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Witten J, Ribbeck K. The particle in the spider's web: transport through biological hydrogels. NANOSCALE 2017; 9:8080-8095. [PMID: 28580973 PMCID: PMC5841163 DOI: 10.1039/c6nr09736g] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Biological hydrogels such as mucus, extracellular matrix, biofilms, and the nuclear pore have diverse functions and compositions, but all act as selectively permeable barriers to the diffusion of particles. Each barrier has a crosslinked polymeric mesh that blocks penetration of large particles such as pathogens, nanotherapeutics, or macromolecules. These polymeric meshes also employ interactive filtering, in which affinity between solutes and the gel matrix controls permeability. Interactive filtering affects the transport of particles of all sizes including peptides, antibiotics, and nanoparticles and in many cases this filtering can be described in terms of the effects of charge and hydrophobicity. The concepts described in this review can guide strategies to exploit or overcome gel barriers, particularly for applications in diagnostics, pharmacology, biomaterials, and drug delivery.
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Affiliation(s)
- Jacob Witten
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Yang J, Toyofuku M, Sakai R, Nomura N. Influence of the alginate production on cell-to-cell communication in Pseudomonas aeruginosa PAO1. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:239-249. [PMID: 28120378 DOI: 10.1111/1758-2229.12521] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 01/13/2017] [Accepted: 01/18/2017] [Indexed: 06/06/2023]
Abstract
Many bacteria communicate with each other through signalling molecules, a process known as cell-to-cell communication. During this process, it is important for the signalling molecules to: (1) reach the target cells; and (2) to be received by the cognate receptor. Barriers such as the presence of extracellular matrix may prevent signals from reaching their targets; however, the influence of the extracellular matrix on cell-to-cell communication has scarcely been studied. Here, we demonstrate that the overproduction of an extracellular matrix, alginate, in a Pseudomonas aeruginosa mucoid variant, alters cell-to-cell communication by interfering with the response to quinolone signals while having no effect on N-acyl-L-homoserine lactones. The inhibition of quinolone signalling by alginate is limited to the alginate overproducer and has no effect on neighbour cells that do not produce alginate. Our study indicates that alginate overproduction affects the cell-to-cell communication of the mucoid variant, which may results in different downstream behaviours when it emerges in the presence of the wild-type (WT).
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Affiliation(s)
- Jiayue Yang
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Masanori Toyofuku
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
- Department of Plant and Microbial Biology, University of Zurich, Zürich, 8008, Switzerland
| | - Ryosuke Sakai
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Nobuhiko Nomura
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
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Sustained tobramycin release from polyphosphate double network hydrogels. Acta Biomater 2017; 50:484-492. [PMID: 27993638 DOI: 10.1016/j.actbio.2016.12.030] [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: 08/29/2016] [Revised: 12/07/2016] [Accepted: 12/13/2016] [Indexed: 11/22/2022]
Abstract
Sustained local delivery of antibiotics from a drug reservoir to treat or prevent bacterial infections can avoid many of the drawbacks of systemic administration of antibiotics. Prolonged local release of high concentrations of antibiotics may also be more effective at treating bacteria in established biofilm populations that are resistant to systemic antibiotics. A double network hydrogel comprising an organic polyphosphate pre-polymer network polymerized within a polyacrylamide network de-swelled to about 50% of its initial volume when the polyphosphate network was crosslinked with polycationic tobramycin, an aminoglycoside antibiotic. The antibiotic-loaded hydrogels contained approximately 200mg/ml of tobramycin. The hydrogels continuously released daily amounts of tobramycin above the Pseudomonas aeruginosa minimal bactericidal concentration for greater than 50days, over the pH range 6.0-8.0, and completely eradicated established P. aeruginosa biofilms within 72h in a flow cell bioreactor. The presence of physiological concentrations of Mg2+ and Ca2+ ions doubled the cumulative release over 60days. The polyphosphate hydrogels show promise as materials for sustained localized tobramycin delivery to prevent post-operative P. aeruginosa infections including infections established in biofilms. STATEMENT OF SIGNIFICANCE Polyphosphate hydrogels were loaded with high concentrations of tobramycin. The hydrogels provided sustained release of bactericidal concentrations of tobramycin for 50days, and were capable of completely eradicating P. aeruginosa in established biofilms. The hydrogels have potential for localized prevention or treatment of P. aeruginosa infections.
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Woods EC, McBride SM. Regulation of antimicrobial resistance by extracytoplasmic function (ECF) sigma factors. Microbes Infect 2017; 19:238-248. [PMID: 28153747 DOI: 10.1016/j.micinf.2017.01.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 01/20/2017] [Accepted: 01/21/2017] [Indexed: 11/27/2022]
Abstract
Extracytoplasmic function (ECF) sigma factors are a subfamily of σ70 sigma factors that activate genes involved in stress-response functions. In many bacteria, ECF sigma factors regulate resistance to antimicrobial compounds. This review will summarize the ECF sigma factors that regulate antimicrobial resistance in model organisms and clinically relevant pathogens.
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Affiliation(s)
- Emily C Woods
- Department of Microbiology and Immunology, Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA.
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55
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Azam A, Arshad M, Dwivedi S, Ashraf MT. Antibacterial Applications of Nanomaterials. RECENT TRENDS IN NANOMATERIALS 2017. [DOI: 10.1007/978-981-10-3842-6_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Affiliation(s)
- J.W. Costerton
- Center for Biofilm Engineering Montana State University 409 Cobleigh Hall Bozeman, Montana 59717
| | - Zbigniew Lewandowski
- Center for Biofilm Engineering Montana State University 409 Cobleigh Hall Bozeman, Montana 59717
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57
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Bos AC, Passé KM, Mouton JW, Janssens HM, Tiddens HAWM. The fate of inhaled antibiotics after deposition in cystic fibrosis: How to get drug to the bug? J Cyst Fibros 2016; 16:13-23. [PMID: 28254026 DOI: 10.1016/j.jcf.2016.10.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 09/26/2016] [Accepted: 10/01/2016] [Indexed: 10/20/2022]
Abstract
BACKGROUND Chronic airway infections in patients with cystic fibrosis (CF) are most often treated with inhaled antibiotics of which deposition patterns have been extensively studied. However, the journey of aerosol particles does not end after deposition within the bronchial tree. OBJECTIVES To review how local conditions affect the clinical efficacy of antibiotic aerosol particles after deposition in the airways of patients with CF. METHODS Electronic databases were searched from inception to September 2015. Original studies describing the effect of CF sputum or bacterial factors on antibiotic efficacy and formulations to increase efficacy were included. RESULTS 35 articles were included which mostly described in vitro studies and mainly investigated aminoglycosides. After deposition, diffusion through the mucus layer was reduced for aminoglycosides, β-lactam antibiotics and fluoroquinolones. Within CF mucus, low oxygen tension adversely affected aminoglycosides, β-lactam antibiotics, and chloramphenicol; and molecules inactivated aminoglycosides but not β-lactam antibiotics. Finally, the alginate layer surrounding Pseudomonas aeruginosa was an important factor in the resistance against all antibiotics. CONCLUSIONS After deposition in the airways, the local efficacy of inhaled antibiotics can be reduced by molecules within CF mucus and the alginate layer surrounding P. aeruginosa.
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Affiliation(s)
- Aukje C Bos
- Department of Paediatric Pulmonology and Allergology, Erasmus Medical Centre (MC) - Sophia Children's Hospital, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands.
| | - Kimberly M Passé
- Department of Paediatric Pulmonology and Allergology, Erasmus Medical Centre (MC) - Sophia Children's Hospital, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands.
| | - Johan W Mouton
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands.
| | - Hettie M Janssens
- Department of Paediatric Pulmonology and Allergology, Erasmus Medical Centre (MC) - Sophia Children's Hospital, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands.
| | - Harm A W M Tiddens
- Department of Paediatric Pulmonology and Allergology, Erasmus Medical Centre (MC) - Sophia Children's Hospital, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands.
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58
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AlgU Controls Expression of Virulence Genes in Pseudomonas syringae pv. tomato DC3000. J Bacteriol 2016; 198:2330-44. [PMID: 27325679 DOI: 10.1128/jb.00276-16] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/14/2016] [Indexed: 01/30/2023] Open
Abstract
UNLABELLED Plant-pathogenic bacteria are able to integrate information about their environment and adjust gene expression to provide adaptive functions. AlgU, an extracytoplasmic function (ECF) sigma factor encoded by Pseudomonas syringae, controls expression of genes for alginate biosynthesis and genes involved with resisting osmotic and oxidative stress. AlgU is active while these bacteria are associated with plants, where its presence supports bacterial growth and disease symptoms. We found that AlgU is an important virulence factor for P. syringae pv. tomato DC3000 but that alginate production is dispensable for disease in host plants. This implies that AlgU regulates additional genes that facilitate bacterial pathogenesis. We used transcriptome sequencing (RNA-seq) to characterize the AlgU regulon and chromatin immunoprecipitation sequencing (ChIP-seq) to identify AlgU-regulated promoters associated with genes directly controlled by this sigma factor. We found that in addition to genes involved with alginate and osmotic and oxidative stress responses, AlgU regulates genes with known virulence functions, including components of the Hrp type III secretion system, virulence effectors, and the hrpL and hrpRS transcription regulators. These data suggest that P. syringae pv. tomato DC3000 has adapted to use signals that activate AlgU to induce expression of important virulence functions that facilitate survival and disease in plants. IMPORTANCE Plant immune systems produce antimicrobial and bacteriostatic conditions in response to bacterial infection. Plant-pathogenic bacteria are adapted to suppress and/or tolerate these conditions; however, the mechanisms controlling these bacterial systems are largely uncharacterized. The work presented here provides a mechanistic explanation for how P. syringae pv. tomato DC3000 coordinates expression of multiple genetic systems, including those dedicated to pathogenicity, in response to environmental conditions. This work demonstrates the scope of AlgU regulation in P. syringae pv. tomato DC3000 and characterizes the promoter sequence regulated by AlgU in these bacteria.
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59
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Satpathy S, Sen SK, Pattanaik S, Raut S. Review on bacterial biofilm: An universal cause of contamination. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2016. [DOI: 10.1016/j.bcab.2016.05.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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60
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Germoni LAP, Bremer PJ, Lamont IL. The effect of alginate lyase on the gentamicin resistance of Pseudomonas aeruginosa in mucoid biofilms. J Appl Microbiol 2016; 121:126-35. [PMID: 27061817 DOI: 10.1111/jam.13153] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 04/05/2016] [Accepted: 04/06/2016] [Indexed: 12/22/2022]
Abstract
AIMS Pseudomonas aeruginosa can secrete large amounts of alginate during chronic infections and this has been associated with high resistance to antibiotics. The major aim of this study was to investigate whether degradation of extracellular alginate by alginate lyase would increase the sensitivity of Ps. aeruginosa to gentamicin, an aminoglycoside antibiotic. METHODS AND RESULTS Degradation of alginate from Ps. aeruginosa was monitored using a spectrometric assay. Alginate lyase depolymerized alginate, but calcium and zinc cations at concentrations found in the cystic fibrosis lung reduced enzyme activity. Biofilms formed on agar were partially degraded by alginate lyase, but staining with crystal violet showed that the biomass of biofilms grown in liquid was not significantly affected by the enzyme. Viability testing showed that the sensitivity to gentamicin of biofilm bacteria and of bacteria released from biofilms was unaffected by alginate lyase. CONCLUSIONS Our results show that at least under the conditions used here alginate lyase does not affect gentamicin resistance of Ps. aeruginosa. SIGNIFICANCE AND IMPACT OF THE STUDY Our study indicates that alginate does not contribute to resistance to gentamicin and so does not provide support for the concept of treating patients with alginate lyase in order to increase the antibiotic sensitivity of Ps. aeruginosa.
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Affiliation(s)
- L A P Germoni
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - P J Bremer
- Department of Food Science, University of Otago, Dunedin, New Zealand
| | - I L Lamont
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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Cao B, Christophersen L, Kolpen M, Jensen PØ, Sneppen K, Høiby N, Moser C, Sams T. Diffusion Retardation by Binding of Tobramycin in an Alginate Biofilm Model. PLoS One 2016; 11:e0153616. [PMID: 27100887 PMCID: PMC4839563 DOI: 10.1371/journal.pone.0153616] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 03/31/2016] [Indexed: 12/25/2022] Open
Abstract
Microbial cells embedded in a self-produced extracellular biofilm matrix cause chronic infections, e. g. by Pseudomonas aeruginosa in the lungs of cystic fibrosis patients. The antibiotic killing of bacteria in biofilms is generally known to be reduced by 100–1000 times relative to planktonic bacteria. This makes such infections difficult to treat. We have therefore proposed that biofilms can be regarded as an independent compartment with distinct pharmacokinetics. To elucidate this pharmacokinetics we have measured the penetration of the tobramycin into seaweed alginate beads which serve as a model of the extracellular polysaccharide matrix in P. aeruginosa biofilm. We find that, rather than a normal first order saturation curve, the concentration of tobramycin in the alginate beads follows a power-law as a function of the external concentration. Further, the tobramycin is observed to be uniformly distributed throughout the volume of the alginate bead. The power-law appears to be a consequence of binding to a multitude of different binding sites. In a diffusion model these results are shown to produce pronounced retardation of the penetration of tobramycin into the biofilm. This filtering of the free tobramycin concentration inside biofilm beads is expected to aid in augmenting the survival probability of bacteria residing in the biofilm.
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Affiliation(s)
- Bao Cao
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Lars Christophersen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Mette Kolpen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
- Department of Immunology and Microbiology, UC-CARE, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Peter Østrup Jensen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Kim Sneppen
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
- Department of Immunology and Microbiology, UC-CARE, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Thomas Sams
- Biomedical Engineering, Dept. of Electrical Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark
- * E-mail:
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Sheppard DC, Howell PL. Biofilm Exopolysaccharides of Pathogenic Fungi: Lessons from Bacteria. J Biol Chem 2016; 291:12529-12537. [PMID: 27129222 DOI: 10.1074/jbc.r116.720995] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Exopolysaccharides play an important structural and functional role in the development and maintenance of microbial biofilms. Although the majority of research to date has focused on the exopolysaccharide systems of biofilm-forming bacteria, recent studies have demonstrated that medically relevant fungi such as Candida albicans and Aspergillus fumigatus also form biofilms during infection. These fungal biofilms share many similarities with those of bacteria, including the presence of secreted exopolysaccharides as core components of the extracellular matrix. This review will highlight our current understanding of fungal biofilm exopolysaccharides, as well as the parallels that can be drawn with those of their bacterial counterparts.
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Affiliation(s)
- Donald C Sheppard
- Departments of Medicine, Microbiology and Immunology, Research Institute of the McGill University Health Centre, McGill University, Montréal, Québec H4A 3J1; Infectious Diseases and Immunity in Global Health Program, Research Institute of the McGill University Health Centre, McGill University, Montréal, Québec H4A 3J1.
| | - P Lynne Howell
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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García-Gareta E, Davidson C, Levin A, Coathup MJ, Blunn GW. Biofilm formation in total hip arthroplasty: prevention and treatment. RSC Adv 2016. [DOI: 10.1039/c6ra09583f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
This review assesses the current knowledge on treatments, pathogenesis and the prevention of infections associated with orthopaedic implants, with a focus on total hip arthroplasty.
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Affiliation(s)
| | - Christopher Davidson
- John Scales Centre for Biomedical Engineering
- Institute of Orthopaedics and Musculoskeletal Science
- Division of Surgery and Interventional Science
- University College London
- Royal National Orthopaedic Hospital
| | - Alexandra Levin
- RAFT Institute of Plastic Surgery
- Mount Vernon Hospital
- Northwood HA6 2RN
- UK
| | - Melanie J. Coathup
- John Scales Centre for Biomedical Engineering
- Institute of Orthopaedics and Musculoskeletal Science
- Division of Surgery and Interventional Science
- University College London
- Royal National Orthopaedic Hospital
| | - Gordon W. Blunn
- John Scales Centre for Biomedical Engineering
- Institute of Orthopaedics and Musculoskeletal Science
- Division of Surgery and Interventional Science
- University College London
- Royal National Orthopaedic Hospital
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Extracellular DNA Acidifies Biofilms and Induces Aminoglycoside Resistance in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2015; 60:544-53. [PMID: 26552982 DOI: 10.1128/aac.01650-15] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 11/04/2015] [Indexed: 12/16/2022] Open
Abstract
Biofilms consist of surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, exopolysaccharides, and proteins. Extracellular DNA (eDNA) has a structural role in the formation of biofilms, can bind and shield biofilms from aminoglycosides, and induces antimicrobial peptide resistance mechanisms. Here, we provide evidence that eDNA is responsible for the acidification of Pseudomonas aeruginosa planktonic cultures and biofilms. Further, we show that acidic pH and acidification via eDNA constitute a signal that is perceived by P. aeruginosa to induce the expression of genes regulated by the PhoPQ and PmrAB two-component regulatory systems. Planktonic P. aeruginosa cultured in exogenous 0.2% DNA or under acidic conditions demonstrates a 2- to 8-fold increase in aminoglycoside resistance. This resistance phenotype requires the aminoarabinose modification of lipid A and the production of spermidine on the bacterial outer membrane, which likely reduce the entry of aminoglycosides. Interestingly, the additions of the basic amino acid L-arginine and sodium bicarbonate neutralize the pH and restore P. aeruginosa susceptibility to aminoglycosides, even in the presence of eDNA. These data illustrate that the accumulation of eDNA in biofilms and infection sites can acidify the local environment and that acidic pH promotes the P. aeruginosa antibiotic resistance phenotype.
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Gupta P, Sarkar S, Das B, Bhattacharjee S, Tribedi P. Biofilm, pathogenesis and prevention--a journey to break the wall: a review. Arch Microbiol 2015; 198:1-15. [PMID: 26377585 DOI: 10.1007/s00203-015-1148-6] [Citation(s) in RCA: 236] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/02/2015] [Accepted: 09/07/2015] [Indexed: 01/31/2023]
Abstract
Biofilms contain group(s) of microorganisms that are found to be associated with the biotic and abiotic surfaces. Biofilms contain either homogenous or heterogeneous populations of bacteria which remain in the matrix made up of extracellular polymeric substances secreted by constituent population of the biofilm. Biofilms can be either single or multilayered. Biofilms are an increasing issue of concern that is gaining importance with each passing day. Due to the ubiquitous nature of biofilms, it is difficult to eradicate them. It has been seen that many infectious diseases harbour biofilms of bacterial pathogens as the reservoir of persisting infections which can prove fatal at times. The presence of biofilms can be seen in diseases like endocarditis, cystic fibrosis, periodontitis, rhinosinusitis and osteomyelitis. The presence of biofilms has been mostly seen in medical implants and urinary catheters. Various signalling events including two-component signalling, extra cytoplasmic function and quorum sensing are involved in the formation of biofilms. The presence of an extracellular polymeric matrix in biofilms makes it difficult for the antimicrobials to act on them and make the bacteria tolerant to antibiotics and other drugs. The aim of this review was to discuss about the basic formation of a biofilm, various signalling cascades involved in biofilm formation, possible mechanisms of drug resistance in biofilms and recent therapeutic approaches involved in successful eradication of biofilms.
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Affiliation(s)
- Priya Gupta
- Department of Molecular Biology and Bioinformatics, Tripura University (A Central University), Suryamaninagar, Agartala, Tripura, 799022, India.
| | - Subhasis Sarkar
- Department of Molecular Biology and Bioinformatics, Tripura University (A Central University), Suryamaninagar, Agartala, Tripura, 799022, India.
| | - Bannhi Das
- Department of Biotechnology, Mount Carmel College, Bangalore, 560 052, India.
| | - Surajit Bhattacharjee
- Department of Molecular Biology and Bioinformatics, Tripura University (A Central University), Suryamaninagar, Agartala, Tripura, 799022, India.
| | - Prosun Tribedi
- Department of Microbiology, Assam Don Bosco University, Guwahati, Assam, 781017, India.
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Biofilm-related infections: bridging the gap between clinical management and fundamental aspects of recalcitrance toward antibiotics. Microbiol Mol Biol Rev 2015; 78:510-43. [PMID: 25184564 DOI: 10.1128/mmbr.00013-14] [Citation(s) in RCA: 779] [Impact Index Per Article: 86.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Surface-associated microbial communities, called biofilms, are present in all environments. Although biofilms play an important positive role in a variety of ecosystems, they also have many negative effects, including biofilm-related infections in medical settings. The ability of pathogenic biofilms to survive in the presence of high concentrations of antibiotics is called "recalcitrance" and is a characteristic property of the biofilm lifestyle, leading to treatment failure and infection recurrence. This review presents our current understanding of the molecular mechanisms of biofilm recalcitrance toward antibiotics and describes how recent progress has improved our capacity to design original and efficient strategies to prevent or eradicate biofilm-related infections.
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67
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Cao B, Christophersen L, Thomsen K, Sønderholm M, Bjarnsholt T, Jensen PØ, Høiby N, Moser C. Antibiotic penetration and bacterial killing in a Pseudomonas aeruginosa biofilm model. J Antimicrob Chemother 2015; 70:2057-63. [PMID: 25786481 DOI: 10.1093/jac/dkv058] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 02/12/2015] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Treating biofilm infections successfully is a challenge. We hypothesized that biofilms may be considered as independent compartments with particular pharmacokinetics. We therefore studied the pharmacokinetics and pharmacodynamics of tobramycin in a seaweed alginate-embedded biofilm model. METHODS Seaweed alginate beads containing Pseudomonas aeruginosa were cultured in LB medium, sampled at day 1, 3, 5 or 7 and examined for the effect of treatment with tobramycin for 30 min. Treated beads were homogenized and the number of cfu was determined. The antibiotic concentration in the solution of homogenized beads was measured. Finally, beads were examined for live cells by Syto9 staining and for dead cells by propidium iodide staining using a confocal laser scanning microscope. RESULTS The antibiotic level in each bead was relatively stable (range 30-42 mg/L; MIC = 1.5 mg/L). There were fewer cfu in the tobramycin-treated beads than the non-treated beads (P < 0.016) and bacterial killing was reduced as the culture period increased from 1 to 7 days. Throughout the study period, increasing size and more superficial positioning of the microcolonies within the beads were demonstrated by confocal laser scanning microscopy. More dead cells (measured by propidium iodide staining) were observed in the treated group of beads, which supports the results obtained by culture. CONCLUSIONS The present study, simulating the clinical pharmacokinetics of tobramycin, demonstrates fast absorption of tobramycin in an in vitro biofilm model. In addition, this model system enables parallel investigation of pharmacokinetics and pharmacodynamics, providing a model for testing new treatment strategies.
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Affiliation(s)
- Bao Cao
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | | | - Kim Thomsen
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Majken Sønderholm
- Institute of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Bjarnsholt
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark Institute of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | | | - Niels Høiby
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
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Rafii F, Hart ME. Antimicrobial resistance in clinically important biofilms. World J Pharmacol 2015; 4:31-46. [DOI: 10.5497/wjp.v4.i1.31] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/22/2014] [Accepted: 12/17/2014] [Indexed: 02/06/2023] Open
Abstract
A biofilm contains a consortium of cohesive bacterial cells forming a complex structure that is a sedentary, but dynamic, community. Biofilms adhere on biotic and abiotic surfaces, including the surfaces of practically all medical devices. Biofilms are reported to be responsible for approximately 60% of nosocomial infections due to implanted medical devices, such as intravenous catheters, and they also cause other foreign-body infections and chronic infections. The presence of biofilm on a medical device may result in the infection of surrounding tissues and failure of the device, necessitating the removal and replacement of the device. Bacteria from biofilms formed on medical devices may be released and disperse, with the potential for the formation of new biofilms in other locations and the development of a systemic infection. Regardless of their location, bacteria in biofilms are tolerant of the activities of the immune system, antimicrobial agents, and antiseptics. Concentrations of antimicrobial agents sufficient to eradicate planktonic cells have no effect on the same microorganism in a biofilm. Depending on the microbial consortium or component of the biofilm that is involved, various combinations of factors have been suggested to explain the recalcitrant nature of biofilms toward killing by antibiotics. In this mini-review, some of the factors contributing to antimicrobial resistance in biofilms are discussed.
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69
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Reighard KP, Hill DB, Dixon GA, Worley B, Schoenfisch MH. Disruption and eradication of P. aeruginosa biofilms using nitric oxide-releasing chitosan oligosaccharides. BIOFOULING 2015; 31:775-87. [PMID: 26610146 PMCID: PMC4695972 DOI: 10.1080/08927014.2015.1107548] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Biofilm disruption and eradication were investigated as a function of nitric oxide- (NO) releasing chitosan oligosaccharide dose and the results compared with control (i.e., non-NO-releasing) chitosan oligosaccharides and tobramycin. Quantification of biofilm expansion/contraction and multiple-particle tracking microrheology were used to assess the structural integrity of the biofilm before and after antibacterial treatment. While tobramycin had no effect on the physical properties of the biofilm, NO-releasing chitosan oligosaccharides exhibited dose-dependent behavior with biofilm degradation. Control chitosan oligosaccharides increased biofilm elasticity, indicating that the scaffold may mitigate the biofilm disrupting power of nitric oxide somewhat. The results from this study indicate that nitric oxide-releasing chitosan oligosaccharides act as dual-action therapeutics capable of eradicating and physically disrupting P. aeruginosa biofilms.
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Affiliation(s)
- Katelyn P. Reighard
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - David B. Hill
- The Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Graham A. Dixon
- The Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Brittany Worley
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Mark H. Schoenfisch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
- Corresponding author.
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Justo JA, Bookstaver PB. Antibiotic lock therapy: review of technique and logistical challenges. Infect Drug Resist 2014; 7:343-63. [PMID: 25548523 PMCID: PMC4271721 DOI: 10.2147/idr.s51388] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Antibiotic lock therapy (ALT) for the prevention and treatment of catheter-related bloodstream infections is a simple strategy in theory, yet its real-world application may be delayed or avoided due to technical questions and/or logistical challenges. This review focuses on these latter aspects of ALT, including preparation information for a variety of antibiotic lock solutions (ie, aminoglycosides, beta-lactams, fluoroquinolones, folate antagonists, glycopeptides, glycylcyclines, lipopeptides, oxazolidinones, polymyxins, and tetracyclines) and common clinical issues surrounding ALT administration. Detailed data regarding concentrations, additives, stability/compatibility, and dwell times are summarized. Logistical challenges such as lock preparation procedures, use of additives (eg, heparin, citrate, or ethylenediaminetetraacetic acid), timing of initiation and therapy duration, optimal dwell time and catheter accessibility, and risks of ALT are also described. Development of local protocols is recommended in order to avoid these potential barriers and encourage utilization of ALT where appropriate.
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Affiliation(s)
- Julie Ann Justo
- Department of Clinical Pharmacy and Outcomes Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, SC, USA
| | - P Brandon Bookstaver
- Department of Clinical Pharmacy and Outcomes Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, SC, USA
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71
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Extracellular DNA impedes the transport of vancomycin in Staphylococcus epidermidis biofilms preexposed to subinhibitory concentrations of vancomycin. Antimicrob Agents Chemother 2014; 58:7273-82. [PMID: 25267673 DOI: 10.1128/aac.03132-14] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Staphylococcus epidermidis biofilm formation is responsible for the persistence of orthopedic implant infections. Previous studies have shown that exposure of S. epidermidis biofilms to sub-MICs of antibiotics induced an increased level of biofilm persistence. BODIPY FL-vancomycin (a fluorescent vancomycin conjugate) and confocal microscopy were used to show that the penetration of vancomycin through sub-MIC-vancomycin-treated S. epidermidis biofilms was impeded compared to that of control, untreated biofilms. Further experiments showed an increase in the extracellular DNA (eDNA) concentration in biofilms preexposed to sub-MIC vancomycin, suggesting a potential role for eDNA in the hindrance of vancomycin activity. Exogenously added, S. epidermidis DNA increased the planktonic vancomycin MIC and protected biofilm cells from lethal vancomycin concentrations. Finally, isothermal titration calorimetry (ITC) revealed that the binding constant of DNA and vancomycin was 100-fold higher than the previously reported binding constant of vancomycin and its intended cellular d-Ala-d-Ala peptide target. This study provides an explanation of the eDNA-based mechanism of antibiotic tolerance in sub-MIC-vancomycin-treated S. epidermidis biofilms, which might be an important factor for the persistence of biofilm infections.
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72
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Park AJ, Surette MD, Khursigara CM. Antimicrobial targets localize to the extracellular vesicle-associated proteome of Pseudomonas aeruginosa grown in a biofilm. Front Microbiol 2014; 5:464. [PMID: 25232353 PMCID: PMC4153316 DOI: 10.3389/fmicb.2014.00464] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 08/14/2014] [Indexed: 01/21/2023] Open
Abstract
Microbial biofilms are particularly resistant to antimicrobial therapies. These surface-attached communities are protected against host defenses and pharmacotherapy by a self-produced matrix that surrounds and fortifies them. Recent proteomic evidence also suggests that some bacteria, including the opportunistic pathogen Pseudomonas aeruginosa, undergo modifications within a biofilm that make them uniquely resistant compared to their planktonic (free-living) counterparts. This study examines 50 proteins in the resistance subproteome of both surface-associated and free-living P. aeruginosa PAO1 over three time points. Proteins were grouped into categories based on their roles in antimicrobial: (i) binding, (ii) efflux, (iii) resistance, and (iv) susceptibility. In addition, the extracellular outer membrane vesicle-associated proteome is examined and compared between the two growth modes. We show that in whole cells between 12-24% of the proteins are present at significantly different abundance levels over time, with some proteins being unique to a specific growth mode; however, the total abundance levels in the four categories remain consistent. In contrast, marked differences are seen in the protein content of the outer membrane vesicles, which contain a greater number of drug-binding proteins in vesicles purified from late-stage biofilms. These results show how the method of analysis can impact the interpretation of proteomic data (i.e., individual proteins vs. systems), and highlight the advantage of using protein-based methods to identify potential antimicrobial resistance mechanisms in extracellular sample components. Furthermore, this information has the potential to inform the development of specific antipseudomonal therapies that quench possible drug-sequestering vesicle proteins. This strategy could serve as a novel approach for combating the high-level of antimicrobial resistance in P. aeruginosa biofilms.
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Affiliation(s)
- Amber J Park
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
| | - Matthew D Surette
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
| | - Cezar M Khursigara
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
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73
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Baker P, Ricer T, Moynihan PJ, Kitova EN, Walvoort MTC, Little DJ, Whitney JC, Dawson K, Weadge JT, Robinson H, Ohman DE, Codée JDC, Klassen JS, Clarke AJ, Howell PL. P. aeruginosa SGNH hydrolase-like proteins AlgJ and AlgX have similar topology but separate and distinct roles in alginate acetylation. PLoS Pathog 2014; 10:e1004334. [PMID: 25165982 PMCID: PMC4148444 DOI: 10.1371/journal.ppat.1004334] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 07/08/2014] [Indexed: 02/05/2023] Open
Abstract
The O-acetylation of polysaccharides is a common modification used by pathogenic organisms to protect against external forces. Pseudomonas aeruginosa secretes the anionic, O-acetylated exopolysaccharide alginate during chronic infection in the lungs of cystic fibrosis patients to form the major constituent of a protective biofilm matrix. Four proteins have been implicated in the O-acetylation of alginate, AlgIJF and AlgX. To probe the biological function of AlgJ, we determined its structure to 1.83 Å resolution. AlgJ is a SGNH hydrolase-like protein, which while structurally similar to the N-terminal domain of AlgX exhibits a distinctly different electrostatic surface potential. Consistent with other SGNH hydrolases, we identified a conserved catalytic triad composed of D190, H192 and S288 and demonstrated that AlgJ exhibits acetylesterase activity in vitro. Residues in the AlgJ signature motifs were found to form an extensive network of interactions that are critical for O-acetylation of alginate in vivo. Using two different electrospray ionization mass spectrometry (ESI-MS) assays we compared the abilities of AlgJ and AlgX to bind and acetylate alginate. Binding studies using defined length polymannuronic acid revealed that AlgJ exhibits either weak or no detectable polymer binding while AlgX binds polymannuronic acid specifically in a length-dependent manner. Additionally, AlgX was capable of utilizing the surrogate acetyl-donor 4-nitrophenyl acetate to catalyze the O-acetylation of polymannuronic acid. Our results, combined with previously published in vivo data, suggest that the annotated O-acetyltransferases AlgJ and AlgX have separate and distinct roles in O-acetylation. Our refined model for alginate acetylation places AlgX as the terminal acetlytransferase and provides a rationale for the variability in the number of proteins required for polysaccharide O-acetylation. Bacteria utilize many defense strategies to protect themselves against external forces. One mechanism used by the bacterium Pseudomonas aeruginosa is the production of the long sugar polymer alginate. The bacteria use this polymer to form a biofilm – a barrier to protect against antibiotics and the host immune response. During its biosynthesis alginate undergoes a chemical modification whereby acetate is added to the polymer. Acetylation of alginate is important as this modification makes the bacterial biofilm less susceptible to recognition and clearance by the host immune system. In this paper we present the atomic structure of AlgJ; one of four proteins required for O-acetylation of the polymer. AlgJ is structurally similar to AlgX, which we have shown previously is also required for alginate acetylation. To understand why both enzymes are required for O-acetylation we functionally characterized the proteins and found that although AlgJ exhibits acetylesterase activity – catalyzing the removal of acetyl groups from a surrogate substrate – it does not bind to short mannuornic acid polymers. In contrast, AlgX bound alginate in a length-dependent manner and was capable of transfering acetate from a surrogate substrate onto alginate. This has allowed us to not only understand how acetate is added to alginate, but increases our understanding of how acetate is added to other bacterial sugar polymers.
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Affiliation(s)
- Perrin Baker
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tyler Ricer
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Patrick J. Moynihan
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Elena N. Kitova
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | | | - Dustin J. Little
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - John C. Whitney
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Karen Dawson
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Joel T. Weadge
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Howard Robinson
- Photon Sciences Division, Brookhaven National Laboratory, Upton, New York, United States of America
| | - Dennis E. Ohman
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center and McGuire Veterans Affairs Medical Center, Richmond, Virginia, United States of America
| | - Jeroen D. C. Codée
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - John S. Klassen
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Anthony J. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - P. Lynne Howell
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Abstract
Cystic fibrosis is characterised by chronic polymicrobial infection and inflammation in the airways of patients. Antibiotic treatment regimens, targeting recognised pathogens, have substantially contributed to increased life expectancy of patients with this disease. Although the emergence of antimicrobial resistance and selection of highly antibiotic-resistant bacterial strains is of major concern, the clinical relevance in cystic fibrosis is yet to be defined. Resistance has been identified in recognised cystic fibrosis pathogens and in other bacteria (eg, Prevotella and Streptococcus spp) detected in the airway microbiota, but their role in the pathophysiology of infection and inflammation in chronic lung disease is unclear. Increased antibiotic resistance in cystic fibrosis might be attributed to a range of complex factors including horizontal gene transfer, hypoxia, and biofilm formation. Strategies to manage antimicrobial resistance consist of new antibiotics or localised delivery of antimicrobial agents, iron sequestration, inhibition of quorum-sensing, and resistome analysis. Determination of the contributions of every bacterial species to lung health or disease in cystic fibrosis might also have an important role in the management of antibiotic resistance.
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Affiliation(s)
- Laura J Sherrard
- CF and Airways Microbiology Group, Queen's University Belfast, Belfast, UK; School of Pharmacy, Queen's University Belfast, Belfast, UK
| | - Michael M Tunney
- CF and Airways Microbiology Group, Queen's University Belfast, Belfast, UK; School of Pharmacy, Queen's University Belfast, Belfast, UK
| | - J Stuart Elborn
- CF and Airways Microbiology Group, Queen's University Belfast, Belfast, UK; Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK.
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Owlia P, Nosrati R, Alaghehbandan R, Lari AR. Antimicrobial susceptibility differences among mucoid and non-mucoid Pseudomonas aeruginosa isolates. GMS HYGIENE AND INFECTION CONTROL 2014; 9:Doc13. [PMID: 25152858 PMCID: PMC4141634 DOI: 10.3205/dgkh000233] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pseudomonas aeruginosa is one of the most important opportunistic bacteria, causing a wide variety of infections particularly in immunocompromised patients. The extracellular glycocalyx is produced in copious amounts by mucoid strains of P. aeruginosa. Mucoid and non-mucoid P. aeruginosa strains show some differences in their antimicrobial susceptibility pattern. The aim of this study was to investigate the frequency of mucoid and non-mucoid types and their antimicrobial susceptibility patterns isolated from Milad and Mostafa Khomeini Hospital in Tehran, Iran. One hundred P. aeruginosa isolates were collected which all were confirmed by conventional biochemical tests and PCR assay using specific primers for oprI and oprL lipoproteins. Mucoid and non-mucoid types of isolates were determined by culturing isolates on BHI agar containing Congo red and Muir mordant staining method. The susceptibility pattern of isolates against 23 different antibiotics was assessed using MIC sensititre susceptibility plates. Fifty of 100 of isolates were mucoid type, of which 14 isolates were from Mostafa Khomeini Hospital. Frequency of mucoid type of P. aeruginosa in Mostafa Khomeini hospital (70%) was higher than that seen in Milad hospital (45%). The statistical analysis of MICs results showed significant differences in antimicrobial resistance among mucoid and non-mucoid types (non mucoid strains showed more resistance against tested antibiotics). This may be due to the tendency of some antibiotics to attach to extracellular glycocalyx of mucoid strains.
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Affiliation(s)
- Parviz Owlia
- Molecular Microbiology Research Center (MMRC), Shahed University, Tehran, Iran
| | - Rahim Nosrati
- Molecular Microbiology Research Center (MMRC), Shahed University, Tehran, Iran
| | - Reza Alaghehbandan
- Department of Pathology and Immunology, Washington University School of Medicine, Barnes Jewish Hospital, St. Louis, MO, USA
| | - Abdolaziz Rastegar Lari
- Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran ; Department of Microbiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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76
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Differential protection from tobramycin by extracellular polymeric substances from Acinetobacter baumannii and Staphylococcus aureus biofilms. Antimicrob Agents Chemother 2014; 58:4755-61. [PMID: 24913166 DOI: 10.1128/aac.03071-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We investigated biofilms of two pathogens, Acinetobacter baumannii and Staphylococcus aureus, to characterize mechanisms by which the extracellular polymeric substance (EPS) found in biofilms can protect bacteria against tobramycin exposure. To do so, it is critical to study EPS-antibiotic interactions in a homogeneous environment without mass transfer limitations. Consequently, we developed a method to grow biofilms, harvest EPS, and then augment planktonic cultures with isolated EPS and tobramycin. We demonstrated that planktonic cultures respond differently to being treated with different types of EPS (A. baumannii versus S. aureus) in the presence of tobramycin. By harvesting EPS from the biofilms, we found that A. baumannii EPS acts as a "universal protector" by inhibiting tobramycin activity against bacterial cells regardless of species; S. aureus EPS did not show any protective ability in cell cultures. Adding Mg(2+) or Ca(2+) reduced the protective effect of A. baumannii EPS. Finally, when we selectively digested the proteins or DNA of the EPS, we found that the protective ability did not change, suggesting that neither has a significant role in protection. To the best of our knowledge, this is the first study that demonstrates how EPS protects pathogens against antibiotics in a homogeneous system without mass transfer limitations. Our results suggest that EPS protects biofilm communities, in part, by adsorbing antibiotics near the surface. This may limit antibiotic diffusion to the bottom of the biofilms but is not likely to be the only mechanism of protection.
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77
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de Melo WCMA, Avci P, de Oliveira MN, Gupta A, Vecchio D, Sadasivam M, Chandran R, Huang YY, Yin R, Perussi LR, Tegos GP, Perussi JR, Dai T, Hamblin MR. Photodynamic inactivation of biofilm: taking a lightly colored approach to stubborn infection. Expert Rev Anti Infect Ther 2014; 11:669-93. [PMID: 23879608 DOI: 10.1586/14787210.2013.811861] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Microbial biofilms are responsible for a variety of microbial infections in different parts of the body, such as urinary tract infections, catheter infections, middle-ear infections, gingivitis, caries, periodontitis, orthopedic implants, and so on. The microbial biofilm cells have properties and gene expression patterns distinct from planktonic cells, including phenotypic variations in enzymic activity, cell wall composition and surface structure, which increase the resistance to antibiotics and other antimicrobial treatments. There is consequently an urgent need for new approaches to attack biofilm-associated microorganisms, and antimicrobial photodynamic therapy (aPDT) may be a promising candidate. aPDT involves the combination of a nontoxic dye and low-intensity visible light which, in the presence of oxygen, produces cytotoxic reactive oxygen species. It has been demonstrated that many biofilms are susceptible to aPDT, particularly in dental disease. This review will focus on aspects of aPDT that are designed to increase efficiency against biofilms modalities to enhance penetration of photosensitizer into biofilm, and a combination of aPDT with biofilm-disrupting agents.
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Affiliation(s)
- Wanessa C M A de Melo
- The Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
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Hay ID, Wang Y, Moradali MF, Rehman ZU, Rehm BHA. Genetics and regulation of bacterial alginate production. Environ Microbiol 2014; 16:2997-3011. [DOI: 10.1111/1462-2920.12389] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 12/18/2013] [Accepted: 12/22/2013] [Indexed: 12/31/2022]
Affiliation(s)
- Iain D. Hay
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Yajie Wang
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Mohammed F. Moradali
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Zahid U. Rehman
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Bernd H. A. Rehm
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology; Massey University; Palmerston North 4442 New Zealand
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79
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Fothergill JL, Winstanley C, James CE. Novel therapeutic strategies to counterPseudomonas aeruginosainfections. Expert Rev Anti Infect Ther 2014; 10:219-35. [DOI: 10.1586/eri.11.168] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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80
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Sharma G, Rao S, Bansal A, Dang S, Gupta S, Gabrani R. Pseudomonas aeruginosa biofilm: Potential therapeutic targets. Biologicals 2014; 42:1-7. [DOI: 10.1016/j.biologicals.2013.11.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 11/07/2013] [Indexed: 10/26/2022] Open
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81
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Billings N, Ramirez Millan M, Caldara M, Rusconi R, Tarasova Y, Stocker R, Ribbeck K. The extracellular matrix Component Psl provides fast-acting antibiotic defense in Pseudomonas aeruginosa biofilms. PLoS Pathog 2013; 9:e1003526. [PMID: 23950711 PMCID: PMC3738486 DOI: 10.1371/journal.ppat.1003526] [Citation(s) in RCA: 206] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 06/14/2013] [Indexed: 02/01/2023] Open
Abstract
Bacteria within biofilms secrete and surround themselves with an extracellular matrix, which serves as a first line of defense against antibiotic attack. Polysaccharides constitute major elements of the biofilm matrix and are implied in surface adhesion and biofilm organization, but their contributions to the resistance properties of biofilms remain largely elusive. Using a combination of static and continuous-flow biofilm experiments we show that Psl, one major polysaccharide in the Pseudomonas aeruginosa biofilm matrix, provides a generic first line of defense toward antibiotics with diverse biochemical properties during the initial stages of biofilm development. Furthermore, we show with mixed-strain experiments that antibiotic-sensitive “non-producing” cells lacking Psl can gain tolerance by integrating into Psl-containing biofilms. However, non-producers dilute the protective capacity of the matrix and hence, excessive incorporation can result in the collapse of resistance of the entire community. Our data also reveal that Psl mediated protection is extendible to E. coli and S. aureus in co-culture biofilms. Together, our study shows that Psl represents a critical first bottleneck to the antibiotic attack of a biofilm community early in biofilm development. Many bacteria have the ability to form multicellular communities, termed biofilms. An important characteristic of a biofilm is the ability of cells to synthesize and secrete an extracellular matrix. This matrix offers structural support, community organization, and added protection, often making the cells impervious to desiccation, predation, and antimicrobials. In this study, we investigate the contributions of polysaccharide components found in the extracellular matrix of Pseudomonas aeruginosa at progressive stages in biofilm development. We first show that one specific polysaccharide, Psl, provides an added defense for P. aeruginosa biofilms against antimicrobials of different properties for young biofilms. Then, by cultivating biofilms that contain both Psl producing and Psl non-producing strains, we find that P. aeruginosa, E. coli, and S. aureus species that lack Psl take advantage of the protection offered by cells producing Psl. Collectively, the data indicate that Psl is likely to play a key protective role in early development of P. aeruginosa biofilm associated infections.
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Affiliation(s)
- Nicole Billings
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Maria Ramirez Millan
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Marina Caldara
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Roberto Rusconi
- Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Yekaterina Tarasova
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Roman Stocker
- Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Katharina Ribbeck
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
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82
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Jakobsen TH, Bjarnsholt T, Jensen PØ, Givskov M, Høiby N. Targeting quorum sensing in Pseudomonas aeruginosa biofilms: current and emerging inhibitors. Future Microbiol 2013; 8:901-21. [DOI: 10.2217/fmb.13.57] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Bacterial resistance to conventional antibiotics combined with an increasing acknowledgement of the role of biofilms in chronic infections has led to a growing interest in new antimicrobial strategies that target the biofilm mode of growth. In the aggregated biofilm mode, cell-to-cell communication systems involved in the process known as quorum sensing regulate coordinated expression of virulence with immune shielding mechanisms and antibiotic resistance. For two decades, the potential of interference with quorum sensing by small chemical compounds has been investigated with the aim of developing alternative antibacterial strategies. Here, we review state of the art research of quorum sensing inhibitors against the opportunistic human pathogen Pseudomonas aeruginosa, which is found in a number of biofilm-associated infections and identified as the predominant organism infecting the lungs of cystic fibrosis patients.
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Affiliation(s)
- Tim Holm Jakobsen
- Costerton Biofilm Center, Department of International Health, Immunology & Microbiology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Thomas Bjarnsholt
- Costerton Biofilm Center, Department of International Health, Immunology & Microbiology, University of Copenhagen, DK-2200 Copenhagen, Denmark
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Peter Østrup Jensen
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Michael Givskov
- Costerton Biofilm Center, Department of International Health, Immunology & Microbiology, University of Copenhagen, DK-2200 Copenhagen, Denmark
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Niels Høiby
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen, Denmark
- Costerton Biofilm Center, Department of International Health, Immunology & Microbiology, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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83
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Tseng BS, Zhang W, Harrison JJ, Quach TP, Song JL, Penterman J, Singh PK, Chopp DL, Packman AI, Parsek MR. The extracellular matrix protects Pseudomonas aeruginosa biofilms by limiting the penetration of tobramycin. Environ Microbiol 2013; 15:2865-78. [PMID: 23751003 DOI: 10.1111/1462-2920.12155] [Citation(s) in RCA: 246] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 05/03/2013] [Accepted: 05/07/2013] [Indexed: 01/20/2023]
Abstract
Biofilm cells are less susceptible to antimicrobials than their planktonic counterparts. While this phenomenon is multifactorial, the ability of the matrix to reduce antibiotic penetration into the biofilm is thought to be of limited importance studies suggest that antibiotics move fairly rapidly through biofilms. In this study, we monitored the transport of two clinically relevant antibiotics, tobramycin and ciprofloxacin, into non-mucoid Pseudomonas aeruginosa biofilms. To our surprise, we found that the positively charged antibiotic tobramycin is sequestered to the biofilm periphery, while the neutral antibiotic ciprofloxacin readily penetrated. We provide evidence that tobramycin in the biofilm periphery both stimulated a localized stress response and killed bacteria in these regions but not in the underlying biofilm. Although it is unclear which matrix component binds tobramycin, its penetration was increased by the addition of cations in a dose-dependent manner, which led to increased biofilm death. These data suggest that ionic interactions of tobramycin with the biofilm matrix limit its penetration. We propose that tobramycin sequestration at the biofilm periphery is an important mechanism in protecting metabolically active cells that lie just below the zone of sequestration.
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Affiliation(s)
- Boo Shan Tseng
- Department of Microbiology, University of Washington, Seattle, WA, USA
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84
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Mertens A, Ghebremedhin B. Genetic determinants and biofilm formation of clinical Staphylococcus epidermidis isolates from blood cultures and indwelling devises. Eur J Microbiol Immunol (Bp) 2013; 3:111-9. [PMID: 24265927 DOI: 10.1556/eujmi.3.2013.2.4] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 04/07/2013] [Indexed: 11/19/2022] Open
Abstract
For a long time, Staphylococcus epidermidis, as a member of the coagulase-negative staphylococci, was considered as part of the physiological skin flora of the human being with no pathogenic significance. Today, we know that S. epidermidis is one of the most prevalent causes for implant-associated and nosocomial infections. We performed pheno- and genotypic analysis (ica, IS256, SCCmec types, agr groups) of biofilm formation in 200 isolates. Fifty percent were genetically ica-positive and produced biofilm. Among all studied isolates, agr II and III and SCCmec type I were the most prevalent, whereas within the selected multi-resistant isolates (29%), agr I and III and SCCmec type II dominated. SCCmec type I and mecA-negative S. epidermidis isolates were associated with agr II. The majority of the blood culture and biopsy isolates were assigned to agr III and SCCmec type I, whereas agr II was predominantly detected in mecA-negative S. epidermidis isolated from catheter and implant materials. MLST analysis revealed the major clonal lineages of ST2, ST5, ST10, and ST242 (total 13 STs). ST2 isolates from blood cultures were icaA/D-positive and harbored SCCmec types II and III and IS256, whereas the icaA/D- and IS256-positive ST23 isolates were assigned to SCCmec types I and IV.
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85
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Penetration kinetics of four mouthrinses into Streptococcus mutans biofilms analyzed by direct time-lapse visualization. Clin Oral Investig 2013; 18:625-34. [DOI: 10.1007/s00784-013-1002-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
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86
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Martínez-Gil M, Quesada JM, Ramos-González MI, Soriano MI, de Cristóbal RE, Espinosa-Urgel M. Interplay between extracellular matrix components of Pseudomonas putida biofilms. Res Microbiol 2013; 164:382-9. [PMID: 23562948 DOI: 10.1016/j.resmic.2013.03.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Accepted: 03/19/2013] [Indexed: 11/28/2022]
Abstract
The extracellular matrix of bacterial biofilms has at least two key functions: to serve as a structural scaffold for the multicellular community, and to play a protective role against external stress. In this work, we report a compensatory effect whereby Pseudomonas putida reacts to the lack of either of the two main surface proteins involved in biofilm formation, LapA and LapF, by increasing expression and production of a species-specific EPS. Elevated levels of the second messenger molecule cyclic di-GMP alter the balance of extracellular matrix components, and the phenotypes of lapA and lapF mutants under these conditions are indicative of direct interactions taking place between large secreted proteins and exopolysaccharides. Our data suggest the existence of a mechanism by which bacteria would sense alterations in the composition of the extracellular matrix, leading to changes in expression of the different elements.
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Affiliation(s)
- Marta Martínez-Gil
- Department of Environmental Protection, Estación Experimental Del Zaidín, CSIC, Profesor Albareda, 1. Granada 18008, Spain.
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87
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Takenaka S, Ohshima H, Ohsumi T, Okiji T. Current and future strategies for the control of mature oral biofilms—Shift from a bacteria-targeting to a matrix-targeting approach. J Oral Biosci 2012. [DOI: 10.1016/j.job.2012.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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88
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Dufour D, Leung V, Lévesque CM. Bacterial biofilm: structure, function, and antimicrobial resistance. ACTA ACUST UNITED AC 2012. [DOI: 10.1111/j.1601-1546.2012.00277.x] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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89
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Klepac-Ceraj V, Patel N, Song X, Holewa C, Patel C, Kent R, Amiji MM, Soukos NS. Photodynamic effects of methylene blue-loaded polymeric nanoparticles on dental plaque bacteria. Lasers Surg Med 2012; 43:600-6. [PMID: 22057487 DOI: 10.1002/lsm.21069] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND AND OBJECTIVES Photodynamic therapy (PDT) is increasingly being explored for treatment of oral infections. Here, we investigate the effect of PDT on human dental plaque bacteria in vitro using methylene blue (MB)-loaded poly(lactic-co-glycolic) (PLGA) nanoparticles with a positive or negative charge and red light at 665 nm. STUDY DESIGN/MATERIALS AND METHODS Dental plaque samples were obtained from 14 patients with chronic periodontitis. Suspensions of plaque microorganisms from seven patients were sensitized with anionic, cationic PLGA nanoparticles (50 µg/ml equivalent to MB) or free MB (50 µg/ml) for 20 min followed by exposure to red light for 5 min with a power density of 100 mW/cm2 . Polymicrobial oral biofilms, which were developed on blood agar in 96-well plates from dental plaque inocula obtained from seven patients, were also exposed to PDT as above. Following the treatment, survival fractions were calculated by counting the number of colony-forming units. RESULTS The cationic MB-loaded nanoparticles exhibited greater bacterial phototoxicity in both planktonic and biofilm phase compared to anionic MB-loaded nanoparticles and free MB, but results were not significantly different (P > 0.05). CONCLUSION Cationic MB-loaded PLGA nanoparticles have the potential to be used as carriers of MB for PDT systems.
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Affiliation(s)
- Vanja Klepac-Ceraj
- Applied Molecular Photomedicine Laboratory, The Forsyth Institute, Cambridge, Massachusetts 02142, USA
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90
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Alavi M, Stojadinovic A, Izadjoo M. An overview of biofilm and its detection in clinical samples. J Wound Care 2012; 21:376-83. [DOI: 10.12968/jowc.2012.21.8.376] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- M.R. Alavi
- Diagnostics and Translational Research Center, Henry M. Jackson Foundation for Advancement of Military Medicine, Maryland, USA
- Combat Wound Initiative Program, Maryland, USA
| | - A. Stojadinovic
- Combat Wound Initiative Program, Maryland, USA
- Uniformed Services University of the Health Sciences, Maryland, USA
| | - M.J. Izadjoo
- Diagnostics and Translational Research Center, Henry M. Jackson Foundation for Advancement of Military Medicine, Maryland, USA
- Combat Wound Initiative Program, Maryland, USA
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91
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Correlative time-resolved fluorescence microscopy to assess antibiotic diffusion-reaction in biofilms. Antimicrob Agents Chemother 2012; 56:3349-58. [PMID: 22450986 DOI: 10.1128/aac.00216-12] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The failure of antibiotics to inactivate in vivo pathogens organized in biofilms has been shown to trigger chronic infections. In addition to mechanisms involving specific genetic or physiological cell properties, antibiotic sorption and/or reaction with biofilm components may lessen the antibiotic bioavailability and consequently decrease their efficiency. To assess locally and accurately the antibiotic diffusion-reaction, we used for the first time a set of advanced fluorescence microscopic tools (fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and fluorescence lifetime imaging) that offer a spatiotemporal resolution not available with the commonly used time-lapse confocal imaging method. This set of techniques was used to characterize the dynamics of fluorescently labeled vancomycin in biofilms formed by two Staphylococcus aureus human isolates. We demonstrate that, at therapeutic concentrations of vancomycin, the biofilm matrix was not an obstacle to the diffusion-reaction of the antibiotic that can reach all cells through the biostructure.
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92
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Naghmouchi K, Le Lay C, Baah J, Drider D. Antibiotic and antimicrobial peptide combinations: synergistic inhibition of Pseudomonas fluorescens and antibiotic-resistant variants. Res Microbiol 2011; 163:101-8. [PMID: 22172555 DOI: 10.1016/j.resmic.2011.11.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 11/04/2011] [Indexed: 10/15/2022]
Abstract
Variants resistant to penicillin G (RvP), streptomycin (RvS), lincomycin (RvL) and rifampicin (RvR) were developed from a colistin-sensitive isolate of Pseudomonas fluorescens LRC-R73 (P. fluorescens). Cell fatty acid composition, K(+) efflux and sensitivity to antimicrobial peptides (nisin Z, pediocin PA-1/AcH and colistin) alone or combined with antibiotics were determined. P. fluorescens was highly sensitive to kanamycin, tetracycline and chloramphenicol at minimal inhibitory concentrations of 0.366, 0.305 and 0.732 μg/ml respectively. P. fluorescens, RvP, RvS, RvL and RvR were resistant to nisin Z and pediocin PA-1/AcH at concentrations ≥100 μg/ml but sensitive to colistin at 0.076, 0.043, 0.344, 0.344 and 0.258 μg/ml respectively. A synergistic inhibitory effect (FICI ≤0.5) was observed when resistant variants were treated with peptide/antibiotic combinations. No significant effect on K(+) efflux from the resistant variants in the presence of antibiotics or peptides alone or combined was observed. The proportion of C16:0 was significantly higher in antibiotic-resistant variants than in the parent strain, accounting for 32.3%, 46.49%, 43.3%, 40.1% and 44.1% of the total fatty acids in P. fluorescens, RvP, RvS, RvL and RvR respectively. Combination of antibiotics with antimicrobial peptides could allow reduced use of antibiotics in medical applications and could help slow the emergence of bacteria resistant to antibiotics.
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Affiliation(s)
- Karim Naghmouchi
- Lethbridge Research Center, Agricultureg and Agri-Food Canada, Lethbridge, AB, Canada.
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93
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Naves P, Del Prado G, Ponte C, Soriano F. Differences in the in vitro susceptibility of planktonic and biofilm-associated Escherichia coli strains to antimicrobial agents. J Chemother 2011; 22:312-7. [PMID: 21123153 DOI: 10.1179/joc.2010.22.5.312] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The in vitro susceptibility of seven Escherichia coli biofilm-producing strains in their planktonic and biofilm-associated forms to amoxicillin, amoxicillin/clavulanic acid, cefotaxime, gentamicin, and ciprofloxacin was studied. Minimum inhibitory concentrations (MICs) were determined by the standard microdilution method and by the Alamar blue assay (providing the AB-MIC) at two levels of metabolic suppression and using standard and large inocula. Minimal biofilm inhibitory concentrations (AB-MBICs) on preformed biofilms on polystyrene plates were higher than the MICs and AB-MICs. Differences in magnitude depended on the antibiotic, strain, inoculum size, and the level of suppression of metabolism. Ciprofloxacin and gentamicin showed the greatest differences in the AB-MBIC as compared to AB-MIC. the possibility of antibiotic-resistant mutant selection within the biofilms was ruled out since bacteria recovered from the biofilm maintained the same MICs as before exposure to the antimicrobial agents. E. coli biofilms were much less sensitive than their planktonic counterparts.
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Affiliation(s)
- P Naves
- Department of Medical Microbiology and Antimicrobial Chemotherapy, Fundación Jiménez Díaz, Madrid, Spain.
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94
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Hogardt M, Heesemann J. Microevolution of Pseudomonas aeruginosa to a chronic pathogen of the cystic fibrosis lung. Curr Top Microbiol Immunol 2011; 358:91-118. [PMID: 22311171 DOI: 10.1007/82_2011_199] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Pseudomonas aeruginosa is the leading pathogen of chronic cystic fibrosis (CF) lung infection. Life-long persistance of P. aeruginosa in the CF lung requires a sophisticated habitat-specific adaptation of this pathogen to the heterogeneous and fluctuating lung environment. Due to the high selective pressure of inflamed CF lungs, P. aeruginosa increasingly experiences complex physiological and morphological changes. Pulmonary adaptation of P. aeruginosa is mediated by genetic variations that are fixed by the repeating interplay of mutation and selection. In this context, the emergence of hypermutable phenotypes (mutator strains) obviously improves the microevolution of P. aeruginosa to the diverse microenvironments of the CF lung. Mutator phenotypes are amplified during CF lung disease and accelerate the intraclonal diversification of P. aeruginosa. The resulting generation of numerous subclonal variants is advantegous to prepare P. aeruginosa population for unpredictable stresses (insurance hypothesis) and thus supports long-term survival of this pathogen. Oxygen restriction within CF lung environment further promotes persistence of P. aeruginosa due to increased antibiotic tolerance, alginate production and biofilm formation. Finally, P. aeruginosa shifts from an acute virulent pathogen of early infection to a host-adapted chronic virulent pathogen of end-stage infection of the CF lung. Common changes that are observed among chronic P. aeruginosa CF isolates include alterations in surface antigens, loss of virulence-associated traits, increasing antibiotic resistances, the overproduction of the exopolysaccharide alginate and the modulation of intermediary and micro-aerobic metabolic pathways (Hogardt and Heesemann, Int J Med Microbiol 300(8):557-562, 2010). Loss-of-function mutations in mucA and lasR genes determine the transition to mucoidity and loss of quorum sensing, which are hallmarks of the chronic virulence potential of P. aeruginosa. Metabolic factors that are positively selected in response to the specific environment of CF lung include the outer membrane protein OprF, the microaerophilic oxidase Cbb3-2, the blue copper protein azurin, the cytochrome c peroxidase c551 and the enzymes of the arginine deiminase pathway ArcA-ArcD. These metabolic adaptations probably support the growth of P. aeruginosa within oxygen-depleted CF mucus. The deeper understanding of the physiological mechanisms of niche specialization of P. aeruginosa during CF lung infection will help to identify new targets for future anti-pseudomonal treatment strategies to prevent the selection of mutator isolates and the establishment of chronic CF lung infection.
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Affiliation(s)
- Michael Hogardt
- Department of Infectiology, Bavarian Health and Food Safety Authority, Oberschleissheim, Germany.
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95
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González A, Shirokova L, Pokrovsky O, Emnova E, Martínez R, Santana-Casiano J, González-Dávila M, Pokrovski G. Adsorption of copper on Pseudomonas aureofaciens: Protective role of surface exopolysaccharides. J Colloid Interface Sci 2010; 350:305-14. [DOI: 10.1016/j.jcis.2010.06.020] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 06/07/2010] [Accepted: 06/09/2010] [Indexed: 10/19/2022]
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96
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Abstract
Aminoglycosides have been an essential component of the armamentarium in the treatment of life-threatening infections. Unfortunately, their efficacy has been reduced by the surge and dissemination of resistance. In some cases the levels of resistance reached the point that rendered them virtually useless. Among many known mechanisms of resistance to aminoglycosides, enzymatic modification is the most prevalent in the clinical setting. Aminoglycoside modifying enzymes catalyze the modification at different -OH or -NH₂ groups of the 2-deoxystreptamine nucleus or the sugar moieties and can be nucleotidyltransferases, phosphotransferases, or acetyltransferases. The number of aminoglycoside modifying enzymes identified to date as well as the genetic environments where the coding genes are located is impressive and there is virtually no bacteria that is unable to support enzymatic resistance to aminoglycosides. Aside from the development of new aminoglycosides refractory to as many as possible modifying enzymes there are currently two main strategies being pursued to overcome the action of aminoglycoside modifying enzymes. Their successful development would extend the useful life of existing antibiotics that have proven effective in the treatment of infections. These strategies consist of the development of inhibitors of the enzymatic action or of the expression of the modifying enzymes.
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97
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Biofilm formation by the human pathogen Neisseria meningitidis. Med Microbiol Immunol 2010; 199:173-83. [PMID: 20376486 DOI: 10.1007/s00430-010-0149-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Indexed: 10/19/2022]
Abstract
The past decade has seen an increasing interest in biofilm formation by Neisseria meningitidis, a human facultative pathogen causing life-threatening childhood disease commencing from asymptomatic nasopharyngeal colonization. Studying the biology of in vitro biofilm formation improves the understanding of inter-bacterial processes in asymptomatic carriage, of bacterial aggregate formation on host cells, and of meningococcal population biology. This paper reviews publications referring to meningococcal biofilm formation with an emphasis on the role of motility and of extracellular DNA. The theory of sub-dividing the meningococcal population in settler and spreader lineages is discussed, which provides a mechanistic framework for the assumed balance of colonization efficacy and transmission frequency.
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98
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Laverty G, McLaughlin M, Shaw C, Gorman SP, Gilmore BF. Antimicrobial activity of short, synthetic cationic lipopeptides. Chem Biol Drug Des 2010; 75:563-9. [PMID: 20374251 DOI: 10.1111/j.1747-0285.2010.00973.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The increasing emergence of multidrug-resistant micro-organisms presents one of the greatest challenges in the clinical management of infectious diseases. Therefore, novel antimicrobial agents are urgently required to address this issue. In this report, we describe the solid phase synthesis, characterization, microbiological and toxicological evaluation of a library of ultrashort cationic antimicrobial lipopeptides based on the previously described tetrapeptide amide H-Orn-Orn-Trp-Trp-NH2 conjugated with saturated fatty acids which have inherent antimicrobial activity. The microbiological activity of these ultrashort cationic lipopeptides, which exhibit excellent, broad-spectrum antimicrobial activity against a number of clinically important pathogenic bacteria and fungi, including multidrug resistant micro-organisms in both planktonic and sessile (biofilm) cultures is reported.
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Affiliation(s)
- Garry Laverty
- Biomaterials Research Group, School of Pharmacy, Queens University of Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT97BL, UK
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99
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Fong IW. New perspectives of infections in cardiovascular disease. Curr Cardiol Rev 2009; 5:87-104. [PMID: 20436849 PMCID: PMC2805819 DOI: 10.2174/157340309788166679] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 09/27/2008] [Accepted: 09/27/2008] [Indexed: 12/02/2022] Open
Abstract
Infections have been recognized as significant causes of cardiac diseases for many decades. Various microorganisms have been implicated in the etiology of these diseases involving all classes of microbial agents. All components of the heart structure can be affected by infectious agents, i.e. pericardium, myocardium, endocardium, valves, autonomic nervous system, and some evidence of coronary arteries. A new breed of infections have evolved over the past three decades involving cardiac implants and this group of cardiac infectious complications will likely continue to increase in the future, as more mechanical devices are implanted in the growing ageing population. This article will review the progress made in the past decade on understanding the pathobiology of these infectious complications of the heart, through advances in genomics and proteomics, as well as potential novel approach for therapy.An up-to-date, state-of-the-art review and controversies will be outlined for the following conditions: (i) perimyocarditis; (ii) infective endocarditis; (iii) cardiac device infections; (iv) coronary artery disease and potential role of infections.
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Affiliation(s)
- Ignatius W Fong
- University of Toronto, Division of Infectious Diseases, St. Michaels’ Hospital, 4CC 179 Cardinal Carter Wing, 30 Bond St., Toronto, Ontario, M5B 1W8, Canada
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100
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Dror N, Mandel M, Hazan Z, Lavie G. Advances in microbial biofilm prevention on indwelling medical devices with emphasis on usage of acoustic energy. SENSORS (BASEL, SWITZERLAND) 2009; 9:2538-54. [PMID: 22574031 PMCID: PMC3348827 DOI: 10.3390/s90402538] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 03/27/2009] [Accepted: 04/14/2009] [Indexed: 12/12/2022]
Abstract
Microbial biofilms are a major impediment to the use of indwelling medical devices, generating device-related infections with high morbidity and mortality. Major efforts directed towards preventing and eradicating the biofilm problem face difficulties because biofilms protect themselves very effectively by producing a polysaccharide coating, reducing biofilm sensitivity to antimicrobial agents. Techniques applied to combating biofilms have been primarily chemical. These have met with partial and limited success rates, leading to current trends of eradicating biofilms through physico-mechanical strategies. Here we review the different approaches that have been developed to control biofilm formation and removal, focusing on the utilization of acoustic energy to achieve these objectives.
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Affiliation(s)
- Naama Dror
- Department of Cellular and Developmental Biology, Tel-Aviv University, Tel-Aviv, Israel; E-mail: (N.D)
| | - Mathilda Mandel
- Blood Center, Sheba Medical Center, Tel-Hashomer, Israel; E-mail: (M.M)
| | - Zadik Hazan
- Regenera Pharma Ltd., Rehovot, Israel; E-mail: (Z.H)
| | - Gad Lavie
- Department of Cellular and Developmental Biology, Tel-Aviv University, Tel-Aviv, Israel; E-mail: (N.D)
- Blood Center, Sheba Medical Center, Tel-Hashomer, Israel; E-mail: (M.M)
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