Antimicrobial dressings: Comparison of the ability of a panel of dressings to prevent biofilm formation by key burn wound pathogens

Light-degradable nanocomposite hydrogels for antibacterial wound dressing applications

Skin injuries infected by bacteria can cause life-threatening human diseases if not treated properly. In this work, we developed a light-degradable nanocomposite hydrogel to achieve both controlled antibiotic delivery and hydrogel degradation using light as the sole stimulus. Specifically, we incorporated triclosan-loaded, poly(N-isopropylacrylamide)-based nanogels (TCS-NGs) that exhibited potent antibacterial efficacy, into a light-degradable poly (ethylene glycol) (PEG)-based hydrogel matrix via simple physical entrapment method. Upon exposure to 365 nm light, the hydrogel matrix could rapidly degrade, which subsequently released the entrapped TCS-NGs into the surrounding environment. Our results demonstrated that TCS-NGs released from light-degradable nanocomposite hydrogels still possessed remarkable antibacterial efficacy by inhibiting the growth of Staphylococcus aureus both in solution (a fivefold reduction in optical density compared to the blank control) and on bacteria-infected porcine skins (a fivefold reduction in colony-forming units compared to the blank control). Finally, using an alamarBlue assay on human dermal fibroblasts, we determined that each component of the nanocomposite hydrogel exhibited excellent biocompatibility (>90% cell viability) and would not cause significant cytotoxicity. Overall, the fabricated light-degradable nanocomposite hydrogels could serve as novel material for antibacterial wound dressing applications.

A standardized wound infection model for antimicrobial testing of wound dressings in vitro

To investigate the effectiveness of antimicrobial agents against wound infections, experiments using either 2D cultures with planktonic microorganisms or animal infection models are frequently carried out. However, the transferability of the results to human skin is limited by the lack of complexity of the 2D models or by the poor translation of the results from animal models. Hence, there is a need for wound infection models capable of assessing antimicrobial agents. In this study, an easily standardized wound infection model was established. This model consists of a mechanically wounded human skin model on a collagen matrix infected with various clinically relevant bacteria. Infection of the model led to recognition of the pathogens and induction of an inflammatory response. The untreated infection spread over time, causing significant tissue damage. By applying an antimicrobial-releasing wound dressing, the bacterial load could be reduced and the success of the treatment could be further measured by a decrease in the inflammatory reaction. In conclusion, this wound infection model can be used to evaluate new antimicrobial therapeutics as well as to study host-pathogen interactions.

On the potential role of naturally occurring carboxylic organic acids as anti-infective agents: opportunities and challenges

Carboxylic organic acids are intermediates of central carbon metabolic pathways (e.g. acetic, propionic, citric, and lactic acid) long known to have potent antimicrobial potential, mainly at acidic pHs. The food industry has been leveraging those properties for years, using many of these acids as preservatives to inhibit the growth of pathogenic and/or spoilage fungal and bacterial species. A few of these molecules (the most prominent being acetic acid) have been used as antiseptics since Hippocratic medicine, mainly to treat infected wounds in patients with burns. With the growth of antibiotic therapy, the use of carboxylic acids (and other chemical antiseptics) in clinical settings lost relevance; however, with the continuous emergence of multi-antibiotic/antifungal resistant strains, the search for alternatives has intensified. This prospective article raises awareness of the potential of carboxylic acids to control infections in clinical settings, considering not only their previous exploitation in this context (which we overview) but also the positive experience of their safe use in food preservation. At a time of great concern with antimicrobial resistance and the slow arrival of new antimicrobial therapeutics to the market, further exploration of organic acids as anti-infective molecules may pave the way to more sustainable prophylactic and therapeutic approaches.

The Antimicrobial Efficacy of Topically Applied Mafenide Acetate, Citric Acid and Wound Irrigation Solutions Lavanox and Prontosan against Pseudomonas aeruginosa

Since burn wound infections caused by Pseudomonas aeruginosa (PA) lead to major complications and sepsis, this study evaluates the antimicrobial efficacy of the wound irrigation solutions Prontosan (PRT), Lavanox (LAV), citric acid (CA) and mafenide acetate (MA) using microbiology assays and an ex vivo skin wound model. In suspension assays, all the solutions showed significant reductions in bacterial number (log10 reduction: CA 5.77; LAV 4.91; PRT 4.74; MA 1.23). The biofilm assay revealed that PRT and LAV reduced biofilm formation by ~25% after a 15 min treatment, while PRT was most effective after a 24 h treatment (~68%). The number of PA in biofilms measured directly after a 15 min treatment was reduced most effectively with CA and LAV (log10 reductions ~2.5), whereas after a 24 h treatment, all solutions achieved only 1.36-1.65 log10 reductions. In the skin wound model, PRT and LAV provided the highest bacterial reduction after a 15 min treatment (log10 reduction 1.8-1.9), while MA was more effective after a 22 h treatment (log10 reduction 3.6). The results demonstrated the antimicrobial efficacy of all solutions against PA. Further investigation is needed to explore the potential clinical applications of a combination or alternating use of these solutions for infection prophylaxis and treatment of wound infections caused by PA.

Efficacy and optimal dose of acetic acid to treat colonised burns wounds: protocol for a pilot randomised controlled trial

INTRODUCTION

Despite of recent advancement in the burns wound management, burn wound infection (BWI) is still one of the major cause of burns mortality. Patients who survive their burns injury still suffers from BWI related complication like delayed wound healing and poor scarring. BWI has been treated by application of topical antimicrobial agents or systemic antibiotics. Due to the global risk of developing systemic antibiotics resistance, medical research focuses on identifying single topical agent which has effective antimicrobial activity, easily available and cost effective. One such agent is acetic acid (AA). AA has been used as a topical antibacterial agent for the treatment of burns wounds for many years and has shown to have activity against gram-negative organisms including Pseudomonas aeruginosa. So far there has been no consensus on optimal concentration that has effective antimicrobial activity, frequency of application, duration of treatment and most importantly good patient's tolerability. A randomised control study is required to answer all these questions.

OBJECTIVE

To investigate the efficacy and tolerability of 0.5% and 2% of AA when applied to colonised burns wounds for 3 days after admittance to the Queen Elizabeth Hospital Birmingham.

METHODS AND ANALYSIS

This is a double-blinded, prospective, randomised, controlled, single-centre trial. Patients will be screened for eligibility in the inpatient area and those who are found to be eligible will be randomly assigned to one of two treatment groups: group 1: 0.5% AA (10 patients); group 2: 2% AA (10 patients); total number: 20 patients.

OUTCOME MEASURES

Primary outcome: Efficacy will be assessed by measuring the bacterial load from microbiology wound swabs for three consecutive days.Secondary outcomes: (1) The assessment of antimicrobial activity of AA and the minimum inhibitory concentrations. (2) Patient's tolerance by assessing Visual Analogue Scale pain score. (3) Time to 95% wound healing of treatment area. (4) Patient's perceived treatment allocation.

ETHICS AND DISSEMINATION

AceticA trial protocol was approved by the National Research Ethics Service (West Midlands-Edgbaston Research Ethics Committee; 17/WM/0407; IRAS 234132). This article refers to protocol version 5.0 dated 6 July 2020. The analysed results will be presented at national and international conferences related to management of burn patients. The generated articles based on the trial results will be submitted to peer review journals for publication.

TRIAL REGISTRATION NUMBER

ISRCTN11636684.

Sweet and sour synergy: exploring the antibacterial and antibiofilm activity of acetic acid and vinegar combined with medical-grade honeys

Oxymel, a combination of honey and vinegar, has been used as a remedy for wounds and infections in historical and traditional medical settings. While honey is now clinically used to treat infected wounds, this use of a complex, raw natural product (NP) mixture is unusual in modern western medicine. Research into the antimicrobial activity of NPs more usually focuses on finding a single active compound. The acetic acid in vinegar is known to have antibacterial activity at low concentrations and is in clinical use to treat burn wound infections. Here, we investigated the potential for synergistic activity of different compounds present in a complex ingredient used in historical medicine (vinegar) and in an ingredient mixture (oxymel). We conducted a systematic review to investigate published evidence for antimicrobial effects of vinegars against human pathogenic bacteria and fungi. No published studies have explicitly compared the activity of vinegar with that of a comparable concentration of acetic acid. We then characterized selected vinegars by HPLC and assessed the antibacterial and antibiofilm activity of the vinegars and acetic acid, alone and in combination with medical-grade honeys, against Pseudomonas aeruginosa and Staphylococcus aureus. We found that some vinegars have antibacterial activity that exceeds that predicted by their acetic acid content alone, but that this depends on the bacterial species being investigated and the growth conditions (media type, planktonic vs. biofilm). Pomegranate vinegars may be particularly interesting candidates for further study. We also conclude that there is potential for acetic acid, and some vinegars, to show synergistic antibiofilm activity with manuka honey.

Anti-Biofilm Efficacy of Commonly Used Wound Care Products in In Vitro Settings

Considering the prevalence and pathogenicity of biofilms in wounds, this study was designed to evaluate the anti-biofilm capabilities of eight commercially available wound care products using established in vitro assays for biofilms. The products evaluated included dressings with multiple delivery formats for ionic silver including nanocrystalline, gelling fibers, polyurethane (PU) foam, and polymer matrix. Additionally, non-silver-based products including an extracellular polymeric substance (EPS)-dissolving antimicrobial wound gel (BDWG), a collagenase-based debriding ointment and a fish skin-based skin substitute were also evaluated. The products were evaluated on Staphylococcus aureus and Pseudomonas aeruginosa mixed-species biofilms grown using colony drip flow reactor (CDFR) and standard drip flow reactor (DFR) methodologies. Anti-biofilm efficacy was measured by viable plate counts and confocal scanning laser microscopy (CSLM). Four of the eight wound care products tested were efficacious in inhibiting growth of new biofilm when compared with untreated controls. These four products were further evaluated against mature biofilms. BDWG was the only product that achieved greater than 2-log growth reduction (5.88 and 6.58 for S. aureus and P. aeruginosa, respectively) of a mature biofilm. Evaluating both biofilm prevention and mature biofilm disruption capacity is important to a comprehensive understanding of the anti-biofilm efficacy of wound care products.

Biofilms: Formation, Research Models, Potential Targets, and Methods for Prevention and Treatment

Due to the continuous rise in biofilm-related infections, biofilms seriously threaten human health. The formation of biofilms makes conventional antibiotics ineffective and dampens immune clearance. Therefore, it is important to understand the mechanisms of biofilm formation and develop novel strategies to treat biofilms more effectively. This review article begins with an introduction to biofilm formation in various clinical scenarios and their corresponding therapy. Established biofilm models used in research are then summarized. The potential targets which may assist in the development of new strategies for combating biofilms are further discussed. The novel technologies developed recently for the prevention and treatment of biofilms including antimicrobial surface coatings, physical removal of biofilms, development of new antimicrobial molecules, and delivery of antimicrobial agents are subsequently presented. Finally, directions for future studies are pointed out.

Light-activated molecular machines are fast-acting broad-spectrum antibacterials that target the membrane

The increasing occurrence of antibiotic-resistant bacteria and the dwindling antibiotic research and development pipeline have created a pressing global health crisis. Here, we report the discovery of a distinctive antibacterial therapy that uses visible (405 nanometers) light-activated synthetic molecular machines (MMs) to kill Gram-negative and Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, in minutes, vastly outpacing conventional antibiotics. MMs also rapidly eliminate persister cells and established bacterial biofilms. The antibacterial mode of action of MMs involves physical disruption of the membrane. In addition, by permeabilizing the membrane, MMs at sublethal doses potentiate the action of conventional antibiotics. Repeated exposure to antibacterial MMs is not accompanied by resistance development. Finally, therapeutic doses of MMs mitigate mortality associated with bacterial infection in an in vivo model of burn wound infection. Visible light-activated MMs represent an unconventional antibacterial mode of action by mechanical disruption at the molecular scale, not existent in nature and to which resistance development is unlikely.

Prevention and treatment of burn wound infections: the role of topical antimicrobials

INTRODUCTION

Infections related to the skin are the principal drivers of morbidity and mortality following severe burn, therefore a diverse armamentarium of topical antimicrobial agents were developed over the history of burn care. The last 30 years witnessed dramatic changes in the application of surgical intervention and utilization of topical therapies.

AREAS COVERED

We explore well-known topical antimicrobial products used in burn care. First, we investigate how fundamental changes in the practice of burn surgery influenced the choice of topical therapies used. Then, we examine antimicrobial creams and ointments commonly recognized due to their long record of use in burn care. Next, we dive into antimicrobial solutions commonly used as adjuncts to surgical intervention. Finally, we explore representative antimicrobial dressings, an ever-advancing roster of products opening the door to the next era in burn care. We also describe how these new agents relate to already established tools in present-day burn care.

EXPERT OPINION

In the current day, though the wisdom of early excision and wound closure remains valid, we continue to strive to minimize aggressive wound excision and disfiguring donor tissue collection while securing rapid wound closure. To this end, antimicrobial therapies are titrated to optimize operative outcomes and provide non-operative wound care when appropriate. Antimicrobial agents bridge the gap with the next generation of skin substitute and skin replacement therapies.

Design, preparation and in vitro characterization of biomimetic and bioactive chitosan/polyethylene oxide based nanofibers as wound dressings

Chitosan-based nanofibers (CS-NFs) are excellent artificial extracellular matrices (ECMs) due to the resemblance of CS with the glycosaminoglycans of the natural ECMs. Despite this excellent feature, the poor electrospinnability and mechanical properties of CS are responsible for important limitations in respect to its biomedical applications. To improve the CS's physico-chemical properties, new bioactive and biomimetic CS-NFs were formulated with polyethylene oxide (PEO), having incorporated different active components (ACs) with important beneficial effects for healing. Manuka honey (trophic and antimicrobial effects), propolis (antimicrobial effects), Calendula officinalis infusion (antioxidant effect, reepithelialization stimulating agent), insulin (trophic effect), and L-arginine (angiogenic effect) were selected as ACs. SEM morphology analysis revealed well-alignment, unidirectional arrays, with small diameters, no beads, and smooth surfaces for developed CS_PEO-ACs NFs. The developed NFs showed good biodegradability (NFs mats lost up to 60% of their initial weight in PBS), increased hemocompatibility (hemolytic index less than 4%), and a reduced cytotoxicity degree (cell viability degree more than 90%). In addition, significant antioxidant and antimicrobial effects were noted for the developed NFs which make them suitable for chronic wounds, due to the role of oxidative stress and infection risk in delaying normal wound healing. The most suitable for wound healing applications seems to be CS_PEO@P_C which showed an improved hemolysis index (2.92 ± 0.16%), is non-toxic (cell viability degree more than 97%), and has also significant radical scavenging effect (DPPH inhibition more than 65%). In addition, CS_PEO@P_C presents increased antimicrobial effects, more noticeably for Staphylococcus aureus strain, which is a key feature in preventing wound infection and delaying the healing process. It can be concluded that the developed CS/PEO-ACs NFs are very promising biomaterials for wound care, especially CS_PEO@P_C.

Multifunctional Gelatin/Chitosan Electrospun Wound Dressing Dopped with Undaria pinnatifida Phlorotannin-Enriched Extract for Skin Regeneration

The similarities of electrospun fibers with the skin extracellular matrix (ECM) make them promising structures for advanced wound dressings. Moreover, infection and resistance in wounds are a major health concern that may be reduced with antibacterial wound dressings. In this work, a multifunctional wound dressing was developed based on gelatin/chitosan hybrid fibers dopped with phlorotannin-enrich extract from the seaweed Undaria pinnatifida. The intrinsic electrospun structure properties combined with the antimicrobial and anti-inflammatory properties of phlorotannin-enrich extract will enhance the wound healing process. Electrospun meshes were produced by incorporating 1 or 2 wt% of extract, and the structure without extract was used as a control. Physico-chemical, mechanical, and biological properties were evaluated for all conditions. Results demonstrated that all developed samples presented a homogenous fiber deposition with the average diameters closer to the native ECM fibrils, and high porosities (~90%) that will be crucial to control the wound moist environment. According to the tensile test assays, the incorporation of phlorotannin-enriched extract enhances the elastic performance of the samples. Additionally, the extract incorporation made the structure stable over time since its in vitro degradation rates decreased under enzymatic medium. Extract release profile demonstrated a longstanding delivery (up to 160 days), reaching a maximum value of ~98% over time. Moreover, the preliminary antimicrobial results confirm the mesh's antimicrobial activity against Pseudomonas aeruginosa and Staphylococcus aureus. In terms of biological characterization, no condition presented cytotoxicity effects on hDNF cells, allowing their adhesion and proliferation over 14 days, except the condition of 2 wt% after 7 days. Overall, the electrospun structure comprising phlorotannins-enriched extract is a promising bioactive structure with potential to be used as a drug delivery system for skin regeneration by reducing the bacterial infection in the wound bed.

Reducing Biofilm Infections in Burn Patients' Wounds and Biofilms on Surfaces in Hospitals, Medical Facilities and Medical Equipment to Improve Burn Care: A Systematic Review

Biofilms in burns are major problems: bacterial communities rapidly develop antibiotic resistance, and 60% of burn mortality is attributed to biofilms. Key pathogens are Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and multidrug-resistant Acinetobacter baumanii. Purpose: identify current and novel interventions to reduce biofilms on patients' burns and hospital surfaces and equipment. Medline and Embase were searched without date or language limits, and 31 possible interventions were prioritised: phages, nano-silver, AgSD-NLs@Cur, Acticoat and Mepilex silver, acetic acid, graphene-metal combinations, CuCo2SO4 nanoparticles, Chlorhexidene acetate nanoemulsion, a hydrogel with moxifloxacin, carbomer, Chitosan and Boswellia, LED light therapy with nano-emodin or antimicrobial blue light + Carvacrol to release reactive oxygen species, mannosidase + trypsin, NCK-10 (a napthalene compound with a decyl chain), antimicrobial peptide PV3 (includes two snake venoms), and polypeptides P03 and PL2. Most interventions aimed to penetrate cell membranes and reported significant reductions in biofilms in cfu/mL or biofilm mass or antibiotic minimal inhibitory concentrations or bacterial expression of virulence or quorum sensing genes. Scanning electron microscopy identified important changes in bacterial surfaces. Patients with biofilms need isolating and treating before full admission to hospital. Cleaning and disinfecting needs to include identifying biofilms on keyboards, tablets, cell phones, medical equipment (especially endoscopes), sinks, drains, and kitchens.

Acetic acid dressings used to treat pseudomonas colonised burn wounds: A UK national survey

INTRODUCTION

Wound infection following burn injury can be clinically challenging to manage. Its presence in a thermally compromised patient can detrimentally affect the ability of the wound to heal leading not only to wound progression but ultimately contribute to a large part of the economic health burden expenditure in the National Health Service. Despite meticulous wound care and infection control measures the colonisation of burn wounds by bacterial pathogens has and continues to be the case. There has been a growing interest in the use of antimicrobial applications when managing localised burn wound infections due to a constantly increasing number of antibiotic-resistant organisms.

AIM

To survey which antimicrobial dressings are currently being used across UK burns services when managing localised pseudomonas wound infections.

METHODS

We conducted a nationwide telephone survey of UK burns services during October 2019 to determine which topical antimicrobial agent was used to treat local pseudomonas burn wound infections.

RESULTS

Six burns services (31.6%) used acetic acid-soaked dressings, one of which alternates acetic acid with sodium hypochlorite solution. Silver-based dressings were also used by six burns services (31.6%) - again, one department alternates silver-based dressings with sodium hypochlorite solution. Betadine-soaked, gauze-based dressings were used across five burns services (26.3%) and the remaining two burns services (10.5%) used sodium hypochlorite solution and non-medicated dressings respectively.

CONCLUSION

We identified a significant difference in the UK burns services' approach to pseudomonas burn wound infections. Our literature review demonstrates that a daily dressing regime of 2.5-3% acetic acid is a well-tolerated treatment regime in burn patients and that it is in use in UK burns services. There are no current randomised controlled trials that evaluate the usage of acetic acid. The variation in usage suggests that there is scope for further study in order to develop evidence to generate a UK wide approach based on national standardised guidelines.

Bioresponsive supramolecular hydrogels for hemostasis, infection control and accelerated dermal wound healing

Injectable, drug-releasing hydrogel scaffolds with multifunctional properties including hemostasis and anti-bacterial activity are essential for successful wound healing; however, designing ideal materials is still challenging. Herein, we demonstrate the fabrication of a biodegradable, temperature-pH dual responsive supramolecular hydrogel (SHG) scaffold based on sodium alginate/poly(N-vinyl caprolactam) (AG/PVCL) through free radical polymerization and the subsequent chemical and ionic cross-linking. A natural therapeutic molecule, tannic acid (TA)-incorporated SHG (AG/PVCL-TA), was also fabricated and its hemostatic and wound healing efficiency were studied. In the AG/PVCL-TA system, TA acts as a therapeutic molecule and also substitutes as an effective gelation binder. Notably, the polyphenol-arm structure and diverse bonding abilities of TA can hold polymer chains through multiple bonding and co-ordinate cross-linking, which were vital in the formation of the mechanically robust AG/PVCL-TA. The SHG formation was successfully balanced by varying the composition of SA, VCL, TA and cross-linkers. The AG/PVCL-TA scaffold was capable of releasing a therapeutic dose of TA in a sustained manner under physiological temperature-pH conditions. AG/PVCL-TA displayed excellent free radical scavenging, anti-inflammatory, anti-bacterial, and cell proliferation activity towards the 3T3 fibroblast cell line. The wound healing performance of AG/PVCL-TA was further confirmed in skin excision wound models, which demonstrated the potential application of AG/PVCL-TA for skin regeneration and rapid wound healing.

New Hyaluronic Acid/Polyethylene Oxide-Based Electrospun Nanofibers: Design, Characterization and In Vitro Biological Evaluation

Natural compounds have been used as wound-healing promoters and are also present in today's clinical proceedings. In this research, different natural active components such as propolis, Manuka honey, insulin, L-arginine, and Calendula officinalis infusion were included into hyaluronic acid/poly(ethylene)oxide-based electrospun nanofiber membranes to design innovative wound-dressing biomaterials. Morphology and average fiber diameter were analyzed by scanning electron microscopy. Chemical composition was proved by Fourier transform infrared spectroscopy, which indicated successful incorporation of the active components. The nanofiber membranes with propolis and Calendula officinalis showed best antioxidant activity, cytocompatibility, and antimicrobial properties against pathogen strains Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa and had an average diameter of 217 ± 19 nm with smooth surface aspect. Water vapor transmission rate was in agreement with the range suitable for preventing infections or wound dehydration (~5000 g/m2 24 h). Therefore, the developed hyaluronic acid/poly(ethylene)oxide nanofibers with additional natural components showed favorable features for clinical use as wound dressings.

Antimicrobial stewardship of antiseptics that are pertinent to wounds: the need for a united approach

Long before the nature of infection was recognized, or the significance of biofilms in delayed healing was understood, antimicrobial agents were being used in wound care. In the last 70 years, antibiotics have provided an effective means to control wound infection, but the continued emergence of antibiotic-resistant strains and the documented antibiotic tolerance of biofilms has reduced their effectiveness. A range of wound dressings containing an antimicrobial (antibiotic or non-antibiotic compound) has been developed. Whereas standardized methods for determining the efficacy of non-antibiotic antimicrobials in bacterial suspension tests were developed in the early twentieth century, standardized ways of evaluating the efficacy of antimicrobial dressings against microbial suspensions and biofilms are not available. Resistance to non-antibiotic antimicrobials and cross-resistance with antibiotics has been reported, but consensus on breakpoints is absent and surveillance is impossible. Antimicrobial stewardship is therefore in jeopardy. This review highlights these difficulties and in particular the efficacy of current non-antibiotic antimicrobials used in dressings, their efficacy, and the challenges of translating in vitro efficacy data to the efficacy of dressings in patients. This review calls for a unified approach to developing standardized methods of evaluating antimicrobial dressings that will provide an improved basis for practitioners to make informed choices in wound care.

Nanoparticle-Based Devices in the Control of Antibiotic Resistant Bacteria

Antimicrobial resistance (AR) is one of the most important public health challenges worldwide as it represents a serious complication that is able to increase the mortality, morbidity, disability, hospital stay and economic burden related to infectious diseases. As such, the spread of AR–pathogens must be considered as an emergency, and interdisciplinary approaches must be undertaken in order to develop not only drugs, but holistic strategies to undermine the epidemic and pathogenic potentials of multi-drug resistant (MDR) pathogens. One of such approaches has focused on the use of antimicrobial nanoparticles (ANPs), as they have demonstrated to possess strong antimicrobial effects on MDR pathogens. On the other hand, the ability of bacteria to develop resistance to such agents is minimal. In this way, ANPs may seem a good choice for the development of new drugs, but there is no certainty about their safety, which may delay its translation to the clinical setting. As MDR pathogens are quickly becoming more prevalent and drug development is slow and expensive, there is an increasing need for the rapid development of new strategies to control such agents. We hereby explore the possibility of designing ANP-based devices such as surgical masks and fabrics, wound dressings, catheters, prostheses, dentifrices, water filters, and nanoparticle-coated metals to exploit the potential of such materials in the combat of MDR pathogens, with a good potential for translation into the clinical setting.

A Risk-Stratified Peri-Operative Protocol for Reducing Surgical Site Infection after Cesarean Delivery

Background: Surgical site infections (SSI) are multifaceted. Pre-operative, intra-operative, and post-operative factors influence the risk of developing an infection. Our objective was to evaluate the effectiveness of an infection risk-stratification checklist, utilizing known SSI risk factors, and a tailored surgical protocol for SSI prevention in women undergoing cesarean delivery. Patients and Methods: A prospective project to reduce SSI was conducted for women undergoing cesarean delivery on the resident staff service at a midwestern, urban tertiary care hospital. Patients were categorized according to an SSI risk-stratification checklist as high risk or low risk. The low-risk group received the local standard of care (single prophylactic dose of pre-operative intravenous antibiotics and a standard pressure dressing). In the high-risk group, prophylactic antibiotic agents were given pre-operatively and continued for the first 24 hours post-operatively. Additionally, patients at high risk received an absorbent dressing (Mepilex Ag^®; Mölnlycke Health Care AB, Gothenburg, Sweden) that was applied in the operating room and worn for one week. Results: The overall rate of SSIs decreased from 6.1% (pre-study rate) to 1.4% after initiation of the protocol, a 77% reduction (p < 0.001). The low- and high-risk groups did not differ in infection rate (0% and 1.4%, respectively; p < 0.59). Both deep incisional and organ/space SSIs decreased after initiation of the protocol (91% and 62% decrease, respectively). Conclusion: Stratifying patients into high- and low-risk groups with tailored peri-operative management strategies reduced overall SSIs. The protocol incorporates known risk factors for SSI in a surgical procedure with high rates of SSI. This approach offers a structured method that can be adopted by other hospital systems for SSI prevention in patients undergoing cesarean delivery.

A human skin equivalent burn model to study the effect of a nanocrystalline silver dressing on wound healing

In this study, a deep burn wound model was established using a 3D human skin equivalent (HSE) model and this was compared to native skin. HSEs were constructed from dermis derived from abdominoplasty/breast surgery and this dermal template was seeded with primary keratinocytes and fibroblasts. The HSE model was structurally similar to native skin with a stratified and differentiated epidermis. A contact burn (60 °C, 80 °C, 90 °C) was applied with a modified soldering iron and wounds were observed at day 1 and 7 after burn. The HSEs demonstrated re-growth with keratinocyte proliferation and formation of a neo-epidermis after burn injury, whereas the ex vivo native skin did not. To assess the suitability of the 3D HSE model for penetration and toxicity studies, a nanocrystalline silver dressing was applied to the model for 7 days, with and without burn injury. The effect of silver on skin re-growth and its penetration and subcellular localization was assessed in HSEs histologically and with laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The silver treatment delayed or reduced skin re-growth, and silver particles were detected on the top of the epidermis, and within the papillary dermis. This novel in vitro 3D multicellular deep burn wound model is effective for studying the pathology and treatment of burn wound injury and is suitable for penetration and toxicity studies of wound healing treatments.

A consecutive case series of defects reconstructed using NovoSorbⓇ Biodegradable Temporising Matrix: Initial experience and early results

BACKGROUND

NovoSorb^Ⓡ Biodegradable Temporising Matrix (BTM) is a synthetic dermal template recently approved for treatment of full thickness defects of the skin. It requires a two-stage reconstruction where it is initially placed into a defect to generate a neodermis, which is later covered by a split skin graft. It has previously been described for the treatment of acute full thickness burn injury, necrotising fasciitis and free flap donor site reconstruction.

METHODS

A consecutive case series review of patients treated with BTM at Middlemore Hospital was performed. Patient demographics, defect aetiology, indications for dermal matrix use, surgical details, and complications were recorded using information gathered from the medical records.

RESULTS

This case series included 25 patients with a range of defects resulting from acute full thickness burn injury, burn scar revision, necrotising soft-tissue infection, tumour excision and traumatic loss. In these patients, 72% of wounds were identified as complex defects with exposed bone or tendon. Complications encountered included infection, non-adherence and incomplete vascularisation.

CONCLUSION

BTM provided a good reconstructive option for a wide range of defects, many of which were not amenable to immediate skin grafting. Once vascularised and ready for the second stage, it developed a red-pink colour and demonstrated capillary refill. Similar to other dermal matrices, infection was a commonly encountered problem. However, BTM proved more tolerant to this and was able to be salvaged in most cases, allowing the second stage to proceed as normal.

Burn Infection and Burn Sepsis

Background: Infection is the most common complication and cause of death in patients suffering burn injuries. These patients are susceptible to infection and burn wound sepsis secondary to the alterations in their physiology. Diagnosis and management of infections rely on physical examination, cultures, and the pathology of the burn wound. Method: We performed an electronic search for articles in the Google Scholar and PubMed databases using the search terms "burn sepsis," "burn infection," and "burn critical care." Results: Multiple factors increase burn patients' risk of invasive infection and sepsis, including underlying factors and co-morbidities, the percent total body surface area of the burn, delays in burn wound excision, and microbial virulence/bacterial count. Organisms causing burn wound infection differ, depending on the time since injury and its location; and diagnosis is multi-factorial. The most common pathogens remain Staphylococcus and Pseudomonas spp. Conclusion: Overall, the recognition of burn sepsis is based on clinical findings. Treatment consists of a combination of local dressings, early burn excision, and systemic antimicrobial therapy. The mortality rate has decreased significantly over the past 10 years, but continued efforts at timely management and infection prevention are essential.

A biocompatible bacterial cellulose/tannic acid composite with antibacterial and anti-biofilm activities for biomedical applications

Biofilm-associated infections are in a high rate of recurrence and biofilms show formidable resistance to current antibiotics, making them a growing challenge in biomedical field. In this study, a biocompatible composite was developed by incorporating tannic acid (TA) and MgCl₂ to bacterial cellulose (BC) for antimicrobial and anti-biofilm purposes. The morphology was investigated by scanning electron microscopy (SEM), and chemical structure were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectra (XPS). In vitro release profiles of tannic acid revealed that the Mg²⁺ cross-links help impede the release of TA from BC matrix, while composite BC-TA lacked Mg²⁺ ionic cross-links, thus more TA was released from the hydrogel. The BC-TA-Mg composites also displayed strong antibacterial activity against S. aureus, E. coli and P. aeruginosa. Moreover, the composites significantly reduced biofilm formation of S. aureus and P. aeruginosa after 24 h incubation by ∼80% and ∼87%, respectively. As a consequence, the BC-TA-Mg composites are a very promising material for combating biofilm-associated infections in biomedical and public health fields.

Restoring balance: biofilms and wound dressings

Biofilms are responsible for stimulating and maintaining wound inflammation, increasing infection risk and delaying wound closure. Appropriate biofilm management is required to fight against local and systemic infection and to restore balance to the wound environment. The most effective way to remove biofilms involves the use of mechanical techniques, with the wound dressing representing an important component of this strategy. Wound dressing fibres, such as polyacrylate fibres, have been shown to be effective in affecting biofilm architecture by disrupting the biofilm matrix. This helps enhance the efficacy of antimicrobials, such as silver. Focusing an antibiofilm strategy on active agents alone does not constitute a sustainable approach to biofilm management. Furthermore, adding too many active chemicals into a wound can be highly detrimental to the wound bed, and potentially may have both short- and long-term biological concerns. Particular attention on the characteristics and key features of wound dressings is discussed in this paper. The aim of the paper is to review the ideal characteristics of wound dressings, in conjunction with antimicrobials, that are considered a fundamental part of an antibiofilm strategy and growing requirement for enhanced wound healing.

Management and prevention of drug resistant infections in burn patients

Introduction: Despite modern advances, the primary cause of death after burns remains infection and sepsis. A key factor in determining outcomes is colonization with multi-drug resistant (MDR) organisms. Infections secondary to MDR organisms are challenging due to lack of adequate antibiotic treatment, subsequently prolonging hospital stay and increasing risk of adverse outcomes. Areas covered: This review highlights the most frequent organisms colonizing burn wounds as well as the most common MDR bacterial infections. Additionally, we discuss different treatment modalities and MDR infection prevention strategies as their appropriate management would minimize morbidity and mortality in this population. We conducted a search for articles on PubMed, Web of Science, Embase, Cochrane, Scopus and UpToDate with applied search strategies including a combination of: "burns, 'thermal injury,' 'infections,' 'sepsis,' 'drug resistance,' and 'antimicrobials.' Expert opinion: Management and prevention of MDR infections in burns is an ongoing challenge. We highlight the importance of preventative over therapeutic strategies, which are easy to implement and cost-effective. Additionally, targeted, limited use of antimicrobials can be beneficial in burn patients. A promising future area of investigation within this field is post-trauma microbiome profiling. Currently, the best treatment strategy for MDR in burn patients is prevention.

Use of an engineered honey to eradicate preformed biofilms of important wound pathogens: an in vitro study

OBJECTIVE

We previously reported on the ability of SurgihoneyRO (SHRO), an engineered honey, to prevent biofilm formation in vitro, but data were lacking regarding the activity against preformed biofilms. This study aims to assess whether SHRO has any antibacterial activity against mature, preformed biofilms and whether there is any evidence to support the observed clinical effectiveness when SHRO has been used anecdotally on acute and chronic wounds where biofilm is most likely present.

METHOD

We tested the in vitro antibacterial activity of SHRO against the mature biofilms of 16 clinically relevant wound pathogens, in terms of impacts on biofilm seeding and biofilm biomass. The honey was serially double diluted from 1:3 down to 1:6144, and the lowest dilution achieving a statistically significant reduction in biomass of ≥50%, compared with untreated controls, was recorded.

RESULTS

All 16 bacterial isolates were susceptible to SHRO, with reduced biofilm seeding observed for all, and percentage reductions ranging from 58% (ACI_C59) to 94.3% (MDR_B) for the strongest concentration of honey (1:3). Furthermore at this concentration, biofilm seeding of the test biofilm was reduced by 80-94.3% (when compared with the positive control) for 12/16 isolates. We additionally demonstrated that SHRO has antibiofilm impacts, with the 24 hour exposure resulting in disruption of the biofilm, reduced seeding and reduced biomass.

CONCLUSION

SHRO is effective at reducing seeding of preformed biofilms of clinically important wound pathogens in vitro, and also has antibiofilm activity. This supports the anecdotal clinical data for antibiofilm efficacy, and supports the use of SHRO as a promising topical wound care agent.

Naturally-derived electrospun wound dressings for target delivery of bio-active agents

Electrospun nanofibers are known as the advanced means for wound dressing. They have represented remarkable potency to encapsulate and deliver biomolecules promoting the wound healing process. Compared to synthetic polymers, naturally derived polymers (NDP) are more qualified candidates for fabrication of biomedical electrospun scaffolds. Not only nanofibers of NDP illustrate higher biocompatibility and biodegradability rates, but also they mimic the native extracellular matrix more closely, which leads to the wound closure acceleration by enhancing tissue regeneration. Aside, incorporation of bioactive molecules and therapeutic agents into the nanofibers can generate innovative bioactive wound dressings with significantly improved healing potentials. This paper starts with a brief discussion on the steps and factors influencing the wound healing process. Then, the recent applications of electrospun nanofibers as wound dressing with healing accelerating properties are reviewed. Further, the various healing agents and alternative strategies for modification and functionalization of bioactive naturally-derived electrospun nanofibers are discussed.

Silver, biofilms and wounds: resistance revisited

Silver is added to an array of commercially available healthcare products including wound dressings. However, overuse of silver is being raised as a potential health concern due to the possible selection of tolerant or resistant bacteria and as a factor that may induce cross resistance to antibiotics. To date, there are only a limited number of studies that have documented evidence of silver resistance in bacteria isolated from medical situations. These studies have indicated low levels of silver resistance in bacteria. However, in comparison to antibiotics, only a small number of studies have been undertaken to investigate silver resistance. It is clear that more studies are required to confirm the most effective therapeutic levels of silver that are needed to kill microbes. In addition, it is probable that sub-therapeutic levels of silver may potentially select for enhanced microbial tolerance. Nevertheless, to date, there still remains very little evidence that silver resistance is a growing health concern in wound care; more studies are clearly needed to substantiate this concern, which has not been observed clinically to any major degree. The issue of biofilm tolerance to silver is more complicated and data on the effect of silver on biofilms is sparse at present.

Nano-silver modified porcine small intestinal submucosa for the treatment of infected partial-thickness burn wounds

BACKGROUND AND AIM

Silver has been widely used as a topical antimicrobial agent in burn wound care. In a previous study, we demonstrated the introduction of nano-silver particles to porcine small intestinal submucosa (NS-PSIS) led to significant enhancement in antibacterial property in repairing contaminated abdominal defect. In this study, we explored the efficacy of NS-PSIS in the treatment of Pseudomonas aeruginosa-infected partial-thickness burn wounds.

METHODS

48 male Sprague-Dawley rats were divided into four groups of equal number. Standardized and reproducible Pseudomonas aeruginosa-infected partial-thickness thermal burns wound model were created using these rats. NS-PSIS, PSIS (porcine small intestinal submucosa) or lipido-colloid dressingss (Urgotul™) were tested for 14days to assess their ability to heal the rats' burn wounds. Control group was without any treatment after the establishment of infected burn-wound. The wound contraction rate, animal body weight change, histological examination, and the quantification of IL-6 and C-reactive protein (CRP) were measured to evaluate the healing effects.

RESULTS

NS-PSIS significantly promoted wound healing and recovered the normal growth of rats. There were significantly lower expression levels of pro-inflammatory cytokine (IL-6) and CRP in NS-PSIS group as compared with the PSIS or Urgotul group in the treatment of infected partial-thickness burn wounds. Histological exams revealed significant less inflammatory cells infiltrating, more re-epithelization and neovascularization in NS-PSIS group. There were also less inflammatory cells infiltrations in the major organs in NS-PSIS group.

CONCLUSIONS

Nano-silver modified porcine small intestinal submucosa (NS-PSIS) can be used as a biological derivative dressing for the treatment of infected partial-thickness burn wounds.

In vitro evaluation of drug release and antibacterial activity of a silver-loaded wound dressing coated with a multilayer system

The goal of the study was to elaborate an antibacterial silver wound dressing covered by a protective coating that would prevent silver diffusion toward skin without losing its biocide properties. Therefore, non woven polyethyleneterephtalate (PET) textiles were pre-treated by two types of polysaccharides - chitosan and cyclodextrin - both crosslinked with citric acid by a pad/dry/cure process. Both types of resulting thermofixed textiles carrying the citrate crosslinks were then impregnated in silver solution followed by a thermal treatment and were finally coated by Layer-by-Layer (L-b-L) deposition of a polyelectrolyte multilayer (PEM) film consisting of anionic water-soluble poly-cyclodextrin and cationic chitosan. The influence of the process parameters was investigated in terms of silver adsorption capacity, PEM system build-up, silver kinetics of release and antibacterial activity. We demonstrate i) the utility of the intermediate thermal treatment step in the reduction of silver leakage in the polyelectrolyte solutions used in the L-b-L process, ii) that silver adsorption on the preliminary thermofixed layers did not affect the PEM system build-up, iii) the slowing down of silver release kinetic thanks to the PEM coating, iv) the preservation of the antibacterial activity despite the PEM coating.

Bismuth Phosphinates in Bi-Nanocellulose Composites and their Efficacy towards Multi-Drug Resistant Bacteria

A series of poorly soluble phenyl bis-phosphinato bismuth(III) complexes [BiPh(OP(=O)R¹ R² )₂ ] (R¹ =R² =Ph; R¹ =R² =p-OMePh; R¹ =R² =m-NO₂ Ph; R¹ =Ph, R² =H; R¹ =R² =Me) have been synthesised and characterised, and shown to have effective antibacterial activity against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). The bismuth complexes were incorporated into microfibrillated (nano-) cellulose generating a bismuth-cellulose composite as paper sheets. Antibacterial evaluation indicates that the Bi-cellulose materials have analogous or greater activity against Gram positive bacteria when compared with commercial silver based additives: silver sulfadiazine loaded at 0.43 wt % into nanocellulose produces a 10 mm zone of inhibition on the surface of agar plates containing S. aureus whereas [BiPh(OP(=O)Ph₂ )₂ ] loaded at 0.34 wt % produces an 18 mm zone of inhibition. These phenyl bis-phosphinato bismuth(III) complexes show potential to be applied in materials in healthcare facilities, to inhibit the growth of bacteria capable of causing serious disease.

Topical Antimicrobials in Burn Care: Part 1-Topical Antiseptics

Burn wounds disrupt the body's primary defense against invasion and colonization by microorganisms. Topical antimicrobials are one component in burn wound care. These agents suppress microbial growth to advantage skin cells and wound healing. Topical antimicrobials can be divided into 2 superclasses: antiseptics and antibiotics. We review the 4 main classes of topical antiseptics (emulsifiers, acids, oxidizers, and heavy metals) and antiseptic-impregnated dressings in current clinical use and address the mechanisms, as well as the advantages and disadvantages of each antiseptic for burn wound management.

Evaluation of the penetration of nanocrystalline silver through various wound dressing mediums: An in vitro study

BACKGROUND

The nanocrystalline silver (NCS) dressing Acticoat is commonly used in clinical practice for the treatment of burns and other open wounds as a topical antimicrobial. The dressing may dry resulting in traumatic dressing changes; hence the variety of contact layer dressings used in conjunction with it. Dressing combinations that do not permit NCS penetration are not cost effective and deprives the wound of the needed anti-microbial.

METHODS

Common wound pathogens were subjected to a variety of contact layer dressings underlying the NCS dressings. The zone of inhibition (ZOI) obtained was measured and compared to a control.

RESULTS

Intrasite gel demonstrated a synergistic effect with Acticoat. Iruxol exhibits antagonism by preventing penetration and is known to be partially deactivated by NCS. Intrasite conformable and Adaptic allowed partial penetration while the discs of Biobrane, unstretched/non-fenestrated Pelnac and Telfa transparent film did not allow for sufficient penetration to inhibit the underlying bacteria in this study. The cadaver skin from the South African skin bank (Tshwane university of Technology) displayed a greater antimicrobial effect than even the Acticoat control.

CONCLUSION

Our results illustrate that we should perhaps reconsider dressing combination choices with Acticoat in view of their redundancy or synergistic effect.

Monitoring wound healing in minor burns-A novel approach

Assessment of minor burn wound closure is predominately determined by visual inspection and clinical specialist assessment, which remains largely a subjective analysis and results may vary depending on the clinician's experience. Bioimpedance spectroscopy (BIS) is an instrument that has a demonstrated ability to objectively monitor the wound healing process in various patient populations but has not yet been used in acute burn wounds. The aim of the pilot study was to examine whether the BIS technique is a valid measure of wound healing. Localised BIS resistance and phase angle triplicate measures, of minor limb burns, were collected on two serial occasions. Circumference limb measures were taken at the localised burn site to determine a truncated limb volume. Proportional-odds ordered logistic regression analyses determined resistance at zero frequency (R₀, indicative of edema) and resistance of total body fluid (R_inf) were significantly associated with healing after adjustment for the influence of surgery. A one unit increase in R₀ and R_inf increased the odds of wound healing by 6% and 5% respectively (p<0.01). Phase angle at 50kHz and R_i were not significantly associated with the markers of the wound healing process. Spearman's correlation determined there was a significant association between a healing wound and limb segment volume (ml) (rho -0.30, p<0.01). BIS is a technique, which has the potential to monitor the progress of wound healing.

Functionalization of electrospun polymeric wound dressings with antimicrobial peptides

Wound dressings have evolved considerably since ancient times. Modern dressings are now important systems that combine the physical and biochemical properties of natural and synthetic polymers with active compounds that are beneficial to wound healing. Antimicrobial peptides (AMPs) are the most recent addition to these systems. These aim to control the microbial proliferation and colonization of pathogens and to modulate the host's immune response. In the last decade, electrospun wound dressings have been extensively studied and the electrospinning technique recognized as an efficient approach for the production of nanoscale fibrous mats. The control of the electrospinning processing parameters, the selection of the polymer and AMPs, and the definition of the most appropriate AMPs' functionalization method contribute to the successful treatment of acute and chronic wounds. Although the use of electrospinning in wound dressings' production has been previously reviewed, the increased development of AMPs and the establishment of functionalization methods for wound dressings over recent years has increased the need for such research. In the present review, we approach all these subjects and reveal the promising therapeutic potential of wound dressings functionalized with AMPs.

Acute Management of Hand Burns

The hand is extremely susceptible to burn injuries, and hand burns can occur in up to 90% of all major burns. A thorough neurovascular examination of the hand should be performed in the acute setting. Escharotomies are required in patients with full-thickness or circumferential burns, when perfusion of the upper extremity is compromised. The decision for excision and grafting is based on whether the wound will heal in the first 2 to 3 weeks after the burn injury. Acute care and resuscitation are always importance in this patient population; subsequent care leads to optimal hand functionality and cosmetic long-term outcomes.

Fluorescence-tunable Ag-DNA biosensor with tailored cytotoxicity for live-cell applications

DNA-stabilized silver clusters (Ag-DNA) show excellent promise as a multi-functional nanoagent for molecular investigations in living cells. The unique properties of these fluorescent nanomaterials allow for intracellular optical sensors with tunable cytotoxicity based on simple modifications of the DNA sequences. Three Ag-DNA nanoagent designs are investigated, exhibiting optical responses to the intracellular environments and sensing-capability of ions, functional inside living cells. Their sequence-dependent fluorescence responses inside living cells include (1) a strong splitting of the fluorescence peak for a DNA hairpin construct, (2) an excitation and emission shift of up to 120 nm for a single-stranded DNA construct, and (3) a sequence robust in fluorescence properties. Additionally, the cytotoxicity of these Ag-DNA constructs is tunable, ranging from highly cytotoxic to biocompatible Ag-DNA, independent of their optical sensing capability. Thus, Ag-DNA represents a versatile live-cell nanoagent addressable towards anti-cancer, patient-specific and anti-bacterial applications.

Antibacterial and Anti-Inflammatory pH-Responsive Tannic Acid-Carboxylated Agarose Composite Hydrogels for Wound Healing

pH-sensitive hydrogels play an important role in controlled drug release applications and have the potential to impact the management of wounds. In this study, we report the fabrication of novel carboxylated agarose/tannic acid hydrogel scaffolds cross-linked with zinc ions for the pH-controlled release of tannic acid. The resulting hydrogels exhibited negligible release of tannic acid at neutral and alkaline pH and sustained release at acidic pH, where they also displayed maximum swelling. The hydrogels also displayed favorable antibacterial and anti-inflammatory properties, and a lack of cytotoxicity toward 3T3 fibroblast cell lines. In simulated wound assays, significantly greater cell migration and proliferation was observed for cells exposed to tannic acid hydrogel extracts. In addition, the tannic acid hydrogels were able to suppress NO production in stimulated human macrophages in a concentration-dependent manner, indicating effective anti-inflammatory activity. Taken together, the cytocompatibility, antibacterial, and anti-inflammatory characteristics of these novel pH-sensitive hydrogels make them promising candidates for wound dressings.

Prototype Development of the Intelligent Hydrogel Wound Dressing and Its Efficacy in the Detection of Model Pathogenic Wound Biofilms

The early detection of wound infection in situ can dramatically improve patient care pathways and clinical outcomes. There is increasing evidence that within an infected wound the main bacterial mode of living is a biofilm: a confluent community of adherent bacteria encased in an extracellular polymeric matrix. Here we have reported the development of a prototype wound dressing, which switches on a fluorescent color when in contact with pathogenic wound biofilms. The dressing is made of a hydrated agarose film in which the fluorescent dye containing vesicles were mixed with agarose and dispersed within the hydrogel matrix. The static and dynamic models of wound biofilms, from clinical strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis, were established on nanoporous polycarbonate membrane for 24, 48, and 72 h, and the dressing response to the biofilms on the prototype dressing evaluated. The dressing indicated a clear fluorescent/color response within 4 h, only observed when in contact with biofilms produced by a pathogenic strain. The sensitivity of the dressing to biofilms was dependent on the species and strain types of the bacterial pathogens involved, but a relatively higher response was observed in strains considered good biofilm formers. There was a clear difference in the levels of dressing response, when dressings were tested on bacteria grown in biofilm or in planktonic cultures, suggesting that the level of expression of virulence factors is different depending of the growth mode. Colorimetric detection on wound biofilms of prevalent pathogens (S. aureus, P. aeruginosa, and E. faecalis) is also demonstrated using an ex vivo porcine skin model of burn wound infection.

In vitro activity of an engineered honey, medical-grade honeys, and antimicrobial wound dressings against biofilm-producing clinical bacterial isolates

OBJECTIVE

Honey is recognised to be a good topical wound care agent owing to a broad-spectrum of antimicrobial activity combined with healing properties. Surgihoney RO (SH1) is a product based on honey that is engineered to produce enhanced reactive oxygen species (ROS) and has been reported to be highly antimicrobial. The objective was to investigate the ability of the engineered honey and its comparators to prevent biofilm formation in vitro.

METHOD

We tested the ability of three medical-grade honeys SH1, Activon manuka honey (MH) and Medihoney manuka honey (Med), alongside five antimicrobial dressings (AMDs) to prevent the formation of biofilms by 16 isolates. Honeys were serially double diluted from 1:3 down to 1:6144 and the lowest dilution achieving a statistically significant reduction in biomass of at least 50%, compared with untreated controls, was recorded.

RESULTS

Although all the honeys were antibacterial and were able to prevent the formation of biofilms, SH1 was the most potent, with efficacy at lower dilutions than the medical honeys for five isolates, and equivalent dilutions for a further six. Additionally, SH1 was superior in antibacterial potency to three commercially available AMDs that contain honey.

CONCLUSION

SH1 is effective at preventing bioflms from forming and is superior to medical honeys and AMDs in in vitro tests.

DECLARATION OF INTEREST

Surgihoney RO was provided free of charge for testing by Matoke Holdings, UK and the hospital pharmacy provided the other honeys and dressings. This paper presents independent research funded by the National Institute for Health Research (NIHR). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.