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Abstract
INTRODUCTION Biofilm formation represents a protected mode of growth that renders bacterial cells less susceptible to antimicrobials and to killing by host immune effector mechanisms and so enables the pathogens to survive in hostile environments and also to disperse and colonize new niches. Biofilm disease includes device-related infections, chronic infections in the absence of a foreign body, and even malfunction of medical devices. Areas covered: This review puts forward a new medical entity that represents a major public health issue, which we have named 'biofilm-related disease'. We highlight the characteristics of biofilm disease including its pathogenesis, microbiological features, clinical presentation, and treatment challenges. Expert commentary: The diversity of biofilm-associated infections is increasing over time and its impact may be underestimated. This peculiar form of development endows associated bacteria with a high tolerance to conventional antimicrobial agents. A small percentage of persister cells developing within the biofilm is known to be highly tolerant to antibiotics and has typically been involved in causing relapse of infections. Knowledge of the pivotal role played by biofilm-growing microorganisms in related infections will provide new treatment dynamics for this biofilm-related disease.
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Affiliation(s)
- Jose Luis Del Pozo
- a Infectious Diseases Division , Clínica Universidad de Navarra , Pamplona , Spain.,b Department of Clinical Microbiology , Clínica Universidad de Navarra , Pamplona , Spain.,c Laboratory of Microbial Biofilms , Clínica Universidad de Navarra , Pamplona , Spain
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202
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Schultz G, Bjarnsholt T, James GA, Leaper DJ, McBain AJ, Malone M, Stoodley P, Swanson T, Tachi M, Wolcott RD. Consensus guidelines for the identification and treatment of biofilms in chronic nonhealing wounds. Wound Repair Regen 2017; 25:744-757. [PMID: 28960634 DOI: 10.1111/wrr.12590] [Citation(s) in RCA: 191] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 09/11/2017] [Indexed: 12/13/2022]
Abstract
BACKGROUND Despite a growing consensus that biofilms contribute to a delay in the healing of chronic wounds, conflicting evidence pertaining to their identification and management can lead to uncertainty regarding treatment. This, in part, has been driven by reliance on in vitro data or animal models, which may not directly correlate to clinical evidence on the importance of biofilms. Limited data presented in human studies have further contributed to the uncertainty. Guidelines for care of chronic wounds with a focus on biofilms are needed to help aid the identification and management of biofilms, providing a clinical focus to support clinicians in improving patient care through evidence-based medicine. METHODS A Global Wound Biofilm Expert Panel, comprising 10 clinicians and researchers with expertise in laboratory and clinical aspects of biofilms, was identified and convened. A modified Delphi process, based on published scientific data and expert opinion, was used to develop consensus statements that could help identify and treat biofilms as part of the management of chronic nonhealing wounds. Using an electronic survey, panel members rated their agreement with statements about biofilm identification and treatment, and the management of chronic nonhealing wounds. Final consensus statements were agreed on in a face-to-face meeting. RESULTS Participants reached consensus on 61 statements in the following topic areas: understanding biofilms and the problems they cause clinicians; current diagnostic options; clinical indicators of biofilms; future options for diagnostic tests; treatment strategies; mechanical debridement; topical antiseptics; screening antibiofilm agents; and levels of evidence when choosing antibiofilm treatments. CONCLUSION This consensus document attempts to clarify misunderstandings about the role of biofilms in clinical practice, and provides a basis for clinicians to recognize biofilms in chronic nonhealing wounds and manage patients optimally. A new paradigm for wound care, based on a stepped-down treatment approach, was derived from the consensus statements.
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Affiliation(s)
- Gregory Schultz
- Department of Obstetrics & Gynecology, Institute for Wound Research, University of Florida, Gainesville, Florida
| | - Thomas Bjarnsholt
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Microbiology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Garth A James
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana
| | - David J Leaper
- Clinical Sciences, University of Huddersfield, Huddersfield, United Kingdom
| | - Andrew J McBain
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Matthew Malone
- Liverpool Hospital, South West Sydney LHD, Sydney, New South Wales, Australia.,LIVEDIAB, Ingham Institute of Applied Medical Research, Sydney, New South Wales, Australia
| | - Paul Stoodley
- Departments of Microbial Infection and Immunity, and Orthopaedics, Ohio State University, Columbus, Ohio
| | | | - Masahiro Tachi
- Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Tohoku University, Sendai, Japan
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203
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204
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Johani K, Malone M, Jensen S, Gosbell I, Dickson H, Hu H, Vickery K. Microscopy visualisation confirms multi-species biofilms are ubiquitous in diabetic foot ulcers. Int Wound J 2017; 14:1160-1169. [PMID: 28643380 PMCID: PMC7949972 DOI: 10.1111/iwj.12777] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/17/2017] [Indexed: 12/22/2022] Open
Abstract
Increasing evidence within the literature has identified the presence of biofilms in chronic wounds and proposed that they contribute to delayed wound healing. This research aimed to investigate the presence of biofilm in diabetic foot ulcers (DFUs) using microscopy and molecular approaches and define if these are predominantly mono- or multi-species. Secondary objectives were to correlate wound observations against microscopy results in ascertaining if clinical cues are useful in detecting wound biofilm. DFU tissue specimens were obtained from 65 subjects. Scanning electron microscopy (SEM) and peptide nucleic acid fluorescent in situ hybridisation (PNA-FISH) techniques with confocal laser scanning microscopy (CLSM) were used to visualise biofilm structures. Next-generation DNA sequencing was performed to explore the microbial diversity. Clinical cues that included the presence of slough, excessive exudate, a gel material on the wound bed that reforms quickly following debridement, poor granulation and pyocyanin were correlated to microscopy results. Of the 65 DFU specimens evaluated by microscopy, all were characterised as containing biofilm (100%, P < 0·001). The presence of both mono-species and multi-species biofilms within the same tissue sections were detected, even when DNA sequencing analysis of DFU specimens revealed diverse polymicrobial communities. No clinical correlations were identified to aid clinicians in identifying wound biofilm. Microscopy visualisation, when combined with molecular approaches, confirms biofilms are ubiquitous in DFUs and form either mono- or multi-species biofilms. Clinical cues to aid clinicians in detecting wound biofilm are not accurate for use in DFUs. A paradigm shift of managing DFUs needs to consider anti-biofilm strategies.
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Affiliation(s)
- Khalid Johani
- Surgical Infection Research Group, Faculty of Medicine and Health SciencesMacquarie UniversitySydneyNSWAustralia
- Central Military Laboratories and Blood Bank, Prince Sultan Military Medical CityRiyadhSaudi Arabia
| | - Matthew Malone
- Infectious Diseases and Microbiology, School of MedicineWestern Sydney UniversitySydneyNSWAustralia
- Liverpool Diabetes Collaborative Research Unit, Ingham Institute of Applied Medical ResearchSydneyNSWAustralia
- High Risk Foot ServiceLiverpool Hospital, South West Sydney LHDSydneyNSWAustralia
| | - Slade Jensen
- Infectious Diseases and Microbiology, School of MedicineWestern Sydney UniversitySydneyNSWAustralia
- Antimicrobial Resistance and Mobile Elements Group, Ingham Institute of Applied Medical ResearchSydneyNSWAustralia
| | - Iain Gosbell
- Infectious Diseases and Microbiology, School of MedicineWestern Sydney UniversitySydneyNSWAustralia
- Antimicrobial Resistance and Mobile Elements Group, Ingham Institute of Applied Medical ResearchSydneyNSWAustralia
| | - Hugh Dickson
- Liverpool Diabetes Collaborative Research Unit, Ingham Institute of Applied Medical ResearchSydneyNSWAustralia
- South Western Sydney Clinical School, Faculty of MedicineUniversity of New South WalesSydneyNSWAustralia
- Ambulatory Care Department (PIXI)Liverpool Hospital, South West Sydney LHDSydneyNSWAustralia
| | - Honhua Hu
- Surgical Infection Research Group, Faculty of Medicine and Health SciencesMacquarie UniversitySydneyNSWAustralia
| | - Karen Vickery
- Surgical Infection Research Group, Faculty of Medicine and Health SciencesMacquarie UniversitySydneyNSWAustralia
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205
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Starr AE, Deeke SA, Li L, Zhang X, Daoud R, Ryan J, Ning Z, Cheng K, Nguyen LVH, Abou-Samra E, Lavallée-Adam M, Figeys D. Proteomic and Metaproteomic Approaches to Understand Host–Microbe Interactions. Anal Chem 2017; 90:86-109. [DOI: 10.1021/acs.analchem.7b04340] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Amanda E. Starr
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Shelley A. Deeke
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Leyuan Li
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Xu Zhang
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Rachid Daoud
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - James Ryan
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Zhibin Ning
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Kai Cheng
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Linh V. H. Nguyen
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Elias Abou-Samra
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Mathieu Lavallée-Adam
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Daniel Figeys
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
- Molecular Architecture of Life Program, Canadian Institute for Advanced Research, Toronto, Ontario, M5G 1M1, Canada
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206
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Malone M, Swanson T. Biofilm-based wound care: the importance of debridement in biofilm treatment strategies. Br J Community Nurs 2017; 22:S20-S25. [PMID: 28570133 DOI: 10.12968/bjcn.2017.22.sup6.s20] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Matthew Malone
- High Risk Foot Service, Liverpool Hospital, South West Sydney LHD; Liverpool Diabetes Collaborative Research Unit, Ingham Institute of Applied Medical Research; Medical Sciences Research Group, Infectious Diseases and Microbiology, Faculty of Medicine Western Sydney University
| | - Terry Swanson
- South West Healthcare, Warrnambool, Victoria, Australia
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207
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Alvarado-Gomez E, Perez-Diaz M, Valdez-Perez D, Ruiz-Garcia J, Magaña-Aquino M, Martinez-Castañon G, Martinez-Gutierrez F. Adhesion forces of biofilms developed in vitro from clinical strains of skin wounds. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2017; 82:336-344. [PMID: 29025667 DOI: 10.1016/j.msec.2017.08.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 07/08/2017] [Accepted: 08/10/2017] [Indexed: 11/16/2022]
Abstract
A biofilm is a very complex consortium formed by a mix of different microorganisms, which have become an important health problem, because its formation is a resistance mechanism used by bacteria against antibiotics or the immune system. In this work, we show differences between some physicochemical properties of biofilms in mono- and multi-species, formed by bacteria from clinical samples of infected chronic wounds. Of the most prevalent bacteria in wounds, two mono- and one multi-species biofilms were developed in vitro by Drip Flow Reactor: one biofilm was developed by S. aureus, other by P. aeruginosa, and a third one by the mix of both strains. With these biofilms, we determined microbial growth by plate counting, and their physicochemical characterization by Atomic Force Microscopy, Raman Micro-Spectroscopy and Scanning Electron Microscopy. We found that the viability of S. aureus was less than P. aeruginosa in multi-species biofilm. However, the adhesion force of S. aureus is much higher than that of P. aeruginosa, but it decreased while that of P. aeruginosa increased in the multi-species biofilm. In addition, we found free pyrimidines functional groups in the P. aeruginosa biofilm and its mix with S. aureus. Surprisingly, each bacterium alone formed single layer biofilms, while the mix bacteria formed a multilayer biofilm at the same observation time. Our results show the necessity to evaluate biofilms from clinically isolated strains and have a better understanding of the adhesion forces of bacteria in biofilm multispecies, which could be of prime importance in developing more effective treatments against biofilm formation.
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Affiliation(s)
- Elizabeth Alvarado-Gomez
- Microbiology Laboratory, Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava No. 6, CP 78210 San Luis Potosi, S.L.P., Mexico
| | - Mario Perez-Diaz
- Microbiology Laboratory, Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava No. 6, CP 78210 San Luis Potosi, S.L.P., Mexico
| | - Donato Valdez-Perez
- Instituto Politecnico Nacional, UPALM, Edif. Z-4 3er Piso, CP 07738 Mexico D.F., Mexico
| | - Jaime Ruiz-Garcia
- Biological Physics Laboratory, Instituto de Fisica, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava No. 6, CP 78210 San Luis Potosi, S.L.P., Mexico
| | - Martin Magaña-Aquino
- Infectology Department, Hospital Central "Dr. Ignacio Morones Prieto", Av. Venustiano Carranza No. 2395, Zona Universitaria, CP 78290 San Luis Potosi, S.L.P., Mexico
| | - Gabriel Martinez-Castañon
- Facultad de Estomatologia, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava No. 6, CP 78210 San Luis Potosi, S.L.P., Mexico
| | - Fidel Martinez-Gutierrez
- Microbiology Laboratory, Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava No. 6, CP 78210 San Luis Potosi, S.L.P., Mexico.
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208
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A broad range quorum sensing inhibitor working through sRNA inhibition. Sci Rep 2017; 7:9857. [PMID: 28851971 PMCID: PMC5575346 DOI: 10.1038/s41598-017-09886-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/21/2017] [Indexed: 11/15/2022] Open
Abstract
For the last decade, chemical control of bacterial virulence has received considerable attention. Ajoene, a sulfur-rich molecule from garlic has been shown to reduce expression of key quorum sensing regulated virulence factors in the opportunistic pathogen Pseudomonas aeruginosa. Here we show that the repressing effect of ajoene on quorum sensing occurs by inhibition of small regulatory RNAs (sRNA) in P. aeruginosa as well as in Staphylococcus aureus, another important human pathogen that employs quorum sensing to control virulence gene expression. Using various reporter constructs, we found that ajoene lowered expression of the sRNAs RsmY and RsmZ in P. aeruginosa and the small dual-function regulatory RNA, RNAIII in S. aureus, that controls expression of key virulence factors. We confirmed the modulation of RNAIII by RNA sequencing and found that the expression of many QS regulated genes encoding virulence factors such as hemolysins and proteases were lowered in the presence of ajoene in S. aureus. Importantly, our findings show that sRNAs across bacterial species potentially may qualify as targets of anti-virulence therapy and that ajoene could be a lead structure in search of broad-spectrum compounds transcending the Gram negative-positive borderline.
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209
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Abstract
Polymicrobial interactions are complex and can influence the course of an infection, as is the case when two or more species exhibit a synergism that produces a disease state not seen with any of the individual species alone. Cell-to-cell signaling is key to many of these interactions, but little is understood about how the host environment influences polymicrobial interactions or signaling between bacteria. Chronic wounds are typically polymicrobial, with Staphylococcus aureus and Pseudomonas aeruginosa being the two most commonly isolated species. While P. aeruginosa readily kills S. aureusin vitro, the two species can coexist for long periods together in chronic wound infections. In this study, we investigated the ability of components of the wound environment to modulate interactions between P. aeruginosa and S. aureus We demonstrate that P. aeruginosa quorum sensing is inhibited by physiological levels of serum albumin, which appears to bind and sequester some homoserine lactone quorum signals, resulting in the inability of P. aeruginosa to produce virulence factors that kill S. aureus These data could provide important clues regarding the virulence of P. aeruginosa in albumin-depleted versus albumin-rich infection sites and an understanding of the nature of friendly versus antagonistic interactions between P. aeruginosa and S. aureus.
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210
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Barker JC, Khansa I, Gordillo GM. A Formidable Foe Is Sabotaging Your Results: What You Should Know about Biofilms and Wound Healing. Plast Reconstr Surg 2017; 139:1184e-1194e. [PMID: 28445380 DOI: 10.1097/prs.0000000000003325] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
LEARNING OBJECTIVES After reading this article, the participant should be able to: 1. Describe biofilm pathogenesis as it relates to problem wounds. 2. Understand the preclinical and clinical evidence implicating biofilm in problem wounds. 3. Explain the diagnostic and treatment challenges that biofilms create for problem wounds. 4. Demonstrate a basic understanding of emerging strategies aimed at counteracting these processes. SUMMARY Biofilm represents a protected mode of growth for bacteria, allowing them to evade standard diagnostic techniques and avoid eradication by standard therapies. Although only recently discovered, biofilm has existed for millennia and complicates nearly every aspect of medicine. Biofilm impacts wound healing by allowing bacteria to evade immune responses, prolonging inflammation and disabling skin barrier function. It is important to understand why problem wounds persist despite state-of-the-art treatment, why they are difficult to accurately diagnose, and why they recur. The aim of this article is to focus on current gaps in knowledge related to problem wounds, specifically, biofilm infection.
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Affiliation(s)
- Jenny C Barker
- Columbus, Ohio.,From the Department of Plastic Surgery, Comprehensive Wound Center, The Ohio State University
| | - Ibrahim Khansa
- Columbus, Ohio.,From the Department of Plastic Surgery, Comprehensive Wound Center, The Ohio State University
| | - Gayle M Gordillo
- Columbus, Ohio.,From the Department of Plastic Surgery, Comprehensive Wound Center, The Ohio State University
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211
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Costa AM, Mergulhão FJ, Briandet R, Azevedo NF. It is all about location: how to pinpoint microorganisms and their functions in multispecies biofilms. Future Microbiol 2017; 12:987-999. [PMID: 28745517 DOI: 10.2217/fmb-2017-0053] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Multispecies biofilms represent the dominant mode of life for the vast majority of microorganisms. Bacterial spatial localization in such biostructures governs ecological interactions between different populations and triggers the overall community functions. Here, we discuss the pros and cons of fluorescence-based techniques used to decipher bacterial species patterns in biofilms at single cell level, including fluorescence in situ hybridization and the use of genetically modified bacteria that express fluorescent proteins, reporting the significant improvements of those techniques. The development of tools for spatial and temporal study of multispecies biofilms will allow live imaging and spatial localization of cells in naturally occurring biofilms coupled with metabolic information, increasing insight of microbial community and the relation between its structure and functions.
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Affiliation(s)
- Angela M Costa
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal.,i3S - Instituto de Investigação e Inovação em Saúde, University of Porto, Portugal.,INEB - Institute of Biomedical Engineering, University of Porto, Porto, Portugal
| | - Filipe J Mergulhão
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
| | - Romain Briandet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Nuno F Azevedo
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
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212
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Saliva-Derived Host Defense Peptides Histatin1 and LL-37 Increase Secretion of Antimicrobial Skin and Oral Mucosa Chemokine CCL20 in an IL-1 α-Independent Manner. J Immunol Res 2017; 2017:3078194. [PMID: 28815185 PMCID: PMC5549474 DOI: 10.1155/2017/3078194] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/19/2017] [Indexed: 11/23/2022] Open
Abstract
Even though skin and oral mucosae are continuously in contact with commensal and opportunistic microorganisms, they generally remain healthy and uninflamed. Host defense peptides (HDPs) make up the body's first line of defense against many invading pathogens and are involved in the orchestration of innate immunity and the inflammatory response. In this study, we investigated the effect of two salivary HDPs, LL-37 and Hst1, on the inflammatory and antimicrobial response by skin and oral mucosa (gingiva) keratinocytes and fibroblasts. The potent antimicrobial chemokine CCL20 was investigated and compared with chemokines CCL2, CXCL1, CXCL8, and CCL27 and proinflammatory cytokines IL-1α and IL-6. Keratinocyte-fibroblast cocultures showed a synergistic increase in CCL20 secretion upon Hst1 and LL-37 exposure compared to monocultures. These cocultures also showed increased IL-6, CXCL1, CXCL8, and CCL2 secretion, which was IL-1α dependent. Secretion of the antimicrobial chemokine CCL20 was clearly IL-1α independent. These results indicate that salivary peptides can stimulate skin as well as gingiva cells to secrete antimicrobial chemokines as part of the hosts' defense to counteract infection.
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213
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Zautner AE, Groß U, Emele MF, Hagen RM, Frickmann H. More Pathogenicity or Just More Pathogens?-On the Interpretation Problem of Multiple Pathogen Detections with Diagnostic Multiplex Assays. Front Microbiol 2017; 8:1210. [PMID: 28706515 PMCID: PMC5489565 DOI: 10.3389/fmicb.2017.01210] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 06/14/2017] [Indexed: 12/15/2022] Open
Abstract
Modern molecular diagnostic approaches in the diagnostic microbiological laboratory like real-time quantitative polymerase chain reaction (qPCR) have led to a considerable increase of diagnostic sensitivity. They usually outperform the diagnostic sensitivity of culture-based approaches. Culture-based diagnostics were found to be insufficiently sensitive for the assessment of the composition of biofilms in chronic wounds and poorly standardized for screenings for enteric colonization with multi-drug resistant bacteria. However, the increased sensitivity of qPCR causes interpretative challenges regarding the attribution of etiological relevance to individual pathogen species in case of multiple detections of facultative pathogenic microorganisms in primarily non-sterile sample materials. This is particularly the case in high-endemicity settings, where continuous exposition to respective microorganisms leads to immunological adaptation and semi-resistance while considerable disease would result in case of exposition of a non-adapted population. While biofilms in chronic wounds show higher pathogenic potential in case of multi-species composition, detection of multiple pathogens in respiratory samples is much more difficult to interpret and asymptomatic enteric colonization with facultative pathogenic microorganisms is frequently observed in high endemicity settings. For respiratory samples and stool samples, cycle-threshold-value-based semi-quantitative interpretation of qPCR results has been suggested. Etiological relevance is assumed if cycle-threshold values are low, suggesting high pathogen loads. Although the procedure is challenged by lacking standardization and methodical issues, first evaluations have led to promising results. Future studies should aim at generally acceptable quantitative cut-off values to allow discrimination of asymptomatic colonization from clinically relevant infection.
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Affiliation(s)
- Andreas E. Zautner
- Institut für Medizinische Mikrobiologie, Universitätsmedizin GöttingenGöttingen, Germany
| | - Uwe Groß
- Institut für Medizinische Mikrobiologie, Universitätsmedizin GöttingenGöttingen, Germany
| | - Matthias F. Emele
- Institut für Medizinische Mikrobiologie, Universitätsmedizin GöttingenGöttingen, Germany
| | - Ralf M. Hagen
- Abteilung A Lehre Gesundheitsversorgung, Sanitätsakademie der BundeswehrMünchen, Germany
| | - Hagen Frickmann
- Fachbereich Tropenmedizin am Bernhard-Nocht Institut, Bundeswehrkrankenhaus HamburgHamburg, Germany
- Institut für Medizinische Mikrobiologie, Virologie und Hygiene, Universitätsmedizin RostockRostock, Germany
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214
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Abstract
The skin microbiome exists in dynamic equilibrium with the host, but when the skin is compromised, bacteria can colonize the wound and impair wound healing. Thus, the interplay between normal skin microbial interactions versus pathogenic microbial interactions in wound repair is important. Bacteria are recognized by innate host pattern recognition receptors, and we previously showed an important role for the pattern recognition receptor NOD2 in skin wound repair. NOD2 is implicated in changes in the composition of the intestinal microbiota in Crohn’s disease, but its role on skin microbiota is unknown. Nod2-deficient (Nod2–/–) mice had an inherently altered skin microbiome compared with wild-type controls. Furthermore, we found that Nod2–/– skin microbiome dominated and caused impaired healing, shown in cross-fostering experiments of wild-type pups with Nod2–/– pups, which then acquired altered cutaneous bacteria and delayed healing. High-throughput sequencing and quantitative real-time PCR showed a significant compositional shift, specifically in the genus Pseudomonas in Nod2–/– mice. To confirm whether Pseudomonas species directly impair wound healing, wild-type mice were infected with Pseudomonas aeruginosa biofilms and, akin to Nod2–/– mice, were found to exhibit a significant delay in wound repair. Collectively, these studies show the importance of the microbial communities in skin wound healing outcome.
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215
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Ibberson CB, Stacy A, Fleming D, Dees JL, Rumbaugh K, Gilmore MS, Whiteley M. Co-infecting microorganisms dramatically alter pathogen gene essentiality during polymicrobial infection. Nat Microbiol 2017; 2:17079. [PMID: 28555625 PMCID: PMC5774221 DOI: 10.1038/nmicrobiol.2017.79] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 04/14/2017] [Indexed: 11/09/2022]
Abstract
Identifying genes required by pathogens during infection is critical for antimicrobial development. Here, we use a Monte Carlo simulation-based method to analyse high-throughput transposon sequencing data to determine the role of infection site and co-infecting microorganisms on the in vivo 'essential' genome of Staphylococcus aureus. We discovered that co-infection of murine surgical wounds with Pseudomonas aeruginosa results in conversion of ∼25% of the in vivo S. aureus mono-culture essential genes to non-essential. Furthermore, 182 S. aureus genes are uniquely essential during co-infection. These 'community dependent essential' (CoDE) genes illustrate the importance of studying pathogen gene essentiality in polymicrobial communities.
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Affiliation(s)
- Carolyn B. Ibberson
- Department of Molecular Biosciences, Institute of Cellular and Molecular Biology, LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX, USA
| | - Apollo Stacy
- Department of Molecular Biosciences, Institute of Cellular and Molecular Biology, LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX, USA
| | - Derek Fleming
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Justine L. Dees
- Department of Molecular Biosciences, Institute of Cellular and Molecular Biology, LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX, USA
| | - Kendra Rumbaugh
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Michael S. Gilmore
- Department of Ophthalmology and Department of Microbiology and Immunobiology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - Marvin Whiteley
- Department of Molecular Biosciences, Institute of Cellular and Molecular Biology, LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX, USA
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216
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Abstract
Chronic polymicrobial infections are associated with increased virulence compared to monospecies infections. However, our understanding of microbial dynamics during polymicrobial infection is limited. A recent study by Limoli and colleagues (D. H. Limoli, G. B. Whitfield, T. Kitao, M. L. Ivey, M. R. Davis, Jr., et al., mBio 8:e00186-17, 2017, https://doi.org/10.1128/mBio.00186-17) provides insight into a mechanism that may contribute to the coexistence of Pseudomonas aeruginosa and Staphylococcus aureus in the cystic fibrosis (CF) lung. CF lung infections have frequently been used to investigate microbial interactions due to both the complex polymicrobial community and chronic nature of these infections. The hypothesis of Limoli et al. is that the conversion of P. aeruginosa to its mucoidy phenotype during chronic CF infection promotes coexistence by diminishing its ability to kill S. aureus Highlighting a new facet of microbial interaction between two species that are traditionally thought of as competitors, this study provides a platform for studying community assembly in a relevant infection setting.
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217
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Biofilm is a Major Virulence Determinant in Bacterial Colonization of Chronic Skin Ulcers Independently from the Multidrug Resistant Phenotype. Int J Mol Sci 2017; 18:ijms18051077. [PMID: 28513576 PMCID: PMC5454986 DOI: 10.3390/ijms18051077] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 05/06/2017] [Accepted: 05/11/2017] [Indexed: 01/28/2023] Open
Abstract
Bacterial biofilm is a major factor in delayed wound healing and high levels of biofilm production have been repeatedly described in multidrug resistant organisms (MDROs). Nevertheless, a quantitative correlation between biofilm production and the profile of antimicrobial drug resistance in delayed wound healing remains to be determined. Microbial identification, antibiotic susceptibility and biofilm production were assessed in 135 clinical isolates from 87 patients. Gram-negative bacteria were the most represented microorganisms (60.8%) with MDROs accounting for 31.8% of the total isolates. Assessment of biofilm production revealed that 80% of the strains were able to form biofilm. A comparable level of biofilm production was found with both MDRO and not-MDRO with no significant differences between groups. All the methicillin-resistant Staphylococcus aureus (MRSA) and 80% of Pseudomonas aeruginosa MDR strains were found as moderate/high biofilm producers. Conversely, less than 17% of Klebsiella pneumoniae extended-spectrum beta-lactamase (ESBL), Escherichia coli-ESBL and Acinetobacter baumannii were moderate/high biofilm producers. Notably, those strains classified as non-biofilm producers, were always associated with biofilm producer bacteria in polymicrobial colonization. This study shows that biofilm producers were present in all chronic skin ulcers, suggesting that biofilm represents a key virulence determinant in promoting bacterial persistence and chronicity of ulcerative lesions independently from the MDRO phenotype.
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218
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The Fitness of Pseudomonas aeruginosa Quorum Sensing Signal Cheats Is Influenced by the Diffusivity of the Environment. mBio 2017; 8:mBio.00353-17. [PMID: 28465424 PMCID: PMC5414003 DOI: 10.1128/mbio.00353-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Experiments examining the social dynamics of bacterial quorum sensing (QS) have focused on mutants which do not respond to signals and the role of QS-regulated exoproducts as public goods. The potential for QS signal molecules to themselves be social public goods has received much less attention. Here, we analyze how signal-deficient (lasI) mutants of the opportunistic pathogen Pseudomonas aeruginosa interact with wild-type cells in an environment where QS is required for growth. We show that when growth requires a "private" intracellular metabolic mechanism activated by the presence of QS signal, lasI mutants act as social cheats and outcompete signal-producing wild-type bacteria in mixed cultures, because they can exploit the signals produced by wild-type cells. However, reducing the ability of signal molecules to diffuse through the growth medium results in signal molecules becoming less accessible to mutants, leading to reduced cheating. Our results indicate that QS signal molecules can be considered social public goods in a way that has been previously described for other exoproducts but that spatial structuring of populations reduces exploitation by noncooperative signal cheats.IMPORTANCE Bacteria communicate via signaling molecules to regulate the expression of a whole range of genes. This process, termed quorum sensing (QS), moderates bacterial metabolism under many environmental conditions, from soil and water (where QS-regulated genes influence nutrient cycling) to animal hosts (where QS-regulated genes determine pathogen virulence). Understanding the ecology of QS could therefore yield vital clues to how we might modify bacterial behavior for environmental or clinical gains. Here, we demonstrate that QS signals act as shareable public goods. This means that their evolution, and therefore population-level responses to interference with QS, will be constrained by population structure. Further, we show that environmental structure (constraints on signal diffusion) alters the accessibility of QS signals and demonstrates that we need to consider population and environmental structure to help us further our understanding of QS signaling systems.
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219
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Yadav MK, Chae SW, Go YY, Im GJ, Song JJ. In vitro Multi-Species Biofilms of Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa and Their Host Interaction during In vivo Colonization of an Otitis Media Rat Model. Front Cell Infect Microbiol 2017; 7:125. [PMID: 28459043 PMCID: PMC5394157 DOI: 10.3389/fcimb.2017.00125] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 03/27/2017] [Indexed: 01/30/2023] Open
Abstract
Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) are known to cause biofilm-related infections. MRSA and PA have been frequently isolated from chronically infected wounds, cystic fibrosis, chronic suppurative otitis media (CSOM), and from indwelling medical devices, and these bacteria co-exist; however, their interaction with each-other or with the host is not well known. In this study, we investigated MRSA and PA multi-species biofilm communities in vitro and their interaction with the host during in vivo colonization using an OM rat-model. In-vitro biofilm formation and in-vivo colonization were studied using CV-microtiter plate assay and OM rat-model respectively. The biofilms were viewed under scanning electron microscope and bacteria were enumerated using cfu counts. The differential gene expressions of rat mucosa colonized with single or multi-species of MRSA or PA were studied using RNA-sequencing of total transcriptome. In multi-species in-vitro biofilms PA partially inhibited SA growth. However, no significant inhibition of MRSA was detected during in-vivo colonization of multi-species in rat bullae. A total of 1,797 genes were significantly (p < 0.05) differentially expressed in MRSA or PA or MRSA + PA colonized rat middle ear mucosa with respect to the control. The poly-microbial colonization of MRSA and PA induced the differential expression of a significant number of genes that are involved in immune response, inflammation, signaling, development, and defense; these were not expressed with single species colonization by either MRSA or PA. Genes involved in defense, immune response, inflammatory response, and developmental process were exclusively up-regulated, and genes that are involved in nervous system signaling, development and transmission, regulation of cell growth and development, anatomical and system development, and cell differentiation were down-regulated after multi-species inoculation. These results indicate that poly-microbial colonization induces a host response that is different from that induced by single species infection.
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Affiliation(s)
- Mukesh K Yadav
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea.,Institute for Medical Device Clinical Trials, Korea University College of MedicineSeoul, South Korea
| | - Sung-Won Chae
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea
| | - Yoon Young Go
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea
| | - Gi Jung Im
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea
| | - Jae-Jun Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea
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220
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Pseudomonas aeruginosa Aggregate Formation in an Alginate Bead Model System Exhibits In Vivo-Like Characteristics. Appl Environ Microbiol 2017; 83:AEM.00113-17. [PMID: 28258141 PMCID: PMC5394317 DOI: 10.1128/aem.00113-17] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 02/23/2017] [Indexed: 11/20/2022] Open
Abstract
Alginate beads represent a simple and highly reproducible in vitro model system for diffusion-limited bacterial growth. In this study, alginate beads were inoculated with Pseudomonas aeruginosa and followed for up to 72 h. Confocal microscopy revealed that P. aeruginosa formed dense clusters similar in size to in vivo aggregates observed ex vivo in cystic fibrosis lungs and chronic wounds. Bacterial aggregates primarily grew in the bead periphery and decreased in size and abundance toward the center of the bead. Microsensor measurements showed that the O2 concentration decreased rapidly and reached anoxia ∼100 μm below the alginate bead surface. This gradient was relieved in beads supplemented with NO3− as an alternative electron acceptor allowing for deeper growth into the beads. A comparison of gene expression profiles between planktonic and alginate-encapsulated P. aeruginosa confirmed that the bacteria experienced hypoxic and anoxic growth conditions. Furthermore, alginate-encapsulated P. aeruginosa exhibited a lower respiration rate than the planktonic counterpart and showed a high tolerance toward antibiotics. The inoculation and growth of P. aeruginosa in alginate beads represent a simple and flexible in vivo-like biofilm model system, wherein bacterial growth exhibits central features of in vivo biofilms. This was observed by the formation of small cell aggregates in a secondary matrix with O2-limited growth, which was alleviated by the addition of NO3− as an alternative electron acceptor, and by reduced respiration rates, as well as an enhanced tolerance to antibiotic treatment. IMPORTANCEPseudomonas aeruginosa has been studied intensively for decades due to its involvement in chronic infections, such as cystic fibrosis and chronic wounds, where it forms biofilms. Much research has been dedicated to biofilm formation on surfaces; however, in chronic infections, most biofilms form small aggregates of cells not attached to a surface, but embedded in host material. In this study, bacteria were encapsulated in small alginate beads and formed aggregates similar to what is observed in chronic bacterial infections. Our findings show that aggregates are exposed to steep oxygen gradients, with zones of oxygen depletion, and that nitrate may serve as an alternative to oxygen, enabling growth in oxygen-depleted zones. This is important, as slow growth under low-oxygen conditions may render the bacteria tolerant toward antibiotics. This model provides an alternative to surface biofilm models and adds to the comprehension that biofilms do not depend on a surface for formation.
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221
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Hotterbeekx A, Kumar-Singh S, Goossens H, Malhotra-Kumar S. In vivo and In vitro Interactions between Pseudomonas aeruginosa and Staphylococcus spp. Front Cell Infect Microbiol 2017; 7:106. [PMID: 28421166 PMCID: PMC5376567 DOI: 10.3389/fcimb.2017.00106] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 03/16/2017] [Indexed: 01/04/2023] Open
Abstract
The significance of polymicrobial infections is increasingly being recognized especially in a biofilm context wherein multiple bacterial species—including both potential pathogens and members of the commensal flora—communicate, cooperate, and compete with each other. Two important bacterial pathogens that have developed a complex network of evasion, counter-inhibition, and subjugation in their battle for space and nutrients are Pseudomonas aeruginosa and Staphylococcus aureus. Their strain- and environment-specific interactions, for instance in the cystic fibrosis lung or in wound infections, show severe competition that is generally linked to worse patient outcomes. For instance, the extracellular factors secreted by P. aeruginosa have been shown to subjugate S. aureus to persist as small colony variants (SCVs). On the other hand, data also exist where S. aureus inhibits biofilm formation by P. aeruginosa but also protects the pathogen by inhibiting its phagocytosis. Interestingly, such interspecies interactions differ between the planktonic and biofilm phenotype, with the extracellular matrix components of the latter likely being a key, and largely underexplored, influence. This review attempts to understand the complex relationship between P. aeruginosa and Staphylococcus spp., focusing on S. aureus, that not only is interesting from the bacterial evolution point of view, but also has important consequences for our understanding of the disease pathogenesis for better patient management.
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Affiliation(s)
- An Hotterbeekx
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of AntwerpWilrijk, Belgium
| | - Samir Kumar-Singh
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of AntwerpWilrijk, Belgium.,Molecular Pathology Group, Cell Biology and Histology, University of AntwerpWilrijk, Belgium
| | - Herman Goossens
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of AntwerpWilrijk, Belgium
| | - Surbhi Malhotra-Kumar
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of AntwerpWilrijk, Belgium
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222
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Rahim K, Saleha S, Zhu X, Huo L, Basit A, Franco OL. Bacterial Contribution in Chronicity of Wounds. MICROBIAL ECOLOGY 2017; 73:710-721. [PMID: 27742997 DOI: 10.1007/s00248-016-0867-9] [Citation(s) in RCA: 230] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/21/2016] [Indexed: 05/11/2023]
Abstract
A wound is damage of a tissue usually caused by laceration of a membrane, generally the skin. Wound healing is accomplished in three stages in healthy individuals, including inflammatory, proliferative, and remodeling stages. Healing of wounds normally starts from the inflammatory phase and ends up in the remodeling phase, but chronic wounds remain in an inflammatory stage and do not show progression due to some specific reasons. Chronic wounds are classified in different categories, such as diabetic foot ulcer (DFU), venous leg ulcers (VLU) and pressure ulcer (PU), surgical site infection (SSI), abscess, or trauma ulcers. Globally, the incidence rate of DFU is 1-4 % and prevalence rate is 5.3-10.5 %. However, colonization of pathogenic bacteria at the wound site is associated with wound chronicity. Most chronic wounds contain more than one bacterial species and produce a synergetic effect that results in previously non-virulent bacterial species becoming virulent and causing damage to the host. While investigating bacterial diversity in chronic wounds, Staphylococcus, Pseudomonas, Peptoniphilus, Enterobacter, Stenotrophomonas, Finegoldia, and Serratia were found most frequently in chronic wounds. Recently, it has been observed that bacteria in chronic wounds develop biofilms that contribute to a delay in healing. In a mature biofilm, bacteria grow slowly due to deficiency of nutrients that results in the resistance of bacteria to antibiotics. The present review reflects the reasons why acute wounds become chronic. Interesting findings include the bacterial load, which forms biofilms and shows high-level resistance toward antibiotics, which is a threat to human health in general and particularly to some patients who have acute wounds.
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Affiliation(s)
- Kashif Rahim
- Institute of Biochemistry and Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Shamim Saleha
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology (KUST), Khyber Pakhtunkhwa Kohat, 26000, Pakistan
| | - Xudong Zhu
- Institute of Biochemistry and Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Liang Huo
- Institute of Biochemistry and Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Abdul Basit
- College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Octavio Luiz Franco
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brazil, 70790-160, Brazil.
- S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, CEP 79.117-900, Brazil.
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223
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Limoli DH, Whitfield GB, Kitao T, Ivey ML, Davis MR, Grahl N, Hogan DA, Rahme LG, Howell PL, O'Toole GA, Goldberg JB. Pseudomonas aeruginosa Alginate Overproduction Promotes Coexistence with Staphylococcus aureus in a Model of Cystic Fibrosis Respiratory Infection. mBio 2017; 8:e00186-17. [PMID: 28325763 PMCID: PMC5362032 DOI: 10.1128/mbio.00186-17] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 02/22/2017] [Indexed: 01/30/2023] Open
Abstract
While complex intra- and interspecies microbial community dynamics are apparent during chronic infections and likely alter patient health outcomes, our understanding of these interactions is currently limited. For example, Pseudomonas aeruginosa and Staphylococcus aureus are often found to coinfect the lungs of patients with cystic fibrosis (CF), yet these organisms compete under laboratory conditions. Recent observations that coinfection correlates with decreased health outcomes necessitate we develop a greater understanding of these interbacterial interactions. In this study, we tested the hypothesis that P. aeruginosa and/or S. aureus adopts phenotypes that allow coexistence during infection. We compared competitive interactions of P. aeruginosa and S. aureus isolates from mono- or coinfected CF patients employing in vitro coculture models. P. aeruginosa isolates from monoinfected patients were more competitive toward S. aureus than P. aeruginosa isolates from coinfected patients. We also observed that the least competitive P. aeruginosa isolates possessed a mucoid phenotype. Mucoidy occurs upon constitutive activation of the sigma factor AlgT/U, which regulates synthesis of the polysaccharide alginate and dozens of other secreted factors, including some previously described to kill S. aureus Here, we show that production of alginate in mucoid strains is sufficient to inhibit anti-S. aureus activity independent of activation of the AlgT regulon. Alginate reduces production of siderophores, 2-heptyl-4-hydroxyquinolone-N-oxide (HQNO), and rhamnolipids-each required for efficient killing of S. aureus These studies demonstrate alginate overproduction may be an important factor driving P. aeruginosa coinfection with S. aureusIMPORTANCE Numerous deep-sequencing studies have revealed the microbial communities present during respiratory infections in cystic fibrosis (CF) patients are diverse, complex, and dynamic. We now face the challenge of determining the influence of these community dynamics on patient health outcomes and identifying candidate targets to modulate these interactions. We make progress toward this goal by determining that the polysaccharide alginate produced by mucoid strains of P. aeruginosa is sufficient to inhibit multiple secreted antimicrobial agents produced by this organism. Importantly, these secreted factors are required to outcompete S. aureus, when the microbes are grown in coculture; thus we propose a mechanism whereby mucoid P. aeruginosa can coexist with S. aureus Finally, the approach used here can serve as a platform to investigate the interactions among other CF pathogens.
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Affiliation(s)
- Dominique H Limoli
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Tomoe Kitao
- Department of Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, USA
- Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
- Shriners Hospitals for Children Boston, Boston, Massachusetts, USA
| | - Melissa L Ivey
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Michael R Davis
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Nora Grahl
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Deborah A Hogan
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Laurence G Rahme
- Department of Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, USA
- Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
- Shriners Hospitals for Children Boston, Boston, Massachusetts, USA
| | - P Lynne Howell
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - George A O'Toole
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Joanna B Goldberg
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
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224
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Ngba Essebe C, Visvikis O, Fines-Guyon M, Vergne A, Cattoir V, Lecoustumier A, Lemichez E, Sotto A, Lavigne JP, Dunyach-Remy C. Decrease of Staphylococcus aureus Virulence by Helcococcus kunzii in a Caenorhabditis elegans Model. Front Cell Infect Microbiol 2017; 7:77. [PMID: 28361041 PMCID: PMC5352687 DOI: 10.3389/fcimb.2017.00077] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 02/27/2017] [Indexed: 12/30/2022] Open
Abstract
Social bacterial interactions are considered essential in numerous infectious diseases, particularly in wounds. Foot ulcers are a common complication in diabetic patients and these ulcers become frequently infected. This infection is usually polymicrobial promoting cell-to-cell communications. Staphylococcus aureus is the most prevalent pathogen isolated. Its association with Helcococcus kunzii, commensal Gram-positive cocci, is frequently described. The aim of this study was to assess the impact of co-infection on virulence of both H. kunzii and S. aureus strains in a Caenorhabditis elegans model. To study the host response, qRT-PCRs targeting host defense genes were performed. We observed that H. kunzii strains harbored a very low (LT50: 5.7 days ± 0.4) or an absence of virulence (LT50: 6.9 days ± 0.5). In contrast, S. aureus strains (LT50: 2.9 days ± 0.4) were significantly more virulent than all H. kunzii (P < 0.001). When H. kunzii and S. aureus strains were associated, H. kunzii significantly reduced the virulence of the S. aureus strain in nematodes (LT50 between 4.4 and 5.2 days; P < 0.001). To evaluate the impact of these strains on host response, transcriptomic analysis showed that the ingestion of S. aureus led to a strong induction of defense genes (lys-5, sodh-1, and cyp-37B1) while H. kunzii did not. No statistical difference of host response genes expression was observed when C. elegans were infected with either S. aureus alone or with S. aureus + H. kunzii. Moreover, two well-characterized virulence factors (hla and agr) present in S. aureus were down-regulated when S. aureus were co-infected with H. kunzii. This study showed that H. kunzii decreased the virulence of S. aureus without modifying directly the host defense response. Factor(s) produced by this bacterium modulating the staphylococci virulence must be investigated.
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Affiliation(s)
- Christelle Ngba Essebe
- Institut National de la Santé et de la Recherche Médicale, U1047, UFR de Médecine, Université de Montpellier Nîmes, France
| | - Orane Visvikis
- Team Microbial Toxins in Host Pathogen Interactions, Centre Méditerranéen de Médecine Moléculaire, C3M, Institut National de la Santé et de la Recherche Médicale, U1065 Nice, France
| | - Marguerite Fines-Guyon
- Service de Microbiologie, CHU de CaenCaen, France; CNR de la Résistance aux Antibiotiques (Laboratoire Associé Entérocoques et Résistances Particulières chez les Bactéries à Gram Positif)Caen, France
| | - Anne Vergne
- Laboratoire de Biologie Médicale, CH Cahors Cahors, France
| | - Vincent Cattoir
- Service de Microbiologie, CHU de CaenCaen, France; CNR de la Résistance aux Antibiotiques (Laboratoire Associé Entérocoques et Résistances Particulières chez les Bactéries à Gram Positif)Caen, France; Université de Caen NormandieCaen, France
| | | | - Emmanuel Lemichez
- Team Microbial Toxins in Host Pathogen Interactions, Centre Méditerranéen de Médecine Moléculaire, C3M, Institut National de la Santé et de la Recherche Médicale, U1065 Nice, France
| | - Albert Sotto
- Institut National de la Santé et de la Recherche Médicale, U1047, UFR de Médecine, Université de MontpellierNîmes, France; Service de Maladies Infectieuses et Tropicales, CHU CarémeauNîmes, France
| | - Jean-Philippe Lavigne
- Institut National de la Santé et de la Recherche Médicale, U1047, UFR de Médecine, Université de MontpellierNîmes, France; Service de Microbiologie, CHU CarémeauNîmes, France
| | - Catherine Dunyach-Remy
- Institut National de la Santé et de la Recherche Médicale, U1047, UFR de Médecine, Université de MontpellierNîmes, France; Service de Microbiologie, CHU CarémeauNîmes, France
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225
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Jørgensen E, Bay L, Bjarnsholt T, Bundgaard L, Sørensen MA, Jacobsen S. The occurrence of biofilm in an equine experimental wound model of healing by secondary intention. Vet Microbiol 2017; 204:90-95. [PMID: 28532812 DOI: 10.1016/j.vetmic.2017.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/03/2017] [Accepted: 03/08/2017] [Indexed: 11/28/2022]
Abstract
In humans, biofilm is a well-known cause of delayed healing and low-grade inflammation of chronic wounds. In horses, biofilm formation in wounds has been studied to a very limited degree. The objective of this study was thus to investigate the occurrence of biofilm in equine experimental wounds healing by secondary intention. Tissue biopsies from non-contaminated, experimental excisional shoulder and limb wounds were obtained on day 1-2, day 7-10 and day 14-15 post-wounding. Limb wounds were either un-bandaged or bandaged to induce exuberant granulation tissue (EGT) formation and thereby impaired healing. Presence of biofilm in tissue biopsies was assessed by peptide nucleic acid fluorescence in situ hybridization (PNA FISH) and confocal laser scanning microscopy (CLSM). Bandaged limb wounds developed EGT and displayed delayed healing, while shoulder and un-bandaged limb wounds healed normally. Biofilm was detected in limb wounds only. At day 14-15 biofilm was significantly more prevalent in bandaged limb wounds than in un-bandaged limb wounds (P=0.003). Further, bandaged limb wounds had a statistically significant increase in biofilm burden from day 7-10 to day 14-15 (P=0.009). The finding that biofilm was most prevalent in bandaged limb wounds with EGT formation suggests that biofilm may be linked to delayed wound healing in horses, as has been observed in humans. The inability to clear bacteria could be related to hypoxia and low-grade inflammation in the EGT, but the interaction between biofilm forming bacteria and wound healing in horses needs further elucidation.
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Affiliation(s)
- E Jørgensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, DK-2630 Taastrup, Denmark.
| | - L Bay
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen N, Denmark.
| | - T Bjarnsholt
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen N, Denmark; Department of Clinical Microbiology, Juliane Maries Vej 22, 2100 Copenhagen Ø, Rigshospitalet, Denmark.
| | - L Bundgaard
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, DK-2630 Taastrup, Denmark.
| | - M A Sørensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, DK-2630 Taastrup, Denmark.
| | - S Jacobsen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, DK-2630 Taastrup, Denmark.
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226
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Freeland RB, Morello SL, DeLombaert M, Rajamanickam V. Influence of intravenous regional limb perfusion with amikacin sulfate on Staphylococcus aureus
bioburden in distal limb wounds in horses. Vet Surg 2017; 46:663-674. [DOI: 10.1111/vsu.12638] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/30/2016] [Accepted: 12/13/2016] [Indexed: 12/27/2022]
Affiliation(s)
- Russell B. Freeland
- Department of Surgical Sciences; School of Veterinary Medicine, University of Wisconsin-Madison; Madison Wisconsin
| | - Samantha L. Morello
- Department of Surgical Sciences; School of Veterinary Medicine, University of Wisconsin-Madison; Madison Wisconsin
| | - Melissa DeLombaert
- Department of Surgical Sciences; School of Veterinary Medicine, University of Wisconsin-Madison; Madison Wisconsin
| | - Victora Rajamanickam
- Department of Biostatistics and Medical Informatics; School of Medicine and Public Health, Institute for Clinical and Translational Research, University of Wisconsin-Madison; Madison Wisconsin
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227
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Nadell CD, Ricaurte D, Yan J, Drescher K, Bassler BL. Flow environment and matrix structure interact to determine spatial competition in Pseudomonas aeruginosa biofilms. eLife 2017; 6. [PMID: 28084994 PMCID: PMC5283829 DOI: 10.7554/elife.21855] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Accepted: 01/11/2017] [Indexed: 12/11/2022] Open
Abstract
Bacteria often live in biofilms, which are microbial communities surrounded by a secreted extracellular matrix. Here, we demonstrate that hydrodynamic flow and matrix organization interact to shape competitive dynamics in Pseudomonas aeruginosa biofilms. Irrespective of initial frequency, in competition with matrix mutants, wild-type cells always increase in relative abundance in planar microfluidic devices under simple flow regimes. By contrast, in microenvironments with complex, irregular flow profiles – which are common in natural environments – wild-type matrix-producing and isogenic non-producing strains can coexist. This result stems from local obstruction of flow by wild-type matrix producers, which generates regions of near-zero shear that allow matrix mutants to locally accumulate. Our findings connect the evolutionary stability of matrix production with the hydrodynamics and spatial structure of the surrounding environment, providing a potential explanation for the variation in biofilm matrix secretion observed among bacteria in natural environments. DOI:http://dx.doi.org/10.7554/eLife.21855.001 Bacteria often live together – attached to surfaces like river rocks, water pipes, the lining of the gut and catheters – in communities called biofilms. These groups of bacteria are small-scale ecosystems in which cells cooperate and compete with one another to obtain resources, such as food and space to grow. Within a biofilm, a sticky glue-like substance called the matrix binds the cells to each other and to the surface. Cells that make the matrix typically have an advantage over those that do not because they can better resist the shearing forces experienced when liquid flows over the surface. The matrix also helps cells to capture nutrients from the passing liquid. Nevertheless, not all strains of bacteria make matrix, despite its advantages. Because of where they can grow, biofilms are fundamentally important in the environment, in industry and in infections. Resolving why some bacteria make matrix while others do not could therefore allow scientists and engineers to re-design the surfaces involved in these settings to discourage harmful biofilms or to encourage beneficial ones. Nadell, Ricaurte et al. have now used a bacterium called Pseudomonas aeruginosa to explore how the properties of the surface and the flowing liquid affect matrix production among cells in biofilms. P. aeruginosa typically lives in soil and can cause infections in people, especially in hospital patients and people who have weakened immune systems. Nadell, Ricaurte et al. studied normal P. aeruginosa bacteria and a mutant strain that is unable to make matrix. The strains were labeled with fluorescent markers and put into special chambers that simulated different environments. The proportion of each strain was measured after three days of biofilm growth. When biofilms were grown under flowing liquid in simple environments with flat surfaces, matrix producers always outcompeted non-producers. However, the two strains coexisted in more complex and porous environments, like those found in soil. Nadell, Ricaurte et al. went on to show that the strains could co-exist because the matrix producers made biofilms that created areas within the environment where the liquid flows very slowly or not at all. In these regions, non-producing cells could compete successfully because resistance to shearing forces is less important when flow is weak or absent, and so the non-producing cells were not washed away. The results begin to explain why matrix production among cells in environmental settings is diverse and highlight that the environment is important in the evolution of bacterial biofilms. DOI:http://dx.doi.org/10.7554/eLife.21855.002
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Affiliation(s)
- Carey D Nadell
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Deirdre Ricaurte
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Jing Yan
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Bonnie L Bassler
- Department of Molecular Biology, Princeton University, Princeton, United States.,Howard Hughes Medical Institute, Chevy Chase, United States
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228
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Isaacs MA, Durndell LJ, Hilton AC, Olivi L, Parlett CMA, Wilson K, Lee AF. Tunable Ag@SiO2 core–shell nanocomposites for broad spectrum antibacterial applications. RSC Adv 2017. [DOI: 10.1039/c7ra03131a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Silica encapsulated silver nanoparticle core–shell nanocomposites of tunable dimensions were synthesised via a one-pot reverse microemulsion route to achieve controlled release of Ag+ ions for broad spectrum antibacterial application.
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Affiliation(s)
- Mark A. Isaacs
- European Bioenergy Research Institute
- Aston University
- Birmingham
- UK
| | - Lee J. Durndell
- European Bioenergy Research Institute
- Aston University
- Birmingham
- UK
| | | | | | | | - Karen Wilson
- European Bioenergy Research Institute
- Aston University
- Birmingham
- UK
| | - Adam F. Lee
- European Bioenergy Research Institute
- Aston University
- Birmingham
- UK
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229
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Trivedi U, Madsen JS, Rumbaugh KP, Wolcott RD, Burmølle M, Sørensen SJ. A post-planktonic era of in vitro infectious models: issues and changes addressed by a clinically relevant wound like media. Crit Rev Microbiol 2016; 43:453-465. [PMID: 27869519 DOI: 10.1080/1040841x.2016.1252312] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Medical science is pitted against an ever-increasing rise in antibiotic tolerant microorganisms. Concurrently, during the past decade, biofilms have garnered much attention within research and clinical practice. Although the significance of clinical biofilms is becoming very apparent, current methods for diagnostics and direction of therapy plans in many hospitals do not reflect this knowledge; with many of the present tools proving to be inadequate for accurately mimicking the biofilm phenomenon. Based on current findings, we address some of the fundamental issues overlooked by clinical labs: the paradigm shifts that need to occur in assessing chronic wounds; better simulation of physiological conditions in vitro; and the importance of incorporating polymicrobial populations into biofilm models. In addition, this review considers using a biofilm relevant in vitro model for cultivating and determining the antibiotic tolerance and susceptibility of microorganisms associated with chronic wounds. This model presents itself as a highly rapid and functional tool that can be utilized by hospitals in an aim to improve bedside treatments.
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Affiliation(s)
- Urvish Trivedi
- a Department of Biology, Faculty of Science , Section of Microbiology, University of Copenhagen , Copenhagen , Denmark
| | - Jonas S Madsen
- a Department of Biology, Faculty of Science , Section of Microbiology, University of Copenhagen , Copenhagen , Denmark
| | - Kendra P Rumbaugh
- b Department of Surgery , Texas Tech University Health Sciences Center , Lubbock , TX , USA
| | | | - Mette Burmølle
- a Department of Biology, Faculty of Science , Section of Microbiology, University of Copenhagen , Copenhagen , Denmark
| | - Søren J Sørensen
- a Department of Biology, Faculty of Science , Section of Microbiology, University of Copenhagen , Copenhagen , Denmark
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230
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Townsend EM, Sherry L, Rajendran R, Hansom D, Butcher J, Mackay WG, Williams C, Ramage G. Development and characterisation of a novel three-dimensional inter-kingdom wound biofilm model. BIOFOULING 2016; 32:1259-1270. [PMID: 27841027 DOI: 10.1080/08927014.2016.1252337] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 10/19/2016] [Indexed: 06/06/2023]
Abstract
Chronic diabetic foot ulcers are frequently colonised and infected by polymicrobial biofilms that ultimately prevent healing. This study aimed to create a novel in vitro inter-kingdom wound biofilm model on complex hydrogel-based cellulose substrata to test commonly used topical wound treatments. Inter-kingdom triadic biofilms composed of Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus were shown to be quantitatively greater in this model compared to a simple substratum when assessed by conventional culture, metabolic dye and live dead qPCR. These biofilms were both structurally complex and compositionally dynamic in response to topical therapy, so when treated with either chlorhexidine or povidone iodine, principal component analysis revealed that the 3-D cellulose model was minimally impacted compared to the simple substratum model. This study highlights the importance of biofilm substratum and inclusion of relevant polymicrobial and inter-kingdom components, as these impact penetration and efficacy of topical antiseptics.
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Affiliation(s)
- Eleanor M Townsend
- a Oral Sciences Research Group, Glasgow Dental School, School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences , University of Glasgow , Glasgow , UK
- b Institute of Healthcare Policy and Practice , University of West of Scotland , Paisley , UK
| | - Leighann Sherry
- a Oral Sciences Research Group, Glasgow Dental School, School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences , University of Glasgow , Glasgow , UK
- b Institute of Healthcare Policy and Practice , University of West of Scotland , Paisley , UK
| | - Ranjith Rajendran
- a Oral Sciences Research Group, Glasgow Dental School, School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences , University of Glasgow , Glasgow , UK
| | - Donald Hansom
- a Oral Sciences Research Group, Glasgow Dental School, School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences , University of Glasgow , Glasgow , UK
| | - John Butcher
- b Institute of Healthcare Policy and Practice , University of West of Scotland , Paisley , UK
| | - William G Mackay
- b Institute of Healthcare Policy and Practice , University of West of Scotland , Paisley , UK
| | - Craig Williams
- b Institute of Healthcare Policy and Practice , University of West of Scotland , Paisley , UK
| | - Gordon Ramage
- a Oral Sciences Research Group, Glasgow Dental School, School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences , University of Glasgow , Glasgow , UK
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231
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Bhowmick S, Mohanty S, Koul V. Fabrication of transparent quaternized PVA/silver nanocomposite hydrogel and its evaluation as an antimicrobial patch for wound care systems. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2016; 27:160. [PMID: 27638099 DOI: 10.1007/s10856-016-5772-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 08/29/2016] [Indexed: 06/06/2023]
Abstract
Grafting of quaternary nitrogen atoms into the backbone of polymer is an efficient way of developing new generation antimicrobial polymeric wound dressing. In this study, an elastic, non-adhesive and antimicrobial transparent hydrogel based dressing has been designed, which might be helpful for routine observation of wound area without removing the dressing material along with maintaining a sterile environment for a longer period of time. Green synthesized silver nanoparticles have been loaded into the quaternized PVA hydrogel matrix to improve its antimicrobial property. Silver nanoparticles loaded quaternized PVA hydrogel showed enhanced mechanical and swelling properties compared to native quaternized PVA hydrogel. Release kinetics evaluated by atomic absorption spectroscopy revealed that the release mechanism of silver nanoparticles from the hydrogel follows Fickian diffusion. Antimicrobial efficacy of the hydrogels was evaluated by disk diffusion test on Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. After 96 h of release in phosphate buffer, the growth inhibition zone created by silver nanoparticless loaded quaternized PVA hydrogel is comparable to that created by ampicillin. These observations assert that the silver nanoparticles loaded quaternized PVA hydrogel acts as a reservoir of silver nanoparticles, which helps in maintaining a sterile environment for longer time duration by releasing Ag nanocrystallite in sustained manner.
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Affiliation(s)
- Sirsendu Bhowmick
- Max Bergmann Center of Biomaterials, Technische Universität Dresden, Budapester Straße 27, Dresden, 01069, Germany
- Centre for Biomedical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India
- Biomedical Engineering Unit, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Sujata Mohanty
- Stem Cell Facility, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Veena Koul
- Centre for Biomedical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
- Biomedical Engineering Unit, All India Institute of Medical Sciences, New Delhi, 110029, India.
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232
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Crosby HA, Kwiecinski J, Horswill AR. Staphylococcus aureus Aggregation and Coagulation Mechanisms, and Their Function in Host-Pathogen Interactions. ADVANCES IN APPLIED MICROBIOLOGY 2016; 96:1-41. [PMID: 27565579 DOI: 10.1016/bs.aambs.2016.07.018] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The human commensal bacterium Staphylococcus aureus can cause a wide range of infections ranging from skin and soft tissue infections to invasive diseases like septicemia, endocarditis, and pneumonia. Muticellular organization almost certainly contributes to S. aureus pathogenesis mechanisms. While there has been considerable focus on biofilm formation and its role in colonizing prosthetic joints and indwelling devices, less attention has been paid to nonsurface-attached group behavior like aggregation and clumping. S. aureus is unique in its ability to coagulate blood, and it also produces multiple fibrinogen-binding proteins that facilitate clumping. Formation of clumps, which are large, tightly packed groups of cells held together by fibrin(ogen), has been demonstrated to be important for S. aureus virulence and immune evasion. Clumps of cells are able to avoid detection by the host's immune system due to a fibrin(ogen) coat that acts as a shield, and the size of the clumps facilitates evasion of phagocytosis. In addition, clumping could be an important early step in establishing infections that involve tight clusters of cells embedded in host matrix proteins, such as soft tissue abscesses and endocarditis. In this review, we discuss clumping mechanisms and regulation, as well as what is known about how clumping contributes to immune evasion.
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Affiliation(s)
- H A Crosby
- University of Iowa, Iowa City, IA, United States
| | - J Kwiecinski
- University of Iowa, Iowa City, IA, United States
| | - A R Horswill
- University of Iowa, Iowa City, IA, United States
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233
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Polymicrobial–Host Interactions during Infection. J Mol Biol 2016; 428:3355-71. [DOI: 10.1016/j.jmb.2016.05.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/02/2016] [Accepted: 05/04/2016] [Indexed: 02/08/2023]
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234
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Pritchard DI, Čeřovský V, Nigam Y, Pickles SF, Cazander G, Nibbering PH, Bültemann A, Jung W. TIME management by medicinal larvae. Int Wound J 2016; 13:475-84. [PMID: 26179750 PMCID: PMC7950164 DOI: 10.1111/iwj.12457] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/09/2015] [Accepted: 04/13/2015] [Indexed: 12/31/2022] Open
Abstract
Wound bed preparation (WBP) is an integral part of the care programme for chronic wounds. The acronym TIME is used in the context of WBP and describes four barriers to healing in chronic wounds; namely, dead Tissue, Infection and inflammation, Moisture imbalance and a non-migrating Edge. Larval debridement therapy (LDT) stems from observations that larvae of the blowfly Lucilia sericata clean wounds of debris. Subsequent clinical studies have proven debriding efficacy, which is likely to occur as a result of enzymatically active alimentary products released by the insect. The antimicrobial, anti-inflammatory and wound healing activities of LDT have also been investigated, predominantly in a pre-clinical context. This review summarises the findings of investigations into the molecular mechanisms of LDT and places these in context with the clinical concept of WBP and TIME. It is clear from these findings that biotherapy with L. sericata conforms with TIME, through the enzymatic removal of dead tissue and its associated biofilm, coupled with the secretion of defined antimicrobial peptides. This biotherapeutic impact on the wound serves to reduce inflammation, with an associated capacity for an indirect effect on moisture imbalance. Furthermore, larval serine proteinases have the capacity to alter fibroblast behaviour in a manner conducive to the formation of granulation tissue.
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Affiliation(s)
| | - Václav Čeřovský
- Institute of Organic Chemistry and Biochemistry, Prague, Czech Republic
| | - Yamni Nigam
- College of Human and Health Sciences, Swansea University, Swansea, UK
| | | | | | - Peter H Nibbering
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
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235
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Arnold CP, Merryman MS, Harris-Arnold A, McKinney SA, Seidel CW, Loethen S, Proctor KN, Guo L, Sánchez Alvarado A. Pathogenic shifts in endogenous microbiota impede tissue regeneration via distinct activation of TAK1/MKK/p38. eLife 2016; 5. [PMID: 27441386 PMCID: PMC4993586 DOI: 10.7554/elife.16793] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/19/2016] [Indexed: 02/03/2023] Open
Abstract
The interrelationship between endogenous microbiota, the immune system, and tissue regeneration is an area of intense research due to its potential therapeutic applications. We investigated this relationship in Schmidtea mediterranea, a model organism capable of regenerating any and all of its adult tissues. Microbiome characterization revealed a high Bacteroidetes to Proteobacteria ratio in healthy animals. Perturbations eliciting an expansion of Proteobacteria coincided with ectopic lesions and tissue degeneration. The culture of these bacteria yielded a strain of Pseudomonas capable of inducing progressive tissue degeneration. RNAi screening uncovered a TAK1 innate immune signaling module underlying compromised tissue homeostasis and regeneration during infection. TAK1/MKK/p38 signaling mediated opposing regulation of apoptosis during infection versus normal tissue regeneration. Given the complex role of inflammation in either hindering or supporting reparative wound healing and regeneration, this invertebrate model provides a basis for dissecting the duality of evolutionarily conserved inflammatory signaling in complex, multi-organ adult tissue regeneration. DOI:http://dx.doi.org/10.7554/eLife.16793.001 Regeneration, the ability to replace missing or damaged tissue, has fascinated biologists for years and has inspired a new direction for the medical field. Figuring out how some animals easily accomplish this while others do not may help us to develop new therapies that enhance regeneration in humans. Previous work has indicated that the immune system, which is normally used to defend the body against bacteria, plays an important but complicated role in regeneration. By studying the relationships between bacteria, the immune system and regeneration in simple systems, it may be possible to see how their interactions either support or prevent the replacement of lost tissues. Flatworms called planaria can regenerate all of their tissues. Arnold et al. have now investigated what bacteria exist in planaria, how the planarian immune system responds to these bacteria, and how this response affects regeneration. The results reveal that the two main types of bacteria that are present in planaria are also found in humans. In fact, conditions that encourage the growth and spread of one of these types of bacteria (called Proteobacteria, many of which can make humans ill) damaged the worms and prevented them from regenerating. Arnold et al. then looked to see if the worms had genes that were similar to human genes that control the key immune process of inflammation, and found evidence of several such genes. Reducing the activity levels of these genes enabled worms that had been infected with Proteobacteria to regenerate again. However, these genes only seem to be responsible for regeneration when the planaria are infected with bacteria. Thus, planaria could be used as a simple model to discover how changes in resident bacteria can be detected by the immune system and affect the ability to regenerate tissues. Future studies could use planaria to identify even more genes that control regeneration during infection. Also, since the main types of bacteria in planaria are similar to those in humans, planaria may help us to learn how animals can properly balance the levels of these bacteria in order to remain healthy. DOI:http://dx.doi.org/10.7554/eLife.16793.002
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Affiliation(s)
| | - M Shane Merryman
- Stowers Institute for Medical Research, Kansas City, United States
| | | | - Sean A McKinney
- Stowers Institute for Medical Research, Kansas City, United States
| | - Chris W Seidel
- Stowers Institute for Medical Research, Kansas City, United States
| | | | | | - Longhua Guo
- Stowers Institute for Medical Research, Kansas City, United States
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236
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Siafaka PI, Zisi AP, Exindari MK, Karantas ID, Bikiaris DN. Porous dressings of modified chitosan with poly(2-hydroxyethyl acrylate) for topical wound delivery of levofloxacin. Carbohydr Polym 2016; 143:90-9. [DOI: 10.1016/j.carbpol.2016.02.009] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 02/01/2016] [Accepted: 02/02/2016] [Indexed: 02/08/2023]
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237
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Mitri S, Clarke E, Foster KR. Resource limitation drives spatial organization in microbial groups. THE ISME JOURNAL 2016; 10:1471-82. [PMID: 26613343 PMCID: PMC5029182 DOI: 10.1038/ismej.2015.208] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/13/2015] [Accepted: 10/16/2015] [Indexed: 12/20/2022]
Abstract
Dense microbial groups such as bacterial biofilms commonly contain a diversity of cell types that define their functioning. However, we have a limited understanding of what maintains, or purges, this diversity. Theory suggests that resource levels are key to understanding diversity and the spatial arrangement of genotypes in microbial groups, but we need empirical tests. Here we use theory and experiments to study the effects of nutrient level on spatio-genetic structuring and diversity in bacterial colonies. Well-fed colonies maintain larger well-mixed areas, but they also expand more rapidly compared with poorly-fed ones. Given enough space to expand, therefore, well-fed colonies lose diversity and separate in space over a similar timescale to poorly fed ones. In sum, as long as there is some degree of nutrient limitation, we observe the emergence of structured communities. We conclude that resource-driven structuring is central to understanding both pattern and process in diverse microbial communities.
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Affiliation(s)
- Sara Mitri
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
- Department of Zoology, University of Oxford, Oxford, UK
| | | | - Kevin R Foster
- Department of Zoology, University of Oxford, Oxford, UK
- Oxford Centre for Integrative Systems Biology, University of Oxford, Oxford, UK
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238
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Wardlow R, Bing C, VanOsdol J, Maples D, Ladouceur-Wodzak M, Harbeson M, Nofiele J, Staruch R, Ramachandran A, Malayer J, Chopra R, Ranjan A. Targeted antibiotic delivery using low temperature-sensitive liposomes and magnetic resonance-guided high-intensity focused ultrasound hyperthermia. Int J Hyperthermia 2016; 32:254-64. [PMID: 26892114 PMCID: PMC6029942 DOI: 10.3109/02656736.2015.1134818] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Chronic non-healing wound infections require long duration antibiotic therapy, and are associated with significant morbidity and health-care costs. Novel approaches for efficient, readily-translatable targeted and localised antimicrobial delivery are needed. The objectives of this study were to 1) develop low temperature-sensitive liposomes (LTSLs) containing an antimicrobial agent (ciprofloxacin) for induced release at mild hyperthermia (∼42 °C), 2) characterise in vitro ciprofloxacin release, and efficacy against Staphylococcus aureus plankton and biofilms, and 3) determine the feasibility of localised ciprofloxacin delivery in combination with MR-HIFU hyperthermia in a rat model. LTSLs were loaded actively with ciprofloxacin and their efficacy was determined using a disc diffusion method, MBEC biofilm device, and scanning electron microscopy (SEM). Ciprofloxacin release from LTSLs was assessed in a physiological buffer by fluorescence spectroscopy, and in vivo in a rat model using MR-HIFU. Results indicated that < 5% ciprofloxacin was released from the LTSL at body temperature (37 °C), while >95% was released at 42 °C. Precise hyperthermia exposures in the thigh of rats using MR-HIFU during intravenous (i.v.) administration of the LTSLs resulted in a four fold greater local concentration of ciprofloxacin compared to controls (free ciprofloxacin + MR-HIFU or LTSL alone). The biodistribution of ciprofloxacin in unheated tissues was fairly similar between treatment groups. Triggered release at 42 °C from LTSL achieved significantly greater S. aureus killing and induced membrane deformation and changes in biofilm matrix compared to free ciprofloxacin or LTSL at 37 °C. This technique has potential as a method to deliver high concentration antimicrobials to chronic wounds.
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Affiliation(s)
- Rachel Wardlow
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
| | - Chenchen Bing
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Joshua VanOsdol
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
| | - Danny Maples
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
| | | | - Michele Harbeson
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
| | - Joris Nofiele
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Robert Staruch
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX
- Clinical Sites Research Program, Philips Research, Briarcliff Manor, NY
| | | | - Jerry Malayer
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
| | - Rajiv Chopra
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX
| | - Ashish Ranjan
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
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239
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Abstract
Fungal biofilms have become an increasingly important clinical problem. The widespread use of antibiotics, frequent use of indwelling medical devices, and a trend toward increased patient immunosuppression have resulted in a creation of opportunity for clinically important yeasts and molds to form biofilms. This review will discuss the diversity and importance of fungal biofilms in the context of clinical medicine, provide novel insights into the clinical management of fungal biofilm infection, present evidence why these structures are recalcitrant to antifungal therapy, and discuss how our knowledge and understanding may lead to novel therapeutic intervention.
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240
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Strus M, Mikołajczyk D, Machul A, Heczko PB, Chronowska A, Stochel G, Gallienne E, Nicolas C, Martin OR, Kyzioł A. Effects of the Selected Iminosugar Derivatives on Pseudomonas aeruginosa Biofilm Formation. Microb Drug Resist 2016; 22:638-645. [PMID: 27031025 DOI: 10.1089/mdr.2015.0231] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
A lack of an effective way to eliminate pathogenic bacteria hidden in the biofilm is a major problem in the treatment of chronic bacterial infections. Iminosugar derivatives are potential candidates for inhibitors of enzymes taking part in the biosynthesis of exopolysaccharides, which are forming bacterial biofilm. Investigated iminosugars were studied either at an early stage of biofilm formation or later on when the mature biofilm of Pseudomonas aeruginosa was already formed. A series of diverse iminosugar structures significantly inhibited biofilm formation, whereas they showed no influence on already formed biofilm. This indicates a possible mechanism of their action based on inhibition of exopolysaccharide backbone synthesis in the early stages of biofilm formation. Moreover, iminosugar derivatives did not show significant effect on the viable bacterial numbers in both early and mature biofilm forms. Importantly, they were not cytotoxic against human Caco-2 cells in vitro, which may be to their advantage in case of their medical application in preventing P. aeruginosa biofilm formation.
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Affiliation(s)
- Magdalena Strus
- 1 Department of Microbiology, Jagiellonian University Medical College , Kraków, Poland
| | - Diana Mikołajczyk
- 1 Department of Microbiology, Jagiellonian University Medical College , Kraków, Poland
| | - Agnieszka Machul
- 1 Department of Microbiology, Jagiellonian University Medical College , Kraków, Poland
| | - Piotr B Heczko
- 1 Department of Microbiology, Jagiellonian University Medical College , Kraków, Poland
| | | | - Grażyna Stochel
- 2 Faculty of Chemistry, Jagiellonian University , Kraków, Poland
| | - Estelle Gallienne
- 3 Institut de Chimie Organique et Analytique, UMR7311, Université d'Orléans and CNRS , Orléans, France
| | - Cyril Nicolas
- 3 Institut de Chimie Organique et Analytique, UMR7311, Université d'Orléans and CNRS , Orléans, France
| | - Olivier R Martin
- 3 Institut de Chimie Organique et Analytique, UMR7311, Université d'Orléans and CNRS , Orléans, France
| | - Agnieszka Kyzioł
- 2 Faculty of Chemistry, Jagiellonian University , Kraków, Poland
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XerC Contributes to Diverse Forms of Staphylococcus aureus Infection via agr-Dependent and agr-Independent Pathways. Infect Immun 2016; 84:1214-1225. [PMID: 26857575 DOI: 10.1128/iai.01462-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 02/02/2016] [Indexed: 02/06/2023] Open
Abstract
We demonstrate that mutation of xerC, which reportedly encodes a homologue of an Escherichia coli recombinase, limits biofilm formation in the methicillin-resistant Staphylococcus aureus strain LAC and the methicillin-sensitive strain UAMS-1. This was not due to the decreased production of the polysaccharide intracellular adhesin (PIA) in either strain because the amount of PIA was increased in a UAMS-1xerC mutant and undetectable in both LAC and its isogenic xerC mutant. Mutation of xerC also resulted in the increased production of extracellular proteases and nucleases in both LAC and UAMS-1, and limiting the production of either class of enzymes increased biofilm formation in the isogenic xerC mutants. More importantly, the limited capacity to form a biofilm was correlated with increased antibiotic susceptibility in both strains in the context of an established biofilm in vivo. Mutation of xerC also attenuated virulence in a murine bacteremia model, as assessed on the basis of the bacterial loads in internal organs and overall lethality. It also resulted in the decreased accumulation of alpha toxin and the increased accumulation of protein A. These findings suggest that xerC may impact the functional status of agr. This was confirmed by demonstrating the reduced accumulation of RNAIII and AgrA in LAC and UAMS-1xerC mutants. However, this cannot account for the biofilm-deficient phenotype of xerC mutants because mutation of agr did not limit biofilm formation in either strain. These results demonstrate that xerC contributes to biofilm-associated infections and acute bacteremia and that this is likely due to agr-independent and -dependent pathways, respectively.
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242
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Thomsen K, Trøstrup H, Christophersen L, Lundquist R, Høiby N, Moser C. The phagocytic fitness of leucopatches may impact the healing of chronic wounds. Clin Exp Immunol 2016; 184:368-77. [PMID: 26830371 DOI: 10.1111/cei.12773] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chronic non-healing wounds are significantly bothersome to patients and can result in severe complications. In addition, they are increasing in numbers, and a challenging problem to the health-care system. Handling of chronic, non-healing wounds can be discouraging due to lack of improvement, and a recent explanation can be the involvement of biofilm infections in the pathogenesis of non-healing wounds. Therefore, new treatment alternatives to improve outcome are continuously sought-after. Autologous leucopatches are such a new, adjunctive treatment option, showing promising clinical effects. However, the beneficial effect of the patches are not understood fully, although a major contribution is believed to be from the release of stimulating growth factors from activated thrombocytes within the leucopatch. Because the leucopatches also contain substantial numbers of leucocytes, the aim of the present study was to investigate the activity of the polymorphonuclear neutrophils (PMNs) within the leucopatch. By means of burst assay, phagocytosis assay, migration assay, biofilm killing assay and fluorescence in-situ hybridization (FISH) assay we showed significant respiratory burst in PMNs, active phagocytosis and killing of Pseudomonas aeruginosa by the leucopatch. In addition, bacterial-induced migration of PMNs from the leucopatch was shown, as well as uptake of P. aeruginosa by PMNs within the leucopatch. The present study substantiated that at least part of the beneficial clinical effect in chronic wounds by leucopatches is attributed to the activity of the PMNs in the leucopatch.
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Affiliation(s)
- K Thomsen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen
| | - H Trøstrup
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen
| | - L Christophersen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen
| | | | - N Høiby
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen
| | - C Moser
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen
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243
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Kragh KN, Hutchison JB, Melaugh G, Rodesney C, Roberts AEL, Irie Y, Jensen PØ, Diggle SP, Allen RJ, Gordon V, Bjarnsholt T. Role of Multicellular Aggregates in Biofilm Formation. mBio 2016; 7:e00237. [PMID: 27006463 PMCID: PMC4807362 DOI: 10.1128/mbio.00237-16] [Citation(s) in RCA: 209] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 02/22/2016] [Indexed: 11/25/2022] Open
Abstract
UNLABELLED In traditional models ofin vitrobiofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm initiation and development is not known. Here we use a combination of experimental and computational approaches to determine the relative fitness of single cells and preformed aggregates during early development ofPseudomonas aeruginosabiofilms. We find that the relative fitness of aggregates depends markedly on the density of surrounding single cells, i.e., the level of competition for growth resources. When competition between aggregates and single cells is low, an aggregate has a growth disadvantage because the aggregate interior has poor access to growth resources. However, if competition is high, aggregates exhibit higher fitness, because extending vertically above the surface gives cells at the top of aggregates better access to growth resources. Other advantages of seeding by aggregates, such as earlier switching to a biofilm-like phenotype and enhanced resilience toward antibiotics and immune response, may add to this ecological benefit. Our findings suggest that current models of biofilm formation should be reconsidered to incorporate the role of aggregates in biofilm initiation. IMPORTANCE During the past decades, there has been a consensus around the model of development of a biofilm, involving attachment of single planktonic bacterial cells to a surface and the subsequent development of a mature biofilm. This study presents results that call for a modification of this rigorous model. We show how free floating biofilm aggregates can have a profound local effect on biofilm development when attaching to a surface. Our findings show that an aggregate landing on a surface will eventually outcompete the biofilm population arising from single cells attached around the aggregate and dominate the local biofilm development. These results point to a regime where preformed biofilm aggregates may have a fitness advantage over planktonic cells when it comes to accessing nutrients. Our findings add to the increasingly prominent comprehension that biofilm lifestyle is the default for bacteria and that planktonic single cells may be only a transition state at the most.
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Affiliation(s)
- Kasper N Kragh
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Jaime B Hutchison
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas, USA
| | - Gavin Melaugh
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Chris Rodesney
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas, USA
| | - Aled E L Roberts
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Yasuhiko Irie
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Peter Ø Jensen
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Stephen P Diggle
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Rosalind J Allen
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Vernita Gordon
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas, USA Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Thomas Bjarnsholt
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
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244
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Melaugh G, Hutchison J, Kragh KN, Irie Y, Roberts A, Bjarnsholt T, Diggle SP, Gordon VD, Allen RJ. Shaping the Growth Behaviour of Biofilms Initiated from Bacterial Aggregates. PLoS One 2016; 11:e0149683. [PMID: 26934187 PMCID: PMC4774936 DOI: 10.1371/journal.pone.0149683] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 02/03/2016] [Indexed: 01/26/2023] Open
Abstract
Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase so that it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the initial shape the aggregate forms on the surface, we find that the degree of spreading of an aggregate on a surface can play an important role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding unaggregated bacterial cells is low, while initially rounded aggregates perform better when competition with surrounding unaggregated cells is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the social evolution of biofilm communities.
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Affiliation(s)
- Gavin Melaugh
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, United Kingdom
- * E-mail:
| | - Jaime Hutchison
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1199, United States of America
| | - Kasper Nørskov Kragh
- Department of International Health, Immunology and Microbiology, Faculty Of Health Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Yasuhiko Irie
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
- Department of Biology & Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - Aled Roberts
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Thomas Bjarnsholt
- Department of International Health, Immunology and Microbiology, Faculty Of Health Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
- Department for Clinical Microbiology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Stephen P. Diggle
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Vernita D. Gordon
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1199, United States of America
| | - Rosalind J. Allen
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, United Kingdom
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245
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Wagner S, Sommer R, Hinsberger S, Lu C, Hartmann RW, Empting M, Titz A. Novel Strategies for the Treatment of Pseudomonas aeruginosa Infections. J Med Chem 2016; 59:5929-69. [DOI: 10.1021/acs.jmedchem.5b01698] [Citation(s) in RCA: 176] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Stefanie Wagner
- Chemical
Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
| | - Roman Sommer
- Chemical
Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
| | - Stefan Hinsberger
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
- Drug
Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
| | - Cenbin Lu
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
- Drug
Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
| | - Rolf W. Hartmann
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
- Drug
Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
| | - Martin Empting
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
- Drug
Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
| | - Alexander Titz
- Chemical
Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
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246
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Brackman G, Garcia-Fernandez MJ, Lenoir J, De Meyer L, Remon JP, De Beer T, Concheiro A, Alvarez-Lorenzo C, Coenye T. Dressings Loaded with Cyclodextrin-Hamamelitannin Complexes Increase Staphylococcus aureus Susceptibility Toward Antibiotics Both in Single as well as in Mixed Biofilm Communities. Macromol Biosci 2016; 16:859-69. [PMID: 26891369 DOI: 10.1002/mabi.201500437] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/12/2016] [Indexed: 01/16/2023]
Abstract
Bacteria reside within biofilms at the infection site, making them extremely difficult to eradicate with conventional wound care products. Bacteria use quorum sensing (QS) systems to regulate biofilm formation, and QS inhibitors (QSIs) have been proposed as promising antibiofilm agents. Despite this, few antimicrobial therapies that interfere with QS exist. Nontoxic hydroxypropyl-β-cyclodextrin-functionalized cellulose gauzes releasing a burst of the antibiotic vancomycin and the QSI hamamelitannin are developed, followed by a sustained release of both. The gauzes affect QS and biofilm formation of Pseudomonas aeruginosa and Staphylococcus aureus in an in vitro model of chronic wound infection and can be considered as candidates to be used to prevent wound infection as well as treat infected wounds.
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Affiliation(s)
- Gilles Brackman
- Laboratory of Pharmaceutical Microbiology, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Maria José Garcia-Fernandez
- Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Joke Lenoir
- Laboratory of Pharmaceutical Technology, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Laurens De Meyer
- Laboratory of Pharmaceutical Process Analytical Technology, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Jean-Paul Remon
- Laboratory of Pharmaceutical Technology, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Thomas De Beer
- Laboratory of Pharmaceutical Process Analytical Technology, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Angel Concheiro
- Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Carmen Alvarez-Lorenzo
- Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
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247
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Cooper R, Jenkins L. Binding of two bacterial biofilms to dialkyl carbamoyl chloride (DACC)-coated dressings in vitro. J Wound Care 2016; 25:76, 78-82. [DOI: 10.12968/jowc.2016.25.2.76] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- R. Cooper
- At Centre for Biomedical Sciences, Cardiff School of Health Sciences, Cardiff Metropolitan University, Western Avenue, Cardiff CF5 2YB
| | - L. Jenkins
- At Centre for Biomedical Sciences, Cardiff School of Health Sciences, Cardiff Metropolitan University, Western Avenue, Cardiff CF5 2YB
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248
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Bhowmick S, Koul V. Assessment of PVA/silver nanocomposite hydrogel patch as antimicrobial dressing scaffold: Synthesis, characterization and biological evaluation. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 59:109-119. [DOI: 10.1016/j.msec.2015.10.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 09/14/2015] [Accepted: 10/01/2015] [Indexed: 12/25/2022]
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249
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White RJ, Cutting K, Cooper R. The diagnosis of biofilms in wounds. J Wound Care 2016; 25:56. [PMID: 26762499 DOI: 10.12968/jowc.2016.25.1.56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Rose Cooper
- Professor of Microbiology, Centre for Biomedical Sciences, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK
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250
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Williams C, Rajendran R, Ramage G. Aspergillus Biofilms in Human Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 931:1-11. [PMID: 27271678 DOI: 10.1007/5584_2016_4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The biofilm phenotype of Aspergillus species is an important and accepted clinical entity. While industrially these biofilms have been used extensively in important biofermentations, their role in clinical infection is less well defined. A recent flurry of activity has demonstrated that these interesting filamentous moulds have the capacity to form biofilms both in vitro and in vivo, and through various investigations have shown that these are exquisitely resistant to antifungal therapies through a range of adaptive resistance mechanisms independent of defined genetic changes. This review will explore the clinical importance of these biofilms and provide contemporary information with respect to their clinical management.
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Affiliation(s)
- Craig Williams
- Institute of Healthcare Policy and Practice, University of West of Scotland, High St, Paisley, PA1 2BE, UK.
| | - Ranjith Rajendran
- Infection and Immunity Research Group, Glasgow Dental School and Hospital, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland
| | - Gordon Ramage
- Infection and Immunity Research Group, Glasgow Dental School and Hospital, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland
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