101
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Sihto HM, Stephan R, Engl C, Chen J, Johler S. Effect of food-related stress conditions and loss of agr and sigB on seb promoter activity in S. aureus. Food Microbiol 2017; 65:205-212. [PMID: 28400004 DOI: 10.1016/j.fm.2017.03.006] [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: 12/01/2016] [Revised: 02/01/2017] [Accepted: 03/06/2017] [Indexed: 10/20/2022]
Abstract
Staphylococcal enterotoxin B (SEB) causes staphylococcal food poisoning and is produced in up to ten times higher quantities than other major enterotoxins. While Staphylococcus aureus growth is often repressed by competing flora, the organism exhibits a decisive growth advantage under some stress conditions. So far, data on the influence of food-related stressors and regulatory mutations on seb expression is limited and largely based on laboratory strains, which were later reported to harbor mutations. Therefore, the aim of this study was to investigate the influence of stress and regulatory mutations on seb promoter activity. To this end, transcriptional fusions were created in two strains, USA300 and HG003, carrying different seb upstream sequences fused to a blaZ reporter. NaCl, nitrite, and glucose stress led to significantly decreased seb promoter activity, while lactic acid stress resulted in significantly increased seb promoter activity. Loss of agr decreased seb promoter activity and loss of sigB increased promoter activity, with the magnitude of change depending on the strain. These results demonstrate that mild stress conditions encountered during food production and preservation can induce significant changes in seb promoter activity.
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Affiliation(s)
- Henna-Maria Sihto
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland
| | - Christoph Engl
- Skirball Institute of Biomolecular Medicine, New York University Medical Center New York, New York, USA
| | - John Chen
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 5 Science Drive 2, Singapore, Singapore
| | - Sophia Johler
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland; Skirball Institute of Biomolecular Medicine, New York University Medical Center New York, New York, USA.
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102
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Figueiredo AMS, Ferreira FA, Beltrame CO, Côrtes MF. The role of biofilms in persistent infections and factors involved in ica-independent biofilm development and gene regulation in Staphylococcus aureus. Crit Rev Microbiol 2017; 43:602-620. [PMID: 28581360 DOI: 10.1080/1040841x.2017.1282941] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Staphylococcus aureus biofilms represent a unique micro-environment that directly contribute to the bacterial fitness within hospital settings. The accumulation of this structure on implanted medical devices has frequently caused the development of persistent and chronic S. aureus-associated infections, which represent an important social and economic burden worldwide. ica-independent biofilms are composed of an assortment of bacterial products and modulated by a multifaceted and overlapping regulatory network; therefore, biofilm composition can vary among S. aureus strains. In the microniches formed by biofilms-produced by a number of bacterial species and composed by different structural components-drug refractory cell subpopulations with distinct physiological characteristics can emerge and result in therapeutic failures in patients with recalcitrant bacterial infections. In this review, we highlight the importance of biofilms in the development of persistence and chronicity in some S. aureus diseases, the main molecules associated with ica-independent biofilm development and the regulatory mechanisms that modulate ica-independent biofilm production, accumulation, and dispersion.
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Affiliation(s)
- Agnes Marie Sá Figueiredo
- a Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes , Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil
| | - Fabienne Antunes Ferreira
- b Departamento de Microbiologia, Imunologia e Parasitologia , Campus Universitário Setor F, Bloco A. Florianópolis, Universidade Federal de Santa Catarina , Florianopolis , Brazil
| | - Cristiana Ossaille Beltrame
- a Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes , Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil
| | - Marina Farrel Côrtes
- a Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes , Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil
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103
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A Novel Repressor of the ica Locus Discovered in Clinically Isolated Super-Biofilm-Elaborating Staphylococcus aureus. mBio 2017; 8:mBio.02282-16. [PMID: 28143981 PMCID: PMC5285506 DOI: 10.1128/mbio.02282-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Staphylococcus aureus TF2758 is a clinical isolate from an atheroma and a super-biofilm-elaborating/polysaccharide intercellular adhesin (PIA)/poly-N-acetylglucosamine (PNAG)-overproducing strain (L. Shrestha et al., Microbiol Immunol 60:148–159, 2016, https://doi.org/10.1111/1348-0421.12359). A microarray analysis and DNA genome sequencing were performed to identify the mechanism underlying biofilm overproduction by TF2758. We found high transcriptional expression levels of a 7-gene cluster (satf2580 to satf2586) and the ica operon in TF2758. Within the 7-gene cluster, a putative transcriptional regulator gene designated rob had a nonsense mutation that caused the truncation of the protein. The complementation of TF2758 with rob from FK300, an rsbU-repaired derivative of S. aureus strain NCTC8325-4, significantly decreased biofilm elaboration, suggesting a role for rob in this process. The deletion of rob in non-biofilm-producing FK300 significantly increased biofilm elaboration and PIA/PNAG production. In the search for a gene(s) in the 7-gene cluster for biofilm elaboration controlled by rob, we identified open reading frame (ORF) SAOUHSC_2898 (satf2584). Our results suggest that ORF SAOUHSC_2898 (satf2584) and icaADBC are required for enhanced biofilm elaboration and PIA/PNAG production in the rob deletion mutant. Rob bound to a palindromic sequence within its own promoter region. Furthermore, Rob recognized the TATTT motif within the icaR-icaA intergenic region and bound to a 25-bp DNA stretch containing this motif, which is a critically important short sequence regulating biofilm elaboration in S. aureus. Our results strongly suggest that Rob is a long-sought repressor that recognizes and binds to the TATTT motif and is an important regulator of biofilm elaboration through its control of SAOUHSC_2898 (SATF2584) and Ica protein expression in S. aureus. During the search for molecular mechanisms underlying biofilm overproduction of Staphylococcus aureus TF2758, we found a putative transcriptional regulator gene designated rob within a 7-gene cluster showing a high transcriptional expression level by microarray analysis. The deletion of rob in non-biofilm-producing FK300, an rsbU-repaired derivative of NCTC8325-4, significantly increased biofilm elaboration and PIA/PNAG production. The search for a gene(s) in the 7-gene cluster for biofilm elaboration controlled by rob identified ORF SAOUHSC_2898. Besides binding to its own promoter region to control ORF SAOUHSC_2898 expression, Rob recognized the TATTT motif within the icaR-icaA intergenic region and bound to a 25-bp DNA stretch containing this motif, which is a critically important short sequence regulating biofilm elaboration in S. aureus. Our results strongly suggest that Rob is a long-sought repressor that recognizes and binds to the TATTT motif and is a new important regulator of biofilm elaboration through its control of SAOUHSC_2898 and Ica protein expression in S. aureus.
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104
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Aldape MJ, Tao A, Heeney DD, McIndoo ER, French JM, Xu D. Experimental identification and computational characterization of a novel extracellular metalloproteinase produced by Clostridium sordellii. RSC Adv 2017; 7:13928-13938. [PMID: 28515901 PMCID: PMC5358524 DOI: 10.1039/c6ra27654g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 02/22/2017] [Indexed: 11/21/2022] Open
Abstract
The open (white, green) vs. closed (purple, cyan) structures of Clostridium sordellii metalloproteinase.
Clostridium sordellii is a lethal pathogen for both animals and humans. Severe capillary leakage, toxic shock syndrome, and an extreme leukemoid reaction (LR), are hallmark features of C. sordellii infections and contribute to its high mortality rate. Here we report the discovery of a previously unknown and uncharacterized metalloproteinase of C. sordellii (referred as Mcs1) that cleaves human vascular cell adhesion molecule (VCAM)-1 in vitro, an adhesion molecule critical to hematopoietic precursor retention and leukocyte diapedesis. We successfully identified the open reading frame encoding Mcs1 within the ATCC 9714 genome and developed an Δmcs1 mutant strain using the ClosTron mutagenesis technology. No VCAM-1 proteolysis was observed from exotoxins collected from mutant strain cultures. Using advanced protein structural modeling and molecular dynamics simulation techniques, the 3D molecular structure and conformational features of Mcs1 were also characterized. Our data demonstrates that Mcs1 proteolytic activity is controlled by the electrostatic interactions between Glu113 and Arg227 residues and the gating motions within its cleft region. This pilot interdisciplinary investigation provided crucial experimental evidence of the existence of Mcs1 in C. sordellii and molecular insights into its 3D structure and proteolytic activity. These findings have the potential to help advance new therapeutics and diagnostics against deadly C. sordellii infections. Follow-up in vitro and in vivo work is under way to further characterize Mcs1 enzymatic kinetics and its role in C. sordellii pathogenesis.
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Affiliation(s)
- Michael J Aldape
- Veterans Affairs Medical Center, Research and Development, Infectious Diseases Section, 500 West Fort St. (Bldg 117), Boise, ID 83702, USA. ; ; Tel: +1-208-422-1000 ext. 7659.,Northwest Nazarene University, Nampa, ID 83686, USA
| | - Aoxiang Tao
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, Idaho State University, Meridian, ID 83642, USA. ; ; Tel: +1-208-373-1832
| | - Dustin D Heeney
- Veterans Affairs Medical Center, Research and Development, Infectious Diseases Section, 500 West Fort St. (Bldg 117), Boise, ID 83702, USA. ; ; Tel: +1-208-422-1000 ext. 7659
| | - Eric R McIndoo
- Veterans Affairs Medical Center, Research and Development, Infectious Diseases Section, 500 West Fort St. (Bldg 117), Boise, ID 83702, USA. ; ; Tel: +1-208-422-1000 ext. 7659
| | - John M French
- Veterans Affairs Medical Center, Research and Development, Infectious Diseases Section, 500 West Fort St. (Bldg 117), Boise, ID 83702, USA. ; ; Tel: +1-208-422-1000 ext. 7659
| | - Dong Xu
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, Idaho State University, Meridian, ID 83642, USA. ; ; Tel: +1-208-373-1832
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105
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Gerits E, Kucharíková S, Van Dijck P, Erdtmann M, Krona A, Lövenklev M, Fröhlich M, Dovgan B, Impellizzeri F, Braem A, Vleugels J, Robijns SCA, Steenackers HP, Vanderleyden J, De Brucker K, Thevissen K, Cammue BPA, Fauvart M, Verstraeten N, Michiels J. Antibacterial activity of a new broad-spectrum antibiotic covalently bound to titanium surfaces. J Orthop Res 2016; 34:2191-2198. [PMID: 27003909 DOI: 10.1002/jor.23238] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/17/2016] [Indexed: 02/04/2023]
Abstract
Biofilm-associated infections, particularly those caused by Staphylococcus aureus, are a major cause of implant failure. Covalent coupling of broad-spectrum antimicrobials to implants is a promising approach to reduce the risk of infections. In this study, we developed titanium substrates on which the recently discovered antibacterial agent SPI031, a N-alkylated 3, 6-dihalogenocarbazol 1-(sec-butylamino)-3-(3,6-dichloro-9H-carbazol-9-yl)propan-2-ol, was covalently linked (SPI031-Ti). We found that SPI031-Ti substrates prevent biofilm formation of S. aureus and Pseudomonas aeruginosa in vitro, as quantified by plate counting and fluorescence microscopy. To test the effectiveness of SPI031-Ti substrates in vivo, we used an adapted in vivo biomaterial-associated infection model in mice in which SPI031-Ti substrates were implanted subcutaneously and subsequently inoculated with S. aureus. Using this model, we found a significant reduction in biofilm formation (up to 98%) on SPI031-Ti substrates compared to control substrates. Finally, we demonstrated that the functionalization of the titanium surfaces with SPI031 did not influence the adhesion and proliferation of human cells important for osseointegration and bone repair. In conclusion, these data demonstrate the clinical potential of SPI031 to be used as an antibacterial coating for implants, thereby reducing the incidence of implant-associated infections. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2191-2198, 2016.
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Affiliation(s)
- Evelien Gerits
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium
| | - Soňa Kucharíková
- Department of Molecular Microbiology, VIB, KU Leuven, Kasteelpark Arenberg 31 box 2438, 3001 Leuven, Belgium.,Laboratory of Molecular Cell Biology, KU Leuven, Kasteelpark Arenberg 31 box 2438, 3001 Leuven, Belgium
| | - Patrick Van Dijck
- Department of Molecular Microbiology, VIB, KU Leuven, Kasteelpark Arenberg 31 box 2438, 3001 Leuven, Belgium.,Laboratory of Molecular Cell Biology, KU Leuven, Kasteelpark Arenberg 31 box 2438, 3001 Leuven, Belgium
| | | | - Annika Krona
- Department of Structure and Material Design, SP Food and Bioscience, Box 5401, 402 29 Gothenburg, Sweden
| | - Maria Lövenklev
- Department of Structure and Material Design, SP Food and Bioscience, Box 5401, 402 29 Gothenburg, Sweden
| | - Mirjam Fröhlich
- Educell Ltd, Prevale 9, 1236 Trzin, Slovenia.,Faculty of Medicine, Institute of Cell Biology, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | | | | | - Annabel Braem
- Department of Materials Engineering (MTM), KU Leuven, Kasteelpark Arenberg 44 box 2450, 3001 Leuven, Belgium
| | - Jef Vleugels
- Department of Materials Engineering (MTM), KU Leuven, Kasteelpark Arenberg 44 box 2450, 3001 Leuven, Belgium
| | - Stijn C A Robijns
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium
| | - Hans P Steenackers
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium
| | - Jozef Vanderleyden
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium
| | - Katrijn De Brucker
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium
| | - Karin Thevissen
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium
| | - Bruno P A Cammue
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium.,Department of Plant Systems Biology, VIB, Technologiepark 927, 9052 Ghent, Belgium
| | - Maarten Fauvart
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium.,Department of Life Science Technologies, imec, Smart Systems and Emerging Technologies Unit, Kapeldreef 75, 3001 Leuven, Belgium
| | - Natalie Verstraeten
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium
| | - Jan Michiels
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20 box 2460, 3001 Leuven, Belgium
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106
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Versatility of Biofilm Matrix Molecules in Staphylococcus epidermidis Clinical Isolates and Importance of Polysaccharide Intercellular Adhesin Expression during High Shear Stress. mSphere 2016; 1:mSphere00165-16. [PMID: 27747298 PMCID: PMC5064449 DOI: 10.1128/msphere.00165-16] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/20/2016] [Indexed: 01/13/2023] Open
Abstract
Staphylococcus epidermidis is a leading cause of infections related to biomaterials, mostly due to their ability to form biofilm. Biofilm accumulation mechanisms vary, including those that are dependent on specific proteins, environmental DNA (eDNA), or polysaccharide intercellular adhesin (PIA). We found that those isolates obtained from high-shear environments, such as the lumen of a catheter, are more likely to produce PIA-mediated biofilms than those isolates obtained from a low-shear biomaterial-related infection. This suggests that PIA functions as a mechanism that is protective against shear flow. Finally, we performed selection experiments documenting the heterogeneity of biofilm accumulation molecules that function in the absence of PIA, further documenting the biofilm-forming potential of S. epidermidis. Staphylococcus epidermidis is a leading cause of hospital-associated infections, including those of intravascular catheters, cerebrospinal fluid shunts, and orthopedic implants. Multiple biofilm matrix molecules with heterogeneous characteristics have been identified, including proteinaceous, polysaccharide, and nucleic acid factors. Two of the best-studied components in S. epidermidis include accumulation-associated protein (Aap) and polysaccharide intercellular adhesin (PIA), produced by the enzymatic products of the icaADBC operon. Biofilm composition varies by strain as well as environmental conditions, and strains producing PIA-mediated biofilms are more robust. Clinically, biofilm-mediated infections occur in a variety of anatomical sites with diverse physiological properties. To test the hypothesis that matrix composition exhibits niche specificity, biofilm-related genetic and physical properties were compared between S. epidermidis strains isolated from high-shear and low-shear environments. Among a collection of 105 clinical strains, significantly more isolates from high-shear environments carried the icaADBC operon than did those from low-shear settings (43.9% versus 22.9%, P < 0.05), while there was no significant difference in the presence of aap (77.2% versus 75.0%, P > 0.05). Additionally, a significantly greater number of high-shear isolates were capable of forming biofilm in vitro in a microtiter assay (82.5% versus 45.8%, P < 0.0001). However, even among high-shear clinical isolates, less than half contained the icaADBC locus; therefore, we selected for ica-negative variants with increased attachment to abiotic surfaces to examine PIA-independent biofilm mechanisms. Sequencing of selected variants identified substitutions capable of enhancing biofilm formation in multiple genes, further highlighting the heterogeneity of S. epidermidis biofilm molecules and mechanisms. IMPORTANCEStaphylococcus epidermidis is a leading cause of infections related to biomaterials, mostly due to their ability to form biofilm. Biofilm accumulation mechanisms vary, including those that are dependent on specific proteins, environmental DNA (eDNA), or polysaccharide intercellular adhesin (PIA). We found that those isolates obtained from high-shear environments, such as the lumen of a catheter, are more likely to produce PIA-mediated biofilms than those isolates obtained from a low-shear biomaterial-related infection. This suggests that PIA functions as a mechanism that is protective against shear flow. Finally, we performed selection experiments documenting the heterogeneity of biofilm accumulation molecules that function in the absence of PIA, further documenting the biofilm-forming potential of S. epidermidis.
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107
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Macroscopic amyloid fiber formation by staphylococcal biofilm associated SuhB protein. Biophys Chem 2016; 217:32-41. [DOI: 10.1016/j.bpc.2016.07.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 07/04/2016] [Accepted: 07/27/2016] [Indexed: 11/22/2022]
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108
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Gándara L, Mamone L, Dotto C, Buzzola F, Casas A. Sae regulator factor impairs the response to photodynamic inactivation mediated by Toluidine blue in Staphylococcus aureus. Photodiagnosis Photodyn Ther 2016; 16:136-141. [PMID: 27619533 DOI: 10.1016/j.pdpdt.2016.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 09/06/2016] [Accepted: 09/08/2016] [Indexed: 10/21/2022]
Abstract
Photodynamic inactivation (PDI) involves the combined use of light and a photosensitizer, which, in the presence of oxygen, originates cytotoxic species capable of inactivating bacteria. Since the emergence of multi-resistant bacterial strains is becoming an increasing public health concern, PDI becomes an attractive choice. The aim of this work was to study the differential susceptibility to Toluidine blue (TB) mediated PDI (TB-PDI) of S. aureus mutants (RN6390 and Newman backgrounds) for different key regulators of virulence factors related to some extent to oxidative stress. Complete bacteria eradication of planktonic cultures of RN6390 S. aureus photosensitized with 13μM TB was obtained upon illumination with a low light dose of 4.2J/cm2 from a non-coherent light source. Similarly, complete cell death was achieved applying 1.3μM TB and 19J/cm2 light dose, showing that higher light doses can lead to equal cell death employing low photosensitizer concentrations. Interestingly, RN6390 in planktonic culture responded significantly better to TB-PDI than the Newman strain. We showed that deficiencies in rsbU, mgrA (transcription factors related to stress response) or agr (quorum sensing system involved in copper resistance to oxidative stress) did not modify the response of planktonic S. aureus to PDI. On the other hand, the two component system sae impaired the response to TB-PDI through a mechanism not related to the Eap adhesin. More severe conditions were needed to inactivate S. aureus biofilms (0.5mM TB, 157J/cm2 laser light). In mutant sae biofilms, strain dependant differential susceptibilities are not noticed.
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Affiliation(s)
- Lautaro Gándara
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET and Hospital de Clínicas José de San Martín, University of Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires, CP1120AAF, Argentina
| | - Leandro Mamone
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET and Hospital de Clínicas José de San Martín, University of Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires, CP1120AAF, Argentina
| | - Cristian Dotto
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM), CONICET-UBA, Argentina
| | - Fernanda Buzzola
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM), CONICET-UBA, Argentina
| | - Adriana Casas
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET and Hospital de Clínicas José de San Martín, University of Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires, CP1120AAF, Argentina.
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109
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Mashruwala AA, Bhatt S, Poudel S, Boyd ES, Boyd JM. The DUF59 Containing Protein SufT Is Involved in the Maturation of Iron-Sulfur (FeS) Proteins during Conditions of High FeS Cofactor Demand in Staphylococcus aureus. PLoS Genet 2016; 12:e1006233. [PMID: 27517714 PMCID: PMC4982691 DOI: 10.1371/journal.pgen.1006233] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 07/10/2016] [Indexed: 01/01/2023] Open
Abstract
Proteins containing DUF59 domains have roles in iron-sulfur (FeS) cluster assembly and are widespread throughout Eukarya, Bacteria, and Archaea. However, the function(s) of this domain is unknown. Staphylococcus aureus SufT is composed solely of a DUF59 domain. We noted that sufT is often co-localized with sufBC, which encode for the Suf FeS cluster biosynthetic machinery. Phylogenetic analyses indicated that sufT was recruited to the suf operon, suggesting a role for SufT in FeS cluster assembly. A S. aureus ΔsufT mutant was defective in the assembly of FeS proteins. The DUF59 protein Rv1466 from Mycobacterium tuberculosis partially corrected the phenotypes of a ΔsufT mutant, consistent with a widespread role for DUF59 in FeS protein maturation. SufT was dispensable for FeS protein maturation during conditions that imposed a low cellular demand for FeS cluster assembly. In contrast, the role of SufT was maximal during conditions imposing a high demand for FeS cluster assembly. SufT was not involved in the repair of FeS clusters damaged by reactive oxygen species or in the physical protection of FeS clusters from oxidants. Nfu is a FeS cluster carrier and nfu displayed synergy with sufT. Furthermore, introduction of nfu upon a multicopy plasmid partially corrected the phenotypes of the ΔsufT mutant. Biofilm formation and exoprotein production are critical for S. aureus pathogenesis and vancomycin is a drug of last-resort to treat staphylococcal infections. Defective FeS protein maturation resulted in increased biofilm formation, decreased production of exoproteins, increased resistance to vancomycin, and the appearance of phenotypes consistent with vancomycin-intermediate resistant S. aureus. We propose that SufT, and by extension the DUF59 domain, is an accessory factor that functions in the maturation of FeS proteins. In S. aureus, the involvement of SufT is maximal during conditions of high demand for FeS proteins.
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Affiliation(s)
- Ameya A. Mashruwala
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Shiven Bhatt
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Saroj Poudel
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, United States of America
| | - Eric S. Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, United States of America
- NASA Astrobiology Institute, Mountain View, California, United States of America
| | - Jeffrey M. Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, United States of America
- * E-mail:
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110
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Resilience in the Face of Uncertainty: Sigma Factor B Fine-Tunes Gene Expression To Support Homeostasis in Gram-Positive Bacteria. Appl Environ Microbiol 2016; 82:4456-4469. [PMID: 27208112 DOI: 10.1128/aem.00714-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Gram-positive bacteria are ubiquitous and diverse microorganisms that can survive and sometimes even thrive in continuously changing environments. The key to such resilience is the ability of members of a population to respond and adjust to dynamic conditions in the environment. In bacteria, such responses and adjustments are mediated, at least in part, through appropriate changes in the bacterial transcriptome in response to the conditions encountered. Resilience is important for bacterial survival in diverse, complex, and rapidly changing environments and requires coordinated networks that integrate individual, mechanistic responses to environmental cues to enable overall metabolic homeostasis. In many Gram-positive bacteria, a key transcriptional regulator of the response to changing environmental conditions is the alternative sigma factor σ(B) σ(B) has been characterized in a subset of Gram-positive bacteria, including the genera Bacillus, Listeria, and Staphylococcus Recent insight from next-generation-sequencing results indicates that σ(B)-dependent regulation of gene expression contributes to resilience, i.e., the coordination of complex networks responsive to environmental changes. This review explores contributions of σ(B) to resilience in Bacillus, Listeria, and Staphylococcus and illustrates recently described regulatory functions of σ(B).
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111
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Chaudhari SS, Thomas VC, Sadykov MR, Bose JL, Ahn DJ, Zimmerman MC, Bayles KW. The LysR-type transcriptional regulator, CidR, regulates stationary phase cell death in Staphylococcus aureus. Mol Microbiol 2016; 101:942-53. [PMID: 27253847 DOI: 10.1111/mmi.13433] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2016] [Indexed: 11/29/2022]
Abstract
The Staphylococcus aureus LysR-type transcriptional regulator, CidR, activates the expression of two operons including cidABC and alsSD that display pro- and anti-death functions, respectively. Although several investigations have focused on the functions of different genes associated with these operons, the collective role of the CidR regulon in staphylococcal physiology is not clearly understood. Here we reveal that the primary role of this regulon is to limit acetate-dependent potentiation of cell death in staphylococcal populations. Although both CidB and CidC promote acetate generation and cell death, the CidR-dependent co-activation of CidA and AlsSD counters the effects of CidBC by redirecting intracellular carbon flux towards acetoin formation. From a mechanistic standpoint, we demonstrate that CidB is necessary for full activation of CidC, whereas CidA limits the abundance of CidC in the cell.
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Affiliation(s)
- Sujata S Chaudhari
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA
| | - Vinai C Thomas
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA
| | - Marat R Sadykov
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA
| | - Jeffrey L Bose
- Department of Microbiology, Molecular Genetics and Immunology, The University of Kansas Medical Center, MSN 3029, 3901 Rainbow Boulevard, Kansas City, KS, 66160, USA
| | - Daniel J Ahn
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA
| | - Matthew C Zimmerman
- Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Kenneth W Bayles
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA.
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Effect of sodium nitrite and regulatory mutations Δagr, ΔsarA, and ΔsigB on the mRNA and protein levels of staphylococcal enterotoxin D. Food Control 2016. [DOI: 10.1016/j.foodcont.2016.01.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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113
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Beltrame CO, Côrtes MF, Bandeira PT, Figueiredo AMS. Optimization of the RNeasy Mini Kit to obtain high-quality total RNA from sessile cells of Staphylococcus aureus. ACTA ACUST UNITED AC 2016; 48:1071-6. [PMID: 26517334 PMCID: PMC4661022 DOI: 10.1590/1414-431x20154734] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 07/23/2015] [Indexed: 12/20/2022]
Abstract
Biofilm formed by Staphylococcus aureus is considered an important
virulence trait in the pathogenesis of infections associated with implantable medical
devices. Gene expression analyses are important strategies for determining the
mechanisms involved in production and regulation of biofilm. Obtaining intact RNA
preparations is the first and most critical step for these studies. In this article,
we describe an optimized protocol for obtaining total RNA from sessile cells of
S. aureus using the RNeasy Mini Kit. This method essentially
consists of a few steps, as follows: 1) addition of acetone-ethanol to sessile cells,
2) lysis with lysostaphin at 37°C/10 min, 3) vigorous mixing, 4) three cycles of
freezing and thawing, and 5) purification of the lysate in the RNeasy column. This
simple pre-kit procedure yields high-quality total RNA from planktonic and sessile
cells of S. aureus.
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Affiliation(s)
- C O Beltrame
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - M F Côrtes
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - P T Bandeira
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - A M S Figueiredo
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
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114
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Kavanaugh JS, Horswill AR. Impact of Environmental Cues on Staphylococcal Quorum Sensing and Biofilm Development. J Biol Chem 2016; 291:12556-12564. [PMID: 27129223 DOI: 10.1074/jbc.r116.722710] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Staphylococci are commensal bacteria that colonize the epithelial surfaces of humans and many other mammals. These bacteria can also attach to implanted medical devices and develop surface-associated biofilm communities that resist clearance by host defenses and available chemotherapies. These communities are often associated with persistent staphylococcal infections that place a tremendous burden on the healthcare system. Understanding the regulatory program that controls staphylococcal biofilm development, as well as the environmental conditions that modulate this program, has been a focal point of research in recent years. A central regulator controlling biofilm development is a peptide quorum-sensing system, also called the accessory gene regulator or agr system. In the opportunistic pathogen Staphylococcus aureus, the agr system controls production of exo-toxins and exo-enzymes essential for causing infections, and simultaneously, it modulates the ability of this pathogen to attach to surfaces and develop a biofilm, or to disperse from the biofilm state. In this review, we explore advances on the interconnections between the agr quorum-sensing system and biofilm mechanisms, and topics covered include recent findings on how different environmental conditions influence quorum sensing, the impact on biofilm development, and ongoing questions and challenges in the field. As our understanding of the quorum sensing and biofilm interconnection advances, there are growing opportunities to take advantage of this knowledge and develop therapeutic approaches to control staphylococcal infections.
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Affiliation(s)
- Jeffrey S Kavanaugh
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - Alexander R Horswill
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242.
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115
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Abstract
Microbes produce a biofilm matrix consisting of proteins, extracellular DNA, and polysaccharides that is integral in the formation of bacterial communities. Historical studies of polysaccharides revealed that their overproduction often alters the colony morphology and can be diagnostic in identifying certain species. The polysaccharide component of the matrix can provide many diverse benefits to the cells in the biofilm, including adhesion, protection, and structure. Aggregative polysaccharides act as molecular glue, allowing the bacterial cells to adhere to each other as well as surfaces. Adhesion facilitates the colonization of both biotic and abiotic surfaces by allowing the bacteria to resist physical stresses imposed by fluid movement that could separate the cells from a nutrient source. Polysaccharides can also provide protection from a wide range of stresses, such as desiccation, immune effectors, and predators such as phagocytic cells and amoebae. Finally, polysaccharides can provide structure to biofilms, allowing stratification of the bacterial community and establishing gradients of nutrients and waste products. This can be advantageous for the bacteria by establishing a heterogeneous population that is prepared to endure stresses created by the rapidly changing environments that many bacteria encounter. The diverse range of polysaccharide structures, properties, and roles highlight the importance of this matrix constituent to the successful adaptation of bacteria to nearly every niche. Here, we present an overview of the current knowledge regarding the diversity and benefits that polysaccharide production provides to bacterial communities within biofilms.
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116
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Tranchemontagne ZR, Camire RB, O'Donnell VJ, Baugh J, Burkholder KM. Staphylococcus aureus Strain USA300 Perturbs Acquisition of Lysosomal Enzymes and Requires Phagosomal Acidification for Survival inside Macrophages. Infect Immun 2016; 84:241-53. [PMID: 26502911 PMCID: PMC4694005 DOI: 10.1128/iai.00704-15] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 10/22/2015] [Indexed: 02/08/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) causes invasive, drug-resistant skin and soft tissue infections. Reports that S. aureus bacteria survive inside macrophages suggest that the intramacrophage environment may be a niche for persistent infection; however, mechanisms by which the bacteria might evade macrophage phagosomal defenses are unclear. We examined the fate of the S. aureus-containing phagosome in THP-1 macrophages by evaluating bacterial intracellular survival and phagosomal acidification and maturation and by testing the impact of phagosomal conditions on bacterial viability. Multiple strains of S. aureus survived inside macrophages, and in studies using the MRSA USA300 clone, the USA300-containing phagosome acidified rapidly and acquired the late endosome and lysosome protein LAMP1. However, fewer phagosomes containing live USA300 bacteria than those containing dead bacteria associated with the lysosomal hydrolases cathepsin D and β-glucuronidase. Inhibiting lysosomal hydrolase activity had no impact on intracellular survival of USA300 or other S. aureus strains, suggesting that S. aureus perturbs acquisition of lysosomal enzymes. We examined the impact of acidification on S. aureus intramacrophage viability and found that inhibitors of phagosomal acidification significantly impaired USA300 intracellular survival. Inhibition of macrophage phagosomal acidification resulted in a 30-fold reduction in USA300 expression of the staphylococcal virulence regulator agr but had little effect on expression of sarA, saeR, or sigB. Bacterial exposure to acidic pH in vitro increased agr expression. Together, these results suggest that S. aureus survives inside macrophages by perturbing normal phagolysosome formation and that USA300 may sense phagosomal conditions and upregulate expression of a key virulence regulator that enables its intracellular survival.
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Affiliation(s)
| | - Ryan B Camire
- Department of Nursing, University of New England, Biddeford, Maine, USA
| | | | - Jessfor Baugh
- Department of Biology, University of New England, Biddeford, Maine, USA
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117
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Le KY, Otto M. Quorum-sensing regulation in staphylococci-an overview. Front Microbiol 2015; 6:1174. [PMID: 26579084 PMCID: PMC4621875 DOI: 10.3389/fmicb.2015.01174] [Citation(s) in RCA: 294] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/12/2015] [Indexed: 11/13/2022] Open
Abstract
Staphylococci are frequent human commensals and some species can cause disease. Staphylococcus aureus in particular is a dangerous human pathogen. In staphylococci, the ability to sense the bacterial cell density, or quorum, and to respond with genetic adaptations is due to one main system, which is called accessory gene regulator (Agr). The extracellular signal of Agr is a post-translationally modified peptide containing a thiolactone structure. Under conditions of high cell density, Agr is responsible for the increased expression of many toxins and degradative exoenzymes, and decreased expression of several colonization factors. This regulation is important for the timing of virulence factor expression during infection and the development of acute disease, while low activity of Agr is associated with chronic staphylococcal infections, such as those involving biofilm formation. Accordingly, drugs inhibiting Agr are being evaluated for their capacity to control acute forms of S. aureus infection.
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Affiliation(s)
- Katherine Y Le
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health Bethesda, MD, USA ; Division of Hospital Internal Medicine, Department of Medicine, Mayo Clinic College of Medicine Rochester, MN, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health Bethesda, MD, USA
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118
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Wolska KI, Grudniak AM, Rudnicka Z, Markowska K. Genetic control of bacterial biofilms. J Appl Genet 2015; 57:225-38. [PMID: 26294280 PMCID: PMC4830867 DOI: 10.1007/s13353-015-0309-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 07/20/2015] [Accepted: 08/07/2015] [Indexed: 12/22/2022]
Abstract
Nearly all bacterial species, including pathogens, have the ability to form biofilms. Biofilms are defined as structured ecosystems in which microbes are attached to surfaces and embedded in a matrix composed of polysaccharides, eDNA, and proteins, and their development is a multistep process. Bacterial biofilms constitute a large medical problem due to their extremely high resistance to various types of therapeutics, including conventional antibiotics. Several environmental and genetic signals control every step of biofilm development and dispersal. From among the latter, quorum sensing, cyclic diguanosine-5'-monophosphate, and small RNAs are considered as the main regulators. The present review describes the control role of these three regulators in the life cycles of biofilms built by Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella enterica serovar Typhimurium, and Vibrio cholerae. The interconnections between their activities are shown. Compounds and strategies which target the activity of these regulators, mainly quorum sensing inhibitors, and their potential role in therapy are also assessed.
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Affiliation(s)
- Krystyna I Wolska
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Anna M Grudniak
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Zofia Rudnicka
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Katarzyna Markowska
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland.
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119
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Moche M, Schlüter R, Bernhardt J, Plate K, Riedel K, Hecker M, Becher D. Time-Resolved Analysis of Cytosolic and Surface-Associated Proteins of Staphylococcus aureus HG001 under Planktonic and Biofilm Conditions. J Proteome Res 2015; 14:3804-22. [DOI: 10.1021/acs.jproteome.5b00148] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Martin Moche
- Institute for Microbiology, Ernst-Moritz-Arndt-University, Friedrich-Ludwig-Jahn-Straße
15, 17487 Greifswald, Germany
| | - Rabea Schlüter
- Institute for Microbiology, Ernst-Moritz-Arndt-University, Friedrich-Ludwig-Jahn-Straße
15, 17487 Greifswald, Germany
| | - Jörg Bernhardt
- Institute for Microbiology, Ernst-Moritz-Arndt-University, Friedrich-Ludwig-Jahn-Straße
15, 17487 Greifswald, Germany
| | - Kristina Plate
- Institute for Microbiology, Ernst-Moritz-Arndt-University, Friedrich-Ludwig-Jahn-Straße
15, 17487 Greifswald, Germany
| | - Katharina Riedel
- Institute for Microbiology, Ernst-Moritz-Arndt-University, Friedrich-Ludwig-Jahn-Straße
15, 17487 Greifswald, Germany
| | - Michael Hecker
- Institute for Microbiology, Ernst-Moritz-Arndt-University, Friedrich-Ludwig-Jahn-Straße
15, 17487 Greifswald, Germany
| | - Dörte Becher
- Institute for Microbiology, Ernst-Moritz-Arndt-University, Friedrich-Ludwig-Jahn-Straße
15, 17487 Greifswald, Germany
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120
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High Glucose Concentration Promotes Vancomycin-Enhanced Biofilm Formation of Vancomycin-Non-Susceptible Staphylococcus aureus in Diabetic Mice. PLoS One 2015; 10:e0134852. [PMID: 26244880 PMCID: PMC4526670 DOI: 10.1371/journal.pone.0134852] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 07/14/2015] [Indexed: 12/14/2022] Open
Abstract
We previously demonstrated that vancomycin treatment increased acquisition of eDNA and enhanced biofilm formation of drug-resistant Staphylococcus aureus through a cidA-mediated autolysis mechanism. Recently we found that such enhancement became more significant under a higher glucose concentration in vitro. We propose that besides improper antibiotic treatment, increased glucose concentration environment in diabetic animals may further enhance biofilm formation of drug-resistant S. aureus. To address this question, the diabetic mouse model infected by vancomycin-resistant S. aureus (VRSA) was used under vancomycin treatment. The capacity to form biofilms was evaluated through a catheter-associated biofilm assay. A 10- and 1000-fold increase in biofilm-bound bacterial colony forming units was observed in samples from diabetic mice without and with vancomycin treatment, respectively, compared to healthy mice. By contrast, in the absence of glucose vancomycin reduced propensity to form biofilms in vitro through the increased production of proteases and DNases from VRSA. Our study highlights the potentially important role of increased glucose concentration in enhancing biofilm formation in vancomycin-treated diabetic mice infected by drug-resistant S. aureus.
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121
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Lister JL, Horswill AR. Staphylococcus aureus biofilms: recent developments in biofilm dispersal. Front Cell Infect Microbiol 2015. [PMID: 25566513 DOI: 10.3389/fcimb201400178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and represents a significant burden on the healthcare system. S. aureus attachment to medical implants and host tissue, and the establishment of a mature biofilm, play an important role in the persistence of chronic infections. The formation of a biofilm, and encasement of cells in a polymer-based matrix, decreases the susceptibility to antimicrobials and immune defenses, making these infections difficult to eradicate. During infection, dispersal of cells from the biofilm can result in spread to secondary sites and worsening of the infection. In this review, we discuss the current understanding of the pathways behind biofilm dispersal in S. aureus, with a focus on enzymatic and newly described broad-spectrum dispersal mechanisms. Additionally, we explore potential applications of dispersal in the treatment of biofilm-mediated infections.
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Affiliation(s)
- Jessica L Lister
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Alexander R Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
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122
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Hammer ND, Cassat JE, Noto MJ, Lojek LJ, Chadha AD, Schmitz JE, Creech CB, Skaar EP. Inter- and intraspecies metabolite exchange promotes virulence of antibiotic-resistant Staphylococcus aureus. Cell Host Microbe 2015; 16:531-7. [PMID: 25299336 DOI: 10.1016/j.chom.2014.09.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 08/04/2014] [Accepted: 08/26/2014] [Indexed: 02/08/2023]
Abstract
Adaptations that enable antimicrobial resistance often pose a fitness cost to the microorganism. Resistant pathogens must therefore overcome such fitness decreases to persist within their hosts. Here we demonstrate that the reduced fitness associated with one resistance-conferring mutation can be offset by community interactions with microorganisms harboring alternative mutations or via interactions with the human microbiota. Mutations that confer antibiotic resistance in the human pathogen Staphylococcus aureus led to decreased fitness, whereas coculture or coinfection of two distinct mutants resulted in collective recovery of fitness comparable to that of wild-type. Such fitness enhancements result from the exchange of metabolites between distinct mutants, leading to enhanced growth, virulence factor production, and pathogenicity. Interspecies fitness enhancements were also identified, as members of the human microbiota can promote growth of antibiotic-resistant S. aureus. Thus, inter- and intraspecies community interactions offset fitness costs and enable S. aureus to develop antibiotic resistance without loss of virulence.
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Affiliation(s)
- Neal D Hammer
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, 1161 21(st) Avenue South, Nashville, TN 37232, USA
| | - James E Cassat
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, 1161 21(st) Avenue South, Nashville, TN 37232, USA; Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University School of Medicine, 1161 21(st) Avenue South, Nashville, TN 37232, USA
| | - Michael J Noto
- Department of Medicine, Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University School of Medicine, 1161 21(st) Avenue South Nashville, TN 37232, USA
| | - Lisa J Lojek
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, 1161 21(st) Avenue South, Nashville, TN 37232, USA
| | - Ashley D Chadha
- Department of Pediatrics, Division of Allergy, Immunology, and Pulmonary Medicine, Vanderbilt University School of Medicine, 1161 21(st) Avenue South, Nashville, TN 37232, USA
| | - Jonathan E Schmitz
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, 1161 21(st) Avenue South, Nashville, TN 37232, USA
| | - C Buddy Creech
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University School of Medicine, 1161 21(st) Avenue South, Nashville, TN 37232, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, 1161 21(st) Avenue South, Nashville, TN 37232, USA.
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123
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Atshan SS, Shamsudin MN, Sekawi Z, Thian Lung LT, Barantalab F, Liew YK, Alreshidi MA, Abduljaleel SA, Hamat RA. Comparative proteomic analysis of extracellular proteins expressed by various clonal types of Staphylococcus aureus and during planktonic growth and biofilm development. Front Microbiol 2015; 6:524. [PMID: 26089817 PMCID: PMC4454047 DOI: 10.3389/fmicb.2015.00524] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 05/12/2015] [Indexed: 12/02/2022] Open
Abstract
Staphylococcus aureus is well known for its biofilm formation with rapid emergence of new clones circulating worldwide. The main objectives of the study were (1) to identify possible differences in protein expression among various and closely related clonal types of S. aureus, (2) to establish the differences in protein expression in terms of size of protein spots and its intensities between bacteria which are grown statically (biofilm formation) with that of under aeration and agitation, and (3) to compare the differences in protein expression as a function of time (in hours). In this study, we selected six clinical isolates comprising two similar (MRSA-527 and MRSA-524) and four different (MRSA-139, MSSA-12E, MSSA-22d, and MSSA-10E) types identified by spa typing, MLST and SCCmec typing. We performed 2D gel migration comparison. Also, two MRSA isolates (527 and 139) were selected to determine quantitative changes in the level of extracellular proteins at different biofilm growth time points of 12, 24, and 48 h. The study was done using a strategy that combines 2-DGE and LC-MS/MS analysis for absolute quantification and identification of the extracellular proteins. The 2DGE revealed that the proteomic profiles for the isolates belonging to the similar spa, MLST, and SCCmec types were still quite different. Among the extracellular proteins secreted at different time points of biofilm formation, significant changes in protein expression were observed at 48 h incubation as compared to the exponential growth at 12 h incubation. The main conclusion of the work is that the authors do observe differences among isolates, and growth conditions do influence the protein content at different time points of biofilm formation.
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Affiliation(s)
- Salman S Atshan
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia Serdang, Malaysia ; Department of Medical Laboratory Sciences, University College of Humanity Studies Najaf, Iraq ; Department of Clinical Laboratory Sciences, Faculty of Pharmacy, Basrah University Basrah, Iraq
| | - Mariana N Shamsudin
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia Serdang, Malaysia
| | - Zamberi Sekawi
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia Serdang, Malaysia
| | - Leslie T Thian Lung
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia Serdang, Malaysia
| | - Fatemeh Barantalab
- Department of Immunology, Faculty of Medicine and Health Science, Universiti Putra Malaysia Serdang, Malaysia
| | - Yun K Liew
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia Serdang, Malaysia
| | - Mateg Ali Alreshidi
- Department of Basic Medical Sciences, Faculty of Medicine, Sulaiman Alrajhi Colleges Albukairiyah, Saudi Arabia
| | | | - Rukman A Hamat
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia Serdang, Malaysia
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124
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Pantrangi M, Singh VK, Shukla SK. Regulation of Staphylococcal Superantigen-Like Gene, ssl8, Expression in Staphylococcus aureus strain, RN6390. Clin Med Res 2015; 13:7-11. [PMID: 24899694 PMCID: PMC4435084 DOI: 10.3121/cmr.2014.1226] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 05/02/2014] [Indexed: 01/23/2023]
Abstract
Staphylococcal superantigen-like (SSL) proteins, which are encoded by a cluster of eleven ssl genes, contribute to the Staphylococcus aureus virulence. Recently we reported ssl8 expression profiles in seven clinically important strains-MW2, USA300FPR3757, MSSA476, Newman, RN6390, Mu50, and N315-and showed the differential expression of ssl8 in Newman, RN6390, and USA300FPR3757 strains, despite harboring identical allelic forms of ssl8, suggesting the roles for different regulatory elements for this gene in different S. aureus strains. In this communication, using RN6390, a common laboratory S. aureus strain and its isogenic knockout mutant strains of agr, sae, sarA, sigB, rot, and the agr-/sigB (-) double mutant, we showed that SarA and Rot are inducer and repressor, respectively, for ssl8 expression in RN6390. This is in contrast to the Newman strain, where ssl8 is positively regulated by Sae but negatively by Agr, indicating the variable expression of ssl8 in clinical strains is more likely due to strain-specific regulatory elements.
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Affiliation(s)
| | - Vineet K Singh
- A.T. Still University of Health Sciences, Kirksville, Missouri, USA
| | - Sanjay K Shukla
- Marshfield Clinic Research Foundation, Marshfield, Wisconsin USA
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125
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Mootz JM, Benson MA, Heim CE, Crosby HA, Kavanaugh JS, Dunman PM, Kielian T, Torres VJ, Horswill AR. Rot is a key regulator of Staphylococcus aureus biofilm formation. Mol Microbiol 2015; 96:388-404. [PMID: 25612137 DOI: 10.1111/mmi.12943] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2015] [Indexed: 01/28/2023]
Abstract
Staphylococcus aureus is a significant cause of chronic biofilm infections on medical implants. We investigated the biofilm regulatory cascade and discovered that the repressor of toxins (Rot) is part of this pathway. A USA300 community-associated methicillin-resistant S. aureus strain deficient in Rot was unable to form a biofilm using multiple different assays, and we found rot mutants in other strain lineages were also biofilm deficient. By performing a global analysis of transcripts and protein production controlled by Rot, we observed that all the secreted protease genes were up-regulated in a rot mutant, and we hypothesized that this regulation could be responsible for the biofilm phenotype. To investigate this question, we determined that Rot bound to the protease promoters, and we observed that activity levels of these enzymes, in particular the cysteine proteases, were increased in a rot mutant. By inactivating these proteases, biofilm capacity was restored to the mutant, demonstrating they are responsible for the biofilm negative phenotype. Finally, we tested the rot mutant in a mouse catheter model of biofilm infection and observed a significant reduction in biofilm burden. Thus S. aureus uses the transcription factor Rot to repress secreted protease levels in order to build a biofilm.
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Affiliation(s)
- Joe M Mootz
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
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126
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Khan BA, Yeh AJ, Cheung GYC, Otto M. Investigational therapies targeting quorum-sensing for the treatment of Staphylococcus aureus infections. Expert Opin Investig Drugs 2015; 24:689-704. [PMID: 25704585 DOI: 10.1517/13543784.2015.1019062] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
INTRODUCTION Antibiotic resistance is a serious global health concern for developed and developing nations. MRSA represents a particularly severe public health threat that is associated with high morbidity and mortality. The lack of novel antibiotics has led scientists to explore therapies targeting bacterial virulence mechanisms and virulence regulators, including those controlling cell-cell communication. AREAS COVERED The authors discuss the role of quorum-sensing in Staphylococcus aureus infections and components of the system that are being targeted using novel investigational drugs. In particular, the authors examine the role of the accessory gene regulator (Agr) system in virulence regulation of S. aureus pathogenesis. Finally, the authors present and compare natural and synthetic compounds that have been found to interfere with Agr functionality. EXPERT OPINION There is a great need to develop new therapeutic methods to combat S. aureus infections. These include anti-virulence therapies that target key global regulators involved with the establishment and propagation of infection. Several molecules have been found to interfere with S. aureus virulence regulation, especially those targeting the Agr quorum-sensing signaling molecule. These preliminary findings warrant further investigation and validation, with the goal of refining a compound that has broad-spectrum inhibitory effects on most S. aureus strains and Agr subtypes.
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Affiliation(s)
- Burhan A Khan
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories , 903 S. 4th St, 1/1110, Hamilton, MT 59840 , USA
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Sahukhal GS, Batte JL, Elasri MO. msaABCR operon positively regulates biofilm development by repressing proteases and autolysis in Staphylococcus aureus. FEMS Microbiol Lett 2015; 362:fnv006. [PMID: 25724778 DOI: 10.1093/femsle/fnv006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Staphylococcus aureus is an important human pathogen that causes nosocomial and community-acquired infections. One of the most important aspects of staphylococcal infections is biofilm development within the host, which renders the bacterium resistant to the host's immune response and antimicrobial agents. Biofilm development is very complex and involves several regulators that ensure cell survival on surfaces within the extracellular polymeric matrix. Previously, we identified the msaABCR operon as an additional positive regulator of biofilm formation. In this study, we define the regulatory pathway by which msaABCR controls biofilm formation. We demonstrate that the msaABCR operon is a negative regulator of proteases. The control of protease production mediates the processing of the major autolysin, Atl, and thus regulates the rate of autolysis. In the absence of the msaABCR operon, Atl is processed by proteases at a high rate, leading to increased cell death and a defect in biofilm maturation. We conclude that the msaABCR operon plays a key role in maintaining the balance between autolysis and growth within the staphylococcal biofilm.
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Affiliation(s)
- Gyan S Sahukhal
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406-0001, USA
| | - Justin L Batte
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406-0001, USA
| | - Mohamed O Elasri
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406-0001, USA
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128
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Lister JL, Horswill AR. Staphylococcus aureus biofilms: recent developments in biofilm dispersal. Front Cell Infect Microbiol 2014; 4:178. [PMID: 25566513 PMCID: PMC4275032 DOI: 10.3389/fcimb.2014.00178] [Citation(s) in RCA: 365] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 12/05/2014] [Indexed: 12/17/2022] Open
Abstract
Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and represents a significant burden on the healthcare system. S. aureus attachment to medical implants and host tissue, and the establishment of a mature biofilm, play an important role in the persistence of chronic infections. The formation of a biofilm, and encasement of cells in a polymer-based matrix, decreases the susceptibility to antimicrobials and immune defenses, making these infections difficult to eradicate. During infection, dispersal of cells from the biofilm can result in spread to secondary sites and worsening of the infection. In this review, we discuss the current understanding of the pathways behind biofilm dispersal in S. aureus, with a focus on enzymatic and newly described broad-spectrum dispersal mechanisms. Additionally, we explore potential applications of dispersal in the treatment of biofilm-mediated infections.
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Affiliation(s)
- Jessica L Lister
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Alexander R Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
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129
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Quave CL, Horswill AR. Flipping the switch: tools for detecting small molecule inhibitors of staphylococcal virulence. Front Microbiol 2014; 5:706. [PMID: 25566220 PMCID: PMC4264471 DOI: 10.3389/fmicb.2014.00706] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 11/27/2014] [Indexed: 11/25/2022] Open
Abstract
Through the expression of the accessory gene regulator quorum sensing cascade, Staphylococcus aureus is able to produce an extensive array of enzymes, hemolysins and immunomodulators essential to its ability to spread through the host tissues and cause disease. Many have argued for the discovery and development of quorum sensing inhibitors (QSIs) to augment existing antibiotics as adjuvant therapies. Here, we discuss the state-of-the-art tools that can be used to conduct screens for the identification of such QSIs. Examples include fluorescent reporters, MS-detection of autoinducing peptide production, agar plate methods for detection of hemolysins and lipase, High performance liquid chromatography-detection of hemolysins from supernatants, and cell-toxicity assays for detecting damage (or relief thereof) against human keratinocyte cells. In addition to providing a description of these various approaches, we also discuss their amenability to low-, medium-, and high-throughput screening efforts for the identification of novel QSIs.
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Affiliation(s)
- Cassandra L Quave
- Department of Dermatology, Emory University School of Medicine Atlanta, GA, USA ; Center for the Study of Human Health, Emory University College of Arts and Sciences Atlanta, GA, USA
| | - Alexander R Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
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130
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Abstract
Biofilm communities contain distinct microniches that result in metabolic heterogeneity and variability in gene expression. Previously, these niches were visualized within Staphylococcus aureus biofilms by observing differential expression of the cid and lrg operons during tower formation. In the present study, we examined early biofilm development and identified two new stages (designated “multiplication” and “exodus”) that were associated with changes in matrix composition and a distinct reorganization of the cells as the biofilm matured. The initial attachment and multiplication stages were shown to be protease sensitive but independent of most cell surface-associated proteins. Interestingly, after 6 h of growth, an exodus of the biofilm population that followed the transition of the biofilm to DNase I sensitivity was demonstrated. Furthermore, disruption of the gene encoding staphylococcal nuclease (nuc) abrogated this exodus event, causing hyperproliferation of the biofilm and disrupting normal tower development. Immediately prior to the exodus event, S. aureus cells carrying a nuc::gfp promoter fusion demonstrated Sae-dependent expression but only in an apparently random subpopulation of cells. In contrast to the existing model for tower development in S. aureus, the results of this study suggest the presence of a Sae-controlled nuclease-mediated exodus of biofilm cells that is required for the development of tower structures. Furthermore, these studies indicate that the differential expression of nuc during biofilm development is subject to stochastic regulatory mechanisms that are independent of the formation of metabolic microniches. In this study, we provide a novel view of four early stages of biofilm formation by the human pathogen Staphylococcus aureus. We identified an initial nucleoprotein matrix during biofilm development that is DNase I insensitive until a critical point when a nuclease-mediated exodus of the population is induced prior to tower formation. Unlike the previously described dispersal of cells that occurs after tower development, we found that the mechanism controlling this exodus event is dependent on the Sae regulatory system and independent of Agr. In addition, we revealed that the gene encoding the secreted staphylococcal nuclease was expressed in only a subpopulation of cells, consistent with a model in which biofilms exhibit multicellular characteristics, including the presence of specialized cells and a division of labor that imparts functional consequences to the remainder of the population.
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131
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Lee JJ, Lee G, Shin JH. σ(B) affects biofilm formation under the dual stress conditions imposed by adding salt and low temperature in Listeria monocytogenes. J Microbiol 2014; 52:849-55. [PMID: 25269605 DOI: 10.1007/s12275-014-4369-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 08/19/2014] [Accepted: 08/26/2014] [Indexed: 12/01/2022]
Abstract
The food-borne pathogenic bacteria Listeria monocytogenes can form biofilms on various surfaces including food-processing equipment. Biofilms offer survival benefits to the organisms entrapped against environmental insults. Moreover, the σ(B) transcription factor of L. monocytogenes plays an important role in its survival under various stress conditions. In this study, we evaluated whether σ(B) contributes to biofilm formation when L. monocytogenes is grown under various temperatures and media. When the wild-type strain was grown under static biofilm culture below ambient temperature (15°C) for 72 h, the difference in viable cell number (in both planktonic and biofilm cells) between the wild-type and ΔsigB mutant increased by adding NaCl to BHI broth (9% salt BHI > 6% salt BHI > BHI, w/v), and the specific activity of β-galactosidase was highly induced in the wild-type strain grown in 6% salt containing BHI broth. Furthermore, we measured surface-adhered biofilm forming ability using the crystal violet staining method. The wild-type strain formed a four times larger biofilm than that of the ΔsigB mutant in 6% salt-BHI medium at 15°C over a 72 h incubation and also showed the highest level of β-galactosidase specific activity. However, both the wild-type and ΔsigB mutant L. monocytogenes were defective for forming a biofilm in 9% salt-BHI medium at 15°C. Our results suggest that σ(B) plays an enhanced role in surface-adhered biofilm formation when L. monocytogenes encounters dual stress conditions, such as 6% NaCl and low temperature.
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Affiliation(s)
- Jin-Ju Lee
- Institute of Science and Technology, College of Science and Technology, Korea University, Sejong, 339-700, Republic of Korea
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132
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Loughran AJ, Atwood DN, Anthony AC, Harik NS, Spencer HJ, Beenken KE, Smeltzer MS. Impact of individual extracellular proteases on Staphylococcus aureus biofilm formation in diverse clinical isolates and their isogenic sarA mutants. Microbiologyopen 2014; 3:897-909. [PMID: 25257373 PMCID: PMC4263513 DOI: 10.1002/mbo3.214] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 08/07/2014] [Accepted: 08/15/2014] [Indexed: 01/01/2023] Open
Abstract
We demonstrate that the purified Staphylococcus aureus extracellular proteases aureolysin, ScpA, SspA, and SspB limit biofilm formation, with aureolysin having the greatest impact. Using protease-deficient derivatives of LAC, we confirmed that this is due to the individual proteases themselves. Purified aureolysin, and to a lesser extent ScpA and SspB, also promoted dispersal of an established biofilm. Mutation of the genes encoding these proteases also only partially restored biofilm formation in an FPR3757 sarA mutant and had little impact on restoring virulence in a murine bacteremia model. In contrast, eliminating the production of all of these proteases fully restored both biofilm formation and virulence in a sarA mutant generated in the closely related USA300 strain LAC. These results confirm an important role for multiple extracellular proteases in S. aureus pathogenesis and the importance of sarA in repressing their production. Moreover, purified aureolysin limited biofilm formation in 14 of 15 methicillin-resistant isolates and 11 of 15 methicillin-susceptible isolates, while dispersin B had little impact in UAMS-1, LAC, or 29 of 30 contemporary isolates of S. aureus. This suggests that the role of sarA and its impact on protease production is important in diverse strains of S. aureus irrespective of their methicillin resistance status.
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Affiliation(s)
- Allister J Loughran
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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133
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Small colony variants have a major role in stability and persistence of Staphylococcus aureus biofilms. J Antibiot (Tokyo) 2014; 68:98-105. [PMID: 25160508 DOI: 10.1038/ja.2014.115] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 06/02/2014] [Accepted: 07/22/2014] [Indexed: 12/26/2022]
Abstract
The present study was conducted to investigate the significance of small colony variants (SCVs) in biofilm life cycle of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA). All of these MRSA and MSSA isolates were recovered from different food commodities. Molecular typing showed that 21 MRSA isolates carry SCCmecA type IV and belong to agr type II. Out of 15 MSSA isolates, 7 were found to carry agr type II, 5 agr type I and 2 agr type III. All of the MRSA isolates studied adopted biofilm mode of growth after exposure to sublethal doses of oxacillin. MSSA isolates, on the other hand, were biofilm producers by nature, that is, without exposure to any stress. The biomass of the biofilm reaches its maximum thickness after 48 h of incubation at 35 °C. It was noticed that biofilm population consists of wild type and SCVs. Moreover, the number of SCVs increases with the age of biofilm. The SCVs of MRSA were unable to readopt biofilm mode of growth independently, irrespective of the presence or absence of oxacillin. The SCVs of MSSA, on the other hand, quickly revert to normal life just after a single subculture and show biofilm formation without any stress. Molecular studies showed a parallel reduction in the expression of the genes icaA, sigβ and sarA, and also in the extracellular matrix production in SCVs of MRSA. This might be due to oxacillin as it seems to be a stress factor responsible for induction of biofilm formation in MRSA isolates. Contrary to the wild type, SCVs are metabolically inactive and do not respond to oxacillin, which is only active against the growing cells. Therefore, stress-responsive genes, that is, sigβ and sarA, are not induced. Conversely, MSSA isolates are natural biofilm producers without induction through any known factors.
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134
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Synergistic interactions of Pseudomonas aeruginosa and Staphylococcus aureus in an in vitro wound model. Infect Immun 2014; 82:4718-28. [PMID: 25156721 DOI: 10.1128/iai.02198-14] [Citation(s) in RCA: 250] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In individuals with polymicrobial infections, microbes often display synergistic interactions that can enhance their colonization, virulence, or persistence. One of the most prevalent types of polymicrobial infection occurs in chronic wounds, where Pseudomonas aeruginosa and Staphylococcus aureus are the two most common causes. Although they are the most commonly associated microbial species in wound infections, very little is known about their interspecies relationship. Evidence suggests that P. aeruginosa-S. aureus coinfections are more virulent than monoculture infection with either species; however, difficulties in growing these two pathogens together in vitro have hampered attempts to uncover the mechanisms involved. Here we describe a simple and clinically relevant in vitro wound model that supported concomitant growth of P. aeruginosa and S. aureus. We observed that the ability of P. aeruginosa and S. aureus to survive antibiotic treatment increased when they were grown together in planktonic cocultures and that antibiotic tolerance was further enhanced when they were grown together in the wound model. We attributed this enhanced tolerance to both the "host-derived" and "bacterium-derived" matrix components. Taken together, our data indicate that P. aeruginosa and S. aureus may benefit each other by coinfecting wounds and that the host-derived matrix may serve as important a role as the bacterium-derived matrix in protecting bacteria from some antibiotics.
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135
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Abstract
Staphylococcus aureus is a Gram-positive pathogen that causes a diverse range of bacterial infections. Invasive S. aureus strains secrete an extensive arsenal of hemolysins, immunomodulators, and exoenzymes to cause disease. Our studies have focused on the secreted enzyme hyaluronidase (HysA), which cleaves the hyaluronic acid polymer at the β-1,4 glycosidic bond. In the study described in this report, we have investigated the regulation and contribution of this enzyme to S. aureus pathogenesis. Using the Nebraska Transposon Mutant Library (NTML), we identified eight insertions that modulate extracellular levels of HysA activity. Insertions in the sigB operon, as well as in genes encoding the global regulators SarA and CodY, significantly increased HysA protein levels and activity. By altering the availability of branched-chain amino acids, we further demonstrated CodY-dependent repression of HysA activity. Additionally, through mutation of the CodY binding box upstream of hysA, the repression of HysA production was lost, suggesting that CodY is a direct repressor of hysA expression. To determine whether HysA is a virulence factor, a ΔhysA mutant of a community-associated methicillin-resistant S. aureus (CA-MRSA) USA300 strain was constructed and found to be attenuated in a neutropenic, murine model of pulmonary infection. Mice infected with this mutant strain exhibited a 4-log-unit reduction in bacterial burden in their lungs, as well as reduced lung pathology and increased levels of pulmonary hyaluronic acid, compared to mice infected with the wild-type, parent strain. Taken together, these results indicate that S. aureus hyaluronidase is a CodY-regulated virulence factor.
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136
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Winkelströter LK, Teixeira FBDR, Silva EP, Alves VF, De Martinis ECP. Unraveling microbial biofilms of importance for food microbiology. MICROBIAL ECOLOGY 2014; 68:35-46. [PMID: 24370864 DOI: 10.1007/s00248-013-0347-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 12/06/2013] [Indexed: 06/03/2023]
Abstract
The presence of biofilms is a relevant risk factors in the food industry due to the potential contamination of food products with pathogenic and spoilage microorganisms. The majority of bacteria are able to adhere and to form biofilms, where they can persist and survive for days to weeks or even longer, depending on the microorganism and the environmental conditions. The biological cycle of biofilms includes several developmental phases such as: initial attachment, maturation, maintenance, and dispersal. Bacteria in biofilms are generally well protected against environmental stress, consequently, extremely difficult to eradicate and detect in food industry. In the present manuscript, some techniques and compounds used to control and to prevent the biofilm formation are presented and discussed. Moreover, a number of novel techniques have been recently employed to detect and evaluate bacteria attached to surfaces, including real-time polymerase chain reaction (PCR), DNA microarray and confocal laser scanning microscopy. Better knowledge on the architecture, physiology and molecular signaling in biofilms can contribute for preventing and controlling food-related spoilage and pathogenic bacteria. The present study highlights basic and applied concepts important for understanding the role of biofilms in bacterial survival, persistence and dissemination in food processing environments.
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Affiliation(s)
- Lizziane Kretli Winkelströter
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo (FCFRP-USP), Av. do Café s/n, 14040-903, Ribeirão Preto, São Paulo, Brazil
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137
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Qin N, Tan X, Jiao Y, Liu L, Zhao W, Yang S, Jia A. RNA-Seq-based transcriptome analysis of methicillin-resistant Staphylococcus aureus biofilm inhibition by ursolic acid and resveratrol. Sci Rep 2014; 4:5467. [PMID: 24970710 PMCID: PMC4073122 DOI: 10.1038/srep05467] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 05/21/2014] [Indexed: 02/08/2023] Open
Abstract
Bacterial biofilms are particularly problematic since they become resistant to most available antibiotics. Hence, novel potential antagonists to inhibit biofilm formation are urgent. Here the influences of two natural products, ursolic acid and resveratrol, on biofilm of the clinical methicillin-resistant Staphylococcus aureus (MRSA) isolate were investigated using RNA-seq, and the differentially expressed genes were analyzed using Cuffdiff. The results showed that ursolic acid inhibition of biofilm formation may reduce amino acids metabolism and adhesins expression and resveratrol may disturb quorum sensing (QS) and the synthesis of surface proteins and capsular polysaccharides. In addition, the transcriptome analysis of resveratrol and the combination of resveratrol with vancomycin inhibition of established biofilm revealed that resveratrol would disturb the expression of genes related to QS, surface and secreted proteins, and capsular polysaccharides. These findings suggest that ursolic acid and resveratrol could be useful to be adjunct therapies for the treatment of MRSA biofilm-involved infections.
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Affiliation(s)
- Nan Qin
- State Key Laboratory for Diagnosis and Treatment of Infectious Disease, the First Affiliated Hospital, Zhejiang University, Hangzhou 310003, China
- These authors contributed equally to this work
| | - Xiaojuan Tan
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
- These authors contributed equally to this work
| | - Yinming Jiao
- Department of Bioinformatics, State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
- These authors contributed equally to this work
| | - Lin Liu
- State Key Laboratory for Diagnosis and Treatment of Infectious Disease, the First Affiliated Hospital, Zhejiang University, Hangzhou 310003, China
- NGS Sequencing Department, Beijing Genomics Institute (BGI), Shenzhen 518083, China
| | - Wangsheng Zhao
- Clinical Laboratory Department of the First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China
| | - Shuang Yang
- NGS Sequencing Department, Beijing Genomics Institute (BGI), Shenzhen 518083, China
| | - Aiqun Jia
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
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138
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Kim MK, Drescher K, Pak OS, Bassler BL, Stone HA. Filaments in curved streamlines: Rapid formation of Staphylococcus aureus biofilm streamers. NEW JOURNAL OF PHYSICS 2014; 16:065024. [PMID: 25484614 PMCID: PMC4255984 DOI: 10.1088/1367-2630/16/6/065024] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Biofilms are surface-associated conglomerates of bacteria that are highly resistant to antibiotics. These bacterial communities can cause chronic infections in humans by colonizing, for example, medical implants, heart valves, or lungs. Staphylococcus aureus, a notorious human pathogen, causes some of the most common biofilm-related infections. Despite the clinical importance of S. aureus biofilms, it remains mostly unknown how physical effects, in particular flow, and surface structure influence biofilm dynamics. Here we use model microfluidic systems to investigate how environmental factors, such as surface geometry, surface chemistry, and fluid flow affect biofilm development in S. aureus. We discovered that S. aureus rapidly forms flow-induced, filamentous biofilm streamers, and furthermore if surfaces are coated with human blood plasma, streamers appear within minutes and clog the channels more rapidly than if the channels are uncoated. To understand how biofilm streamer filaments reorient in flows with curved streamlines to bridge the distances between corners, we developed a mathematical model based on resistive force theory of slender filaments. Understanding physical aspects of biofilm formation in S. aureus may lead to new approaches for interrupting biofilm formation of this pathogen.
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Affiliation(s)
| | - Knut Drescher
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - On Shun Pak
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544
| | - Bonnie L. Bassler
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
- Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Howard A. Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544
- Corresponding author:
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139
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Fischer A, Kambara K, Meyer H, Stenz L, Bonetti EJ, Girard M, Lalk M, Francois P, Schrenzel J. GdpS contributes to Staphylococcus aureus biofilm formation by regulation of eDNA release. Int J Med Microbiol 2014; 304:284-99. [DOI: 10.1016/j.ijmm.2013.10.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 10/25/2013] [Accepted: 10/27/2013] [Indexed: 11/30/2022] Open
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140
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Reconstruction of mreB expression in Staphylococcus aureus via a collection of new integrative plasmids. Appl Environ Microbiol 2014; 80:3868-78. [PMID: 24747904 DOI: 10.1128/aem.00759-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Protein localization has been traditionally explored in unicellular organisms, whose ease of genetic manipulation facilitates molecular characterization. The two rod-shaped bacterial models Escherichia coli and Bacillus subtilis have been prominently used for this purpose and have displaced other bacteria whose challenges for genetic manipulation have complicated any study of cell biology. Among these bacteria is the spherical pathogenic bacterium Staphylococcus aureus. In this report, we present a new molecular toolbox that facilitates gene deletion in staphylococci in a 1-step recombination process and additional vectors that facilitate the insertion of diverse reporter fusions into newly identified neutral loci of the S. aureus chromosome. Insertion of the reporters does not add any antibiotic resistance genes to the chromosomes of the resultant strains, thereby making them amenable for further genetic manipulations. We used this toolbox to reconstitute the expression of mreB in S. aureus, a gene that encodes an actin-like cytoskeletal protein which is absent in coccal cells and is presumably lost during the course of speciation. We observed that in S. aureus, MreB is organized in discrete structures in association with the membrane, leading to an unusual redistribution of the cell wall material. The production of MreB also caused cell enlargement, but it did not revert staphylococcal shape. We present interactions of MreB with key staphylococcal cell wall-related proteins. This work facilitates the use S. aureus as a model system in exploring diverse aspects of cellular microbiology.
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141
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McCourt J, O'Halloran DP, McCarthy H, O'Gara JP, Geoghegan JA. Fibronectin-binding proteins are required for biofilm formation by community-associated methicillin-resistant Staphylococcus aureus strain LAC. FEMS Microbiol Lett 2014; 353:157-64. [PMID: 24628034 DOI: 10.1111/1574-6968.12424] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/05/2014] [Accepted: 03/11/2014] [Indexed: 12/31/2022] Open
Abstract
Community-associated methicillin-resistant Staphylococcus aureus of the USA300 lineage is emerging as an important cause of medical device-related infection. However, few factors required for biofilm accumulation by USA300 strains have been identified, and the processes involved are poorly understood. Here, we identify S. aureus proteins required for the USA300 isolate LAC to form biofilm. A mutant with a deletion of the fnbA and fnbB genes did not express the fibronectin-binding proteins FnBPA and FnBPB and lacked the ability to adhere to fibronectin or to form biofilm. Biofilm formation by the mutant LAC∆fnbAfnbB could be restored by expression of FnBPA or FnBPB from a plasmid demonstrating that both of these proteins can mediate biofilm formation when expressed by LAC. Expression of FnBPA and FnBPB increased bacterial aggregation suggesting that fibronectin-binding proteins can promote the accumulation phase of biofilm. Loss of fibronectin-binding proteins reduced the initial adherence of bacteria, indicating that these proteins are also involved in primary attachment. In summary, these findings improve our understanding of biofilm formation by the USA300 strain LAC by demonstrating that the fibronectin-binding proteins are required.
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Affiliation(s)
- Jennifer McCourt
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
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142
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Park HJ, Moon YH, Yoon HE, Park YM, Yoon JH, Bang IS. Agr function is upregulated by photodynamic therapy for Staphylococcus aureus and is related to resistance to photodynamic therapy. Microbiol Immunol 2014; 57:547-52. [PMID: 23668640 DOI: 10.1111/1348-0421.12070] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 04/10/2013] [Accepted: 05/08/2013] [Indexed: 12/01/2022]
Abstract
Photodynamic therapy (PDT) has been considered a feasible alternative for antimicrobial therapy of multidrug-resistant pathogens. However, bacterial response mechanisms against PDT-generated photo-oxidative stress remain largely unknown. Herein, it is shown that the accessory gene regulator Agr is involved in Staphylococcus aureus response to photo-oxidative stress generated by laser-induced PDT with the photosensitizer chlorin e6 . Transcriptional profiling revealed that sublethal PDT induces a general stress response and also activates Agr-dependent gene regulation. Moreover, mutant S. aureus lacking Agr function showed hypersusceptibility to two independent PDT conditions with higher energy densities, demonstrating Agr-dependent S. aureus resistance against PDT.
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Affiliation(s)
- Hee Jeong Park
- Department of Microbiology and Immunology, Chosun University School of Dentistry, Gwangju, 501-759, Korea
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143
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Foster TJ, Geoghegan JA, Ganesh VK, Höök M. Adhesion, invasion and evasion: the many functions of the surface proteins of Staphylococcus aureus. Nat Rev Microbiol 2014; 12:49-62. [PMID: 24336184 DOI: 10.1038/nrmicro3161] [Citation(s) in RCA: 933] [Impact Index Per Article: 93.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Staphylococcus aureus is an important opportunistic pathogen and persistently colonizes about 20% of the human population. Its surface is 'decorated' with proteins that are covalently anchored to the cell wall peptidoglycan. Structural and functional analysis has identified four distinct classes of surface proteins, of which microbial surface component recognizing adhesive matrix molecules (MSCRAMMs) are the largest class. These surface proteins have numerous functions, including adhesion to and invasion of host cells and tissues, evasion of immune responses and biofilm formation. Thus, cell wall-anchored proteins are essential virulence factors for the survival of S. aureus in the commensal state and during invasive infections, and targeting them with vaccines could combat S. aureus infections.
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Affiliation(s)
- Timothy J Foster
- Microbiology Department, Moyne Institute of Preventive Medicine, Trinity College, Dublin 2, Ireland
| | - Joan A Geoghegan
- Microbiology Department, Moyne Institute of Preventive Medicine, Trinity College, Dublin 2, Ireland
| | - Vannakambadi K Ganesh
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030, USA
| | - Magnus Höök
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030, USA
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Walker JN, Crosby HA, Spaulding AR, Salgado-Pabón W, Malone CL, Rosenthal CB, Schlievert PM, Boyd JM, Horswill AR. The Staphylococcus aureus ArlRS two-component system is a novel regulator of agglutination and pathogenesis. PLoS Pathog 2013; 9:e1003819. [PMID: 24367264 PMCID: PMC3868527 DOI: 10.1371/journal.ppat.1003819] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 10/21/2013] [Indexed: 01/31/2023] Open
Abstract
Staphylococcus aureus is a prominent bacterial pathogen that is known to agglutinate in the presence of human plasma to form stable clumps. There is increasing evidence that agglutination aids S. aureus pathogenesis, but the mechanisms of this process remain to be fully elucidated. To better define this process, we developed both tube based and flow cytometry methods to monitor clumping in the presence of extracellular matrix proteins. We discovered that the ArlRS two-component system regulates the agglutination mechanism during exposure to human plasma or fibrinogen. Using divergent S. aureus strains, we demonstrated that arlRS mutants are unable to agglutinate, and this phenotype can be complemented. We found that the ebh gene, encoding the Giant Staphylococcal Surface Protein (GSSP), was up-regulated in an arlRS mutant. By introducing an ebh complete deletion into an arlRS mutant, agglutination was restored. To assess whether GSSP is the primary effector, a constitutive promoter was inserted upstream of the ebh gene on the chromosome in a wildtype strain, which prevented clump formation and demonstrated that GSSP has a negative impact on the agglutination mechanism. Due to the parallels of agglutination with infective endocarditis development, we assessed the phenotype of an arlRS mutant in a rabbit combined model of sepsis and endocarditis. In this model the arlRS mutant displayed a large defect in vegetation formation and pathogenesis, and this phenotype was partially restored by removing GSSP. Altogether, we have discovered that the ArlRS system controls a novel mechanism through which S. aureus regulates agglutination and pathogenesis. Staphylococcus aureus is a bacterial pathogen that is responsible for causing significant disease in humans. The development of antibiotic resistant strains has made these infections more difficult to treat, and an improved understanding of how this pathogen causes infections will facilitate the development of new tools for treatment. It has long been recognized that S. aureus can bind human matrix proteins to form stable clumps in a process called agglutination, but the importance of agglutination during infection is only just becoming understood. In this work, we developed several techniques to investigate the S. aureus agglutination mechanism. We discovered that the ArlRS two-component regulatory system controls agglutination by regulating the expression of the ebh gene, which encodes the Giant Staphylococcal Surface Protein (GSSP). When ArlRS is non-functional, S. aureus agglutination is prevented through the action of GSSP. These phenotypes were confirmed in a rabbit model of sepsis and infective endocarditis, demonstrating that ArlRS is an important regulator of virulence. Taken together, the identification of ArlRS as a regulator of S. aureus agglutination and pathogenesis may lead to innovative directions for therapeutic development.
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Affiliation(s)
- Jennifer N Walker
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Heidi A Crosby
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Adam R Spaulding
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Wilmara Salgado-Pabón
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Cheryl L Malone
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Carolyn B Rosenthal
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Patrick M Schlievert
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Jeffrey M Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Alexander R Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
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145
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Emergence of the epidemic methicillin-resistant Staphylococcus aureus strain USA300 coincides with horizontal transfer of the arginine catabolic mobile element and speG-mediated adaptations for survival on skin. mBio 2013; 4:e00889-13. [PMID: 24345744 PMCID: PMC3870260 DOI: 10.1128/mbio.00889-13] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
UNLABELLED The arginine catabolic mobile element (ACME) is the largest genomic region distinguishing epidemic USA300 strains of methicillin-resistant Staphylococcus aureus (MRSA) from other S. aureus strains. However, the functional relevance of ACME to infection and disease has remained unclear. Using phylogenetic analysis, we have shown that the modular segments of ACME were assembled into a single genetic locus in Staphylococcus epidermidis and then horizontally transferred to the common ancestor of USA300 strains in an extremely recent event. Acquisition of one ACME gene, speG, allowed USA300 strains to withstand levels of polyamines (e.g., spermidine) produced in skin that are toxic to other closely related S. aureus strains. speG-mediated polyamine tolerance also enhanced biofilm formation, adherence to fibrinogen/fibronectin, and resistance to antibiotic and keratinocyte-mediated killing. We suggest that these properties gave USA300 a major selective advantage during skin infection and colonization, contributing to the extraordinary evolutionary success of this clone. IMPORTANCE Over the past 15 years, methicillin-resistant Staphylococcus aureus (MRSA) has become a major public health problem. It is likely that adaptations in specific MRSA lineages (e.g., USA300) drove the spread of MRSA across the United States and allowed it to replace other, less-virulent S. aureus strains. We suggest that one major factor in the evolutionary success of MRSA may have been the acquisition of a gene (speG) that allows S. aureus to evade the toxicity of polyamines (e.g., spermidine and spermine) that are produced in human skin. Polyamine tolerance likely gave MRSA multiple fitness advantages, including the formation of more-robust biofilms, increased adherence to host tissues, and resistance to antibiotics and killing by human skin cells.
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146
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Abstract
Staphylococcus aureus is a leading pathogen for animals and humans, not only being one of the most frequently isolated bacteria in hospital-associated infections but also causing diseases in the community. To coordinate the expression of its numerous virulence genes for growth and survival, S. aureus uses various signalling pathways that include two-component regulatory systems, transcription factors, and also around 250 regulatory RNAs. Biological roles have only been determined for a handful of these sRNAs, including cis, trans, and cis-trans acting RNAs, some internally encoding small, functional peptides and others possessing dual or multiple functions. Here we put forward an inventory of these fascinating sRNAs; the proteins involved in their activities; and those involved in stress response, metabolisms, and virulence.
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Affiliation(s)
- Julien Guillet
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
| | - Marc Hallier
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
| | - Brice Felden
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
- * E-mail:
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147
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Laverty G, Gorman SP, Gilmore BF. Biomolecular mechanisms of staphylococcal biofilm formation. Future Microbiol 2013; 8:509-24. [PMID: 23534362 DOI: 10.2217/fmb.13.7] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The multitude of biomolecular and regulatory factors involved in staphylococcal adhesion and biofilm formation owe much to their ability to colonize surfaces, allowing the biofilm form to become the preferential bacterial phenotype. Judging by total number, biomass and variety of environments colonized, bacteria can be categorized as the most successful lifeform on earth. This is due to the ability of bacteria and other microorganisms to respond phenotypically via biomolecular processes to the stresses of their surrounding environment. This review focuses on the specific pathways involved in the adhesion of the Gram-positive bacteria Staphylococcus epidermidis and Staphylococcus aureus with reference to the role of specific cell surface adhesins, the ica operon, accumulation-associated proteins and quorum-sensing systems and their significance in medical device-related infection.
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Affiliation(s)
- Garry Laverty
- Queen's University Belfast, School of Biological Sciences, Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK.
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148
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Nicholson TL, Shore SM, Smith TC, Frana TS. Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) isolates of swine origin form robust biofilms. PLoS One 2013; 8:e73376. [PMID: 23951352 PMCID: PMC3739819 DOI: 10.1371/journal.pone.0073376] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 07/22/2013] [Indexed: 01/11/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) colonization of livestock animals is common and prevalence rates for pigs have been reported to be as high as 49%. Mechanisms contributing to the persistent carriage and high prevalence rates of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) strains in swine herds and production facilities have not been investigated. One explanation for the high prevalence of MRSA in swine herds is the ability of these organisms to exist as biofilms. In this report, the ability of swine LA-MRSA strains, including ST398, ST9, and ST5, to form biofilms was quantified and compared to several swine and human isolates. The contribution of known biofilm matrix components, polysaccharides, proteins and extracellular DNA (eDNA), was tested in all strains as well. All MRSA swine isolates formed robust biofilms similar to human clinical isolates. The addition of Dispersin B had no inhibitory effect on swine MRSA isolates when added at the initiation of biofilm growth or after pre-established mature biofilms formed. In contrast, the addition of proteinase K inhibited biofilm formation in all strains when added at the initiation of biofilm growth and was able to disperse pre-established mature biofilms. Of the LA-MRSA strains tested, we found ST398 strains to be the most sensitive to both inhibition of biofilm formation and dispersal of pre-formed biofilms by DNaseI. Collectively, these findings provide a critical first step in designing strategies to control or eliminate MRSA in swine herds.
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Affiliation(s)
- Tracy L Nicholson
- National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, USA.
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149
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Dangel A, Ackermann N, Abdel-Hadi O, Maier R, Önder K, Francois P, Müller CW, Pané-Farré J, Engelmann S, Schrenzel J, Heesemann J, Lindermayr C. A de novo-designed antimicrobial peptide with activity against multiresistant Staphylococcus aureus acting on RsbW kinase. FASEB J 2013; 27:4476-88. [PMID: 23901070 DOI: 10.1096/fj.13-234575] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Antimicrobial peptides are a promising complement to common antibiotics, development of resistance to which is a growing problem. Here we present a de novo-designed peptide, SP1-1 (RKKRLKLLKRLL-NH2), with antimicrobial activity against multiresistant Staphylococcus aureus (minimal inhibitory concentration: 6.25 μM). Elucidation of the mode of action of this peptide revealed a strong interaction with RsbW kinase (Kd: 6.01±2.73 nM), a serine kinase negatively regulating the activity of the transcription factor σB (SigB). SP1-1 binding and functional modulation of RsbW were shown in vitro by a combination of biochemical, molecular, and biophysical methods, which were further genetically evidenced in vivo by analysis of S. aureus ΔsigB deletion mutants. Intracellular localization of the peptide was demonstrated using nanometer-scaled secondary ion mass spectrometry. Moreover, microarray analysis revealed that transcription of numerous genes, involved in cell wall and amino acid metabolism, transport mechanisms, virulence, and pigmentation, is affected. Interestingly, several WalR binding motif containing genes are induced by SP1-1. In sum, the designed peptide SP1-1 seems to have multiple modes of action, including inhibition of a kinase, and therefore might contribute to the development of new antibacterial compounds, giving bacterial kinase inhibition a closer inspection.
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Affiliation(s)
- Alexandra Dangel
- 1Helmholtz Zentrum Munich, Landstrasse, München-Neuherberg, D-85764 Germany.
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Papa R, Artini M, Cellini A, Tilotta M, Galano E, Pucci P, Amoresano A, Selan L. A new anti-infective strategy to reduce the spreading of antibiotic resistance by the action on adhesion-mediated virulence factors in Staphylococcus aureus. Microb Pathog 2013; 63:44-53. [PMID: 23811076 DOI: 10.1016/j.micpath.2013.05.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 04/29/2013] [Accepted: 05/06/2013] [Indexed: 11/19/2022]
Abstract
Staphylococcus aureus is a flexible microbial pathogen frequently isolated from community-acquired and nosocomial infections. S. aureus expresses a wide array of secreted and cell surface-associated virulence factors, including proteins that promote adhesion to damaged tissue and to the surface of host cells, and that bind proteins in blood to help evade immune responses. Furthermore, surface proteins have a fundamental role in virulence related properties of S. aureus, including biofilm formation. The present study evaluates the anti-infective capabilities of a secreted protein of Serratia marcescens (serratiopeptidase, SPEP), in impairing some staphylococcal virulence-related properties, such as attachment to inert surfaces and adhesion/invasion on eukaryotic cells. SPEP seems to exert its action by modulating specific proteins. It is not assessed if this action is due to the proteolytic activity of SPEP or to a specific mechanism which triggers an out/inside signal. Proteomic studies performed on surface proteins extracted from SPEP treated S. aureus cultures revealed that a number of proteins are affected by the treatment. Among these we found the adhesin/autolysin Atl, SdrD, Sbi, EF-Tu and EF-G. EF-Tu and EF-G are known to perform a variety of function, depending on their cytoplasmic or surface localization. All these factors can facilitate bacterial colonization, persistence and invasion of host tissues. Our results suggest that SPEP could be developed as a potential "anti-infective agent" capable to hinder the entry of S. aureus into human tissues, and also impairs the ability of this pathogen to adhere to prostheses, catheters and medical devices.
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Affiliation(s)
- Rosanna Papa
- Department of Public Health and Infectious Diseases, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy
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