Query: wound biofilms 2020

title: A multimodel regime for evaluating effectiveness of antimicrobial wound care products in microbial biofilms
abstract: Microbial biofilms have become increasingly recognized as a cause of wound chronicity. There are several topical antimicrobial wound care products available for use; however, their effectiveness has routinely been demonstrated with planktonic microorganisms. There is no target reference value for antimicrobial effectiveness of wound care products in biofilm models. In addition, data on antimicrobial activity of products in biofilm models are scattered across many test methods in a variety of studies. The aim of this work is to directly compare commercial products containing the commonly used topical antimicrobial agents iodine, silver, polyhexamethylene biguanide, octenidine, hypochlorous acid, benzalkonium chloride, and a surfactant based topical containing poloxamer 188. Five different in vitro biofilm models of varied complexity were used, incorporating several bacterial pathogens such as Staphylococcus, Enterococcus, Streptococcus, Pseudomonas, Acinetobacter, Klebsiella, and Enterobacter. The fungal pathogens Candida albicans and Candida auris were also evaluated. A multispecies bacterial biofilm model was also used to evaluate the products. Additionally, C. albicans was used in combination with S. aureus and P. aeruginosa in a multikingdom version of the polymicrobial biofilm model. Statistically significant differences in antimicrobial performance were observed between treatments in each model and changing microbial growth conditions or combinations of organisms resulted in significant performance differences for some treatments. The iodine and benzalkonium chloride containing products were overall the most effective in vitro and were then selected for in vivo evaluation in an infected immunocompromised murine model. Unexpectedly, the iodine product was statistically (P .05) no different than the untreated control, while the benzalkonium chloride containing product significantly (P .05) reduced the biofilm compared to untreated control. This body of work demonstrates the importance of not only evaluating antimicrobial wound care products in biofilm models but also the importance of using several different models to gain a comprehensive understanding of products' effectiveness.

title: Ultrasound mediated therapies for the treatment of biofilms in chronic wounds: a review of present knowledge
abstract: Bacterial biofilms are an ever growing concern for public health, featuring both inherited genetic resistance and a conferred innate tolerance to traditional antibiotic therapies. Consequently, there is a growing interest in novel methods of drug delivery, in order to increase the efficacy of antimicrobial agents. One such method is the use of acoustically activated microbubbles, which undergo volumetric oscillations and collapse upon exposure to an ultrasound field. This facilitates physical perturbation of the biofilm and provides the means to control drug delivery both temporally and spatially. In line with current literature in this area, this review offers a rounded argument for why ultrasound responsive agents could be an integral part of advancing wound care. To achieve this, we will outline the development and clinical significance of biofilms in the context of chronic infections. We will then discuss current practices used in combating biofilms in chronic wounds and then critically evaluate the use of acoustically activated gas microbubbles as an emerging treatment modality. Moreover, we will introduce the novel concept of microbubbles carrying biologically active gases that may facilitate biofilm dispersal.

title: Fabrication of heteroatom doped NFP MWCNT and NFB MWCNT nanocomposite from imidazolium ionic liquid functionalized MWCNT for antibiofilm and wound healing in Wistar rats: Synthesis, characterization, in vitro and in vivo studies.
abstract: Bacterial biofilm is an obstacle for wound healing because it can affect the epithelialization, development of granular cells, and other regular inflammatory procedures. It plays the role of safeguarding pathogens from antiseptics and antibiotics. In this respect, this research work aims to develop heteroatom (N, F, P/B) incorporated multi walled carbon nanotubes (MWCNT) such as NFP MWCNT and NFB MWCNT, which can maximize the wound healing efficacy via destroying the wound pathogen and biofilms. NFP MWCNT and NFB MWCNT were obtained using self assembling ionic liquids (ILs) such as BMIM PF6 and BMIM BF4 in an acid functionalized MWCNT (A MWCNT) suspension, followed by pyrolysis in a nitrogen atmosphere. The composite formation was established by FTIR, XRD, RAMAN, EDX mapping, and XPS spectroscopy. TEM and SEM analyses confirmed the bamboo stick like morphology. During this reaction, IL molecules might be cross linked with A MWCNT via hydrogen bonding and ionic interaction, with further pyrolysis producing the defects with doping of N, F, P, or B elements. Finally, they were assessed for their antibiofilm activity against typical bacterial strains such as K. pneumoniae, P. aeruginosa, E. coli (Gram negative) and B. subtilis (Gram positive) using a quantitative estimation approach. The results revealed greater effectiveness of NFB MWCNT and NFP MWCNT, compared to pristine MWCNT. The antibiofilm activity of NFP MWCNT and NFB MWCNT was associated with their specific surface chemistry (due to the presence of N, F, P/B heteroatoms) and their nanosize. Moreover, the synthesized material was examined for its wound healing ability in Wistar rats. The results proved that cells cultured on NFB MWCNT and NFP MWCNT displayed exceptional healing ability. The different electronegativity between the heteroatoms creates the surface charge that inhibits the biofilm formation, leading to healing the wounds together with the heteroatom mineral source for mouse fibroblast regeneration and granulation. This is the first study in which the role of different heteroatoms incorporated into MWCNT is examined in the context of antibiofilm associated wound healing ability.

title: A review of iodine based compounds, with a focus on biofilms: results of an expert panel.
abstract: Biofilms play a central role in the chronicity of non healing lesions such as venous leg ulcers and diabetic foot ulcers. Therefore, biofilm management and treatment is now considered an essential part of wound care. Many antimicrobial treatments, whether topical or systemic, have been shown to have limited efficacy in the treatment of biofilm phenotypes. The antimicrobial properties of iodine compounds rely on multiple and diverse interactions to exert their effects on microorganisms. An expert panel, held in Las Vegas during the autumn Symposium on Advanced Wound Care meeting in 2018, discussed these properties, with the focus on iodine and iodophors and their effects on biofilm prevention and treatment.

title: Current in vitro biofilm infected chronic wound models for developing new treatment possibilities.
abstract: The prevalence of chronic wounds is increasing worldwide. The most recent estimates suggest that up to 2% of the population in the industrialized countries are affected.1  During the past few decades, bacterial biofilms have been elucidated as one of the primary reasons why chronic wounds fail to heal.2,3 Critical Issues: There is a lack of direct causation and evidence of the role that biofilms play in persistent wounds, which complicates research on new treatment options, since it is still unknown which factors dominate. For this reason, several different in vitro wound models have been created, that mimic the biofilm infections observed in chronic wounds and other chronic infections. These different models are, amongst other purposes, used to test a variety of wound care products. However, chronic wounds are highly complex, and several different factors must be taken into consideration along with the infection, including physiochemical and human supplemented factors. Furthermore, the limitations of using in vitro models, such as the lack of a responsive immune system should always be given due consideration.  Present understandings of all the elements and interactions that take place within chronic wounds are incomplete. As our insight of in vivo chronic wounds continues to expand, so too must the in vitro models used to mimic these infections evolve and adapt to new knowledge.

title: The zone model: A conceptual model for understanding the microenvironment of chronic wound infection
abstract: In 2008, two articles in Wound Repair and Regeneration changed the clinical perspective on chronic wounds. They stated that chronic wounds that do not heal contain bacterial biofilms and that these biofilms may be one of the reasons for the nonhealing properties of the wounds. However, we still do not understand the exact role biofilms play in the halted healing process, and we are not able to successfully treat them. The reason for this could be that in vivo biofilms differ substantially from in vitro biofilms, and that most of the knowledge about biofilms originates from in vitro research. In this article, we introduce the zone model as a concept for understanding bacterial behavior and the impact of the microenvironment on both the host and the bacteria. Until now, identification of bacteria, gene expression, and postscript regulation have been looking at a bulk of bacteria and averaging the behavior of all the bacteria. As the zone model dictates that every single bacterium reacts to its own microenvironment, the model may facilitate the planning of future research with improved clinical relevance. The zone model integrates physiology and biology from single cells, microbial aggregates, local host response, surrounding tissue, and the systemic context of the whole host. Understanding the mechanisms behind the actions and reactions by a single bacterium when interacting with other neighboring bacteria cells, other microorganisms, and the host will help us overcome the detrimental effects of bacteria in chronic wounds. Furthermore, we propose use of the terminology "bacterial phenotype" when describing the actions and reactions of bacteria, and the term "biofilms" to describe the morphology of the bacterial community.

title: Evidence Based Review of Anti Biofilm Agents for Wound Care.
abstract: Biofilms in vivo are small densely packed aggregations of microbes that are highly resistant to host immune responses and treatment. Biofilms attach to each other and to nearby surfaces. They are difficult to study and identify in a clinical setting as their quantification necessitates the use of advanced microscopy techniques such as confocal scanning laser microscopy (CLSM) Nonetheless it is likely that biofilms contribute to the pathophysiology of chronic skin wounds. Reducing, removing or preventing biofilms is thus a logical approach to help clinicians heal chronic wounds. Recent Advances Wound care products have demonstrated varying degrees of efficacy in destroying biofilms in in vitro and pre clinical models as well as in some clinical studies. Critical Issues Controlled studies exploring the beneficial role of biofilm eradication and its relationship to healing in patients with chronic wounds are limited. This review aims to discuss the mode of action and clinical significance of currently available anti biofilm products including surfactants, dressings and others, with a focus on levels of evidence for efficacy in disrupting biofilms and ability to improve wound healing outcomes.  Few available products have good evidence to support anti biofilm activity and wound healing benefits. Novel therapeutic strategies are on the horizon. More high quality clinical studies are needed. The development of non invasive techniques to quantify biofilms will facilitate increased ease of research about biofilms in wounds and how to combat them.

title: Printed Electroceutical Dressings for the Inhibition of Biofilms and Treatment of Chronic Wounds
abstract: We report on an innovative, fabric based conformable, and easily fabricated electroceutical wound dressing that inhibits bacterial biofilm infections and shows significant promise for healing chronic wounds. Cyclic voltammetry demonstrates the ability of the electroceutical to produce reactive oxygen species, primarily HOCl that is responsible for bacterial inhibition. In vitro investigation with the lawn biofilm grown on a soft tissue mimic assay shows the efficacy of the dressing against both Gram positive and Gram negative bacteria in the biofilm form. In vivo, the printed electroceutical dressing was utilized as an intervention treatment for a canine subject with a non healing wound due to a year long persistent polymicrobial infection. The clinical case study with the canine subject exhibited the applicability in a clinical setting with the results showing infection inhibition within 11 days of initial treatment. This printed electroceutical dressing was integrated with a Bluetooth(r) enabled circuit allowing remote monitoring of the current flow within the wound bed. The potential to monitor wounds remotely in real time with a Bluetooth(r) enabled circuit proposes a new physical biomarker for management of infected, chronic wounds.

title: Chitosan based Scaffolds, Suitable Structures for Wound Healing Dressing: A Short Review
abstract: Different kinds of substances has been used for wound dressing, however, some disadvantages such as unsatisfactory mechanical stability, poor flexibility, severe shrinkage, low porosity, hard separation from the wound site, and non antibacterial activity, has been reported. Over the last two decades, much effort has been made to find suitable biopolymer materials for wound healing applications. Chitosan has revealed various biological properties like biodegradable, biocompatible, non toxic and non allergenic, antibacterial effects thus can be used for the production of biofilms and nano scaffolds. The poor solubility and thermal properties of chitosan restrict its widespread uses, but this polysaccharide is highly compatible with other biopolymers, and researchers are using this property to improve the limitations of chitosan and produce various types of chitosan based hybrids materials. The purpose of this study is to provide an overview of various chitosan based nanoscaffolds as wound healing dressings.  This narrative review was performed using ISI Web of Science, PubMed, SID, Scholar, Scopus, and Science Direct and articles published up to Jan 2020 were included. The keywords of chitosan, chitosan based scaffolds, chitosan based composite, and wound dressing were used.  Many researches have been accomplished to obtain chitosan based scaffolds, including the construction of chitosan based blends and composite scaffolds and etc. The results of most of these researches showed positive effects of chitosan, and its nanocomposite scaffolds/biofilms in blood clotting, activated platelet activity, facilitated tissue regeneration and wound healing process.  The use of chitosan based scaffolds is effective in biological dressings and wound healing. Futuristic and innovative approaches in chitosan derivatives and nanocomposites can lead to the preparation of suitable co polymers and the production of wound dressings with the desired properties. the authors hope that this review will help for researchers.

title: Efficacy of Wound Cleansers on Wound Specific Organisms Using In Vitro and Ex Vivo Biofilm Models.
abstract: Biofilms are believed to be a source of chronic inflammation in non healing wounds.  In this study, the pre clinical anti biofilm efficacy of several wound cleansers was examined using the Calgary minimum biofilm eradication concentration (MBEC) and ex vivo porcine dermal explant (PDE) models on Pseudomonas aeruginosa, methicillin resistant Staphylococcus aureus (MRSA) and Candida albicans biofilms.  A surfactant based cleanser and antimicrobial based cleansers containing ionic silver, hypochlorous acid (HOCl) sodium hypochlorite (NaOCl) and polyhexamethylene biguanide (PHMB) were tested on the MBEC model biofilms with a 10 minute application time. Select cleansers were then tested on the mature PDE biofilms with 10 minute applications followed by the application of cleanser soaked gauze. The PDE model was further expanded to include single and daily applications of the cleansers to mimic daily and 72 hour dressing changes.  In the MBEC model, PHMB and HOCl based cleansers reduced immature MRSA, C albicans, and P aeruginosa biofilm regrowth by 3x when compared with silver, surfactant, and saline cleansers. The major differences could be elucidated in the PDE model in which, after daily application, 1 PHMB based cleanser showed a statistically significant reduction (3 8 CFU/mL log reduction) in all mature biofilms tested, while a NaOCl based cleanser showed significant reduction in 2 microorganisms (3 5 CFU/mL log reduction, P aeruginosa and MRSA).The other PHMB based cleanser showed a statistically significant 3 log CFU/mL reduction in P aeruginosa. The remaining cleansers showed no statistically significant difference from the saline control.  Results confirm that there are model dependent differences in the outcomes of these studies, suggesting the importance of model selection for product screening. The results indicate that 1 PHMB based cleanser was effective in reducing mature P aeruginosa, MRSA, and C albicans biofilms and that sustained antimicrobial presence was necessary to reduce or eliminate these mature biofilms.