated, methicillin-resistant Staphylococcus aureus. BMC Immunol 2011; 12:11. [PMID: 21266054 PMCID: PMC3037927 DOI: 10.1186/1471-2172-12-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 01/25/2011] [Indexed: 11/23/2022] Open
Abstract
Background Infections caused by community-associated strains of methicillin-resistant Staphylococcus aureus (CA-MRSA) are associated with a marked and prolonged host inflammatory response. In a sepsis simulation model, we tested whether the anesthetic ketamine inhibits the macrophage TNF response to antibiotic-exposed CA-MRSA bacteria via its antagonism of N-methyl-D-aspartate (NMDA) receptors. RAW264.7 cells were stimulated for 18 hrs with 105 to 107 CFU/mL inocula of either of two prototypical CA-MRSA isolates, USA300 strain LAC and USA400 strain MW2, in the presence of either vancomycin or daptomycin. One hour before bacterial stimulation, ketamine was added with or without MK-801 (dizocilpine, a chemically unrelated non-competitive NMDA receptor antagonist), APV (D-2-amino-5-phosphono-valerate, a competitive NMDA receptor antagonist), NMDA, or combinations of these agents. Supernatants were collected and assayed for TNF concentration by ELISA. Results RAW264.7 cells exposed to either LAC or MW2 in the presence of daptomycin secreted less TNF than in the presence of vancomycin. The addition of ketamine inhibited macrophage TNF secretion after stimulation with either of the CA-MRSA isolates (LAC, MW2) in the presence of either antibiotic. The NMDA inhibitors, MK-801 and APV, also suppressed macrophage TNF secretion after stimulation with either of the antibiotic-exposed CA-MRSA isolates, and the effect was not additive or synergistic with ketamine. The addition of NMDA substrate augmented TNF secretion in response to the CA-MRSA bacteria, and the addition of APV suppressed the effect of NMDA in a dose-dependent fashion. Conclusions Ketamine inhibits TNF secretion by MRSA-stimulated RAW264.7 macrophages and the mechanism likely involves NMDA receptor antagonism. These findings may have therapeutic significance in MRSA sepsis.
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Affiliation(s)
- Thomas Spentzas
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, USA.
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Community-Acquired Methicillin-Resistant Staphylococcus aureus Pericarditis Presenting as Cardiac Tamponade. South Med J 2010; 103:834-6. [DOI: 10.1097/smj.0b013e3181e631e7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Yamamoto T, Nishiyama A, Takano T, Yabe S, Higuchi W, Razvina O, Shi D. Community-acquired methicillin-resistant Staphylococcus aureus: community transmission, pathogenesis, and drug resistance. J Infect Chemother 2010; 16:225-54. [PMID: 20336341 PMCID: PMC7088255 DOI: 10.1007/s10156-010-0045-9] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Indexed: 11/29/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is able to persist not only in hospitals (with a high level of antimicrobial agent use) but also in the community (with a low level of antimicrobial agent use). The former is called hospital-acquired MRSA (HA-MRSA) and the latter community-acquired MRSA (CA-MRSA). It is believed MRSA clones are generated from S. aureus through insertion of the staphylococcal cassette chromosome mec (SCCmec), and outbreaks occur as they spread. Several worldwide and regional clones have been identified, and their epidemiological, clinical, and genetic characteristics have been described. CA-MRSA is likely able to survive in the community because of suitable SCCmec types (type IV or V), a clone-specific colonization/infection nature, toxin profiles (including Pantone-Valentine leucocidin, PVL), and narrow drug resistance patterns. CA-MRSA infections are generally seen in healthy children or young athletes, with unexpected cases of diseases, and also in elderly inpatients, occasionally surprising clinicians used to HA-MRSA infections. CA-MRSA spreads within families and close-contact groups or even through public transport, demonstrating transmission cores. Re-infection (including multifocal infection) frequently occurs, if the cores are not sought out and properly eradicated. Recently, attention has been given to CA-MRSA (USA300), which originated in the US, and is growing as HA-MRSA and also as a worldwide clone. CA-MRSA infection in influenza season has increasingly been noted as well. MRSA is also found in farm and companion animals, and has occasionally transferred to humans. As such, the epidemiological, clinical, and genetic behavior of CA-MRSA, a growing threat, is focused on in this study.
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Affiliation(s)
- Tatsuo Yamamoto
- Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
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Ventura CL, Malachowa N, Hammer CH, Nardone GA, Robinson MA, Kobayashi SD, DeLeo FR. Identification of a novel Staphylococcus aureus two-component leukotoxin using cell surface proteomics. PLoS One 2010; 5:e11634. [PMID: 20661294 PMCID: PMC2905442 DOI: 10.1371/journal.pone.0011634] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 06/23/2010] [Indexed: 01/13/2023] Open
Abstract
Staphylococcus aureus is a prominent human pathogen and leading
cause of bacterial infection in hospitals and the community.
Community-associated methicillin-resistant S. aureus (CA-MRSA)
strains such as USA300 are highly virulent and, unlike hospital strains, often
cause disease in otherwise healthy individuals. The enhanced virulence of
CA-MRSA is based in part on increased ability to produce high levels of secreted
molecules that facilitate evasion of the innate immune response. Although
progress has been made, the factors that contribute to CA-MRSA virulence are
incompletely defined. We analyzed the cell surface proteome (surfome) of USA300
strain LAC to better understand extracellular factors that contribute to the
enhanced virulence phenotype. A total of 113 identified proteins were associated
with the surface of USA300 during the late-exponential phase of growth
in vitro. Protein A was the most abundant surface molecule
of USA300, as indicated by combined Mascot score following analysis of peptides
by tandem mass spectrometry. Unexpectedly, we identified a previously
uncharacterized two-component leukotoxin–herein named LukS-H and
LukF-G (LukGH)-as two of the most abundant surface-associated proteins of
USA300. Rabbit antibody specific for LukG indicated it was also freely secreted
by USA300 into culture media. We used wild-type and isogenic
lukGH deletion strains of USA300 in combination with human
PMN pore formation and lysis assays to identify this molecule as a leukotoxin.
Moreover, LukGH synergized with PVL to enhance lysis of human PMNs in
vitro, and contributed to lysis of PMNs after phagocytosis. We
conclude LukGH is a novel two-component leukotoxin with cytolytic activity
toward neutrophils, and thus potentially contributes to S.
aureus virulence.
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Affiliation(s)
- Christy L. Ventura
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories,
National Institute of Allergy and Infectious Diseases, National Institutes of
Health, Hamilton, Montana, United States of America
| | - Natalia Malachowa
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories,
National Institute of Allergy and Infectious Diseases, National Institutes of
Health, Hamilton, Montana, United States of America
| | - Carl H. Hammer
- Research Technologies Branch, National Institute of Allergy and
Infectious Diseases, National Institutes of Health, Rockville, Maryland, United
States of America
| | - Glenn A. Nardone
- Research Technologies Branch, National Institute of Allergy and
Infectious Diseases, National Institutes of Health, Rockville, Maryland, United
States of America
| | - Mary Ann Robinson
- Research Technologies Branch, National Institute of Allergy and
Infectious Diseases, National Institutes of Health, Rockville, Maryland, United
States of America
| | - Scott D. Kobayashi
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories,
National Institute of Allergy and Infectious Diseases, National Institutes of
Health, Hamilton, Montana, United States of America
| | - Frank R. DeLeo
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories,
National Institute of Allergy and Infectious Diseases, National Institutes of
Health, Hamilton, Montana, United States of America
- * E-mail:
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David MZ, Daum RS. Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic. Clin Microbiol Rev 2010; 23:616-87. [PMID: 20610826 PMCID: PMC2901661 DOI: 10.1128/cmr.00081-09] [Citation(s) in RCA: 1360] [Impact Index Per Article: 97.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.
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Affiliation(s)
- Michael Z David
- Department of Pediatrics and Department of Medicine, the University of Chicago, 5841 S. Maryland Ave., Chicago, IL 60637, USA.
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Olsen RJ, Musser JM. Molecular pathogenesis of necrotizing fasciitis. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2010; 5:1-31. [PMID: 19737105 DOI: 10.1146/annurev-pathol-121808-102135] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Necrotizing fasciitis, also known as the flesh-eating disease, is a severe invasive infection associated with very high rates of human morbidity and mortality. It is most commonly caused by group A Streptococcus(GAS), a versatile human pathogen that causes diseases ranging in severity from uncomplicated pharyngitis (or strep throat) to life-threatening infections such as necrotizing fasciitis. Herein, we review recent discoveries bearing on the molecular pathogenesis of GAS necrotizing fasciitis. Importantly, the integration of new technologies and the development of human-relevant animal models have markedly expanded our understanding of the key pathogen-host interactions underlying GAS necrotizing fasciitis. For example, we now know that GAS organisms secrete a variety of proteases that disrupt host tissue and that these proteolytic enzymes are regulated by multiple transcriptional and posttranslational processes. This pathogenesis knowledge will be crucial to supporting downstream efforts that seek to develop novel vaccines and therapeutic agents for this serious human infection.
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Affiliation(s)
- Randall J Olsen
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, and Department of Pathology, The Methodist Hospital, Houston, Texas 77030, USA
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de Araújo BES, Borchert JM, Manhães PG, Ferreira FA, Ramundo MS, Silva-Carvalho MC, Seabra AC, Victal SH, Sá Figueiredo AM. A rare case of pyomyositis complicated by compartment syndrome caused by ST30-staphylococcal cassette chromosome mec type IV methicillin-resistant Staphylococcus aureus. Am J Emerg Med 2010; 28:537.e3-6. [PMID: 20466258 DOI: 10.1016/j.ajem.2009.08.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Accepted: 08/03/2009] [Indexed: 01/08/2023] Open
Affiliation(s)
- Bruno Espirito Santo de Araújo
- Centro de Terapia Intensiva Pediátrica e Neonatal, Hospital Central da Polícia Militar do Rio de Janeiro, Rio de Janeiro, Brazil
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Nygaard TK, Pallister KB, Ruzevich P, Griffith S, Vuong C, Voyich JM. SaeR binds a consensus sequence within virulence gene promoters to advance USA300 pathogenesis. J Infect Dis 2010; 201:241-54. [PMID: 20001858 DOI: 10.1086/649570] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
This investigation examines the role of the SaeR/S 2-component system in USA300, a prominent circulating clone of community-associated methicillin-resistant Staphylococcus aureus. Using a saeR/S isogenic deletion mutant of USA300 (USA300DeltasaeR/S) in murine models of sepsis and soft-tissue infection revealed that this sensory system is critical to pathogenesis of USA300 during both superficial and invasive infection. Oligonucleotide microarray and real-time reverse-transcriptase polymerase chain reaction identified numerous extracellular virulence genes that are down-regulated in USA300DeltasaeR/S. Unexpectedly, an up-regulation of mecA and mecR1 corresponded to increased methicillin resistance in USA300DeltasaeR/S. 5'-RACE analysis defined transcript start sites for sbi, efb, mecA, lukS-PV, hlb, SAUSA300_1975, and hla, to underscore a conserved consensus sequence within promoter regions of genes under strong SaeR/S transcriptional regulation. Electrophoretic mobility shift assay experiments illustrated direct binding of SaeR(His) to promoter regions containing the conserved consensus sequence. Collectively, the findings of this investigation demonstrate that SaeR/S directly interacts with virulence gene promoters to significantly influence USA300 pathogenesis.
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Affiliation(s)
- Tyler K Nygaard
- Department of Veterinary Molecular Biology, Montana State University-Bozeman, Bozeman, MT 59717, USA
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Holtfreter S, Kolata J, Bröker BM. Towards the immune proteome of Staphylococcus aureus – The anti-S. aureus antibody response. Int J Med Microbiol 2010; 300:176-92. [PMID: 19889576 DOI: 10.1016/j.ijmm.2009.10.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Silva Holtfreter
- Institut für Immunologie und Transfusionsmedizin, Ernst-Moritz-Arndt-Universität Greifswald, Sauerbruchstrasse, Neubau P, D-17475 Greifswald, Germany
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Fan J, Shu M, Zhang G, Zhou W, Jiang Y, Zhu Y, Chen G, Peacock SJ, Wan C, Pan W, Feil EJ. Biogeography and virulence of Staphylococcus aureus. PLoS One 2009; 4:e6216. [PMID: 19593449 PMCID: PMC2705676 DOI: 10.1371/journal.pone.0006216] [Citation(s) in RCA: 45] [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: 03/19/2009] [Accepted: 06/06/2009] [Indexed: 01/23/2023] Open
Abstract
Background Staphylococcus aureus is commonly carried asymptomatically in the human anterior nares and occasionally enters the bloodstream to cause invasive disease. Much of the global diversity of S. aureus remains uncharacterised, and is not clear how disease propensity varies between strains, and between host populations. Methodology We compared 147 isolates recovered from five kindergartens in Chengdu, China, with 51 isolates contemporaneously recovered from cases of pediatric infection from the main hospital serving this community. The samples were characterised by MLST, the presence/absence of PVL, and antibiotic resistance profiling. Principal Findings Genotype frequencies within individual kindergartens differ, but the sample recovered from cases of disease shows a general enrichment of certain MLST genotypes and PVL positive isolates. Genotypes under-represented in the disease sample tend to correspond to a single sequence cluster, and this cluster is more common in China than in other parts of the world. Conclusions/Significance Virulence propensity likely reflects a synergy between variation in the core genome (MLST) and accessory genome (PVL). By combining evidence form biogeography and virulence we demonstrate the existence of a “native” clade in West China which has lowered virulence, possibility due to acquired host immunity.
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Affiliation(s)
- Juan Fan
- Department of Pediatrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan, the People's Republic of China
| | - Min Shu
- Department of Pediatrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan, the People's Republic of China
| | - Ge Zhang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Wei Zhou
- Department of Pediatrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan, the People's Republic of China
| | - Yongmei Jiang
- Department of Pediatrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan, the People's Republic of China
| | - Yu Zhu
- Department of Pediatrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan, the People's Republic of China
| | - Guihua Chen
- Department of Pediatrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan, the People's Republic of China
| | - Sharon J. Peacock
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Chaomin Wan
- Department of Pediatrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan, the People's Republic of China
- * E-mail: (CW); (WP); (EJF)
| | - Wubin Pan
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan, the People's Republic of China
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, People's Republic of China
- Crown Bioscience, Inc. (Beijing), Light Muller Building, ChangPing Science Park, Beijing, the People's Republic of China
- * E-mail: (CW); (WP); (EJF)
| | - Edward J. Feil
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
- * E-mail: (CW); (WP); (EJF)
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Pournaras S, Iosifidis E, Roilides E. Advances in Antibacterial Therapy Against Emerging Bacterial Pathogens. Semin Hematol 2009; 46:198-211. [DOI: 10.1053/j.seminhematol.2009.03.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Tolbert TA, Binkley HM. Prevention of Community-Associated Methicillin-Resistant Staphylococcus Aureus in the Athletic Environment. Strength Cond J 2009. [DOI: 10.1519/ssc.0b013e3181a5c82b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Molecular basis and phenotype of methicillin resistance in Staphylococcus aureus and insights into new beta-lactams that meet the challenge. Antimicrob Agents Chemother 2009; 53:4051-63. [PMID: 19470504 DOI: 10.1128/aac.00084-09] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Routh JC, Alt AL, Ashley RA, Kramer SA, Boyce TG. Increasing prevalence and associated risk factors for methicillin resistant Staphylococcus aureus bacteriuria. J Urol 2009; 181:1694-8. [PMID: 19233426 DOI: 10.1016/j.juro.2008.11.108] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Indexed: 10/21/2022]
Abstract
PURPOSE Infections due to methicillin resistant Staphylococcus aureus are becoming increasingly prevalent in hospitals and in the community. We reviewed our institutional experience to determine whether methicillin resistant S. aureus is becoming a more common cause of bacteriuria and to determine if there are specific risk factors that may predict the development of methicillin resistant S. aureus bacteriuria. MATERIALS AND METHODS We reviewed all urine cultures with a pure growth of a single organism obtained at our institution from 1997 and 2007. Patients with urine cultures positive for methicillin resistant S. aureus were compared to a cohort with cultures positive for methicillin sensitive S. aureus, and to a third cohort with cultures positive for Escherichia coli to determine patient characteristics and associated risk factors. RESULTS We identified 7,100 and 9,985 positive urine cultures performed in 1997 and 2007, respectively. The most common urinary organism was E. coli. The number of patients with methicillin resistant S. aureus bacteriuria increased from 18 (0.3%) to 74 (0.8%) (p <0.001). On multivariate analysis older age (p = 0.004), catheter use (p = 0.004), hospital exposure (p <0.001) and patient comorbidity (p <0.001) were associated with methicillin resistant S. aureus bacteriuria compared with E. coli bacteriuria. CONCLUSIONS Methicillin resistant S. aureus remains rare as a cause of bacteriuria but its incidence has increased during the last decade. Risk factors for methicillin resistant S. aureus bacteriuria include increased age, patient comorbidity, hospital exposure and catheter use. For patients with these risk factors and new onset urinary symptoms, methicillin resistant S. aureus should be considered a possible cause of urinary tract infection.
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Henriques-Normark B, Blomberg C, Dagerhamn J, Bättig P, Normark S. The rise and fall of bacterial clones: Streptococcus pneumoniae. Nat Rev Microbiol 2008; 6:827-37. [DOI: 10.1038/nrmicro2011] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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