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Abstract
Strains of Staphylococcus aureus, and to a lesser extent other staphylococcal species, are a significant cause of morbidity and mortality. An important factor in the notoriety of these organisms stems from their frequent resistance to many antimicrobial agents used for chemotherapy. This review catalogues the variety of mobile genetic elements that have been identified in staphylococci, with a primary focus on those associated with the recruitment and spread of antimicrobial resistance genes. These include plasmids, transposable elements such as insertion sequences and transposons, and integrative elements including ICE and SCC elements. In concert, these diverse entities facilitate the intra- and inter-cellular gene mobility that enables horizontal genetic exchange, and have also been found to play additional roles in modulating gene expression and genome rearrangement.
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Plotkin BJ, Konakieva MI. Attenuation of antimicrobial activity by the human steroid hormones. Steroids 2017; 128:120-127. [PMID: 28951169 DOI: 10.1016/j.steroids.2017.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 08/28/2017] [Accepted: 09/20/2017] [Indexed: 11/16/2022]
Abstract
Upon entering the human host, Staphylococcus aureus is exposed to endogenous steroid hormones. The interaction between S. aureus and dehydroepiandosterone (DHEA) results in an increased resistance to the host cationic defense peptide, β-1 defensin, as well as vancomycin and other antibiotics that have a positive charge. The increased resistance to vancomycin is phenotypic and appears to correlate with a DHEA-mediated alteration in cell surface architecture. DHEA-mediated cell surface changes include alterations in: cell surface charge, surface hydrophobicity, capsule production, and carotenoid production. In addition, exposure to DHEA results in decreased resistance to lysis by Triton X-100 and lysozyme, indicating activation of murien hydrolase activity. We propose that DHEA is an interspecies quorum-like signal that triggers innate phenotypic host survival strategies in S. aureus that include increased carotenoid production and increased vancomycin resistance. Furthermore, this DHEA-mediated survival system may share the cholesterol-squalene pathway shown to be statin sensitive thus, providing a potential pathway for drug targeting.
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Affiliation(s)
- Balbina J Plotkin
- Department of Microbiology and Immunology, Midwestern University, Downers Grove, IL 60515, United States.
| | - Monika I Konakieva
- Department of Chemistry, American University, Washington, DC 20016, United States.
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Ramsay JP, Firth N. Diverse mobilization strategies facilitate transfer of non-conjugative mobile genetic elements. Curr Opin Microbiol 2017; 38:1-9. [PMID: 28391142 DOI: 10.1016/j.mib.2017.03.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/14/2017] [Indexed: 10/19/2022]
Abstract
Conjugation is a dominant mechanism of horizontal gene transfer and substantially contributes to the plasticity and evolvability of prokaryotic genomes. The impact of conjugation on genetic flux extends well beyond self-transmissible conjugative elements, because non-conjugative 'mobilizable elements' utilize other elements' conjugative apparatus for transfer. Bacterial genome comparisons highlight plasmids as vehicles for dissemination of pathogenesis and antimicrobial-resistance determinants, but for most non-conjugative plasmids, a mobilization mechanism is not apparent. Recently we discovered many Staphylococcus aureus plasmids lacking mobilization genes carry oriT sequences that mimic those on conjugative plasmids, suggesting that significantly more elements may be mobilizable than previously recognized. Here we summarize our findings, review the diverse mobilization strategies employed by mobile genetic elements and discuss implications for future gene-transfer research.
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Affiliation(s)
- Joshua P Ramsay
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia.
| | - Neville Firth
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
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Ramsay JP, Kwong SM, Murphy RJT, Yui Eto K, Price KJ, Nguyen QT, O'Brien FG, Grubb WB, Coombs GW, Firth N. An updated view of plasmid conjugation and mobilization in Staphylococcus. Mob Genet Elements 2016; 6:e1208317. [PMID: 27583185 PMCID: PMC4993578 DOI: 10.1080/2159256x.2016.1208317] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/15/2016] [Accepted: 06/23/2016] [Indexed: 11/13/2022] Open
Abstract
The horizontal gene transfer facilitated by mobile genetic elements impacts almost all areas of bacterial evolution, including the accretion and dissemination of antimicrobial-resistance genes in the human and animal pathogen Staphylococcus aureus. Genome surveys of staphylococcal plasmids have revealed an unexpected paucity of conjugation and mobilization loci, perhaps suggesting that conjugation plays only a minor role in the evolution of this genus. In this letter we present the DNA sequences of historically documented staphylococcal conjugative plasmids and highlight that at least 3 distinct and widely distributed families of conjugative plasmids currently contribute to the dissemination of antimicrobial resistance in Staphylococcus. We also review the recently documented "relaxase-in trans" mechanism of conjugative mobilization facilitated by conjugative plasmids pWBG749 and pSK41, and discuss how this may facilitate the horizontal transmission of around 90% of plasmids that were previously considered non-mobilizable. Finally, we enumerate unique sequenced S. aureus plasmids with a potential mechanism of mobilization and predict that at least 80% of all non-conjugative S. aureus plasmids are mobilizable by at least one mechanism. We suggest that a greater research focus on the molecular biology of conjugation is essential if we are to recognize gene-transfer mechanisms from our increasingly in silico analyses.
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Affiliation(s)
- Joshua P. Ramsay
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Stephen M. Kwong
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - Riley J. T. Murphy
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Karina Yui Eto
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
- School of Chemistry and Biochemistry, The University of Western Australia, Perth, WA, Australia
| | - Karina J. Price
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
| | - Quang T. Nguyen
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
| | - Frances G. O'Brien
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Warren B. Grubb
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Geoffrey W. Coombs
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
- PathWest Laboratory Medicine–WA, Fiona Stanley Hospital, Perth, WA, Australia
| | - Neville Firth
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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Kostova MB, Myers CJ, Beck TN, Plotkin BJ, Green JM, Boshoff HI, Barry CE, Deschamps JR, Konaklieva MI. C4-alkylthiols with activity against Moraxella catarrhalis and Mycobacterium tuberculosis. Bioorg Med Chem 2011; 19:6842-52. [PMID: 22014754 PMCID: PMC3701103 DOI: 10.1016/j.bmc.2011.09.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/11/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
Abstract
Antimicrobial resistance represents a global threat to healthcare. The ability to adequately treat infectious diseases is increasingly under siege due to the emergence of drug-resistant microorganisms. New approaches to drug development are especially needed to target organisms that exhibit broad antibiotic resistance due to expression of β-lactamases which is the most common mechanism by which bacteria become resistant to β-lactam antibiotics. We designed and synthesized 20 novel monocyclic β-lactams with alkyl- and aryl-thio moieties at C4, and subsequently tested these for antibacterial activity. These compounds demonstrated intrinsic activity against serine β-lactamase producing Mycobacterium tuberculosis wild type strain (Mtb) and multiple (n=6) β-lactamase producing Moraxella catarrhalis clinical isolates.
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Affiliation(s)
- Maya B. Kostova
- Department of Chemistry, American University, Washington, DC 20016, USA
| | - Carey J. Myers
- Department of Chemistry, American University, Washington, DC 20016, USA
| | - Tim N. Beck
- Department of Chemistry, American University, Washington, DC 20016, USA
| | - Balbina J. Plotkin
- Department of Microbiology and Immunology, Midwestern University, Downers Grove, IL 60515, USA
| | - Jacalyn M. Green
- Department of Biochemistry, Midwestern University, Downers Grove, IL 60515, USA
| | - Helena I.M. Boshoff
- Tuberculosis Research Section, LCID, NIAID, NIH, 33 North Drive, Bldg 33, Rm 2W20C, Bethesda, MD 20892, USA
| | - Clifton E. Barry
- Tuberculosis Research Section, LCID, NIAID, NIH, 33 North Drive, Bldg 33, Rm 2W20C, Bethesda, MD 20892, USA
| | - Jeffrey R. Deschamps
- Naval Research Laboratory, Code 6930, 4555 Overlook Ave., Washington, DC 20375, USA
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Udo EE, Grubb WB. New Staphylococcus aureus incompatibility group 1 plasmids encoding penicillinase production and resistance to different antibacterial agents. J Chemother 2001; 13:34-42. [PMID: 11233798 DOI: 10.1179/joc.2001.13.1.34] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Eleven Staphylococcus aureus plasmids encoding penicillinase production and resistance to different antibacterial agents were transferred to laboratory recipient strains in mixed-culture transfer and transduction experiments and characterized by restriction endonuclease analysis and incompatibility. The plasmids were differentiated into four types (types A-D) on the basis of their resistance phenotypes and restriction endonuclease patterns. One type encoded resistance to cadmium and arsenate. The second type encoded resistance to cadmium, mercuric compounds and nucleic acid-binding compounds. The third type encoded resistance to cadmium, kanamycin, neomycin and streptomycin while the fourth type encoded resistance to kanamycin, neomycin and ethidium bromide. Plasmids within the same class were structurally related or similar and were different from those in the other classes. Three plasmids, pWBG626, pWBG628, and pWBG663, representing three of the four plasmid types, belonged to incompatibility group 1. These new plasmids add to the number of known incompatibility group 1 plasmids and have resistance phenotypes which should be useful for studying incompatibility of new S. aureus plasmids.
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Affiliation(s)
- E E Udo
- Department of Microbiology, Faculty of Medicine, Kuwait University.
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Udo EE, Jacob LE. Conjugative transfer of high-level mupirocin resistance and the mobilization of non-conjugative plasmids in Staphylococcus aureus. Microb Drug Resist 2000; 4:185-93. [PMID: 9818970 DOI: 10.1089/mdr.1998.4.185] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A 31-kb conjugative plasmid, pXU12, encoding high-level mupirocin resistance via the mupA gene, was isolated from a multiply resistant Staphylococcus aureus isolate, MB494. pXU12 was derived by a deletion of an 8.6-kb EcoRI fragment from a approximately 40-kb plasmid in the parental isolate during curing and conjugation experiments. It transferred rapidly in conjugation experiments, with transconjugants being obtained after 15 min of mating, and mobilized a 3.0-kb erythromycin resistance plasmid, pXU13, from the parental isolate at high frequencies. The cotransfer of pXU13 by pXU12 was unaffected by varying the donor-recipient ratios in the mating mixtures or the length of incubation. pXU12 also mobilized 11 other nonconjugative plasmids belonging to different incompatibility groups and cotransferred at high frequencies. The ability of pXU12 to mobilize different nonconjugative plasmids suggested that it can be used to transfer and isolate non-conjugative plasmids from resistant S. aureus strains in the laboratory, especially from strains where phage-dependent methods of transfer are not applicable.
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Affiliation(s)
- E E Udo
- Department of Microbiology, Faculty of Medicine, Kuwait University, Safat
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