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

Altered Nasal Microbiome in Atrophic Rhinitis: A Novel Theory of Etiopathogenesis and Therapy

Background: Atrophic rhinitis (AtR) is a chronic nasal condition with polygenic and polybacterial etiology. We investigated the clinical outcomes of honey therapy and the associated nasal microbiome in AtR. Methods: For eight weeks, a nonrandomized control trial using a nasal spray of 10% manuka honey and saline on the right and left sides of the nose was conducted on 19 primary AtR patients. A nasal endoscopy was performed and a mucosal biopsy were taken before and after the intervention. Five of the nineteen patients were selected for microbiome and GPR43 expression studies. Results: We used manuka honey to describe an effective prebiotic treatment for atrophic rhinitis. There were nine males and ten females with an average (±SD) age of 33.8 (±10.7) years. Endoscopic scores and clinical symptoms improved in honey-treated nasal cavities (p < 0.003). There was a significant decrease in inflammation, restoration of mucus glands, and increased expression of GPR43 in the nasal cavities with honey therapy. The nasal microbiome composition before and after treatment was documented. Particularly, short chain fatty acid (SCFA) producers were positively enriched after honey therapy and correlated with improved clinical outcomes like nasal crusting, congestion, and discharge. Conclusion: Our approach to treating AtR patients with manuka honey illustrated effective clinical outcomes such as (1) decreased fetid smell, (2) thickening of the mucosa, (3) decreased inflammation with healed mucosal ulcers, (4) increased concentration of the mucosal glands, (5) altered nasal microbiome, and (6) increased expression of SCFA receptors. These changes are consequent to resetting the nasal microbiome due to honey therapy.

Honey: An Advanced Antimicrobial and Wound Healing Biomaterial for Tissue Engineering Applications

Honey was used in traditional medicine to treat wounds until the advent of modern medicine. The rising global antibiotic resistance has forced the development of novel therapies as alternatives to combat infections. Consequently, honey is experiencing a resurgence in evaluation for antimicrobial and wound healing applications. A range of both Gram-positive and Gram-negative bacteria, including antibiotic-resistant strains and biofilms, are inhibited by honey. Furthermore, susceptibility to antibiotics can be restored when used synergistically with honey. Honey’s antimicrobial activity also includes antifungal and antiviral properties, and in most varieties of honey, its activity is attributed to the enzymatic generation of hydrogen peroxide, a reactive oxygen species. Non-peroxide factors include low water activity, acidity, phenolic content, defensin-1, and methylglyoxal (Leptospermum honeys). Honey has also been widely explored as a tissue-regenerative agent. It can contribute to all stages of wound healing, and thus has been used in direct application and in dressings. The difficulty of the sustained delivery of honey’s active ingredients to the wound site has driven the development of tissue engineering approaches (e.g., electrospinning and hydrogels). This review presents the most in-depth and up-to-date comprehensive overview of honey’s antimicrobial and wound healing properties, commercial and medical uses, and its growing experimental use in tissue-engineered scaffolds.

Novel techniques in the treatment of skin and soft tissue infection

PURPOSE OF REVIEW

Global antibiotic resistance is compromising the management of soft tissue infection and Acute Bacterial Skin and Skin Structure Infection (ABSSI). This review describes a novel topical treatment Reactive Oxygen (RO) gel which could compliment and in some situations replace systemic antibiotics.

RECENT FINDINGS

A novel topical treatment RO gel could have an important role in treatment, infection prevention and antimicrobial stewardship. RO is highly antimicrobial against Gram positive and negative bacteria, by slow release of oxygen radicals over a prolonged period of up to 72 h. It prevents and breaks down biofilm and may support healing by cellular signalling. Much clinical investigation remains to be delivered on RO therapy but there seem few disadvantages in its use and early clinical evaluations are extremely promising.

SUMMARY

Managing complicated skin and soft tissue infections require more than just antibiotic treatment. Soft tissue infection healing is often compromised by underlying comorbidities and pathology and increasingly the presence of highly antimicrobial-resistant bacteria. This has been highlighted particularly in war and trauma soft tissue infection. The fundamentals of soft tissue infection repair require early surgical drainage and debridement, correction of compromised physiology and treatment of underlying conditions and appropriate antimicrobial treatment. RO therapy could be an important advance.

Efficacy of a Topical Wound Agent Methanesulfonic Acid and Dimethylsulfoxide on In Vitro Biofilms

A topical desiccating wound agent containing methanesulfonic acid, dimethylsulfoxide and amorphous silica was evaluated in three in vitro models for its efficacy against biofilms produced by Pseudomonas aeruginosa (ATCC-15442) and Staphylococcus aureus (ATCC-6538). The in vitro biofilm models used were; the MBEC Assay^®, Centre for Disease Control (CDC) Biofilm Reactor^® and a Semi-solid biofilm model. A 30-s exposure of a topical wound desiccating agent was used in each model. A complete eradication of viable cells was demonstrated in all models for both strains (p < 0.0001). Imaging with scanning electron microscopy (SEM) was performed where possible. All three models demonstrated complete eradication of viable cells with a 30 s application of a topical wound desiccating agent.

A call for action to the biomaterial community to tackle antimicrobial resistance

The global surge of antimicrobial resistance (AMR) is a major concern for public health and proving to be a key challenge in modern disease treatment, requiring action plans at all levels. Microorganisms regularly and rapidly acquire resistance to antibiotic treatments and new drugs are continuously required. However, the inherent cost and risk to develop such molecules has resulted in a drying of the pipeline with very few compounds currently in development. Over the last two decades, efforts have been made to tackle the main sources of AMR. Nevertheless, these require the involvement of large governmental bodies, further increasing the complexity of the problem. As a group with a long innovation history, the biomaterials community is perfectly situated to push forward novel antimicrobial technologies to combat AMR. Although this involvement has been felt, it is necessary to ensure that the field offers a united front with special focus in areas that will facilitate the development and implementation of such systems. This paper reviews state of the art biomaterials strategies striving to limit AMR. Promising broad-spectrum antimicrobials and device modifications are showcased through two case studies for different applications, namely topical and implantables, demonstrating the potential for a highly efficacious physical and chemical approach. Finally, a critical review on barriers and limitations of these methods has been developed to provide a list of short and long-term focus areas in order to ensure the full potential of the biomaterials community is directed to helping tackle the AMR pandemic.

Evolution of honey resistance in experimental populations of bacteria depends on the type of honey and has no major side effects for antibiotic susceptibility

With rising antibiotic resistance, alternative treatments for communicable diseases are increasingly relevant. One possible alternative for some types of infections is honey, used in wound care since before 2000 BCE and more recently in licensed, medical-grade products. However, it is unclear whether medical application of honey results in the evolution of bacterial honey resistance and whether this has collateral effects on other bacterial traits such as antibiotic resistance. Here, we used single-step screening assays and serial transfer at increasing concentrations to isolate honey-resistant mutants of Escherichia coli. We only detected bacteria with consistently increased resistance to the honey they evolved in for two of the four tested honey products, and the observed increases were small (maximum twofold increase in IC90). Genomic sequencing and experiments with single-gene knockouts showed a key mechanism by which bacteria increased their honey resistance was by mutating genes involved in detoxifying methylglyoxal, which contributes to the antibacterial activity of Leptospermum honeys. Crucially, we found no evidence that honey adaptation conferred cross-resistance or collateral sensitivity against nine antibiotics from six different classes. These results reveal constraints on bacterial adaptation to different types of honey, improving our ability to predict downstream consequences of wider honey application in medicine.

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.

Formulation of a reactive oxygen producing calcium sulphate cement as an anti-bacterial hard tissue scaffold

Prophylactic antibiotic bone cements are extensively used in orthopaedics. However, the development of antimicrobial resistance to antibiotics, demonstrates a need to find alternative treatments. Herein, an antimicrobial honey (SurgihoneyRO-SHRO) has been successfully incorporated into a calcium sulphate (CS) based cement to produce a hard tissue scaffold with the ability to inhibit bacterial growth. Antimicrobial properties elicited from SHRO are predominantly owed to the water-initiated production of reactive oxygen species (ROS). As an alternative to initially loading CS cement with SHRO, in order to prevent premature activation, SHRO was added into the already developing cement matrix, locking available water into the CS crystal structure before SHRO addition. Promisingly, this methodology produced > 2.5 times (715.0 ± 147.3 μM/mL/g) more ROS over 24 h and exhibited a compressive strength (32.2 ± 5.8 MPa) comparable to trabecular bone after 3 weeks of immersion. In-vitro the SHRO loaded CS scaffolds were shown to inhibit growth of clinically relevant organisms, Staphylococcus aureus and Pseudomonas aeruginosa, with comparable potency to equivalent doses of gentamicin. Encouragingly, formulations did not inhibit wound healing or induce an inflammatory response from osteoblasts. Overall this study highlights the prophylactic potential of CS-SHRO cements as an alternative to traditional antibiotics.

Antibiofilm Activity of Heather and Manuka Honeys and Antivirulence Potential of Some of Their Constituents on the DsbA1 Enzyme of Pseudomonas aeruginosa

Heather honey was tested for its effect on the formation of biofilms by Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Salmonella Enteriditis and Acinetobacter baumanii in comparison with Manuka honey. At 0.25 mg/mL, Heather honey inhibited biofilm formation in S. aureus, A. baumanii, E. coli, S. Enteriditis and P. aeruginosa, but promoted the growth of E. faecalis and K. pneumoniae biofilms. Manuka honey inhibited biofilm formation in K. pneumoniae, E. faecalis, and S. Enteriditis, A. baumanii, E. coli and P. aeruginosa, but promoted S. aureus biofilm formation. Molecular docking with Autodock Vina was performed to calculate the predictive binding affinities and ligand efficiencies of Manuka and Heather honey constituents for PaDsbA1, the main enzyme controlling the correct folding of virulence proteins in Pseudomonas aeruginosa. A number of constituents, including benzoic acid and methylglyoxal, present in Heather and/or Manuka honey, revealed high ligand efficiencies for the target enzyme. This helps support, to some extent, the decrease in P. aeruginosa biofilm formation observed for such honeys.

Use of a model to understand the synergies underlying the antibacterial mechanism of H2O2-producing honeys

Honey has been valued as a powerful antimicrobial since ancient times. However, the understanding of the underlying antibacterial mechanism is incomplete. The complexity and variability of honey composition represent a challenge to this scope. In this study, a simple model system was used to investigate the antibacterial effect of, and possible synergies between, the three main stressors present in honey: sugars, gluconic acid, and hydrogen peroxide (H₂O₂), which result from the enzymatic conversion of glucose on honey dilution. Our results demonstrated that the synergy of H₂O₂ and gluconic acid is essential for the antibacterial activity of honey. This synergy caused membrane depolarization, destruction of the cell wall, and eventually growth inhibition of E. coli K-12. The presence of H₂O₂ stimulated the generation of other long-lived ROS in a dose-dependent manner. Sugars caused osmosis-related morphological changes, however, decreased the toxicity of the H₂O₂/gluconic acid. The susceptibility of catalase and general stress response sigma factor mutants confirmed the synergy of the three stressors, which is enhanced at higher H₂O₂ concentrations. By monitoring cellular phenotypic changes caused by model honey, we explained how this can be bactericidal even though the antimicrobial compounds which it contains are at non-inhibitory concentrations.

Formulation of an antimicrobial superabsorbent powder that gels in situ to produce reactive oxygen

The enzymatic oxidation of glucose to produce reactive oxygen species (ROS) provides honey with antimicrobial efficacy. This mechanism offers an alternative to traditional antibiotics; however, topical use of honey is limited due to its adherent and highly viscous properties. This study aims to overcome these issues by engineering a powder-based system that eases delivery and offers in situ activation of ROS. Starch based drying agents were utilised to enable freeze drying of a medical honey, with methylated-β-cyclodextrin (MCD) enabling the highest active incorporation (70%) while still producing a free-flowing powder. Addition of a superabsorbent, sodium polyacrylate (≤40%) was shown to facilitate in situ gelation of the powder, with an absorption capacity of up to 120.7 ± 4.5 mL g^-1. Promisingly efficacy of the optimised superabsorbent powder was demonstrated in vitro against several clinically relevant Gram-negative and Gram-positive bacteria (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa). Alongside this no adverse effects were observed against human dermal fibroblasts. Application of the superabsorbent powder in an ex-vivo porcine wound model revealed capability to form a protective hydrogel barrier in less than 1 min. Overall, this novel ROS producing superabsorbent powder has potential to tackle topical infections without using traditional antibiotics.

Redox dysregulation in the pathogenesis of chronic venous ulceration

In chronic venous ulcers (CVUs), which account for up to 75% of leg ulcers, the inflammatory stage of wound healing fails to down-regulate, preventing progression to proliferation, remodeling and eventual epithelialisation. The roles of reactive oxygen species (ROS) in the oxidative burst and pathogen killing are well known, but ROS also have important functions in extra-cellular and intra-cellular signalling. Iron deposition, resulting from venous reflux, primes macrophages towards a persistent inflammatory response, with ongoing stimulation by bacteria potentially playing a role. Generation of excessive ROS by activated inflammatory cells causes tissue destruction and disintegration of the dermis, and then at later stages, a failure to heal. Here, we review the evidence for ROS in CVU formation and in normal and delayed healing. We also discuss how ROS modulation might be used to influence the healing of these complex wounds, which cause long-term morbidity and are associated with a significant financial burden to healthcare systems.

Manuka honey chelates iron and impacts iron regulation in key bacterial pathogens

AIM

The aim of this study was to test the hypothesis that Manuka honey (MH) chelates iron and promotes an iron-limiting environment, which contributes to its antimicrobial activity.

METHODS AND RESULTS

Employing a ferrozine-based assay, we observed that MH is an iron chelator that depletes iron from solution. Siderophores are small molecules that bind ferric iron (III) with high affinity and their levels are upregulated by bacteria under iron-limiting conditions. We demonstrated by quantitating siderophore production that Escherichia coli and Pseudomonas aeruginosa treated with MH sub-minimum inhibitory concentrations (sub-MIC) experience an iron-limiting environment and increase siderophore production. In addition, supplementation with ferrous iron (II) significantly increased growth of E. coli, Staphylococcus aureus and P. aeruginosa cultured at their MH MIC above that observed in nonsupplemented controls. By contrast, supplementation with ferric iron (III) significantly increased growth for only E. coli and P. aeruginosa, above their nonsupplemented controls.

CONCLUSIONS

Manuka honey chelates iron, thereby generating an iron-limiting environment for E. coli and P. aeruginosa, and to a lesser extent S. aureus, which contributes to its antimicrobial properties.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our work demonstrates that MH-induced iron chelation is an antimicrobial mechanism that differentially impacts the bacterial species tested here. Iron chelation affects multiple diverse physiological processes in bacteria and would contribute to the lack of bacterial resistance to MH. Iron metabolism is tightly regulated; bacteria require this essential nutrient for survival, but in excess it is toxic. Additional exploration of MH's iron chelation mechanism will facilitate its future use in mainstream medicine.

Honey can inhibit and eliminate biofilms produced by Pseudomonas aeruginosa

Chronic wound treatment is becoming increasingly difficult and costly, further exacerbated when wounds become infected. Bacterial biofilms cause most chronic wound infections and are notoriously resistant to antibiotic treatments. The need for new approaches to combat polymicrobial biofilms in chronic wounds combined with the growing antimicrobial resistance crisis means that honey is being revisited as a treatment option due to its broad-spectrum antimicrobial activity and low propensity for bacterial resistance. We assessed four well-characterised New Zealand honeys, quantified for their key antibacterial components, methylglyoxal, hydrogen peroxide and sugar, for their capacity to prevent and eradicate biofilms produced by the common wound pathogen Pseudomonas aeruginosa. We demonstrate that: (1) honey used at substantially lower concentrations compared to those found in honey-based wound dressings inhibited P. aeruginosa biofilm formation and significantly reduced established biofilms; (2) the anti-biofilm effect of honey was largely driven by its sugar component; (3) cells recovered from biofilms treated with sub-inhibitory honey concentrations had slightly increased tolerance to honey; and (4) honey used at clinically obtainable concentrations completely eradicated established P. aeruginosa biofilms. These results, together with their broad antimicrobial spectrum, demonstrate that manuka honey-based wound dressings are a promising treatment for infected chronic wounds, including those with P. aeruginosa biofilms.

Anti-biofilm effects and characterisation of the hydrogen peroxide activity of a range of Western Australian honeys compared to Manuka and multifloral honeys

The antibacterial activity of honeys derived from the endemic flora of the southwest corner of Western Australia, including the trees Jarrah (Eucalyptus marginata) and Marri (Corymbia calophylla), remains largely unexplored. Investigation of these honeys showed minimum inhibitory concentrations (MICs) of 6.7-28.0% (w/v) against Gram positive and negative bacteria. Honey solutions showed enhanced antibacterial activity after hydrogen peroxide was allowed to accumulate prior to testing, with a mean MIC after accumulation of 14.3% compared to 17.4% before accumulation. Antibacterial activity was reduced after treatment with catalase enzyme, with a mean MIC of 29.4% with catalase compared to 15.2% without catalase. Tests investigating the role of the Gram negative outer membrane in honey susceptibility revealed increases in activity after destabilisation of the outer membrane. Honeys reduced both the formation of biofilm and the production of bacterial pigments, which are both regulated by quorum sensing. However, these reductions were closely correlated with global growth inhibition. Honey applied to existing biofilms resulted in decreased metabolic activity and minor decreases in viability. These results enhance our understanding of the mechanisms of antibacterial action of Jarrah and Marri honeys, and provide further support for the use of honey in the treatment of infected wounds.

Violet-Blue Light Arrays at 405 Nanometers Exert Enhanced Antimicrobial Activity for Photodisinfection of Monomicrobial Nosocomial Biofilms

This study reports the efficacy of VBL and blue light (BL) and their antimicrobial activity against mature biofilms of a range of important nosocomial pathogens. While this study investigated the antibacterial activity of a range of wavelengths of between 375 and 450 nm and identified a specific wavelength region (∼405 nm) with increased antibacterial activity, decontamination was dependent on the bacterial species, strain, irradiation parameters, and experimental conditions. Further research with controlled experiments that ameliorate the heating effects and improve the optical properties are required to optimize the dosing parameters to advance the successful clinical translation of this technology.

Light-emitting diodes (LEDs) demonstrate therapeutic effects for a range of biomedical applications, including photodisinfection. Bands of specific wavelengths (centered at 405 nm) are reported to be the most antimicrobial; however, there remains no consensus on the most effective irradiation parameters for optimal photodisinfection. The aim of this study was to assess decontamination efficiency by direct photodisinfection of monomicrobial biofilms using a violet-blue light (VBL) single-wavelength array (SWA) and multiwavelength array (MWA). Mature biofilms of nosocomial bacteria (Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus) were grown on 96-well polypropylene PCR plates. The biofilms were then exposed to VBL for 2,700 s (SWA) and 1,170 s (MWA) to deliver 0 to 670 J/cm², and the antibacterial activity of VBL was assessed by comparing the seeding of the irradiated and the nonirradiated biofilms. Nonirradiated groups were used as controls. The VBL arrays were characterized optically (spectral irradiance and beam profile) and thermally. The SWA delivered 401-nm VBL and the MWA delivered between 379-nm and 452-nm VBL, albeit at different irradiances and with different beam profiles. In both arrays, the irradiated groups were exposed to increased temperatures compared to the nonirradiated controls. All bacterial isolates were susceptible to VBL and demonstrated reductions in the seeding of exposed biofilms compared with the nonirradiated controls. VBL at 405 nm exerted the most antimicrobial activity, exhibiting reductions in seeding of up to 94%. Decontamination efficiency is dependent on the irradiation parameters, bacterial species and strain, and experimental conditions. Controlled experiments that ameliorate the heating effects and improve the optical properties are required to optimize the dosing parameters to advance the successful clinical translation of this technology.

IMPORTANCE This study reports the efficacy of VBL and blue light (BL) and their antimicrobial activity against mature biofilms of a range of important nosocomial pathogens. While this study investigated the antibacterial activity of a range of wavelengths of between 375 and 450 nm and identified a specific wavelength region (∼405 nm) with increased antibacterial activity, decontamination was dependent on the bacterial species, strain, irradiation parameters, and experimental conditions. Further research with controlled experiments that ameliorate the heating effects and improve the optical properties are required to optimize the dosing parameters to advance the successful clinical translation of this technology.

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.

Advanced strategies for combating bacterial biofilms

Biofilms are communities of microorganisms that are formed on and attached to living or nonliving surfaces and are surrounded by an extracellular polymeric material. Biofilm formation enjoys several advantages over the pathogens in the colonization process of medical devices and patients' organs. Unlike planktonic cells, biofilms have high intrinsic resistance to antibiotics and sanitizers, and overcoming them is a significant problematic challenge in the medical and food industries. There are no approved treatments to specifically target biofilms. Thus, it is required to study and present innovative and effective methods to combat a bacterial biofilm. In this review, several strategies have been discussed for combating bacterial biofilms to improve healthcare, food safety, and industrial process.

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.

Medicinal honey in clinical practice: viable alternative or useful adjunct in wound care management?

In light of concerns raised about antimicrobial resistance, especially in hospitals, and the rise in bacteria that are resistant to antibiotics scientists are examining alternative sources and strategies to combat infection. Among the plethora of complementary medicines now being considered is honey, particularly manuka honey. Medicinal honey is a relatively new label given to some types of honey that have been shown to be effective antimicrobial agents in in vitro studies. Large-scale clinical trials are yet to be conducted but there is considerable interest and numerous case studies that demonstrate the benefits of medicinal honey, especially in wound healing.

Antimicrobial emulsions: Formulation of a triggered release reactive oxygen delivery system

The enzyme glucose oxidase mediates the oxidation of glucose to produce reactive oxygen species (ROS), such as hydrogen peroxide. This reaction and its products are key to providing honey with its antimicrobial properties. Currently, honey is an adherent, highly viscous product that produces ROS by means of a water-initiated reaction. These properties reduce clinical usability and present a formulation problem for long term stability. This study aims to engineer a water-in-oil emulsion containing an engineered honey (SurgihoneyRO™) that is easy to administer topically and is controllably activated in-situ. Paraffin oil continuous emulsions formulated using the emulsifier polyglycerol polyricinoleate displayed shear-thinning characteristics. Viscosities between 1.4 and 19.3 Pa·s were achieved at a shear rate representative of post-mixing conditions (4.1 s^-1) by changing the volume of the dispersed phase (30-60%). Notably, this wide viscosity range will be useful in tailoring future formulations for specific application mechanisms. When exposed to water and shear, these emulsion systems were found to undergo catastrophic phase inversion, evidenced by a change in conductivity from 0 μS in the non-aqueous state, to >180 μS in the sheared, inverted state. Encouragingly, sheared formulations containing ≥50% SurgihoneyRO™ generated sufficient levels of ROS to inhibit growth of clinically relevant Gram-positive and Gram-negative bacteria. This study demonstrates an ability to formulate ROS producing emulsions for use as an alternative to current topical antibiotic-based treatments. Promisingly, the ability of this system to release water-sensitive actives in response to shear may be useful for controlled delivery of other therapeutic molecules.

Intralesional application of medical grade honey improves healing of surgically treated lacerations in horses

BACKGROUND

Infection and dehiscence of simple lacerations is common in horses, and consistently effective methods of prevention are yet to be found. Honey has been shown to promote wound healing when applied topically; however, intralesional application prior to wound closure has not been reported.

OBJECTIVES

To examine whether intralesional application of medical grade honey (MGH) would reduce the incidence of infection and dehiscence following wound closure.

STUDY DESIGN

Prospective, open-label randomised block design clinical study.

METHODS

Lacerations, treated by field practitioners, were divided into treatment and control groups using block randomisation. Horses in the treatment group received a single intralesional treatment with l-mesitran gel (MGH). Data were collected at the time of wound closure and at suture removal.

RESULTS

Data from 127 horses were included, 69 MGH-treated and 58 control cases. No adverse effects of the MGH were recorded. MGH-treated horses were more likely to completely heal (P = 0.006, odds ratio [OR] 3.40 95% confidence interval [CI] 1.41-8.20), to have no signs of infection (P = 0.007, OR 3.64, CI 1.42-9.26) and for the veterinarians to report some degree of satisfaction (P = 0.04, OR 2.72, CI 1.05-7.09) compared to control cases. Numbers needed to treat for complete healing was 5.1 (CI 2.8-40).

MAIN LIMITATIONS

Clinical studies have inherent flaws compared to wound healing models, because of variability between wounds. There were more horses with limb injuries in the control group, although not statistically significant, this may have biased the results. Clinical satisfaction and signs of infection were subjective evaluations and evaluators were not blinded to the treatment group.

CONCLUSIONS

Intralesional application of MGH to lacerations prior to wound closure may be beneficial in preventing infection and dehiscence. Larger, blinded studies focusing on wounds at a specific location with more objective assessment should be pursued.

Antimicrobial use of reactive oxygen therapy: current insights

Infections caused by drug-resistant pathogens are a global public health problem. The introduction of a new antimicrobial strategy is an unavoidable option for the management of drug-resistant pathogens. Induction of high levels of reactive oxygen species (ROS) by several procedures has been extensively studied for the treatment of infections. In this article, the general aspects of ROS production and the common procedures that exert their antimicrobial effects due to ROS formation are reviewed. ROS generation is the antimicrobial mechanism of nanoparticles, hyperbaric oxygen therapy, medical honey, and photodynamic therapy. In addition, it is an alternative bactericidal mechanism of clinically traditional antibiotics. The development of ROS delivery methods with a desirable selectivity for pathogens without side effects for the host tissue may be a promising approach for the treatment of infections, especially those caused by drug-resistant organisms.

Enhancing Whole Phage Therapy and Their Derived Antimicrobial Enzymes through Complex Formulation

The resurgence of research into phage biology and therapy is, in part, due to the increasing need for novel agents to treat multidrug-resistant infections. Despite a long clinical history in Eastern Europe and initial success within the food industry, commercialized phage products have yet to enter other sectors. This relative lack of success is, in part, due to the inherent biological limitations of whole phages. These include (but are not limited to) reaching target sites at sufficiently high concentrations to establish an infection which produces enough progeny phages to reduce the bacterial population in a clinically meaningful manner and the limited host range of some phages. Conversely, parallels can be drawn between antimicrobial enzymes derived from phages and conventional antibiotics. In the current article the biological limitations of whole phage-based therapeutics and their derived antimicrobial enzymes will be discussed. In addition, the ability of more complex formulations to address these issues, in the context of medical and non-medical applications, will also be included.

Antimicrobial activity of a novel bioengineered honey against non-typeable Haemophilus influenzae biofilms: an in vitro study

The opportunistic pathogen non-typeable Haemophilus influenzae (NTHi) plays an important role in many chronic respiratory diseases including otitis media, chronic rhinosinusitis, cystic fibrosis and chronic obstructive pulmonary disease. Biofilm formation has been implicated in NTHi colonisation, persistence of infection and recalcitrance towards antimicrobials. There is therefore a pressing need for the development of novel treatment strategies that are effective against NTHi biofilm-associated diseases. SurgihoneyRO is a honey-based product that has been bioengineered to enable the slow release of H₂O₂, a reactive oxygen species to which H. influenzae is susceptible. Treatment of established NTHi biofilms with SurgihoneyRO significantly reduced biofilm viability through enhanced H₂O₂ production and was shown to be more effective than the conventional antibiotic co-amoxiclav.

Towards a better understanding of the therapeutic applications and corresponding mechanisms of action of honey

Honey is a bee-derived supersaturated solution composed of complex contents mainly glucose, fructose, amino acids, vitamins, and minerals. Composition of honey may vary due to the difference in nectar, season, geography, and storage condition. Honey has been used since times immemorial in folk medicine and has recently been rediscovered as an excellent therapeutic agent. In the past, honey was used for a variety of ailments without knowing the scientific background and active ingredients of honey. Today, honey has been scientifically proven for its antioxidant, regulation of glycemic response, antitumor, antimicrobial, anti-inflammatory, and cardiovascular potentiating agent. It can be used as a wound dressing and healing substance. Honey is different in color, flavor, sensory perception, and medical response. Apart from highlighting the nutritional facts of honey, we collected the finding of the published literature to know the mechanism of action of honey in different diseases. This review covers the composition, physiochemical characteristics, and some medical uses.

Medical-Grade Honey Dressing Use in Developing Countries

Compared with other medical honeys, SurgihoneyRO (H&R Healthcare Ltd, Southmoor, Abingdon, United Kingdom), a bioengineered medical-grade honey, delivers low concentrations of reactive oxygen to wounds over a sustained period. This article describes how one provider, Dr Jill Brooks, has successfully used this new antimicrobial dressing in Africa and examines the potential positive impact this dressing could have on wound care in developing countries.

Reactive oxygen species: a novel antimicrobial

The main solution to the global antibiotic resistance crisis is to reduce the volume of antibiotic use in medicine, agriculture and the environment. However, there is also a pressing need for novel antimicrobials. Despite much rhetoric, there are few entirely novel agents in development. One such therapy to reach clinical use is an agent using Reactive Oxygen Species (ROS), oxygen radicals, as an antimicrobial mechanism. ROS can be delivered to the site of infection in various formats. ROS are highly antimicrobial against Gram-positive and Gram-negative bacteria, viruses and fungi. They also prevent and break down biofilm. These functions make ROS potentially highly suitable for chronic inflammatory conditions, where antibiotics are frequently overused and relatively ineffective, including: chronic wounds, ulcers and burns; chronic rhinosinusitis, chronic bronchitis, bronchiectasis, cystic fibrosis and ventilated airways; recurrent cystitis; and prosthetic device infection. ROS could have an important role in infection prevention and antimicrobial stewardship. Much clinical investigation remains to be delivered on ROS therapy, but in vitro work on infection models and early clinical evaluations are extremely promising.

Impact of Surgihoney Reactive Oxygen on surgical site infection (SSI) after complex abdominal wall reconstruction (AWR) of grade 3 and 4 ventral Hernias: A single arm pilot study

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A protocol using Surgihoney in AWR of grade 3/4 Ventral Hernia Repairs is proposed.

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Our primary objective is to reduce wound infections/complications.

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40 post-op wounds will be followed and assessed for infection using ASEPSIS criteria.

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Results to be compared to a retrospective cohort of 40 Ventral Hernia Repair patients.

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Secondary outcomes/complications will also be followed in this cohort of patients.

Introduction

Following Abdominal Wall Reconstruction (AWR) wound infections occur in over one third of patients and rates can be even higher in entero-cutaneous fistula repair. A novel antimicrobial gel has been engineered by microbiologists called Surgihoney Reactive Oxygen (SHRO). SHRO gel will be applied to a group of patients. We aim to conduct a pilot case series with the hope to show a reduction in local wound complications after SHRO application.

Methods and analysis

A single arm pilot study of AWR patients will be carried out on patients with grade 3 and 4 (VHWG grade) ventral hernias. Patients’ pre-operative wounds will be graded according to the CDC classification scale. Post operatively the wounds will be classified according to the Wilson surgical site infection classification. Intervention: SHRO will be applied after abdominal fascial closure and before skin closure through a standardised method. Our results from the series will be compared to our retrospective standard wound care results. Data will be collected from 01.03.2017 to 01.11.2017. Primary outcome: Surgical site infection within 30 days of surgery, assessed by clinicians at 5, 15 and 30 days and by patient’s self-report for the intervening period. Secondary outcomes include other SSOs (haematoma, seroma, wound dehiscence, skin necrosis), duration of stay in hospital, reported side effects from local treatment and other systemic postoperative complications. We will aim for a cohort of 40 patients.

Conclusions

This study will provide an assessment of methods and feasibility of recruiting and following up patients who are treated with SHRO. On the basis of this pilot trial, a full trial may be proposed in the future which will provide additional, robust evidence on the clinical and cost effectiveness of SHRO in wound management following AWR. This may act as a model for the management of wounds in complex patients undergoing AWR.

Chronic Respiratory Infection in Patients with Chronic Obstructive Pulmonary Disease: What Is the Role of Antibiotics?

Chronic infections are associated with exacerbation in patients with chronic obstructive pulmonary disease (COPD). The major objective of the management of these patients is the prevention and effective treatment of exacerbations. Patients that have increased sputum production, associated with purulence and worsening shortness of breath, are the ones that will benefit from antibiotic therapy. It is important to give the appropriate antibiotic therapy to prevent treatment failure, relapse, and the emergence of resistant pathogens. In some patients, systemic corticosteroids are also indicated to improve symptoms. In order to identify which patients are more likely to benefit from these therapies, clinical guidelines recommend stratifying patients based on their risk factor associated with poor outcome or recurrence. It has been identified that patients with more severe disease, recurrent infection and presence of purulent sputum are the ones that will be more likely to benefit from this therapy. Another approach related to disease prevention could be the use of prophylactic antibiotics during steady state condition. Some studies have evaluated the continuous or the intermittent use of antibiotics in order to prevent exacerbations. Due to increased bacterial resistance to antibiotics and the presence of side effects, several antibiotics have been developed to be nebulized for both treatment and prevention of acute exacerbations. There is a need to design long-term studies to evaluate these interventions in the natural history of the disease. The purpose of this publication is to review our understanding of the role of bacterial infection in patients with COPD exacerbation, the role of antibiotics, and future interventions.

Honey as a Complementary Medicine

The beneficial effects of honey on human health have long been recognized. Today, many of those positive effects have been studied to elucidate its mode of action. This review briefly summarizes the best studied features of honey, highlighting it as an appealing alternative medicine. In these reports, the health benefits of honey range from antioxidant, immunomodulatory, and anti-inflammatory activity to anticancer action, metabolic and cardiovascular benefits, prebiotic properties, human pathogen control, and antiviral activity. These studies also support that the honey's biological activity is mainly dependent on its floral or geographic origin. In addition, some promising synergies between honey and antibiotics have been found, as well as some antiviral properties that require further investigation. Altogether, these studies show that honey is effectively a nutraceutical foodstuff.

Hot topics in reactive oxygen therapy: Antimicrobial and immunological mechanisms, safety and clinical applications

Reactive oxygen species (ROS), when combined with various delivery mechanisms, has the potential to become a powerful novel therapeutic agent against difficult-to-treat infections, especially those involving biofilm. It is important in the context of the global antibiotic resistance crisis. ROS is rapidly active in vitro against all Gram-positive and Gram-negative bacteria tested. ROS also has antifungal and antiviral properties. ROS prevents the formation of biofilms caused by a range of bacterial species in wounds and respiratory epithelium. ROS has been successfully used in infection prevention, eradication of multiresistant organisms, prevention of surgical site infection, and intravascular line care. This antimicrobial mechanism has great potential for the control of bioburden and biofilm at many sites, thus providing an alternative to systemic antibiotics on epithelial/mucosal surfaces, for wound and cavity infection, chronic respiratory infections and possibly recurrent urinary infections as well as local delivery to deeper structures and prosthetic devices. Its simplicity and stability lend itself to use in developing economies as well.

Reactive oxygen: A novel antimicrobial mechanism for targeting biofilm-associated infection

Reactive oxygen species (ROS) is a novel therapeutic strategy for topical or local application to wounds, mucosa or internal structures where there may be heavy bacterial bioburden with biofilm and chronic inflammation. Bacterial biofilms are a significant problem in clinical settings owing to their increased tolerance towards conventionally prescribed antibiotics and their propensity for selection of further antibacterial resistance. There is therefore a pressing need for the development of alternative therapeutic strategies that can improve antibiotic efficacy towards biofilms. ROS has been successful in treating chronic wounds and in clearing multidrug-resistant organisms, including methicillin-resistant Staphylococcus aureus (MRSA), and carbapenemase-producing isolates from wounds and vascular line sites. There is significant antifungal activity of ROS against planktonic and biofilm forms. Nebulised ROS has been evaluated in limited subjects to assess reductions in bioburden in chronically colonised respiratory tracts. The antibiofilm activity of ROS could have great implications for the treatment of a variety of persistent respiratory conditions. Use of ROS on internal prosthetic devices shows promise. A variety of novel delivery mechanisms are being developed to apply ROS activity to different anatomical sites.

A multi-centre clinical evaluation of reactive oxygen topical wound gel in 114 wounds

OBJECTIVE

This article reports the outcomes of the use of Surgihoney RO (SHRO), topical wound dressing in a multi-centre, international setting. The aims were to explore the clinical effects of SHRO, including a reduction in bacterial load and biofilm and improvement in healing in a variety of challenging non-healing and clinically infected wounds.

METHOD

This was a non-comparative evaluation, where both acute and chronic wounds with established delayed healing were treated with the dressing. Clinicians prospectively recorded wound improvement or deterioration, level of wound exudate, presence of pain, and presence of slough and necrosis. Analysis of this data provided information on clinical performance of the dressing. Semi-quantitative culture to assess bacterial bioburden was performed where possible.

RESULTS

We recruited 104 patients, mean age 61 years old, with 114 wounds. The mean duration of wounds before treatment was 3.7 months and the mean duration of treatment was 25.7 days. During treatment 24 wounds (21%) healed and the remaining 90 (79%) wounds improved following application of the dressing. No deterioration in any wound was observed. A reduction in patient pain, level of wound exudate and in devitalised tissue were consistently reported. These positive improvements in wound progress were reflected in the wound cultures that showed a reduction in bacterial load in 39 out of the 40 swabs taken. There were two adverse events recorded: a stinging sensation following application of the dressing was experienced by 2 patients, and 2 elderly patients died of causes unrelated to the dressing or to the chronic wound. These patients' wounds and their response to SHRO have been included in the analysis.

CONCLUSION

SHRO was well tolerated and shows great promise as an effective potent topical antimicrobial in the healing of challenging wounds.

DECLARATION OF INTEREST

Matthew Dryden has become a shareholder in Matoke Holdings, the manufacturer of Surgihoney RO, since the completion of this study. Keith Cutting is a consultant to Matoke Holdings.

Reactive Oxygen: a new solution to antimicrobial resistance

In April of this year tissue viability nurses, professors, surgeons, and microbiologists met at the University of Birmingham to discuss a real solution to the developing antibiotic resistance catastrophe.

Therapeutic Manuka Honey: No Longer So Alternative

Medicinal honey research is undergoing a substantial renaissance. From a folklore remedy largely dismissed by mainstream medicine as “alternative”, we now see increased interest by scientists, clinical practitioners and the general public in the therapeutic uses of honey. There are a number of drivers of this interest: first, the rise in antibiotic resistance by many bacterial pathogens has prompted interest in developing and using novel antibacterials; second, an increasing number of reliable studies and case reports have demonstrated that certain honeys are very effective wound treatments; third, therapeutic honey commands a premium price, and the honey industry is actively promoting studies that will allow it to capitalize on this; and finally, the very complex and rather unpredictable nature of honey provides an attractive challenge for laboratory scientists. In this paper we review manuka honey research, from observational studies on its antimicrobial effects through to current experimental and mechanistic work that aims to take honey into mainstream medicine. We outline current gaps and remaining controversies in our knowledge of how honey acts, and suggest new studies that could make honey a no longer “alternative” alternative.