The unusual antibacterial activity of medical-grade Leptospermum honey: antibacterial spectrum, resistance and transcriptome analysis

Selected honey as a multifaceted antimicrobial agent: review of compounds, mechanisms, and research challenges

Honey, derived from floral nectar, has been valued for its nutritional and therapeutic properties, with recent studies emphasizing its broad-spectrum antimicrobial potential, especially against antimicrobial resistance (AMR). Honey's antimicrobial activity stems from its unique composition, including high sugar content, low pH, and bioactive compounds like hydrogen peroxide, methylglyoxal (MGO), and phenolic compounds. Distinct honey types, such as Manuka, Sidr, and Tualang, demonstrate varying antimicrobial effects based on their botanical and geographical origins. Manuka honey, rich in MGO, is notably effective against multidrug-resistant pathogens, while Sidr and heather honeys excel in biofilm inhibition and antioxidative properties. Bioactive components, including phenolics, flavonoids, enzymes, and antimicrobial peptides, disrupt microbial membranes, inhibit metabolic pathways, and induce oxidative stress. Advanced analytical techniques like HPLC and GC-MS have identified these compounds, though gaps remain in understanding secondary metabolites and synergistic actions. This review highlights honey's potential as a sustainable antimicrobial resource, emphasizing the need for standardization, clinical validation, and interdisciplinary research. Honey represents a promising solution to AMR and offers opportunities for integration into modern medicine and healthcare strategies.

Methylglyoxal Alone or Combined with Light-Emitting Diodes/Complex Electromagnetic Fields Represent an Effective Response to Microbial Chronic Wound Infections

Background: antimicrobial resistance represents a critical issue leading to delayed wound healing; hence, it is necessary to develop novel strategies to address this phenomenon. Objectives: this study aimed to explore the antimicrobial/anti-virulence action of Methylglyoxal-MGO alone or combined with novel technologies such as Light-Emitting Diodes-LED and Complex Magnetic Fields-CMFs against resistant clinical strains isolated from chronic wounds. Methods: characterized planktonic Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans isolates were used. Antimicrobial activity was evaluated by measuring optical density, Colony Forming Units-CFU, and synergy between MGO/LED or CMFs. Cellular membrane permeability by propidium iodide fluorescence and fluidity by Laurdan generalized polarization measurements were performed. P. aeruginosa motility was tested using the soft agar method. A docking study was performed to evaluate the possible interaction between MGO and urease in P. aeruginosa. Results: single/combined treatments showed significant antimicrobial activity. Major CFU reduction was detected after CMFs/MGO+CMFs application on C. albicans. Treatments exhibited significant changes in membrane permeability and fluidity. The treatments decreased P. aeruginosa motility with a major reduction after LED application. Docking analysis showed that MGO could bind with P. aeruginosa urease leading to defective folding and functional alterations. Conclusions: the results suggest that these treatments could represent promising and green therapeutic solutions against resistant isolates from chronic wounds.

Antimicrobial Properties of Hive Products and Their Potential Applications in Human and Veterinary Medicine

Hive products, encompassing honey, propolis, bee venom, royal jelly, and pollen, are recognized for their antimicrobial and therapeutic properties. This review examines their chemical composition, explores their mechanisms of action, and discusses their potential applications in both human and veterinary medicine, particularly in addressing the challenge of antimicrobial resistance. This study utilized a comprehensive literature search strategy, gathering data from Google Scholar, MEDLINE PubMed, SciELO, and SCOPUS databases. Relevant search terms were employed to ensure a thorough retrieval of the pertinent literature. Honey, rich in bioactive compounds such as hydrogen peroxide and methylglyoxal, effectively disrupts biofilms and combats multi-drug-resistant pathogens, showing promise in treating a range of infections. Propolis, with its flavonoids and phenolic acids, demonstrates synergistic effects when used in conjunction with antibiotics. Bee venom, particularly its component melittin, exhibits antibacterial and immunomodulatory properties, although further research is needed to address toxicity concerns. Pollen and royal jelly demonstrate broad-spectrum antimicrobial activity, which is particularly relevant to animal health. Existing pre-clinical and clinical data support the therapeutic potential of these hive products. Hive products represent a vast and largely untapped natural resource for combating antimicrobial resistance and developing sustainable therapies, particularly in the field of veterinary medicine. However, challenges remain due to the inherent variability in their composition and the lack of standardized protocols for their preparation and application. Further research is essential to fully elucidate their mechanisms of action, optimize formulations for enhanced efficacy, and establish standardized protocols to ensure their safe and effective clinical use.

Biomimetic Mineralized Collagen Scaffolds for Bone Tissue Engineering: Strategies on Elaborate Fabrication for Bioactivity Improvement

Biomimetic mineralized collagen (BMC) scaffolds represent an innovative class of bone-repair biomaterials inspired by the natural biomineralization process in bone tissue. Owing to their favorable biocompatibility and mechanical properties, BMC scaffolds have garnered significant attention in bone tissue engineering. However, most studies have overlooked the importance of bioactivity, resulting in collagen scaffolds with suboptimal osteogenic potential. In this review, the composition of the mineralized extracellular matrix (ECM) in bone tissue is discussed to provide guidance for biomimetic collagen mineralization. Subsequently, according to the detailed fabrication procedure of BMC scaffolds, the substances that can regulate both the fabrication process and biological activities is summarized. Furthermore, a potential strategy for developing BMC scaffolds with superior mechanical properties and biological activities for bone tissue engineering is proposed.

An Interventional Study of Application of Manuka Honey in Post Mastoidectomy Surgery

The aim of present study was to observe the effect of topical application of manuka honey in healing in the healing of postoperative mastoid cavity. A total of 100 patients diagnosed with chronic suppurative otitis media with cholesteatoma underwent canal wall down mastoidectomy, Manuka honey-soaked roller gauze pack was placed on Day 10 and was removed on day 17 and manuka honey was applied on day 17. Cavity was assessed on day 47 and day 90 on follow-up. Otoendoscopy was done on every visit to assess mastoid cavity. The primary outcome measure was the creation of a dry cavity as measured by a semi-quantitative scale as described by Merchant et al. Then Mastoid Cavity Healing Score was calculated on every visit and scoring was done at the end. On intragroup comparison it appeared that both the treatment methods exhibited improvised merchant grade score with the course of time (p-value = < 0.001). At 47th day and 90th day, the healing score in Group A was significantly higher than in Group B [p-value = < 0.001 and 0.001] respectively. We recommend Manuka honey as an adjunct to achieve a safe, dry ear in view of faster epithelization after mastoidectomy.

Evaluation of Full Thickness Wounds Following Application of a Visco-Liquid Hemostat in a Swine Model

Wound healing is a complex dynamic biomechanical process as the body attempts to restore the integrity of traumatized or devitalized tissues. There are four stages of wound of healing that begins with hemostasis followed by inflammation, proliferation and finally weeks later wound remodeling. Full thickness wounds usually are covered with a dressing material after hemostasis, which allows for controlled hydration. We investigated the potential of a visco-liquid hemostat, polyhedral oligomeric silsesquioxane (POSS), for providing hemostasis and to maintain a microenvironment in the wound bed that would maintain moisture content and promote early re-epithelialization. We hypothesized that the hemostatic agent POSS if left in the wound bed would maintain a protective barrier and accelerate wound healing similar to using saline to irrigate the wound to keep the wound moist. We compared the early phase of wound repair (3-7 days) in a porcine full thickness wound model to evaluate the efficacy of the material. Biopsies were taken after 3 and 7 days to determine the acute response of the POSS hemostat or saline on inflammation, cell migration, concentrations of metalloproteinase (MMPs), and tissue inhibitors of metalloproteinase (TIMPs). Accelerated healing was observed in POSS treated wounds by changes in wound contraction, keratinocyte migration, and development of granulation tissue in comparison to saline treated wounds. Increased concentrations at day 3 of MMP-2, MMP-3, and in MMP-1 at day 7 in POSS treated wounds compared to saline coincide with keratinocyte migration observed in the tissue histology and changes in wound contraction. Tissue concentrations of TIMP-1 and TIMP-2 in POSS treated wounds appear to coordinate the sequence of MMP events in the healing tissue. Matrix metalloproteinase-13, a marker for tissue remodeling, was not upregulated in the early wound healing cascade in either POSS or saline treated wounds at 3 or 7 days. Overall, the data suggests POSS treatment contributed to enhanced early cell migration and wound closure compared to saline treatment.

Bee-Inspired Healing: Apitherapy in Veterinary Medicine for Maintenance and Improvement Animal Health and Well-Being

This review aims to present current knowledge on the effects of honey bee products on animals based on in vivo studies, focusing on their application in clinical veterinary practice. Honey's best-proven effectiveness is in treating wounds, including those infected with antibiotic-resistant microorganisms, as evidenced in horses, cats, dogs, mice, and rats. Propolis manifested a healing effect in numerous inflammatory and painful conditions in mice, rats, dogs, and pigs and also helped in oncological cases in mice and rats. Bee venom is best known for its effectiveness in treating neuropathy and arthritis, as shown in dogs, mice, and rats. Besides, bee venom improved reproductive performance, immune response, and general health in rabbits, chickens, and pigs. Pollen was effective in stimulating growth and improving intestinal microflora in chickens. Royal jelly might be used in the management of animal reproduction due to its efficiency in improving fertility, as shown in rats, rabbits, and mice. Drone larvae are primarily valued for their androgenic effects and stimulation of reproductive function, as evidenced in sheep, chickens, pigs, and rats. Further research is warranted to determine the dose and method of application of honey bee products in animals.

Antifungal efficacy of natural antiseptic products against Candida auris

Candida auris is an emerging fungal pathogen responsible for healthcare-associated infections and outbreaks with high mortality around the world. It readily colonizes the skin, nares, respiratory and urinary tract of hospitalized patients, and such colonization may lead to invasive Candida infection in susceptible patients. However, there is no recommended decolonization protocol for C. auris by international health authorities. The aim of this study is to evaluate the susceptibility of C. auris to commonly used synthetic and natural antiseptic products using an in vitro, broth microdilution assay. Synthetic antiseptics including chlorhexidine, povidone-iodine, and nystatin were shown to be fungicidal against C. auris. Among the natural antiseptics tested, tea tree oil and manuka oil were both fungicidal against C. auris at concentrations less than or equal to 1.25% (v/v). Manuka honey inhibited C. auris at 25% (v/v) concentrations. Among the commercial products tested, manuka body wash and mouthwash were fungicidal against C. auris at concentrations less than or equal to 0.39% (w/v) and 6.25% (v/v) of products as supplied for use, respectively, while tea tree body wash and MedihoneyTM wound gel demonstrated fungistatic properties. In conclusion, this study demonstrated good in vitro antifungal efficacy of tea tree oil, manuka oil, manuka honey, and commercially available antiseptic products containing these active ingredients. Future studies are warranted to evaluate the effectiveness of these antiseptic products in clinical settings.

Incorporation of natural and synthetic polymers into honey hydrogel for wound healing: A review

Background and Aims

The difficulty in treating chronic wounds due to the prolonged inflammation stage has affected a staggering 6.5 million people, accompanied by 25 billion USD annually in the United States alone. A 1.9% rise in chronic wound prevalence among Medicare beneficiaries was reported from 2014 to 2019. Besides, the global wound care market values were anticipated to increase from USD 20.18 billion in 2022 to USD 30.52 billion in 2030, suggesting an expected rise in chronic wounds financial burdens. The lack of feasibility in using traditional dry wound dressings sparks hydrogel development as an alternative approach to tackling chronic wounds. Since ancient times, honey has been used to treat wounds, including burns, and ongoing studies have also demonstrated its wound-healing capabilities on cellular and animal models. However, the fluidity and low mechanical strength in honey hydrogel necessitate the incorporation of other polymers. Therefore, this review aims to unravel the characteristics and feasibility of natural (chitosan and gelatin) and synthetic (polyvinyl alcohol and polyethylene glycol) polymers to be incorporated in the honey hydrogel.

Methods

Relevant articles were identified from databases (PubMed, Google Scholar, and Science Direct) using keywords related to honey, hydrogel, and polymers. Relevant data from selected studies were synthesized narratively and reported following a structured narrative format.

Results

The importance of honey's roles and mechanisms of action in wound dressings were discussed. Notable studies concerning honey hydrogels with diverse polymers were also included in this article to provide a better perspective on fabricating customized hydrogel wound dressings for various types of wounds in the future.

Conclusion

Honey's incapability to stand alone in hydrogel requires the incorporation of natural and synthetic polymers into the hydrogel. With this review, it is hoped that the fabrication and commercialization of the desired honey composite hydrogel for wound treatment could be brought forth.

Manuka honey as a non-antibiotic alternative against Staphylococcus spp. and their small colony variant (SCVs) phenotypes

The antibiotic resistance (ABR) crisis is an urgent global health priority. Staphylococci are among the problematic bacteria contributing to this emergency owing to their recalcitrance to many clinically important antibiotics. Staphylococcal pathogenesis is further complicated by the presence of small colony variants (SCVs), a bacterial subpopulation displaying atypical characteristics including retarded growth, prolific biofilm formation, heightened antibiotic tolerance, and enhanced intracellular persistence. These capabilities severely impede current chemotherapeutics, resulting in chronic infections, poor patient outcomes, and significant economic burden. Tackling ABR requires alternative measures beyond the conventional options that have dominated treatment regimens over the past 8 decades. Non-antibiotic therapies are gaining interest in this arena, including the use of honey, which despite having ancient therapeutic roots has now been reimagined as an alternative treatment beyond just traditional topical use, to include the treatment of an array of difficult-to-treat staphylococcal infections. This literature review focused on Manuka honey (MH) and its efficacy as an anti-staphylococcal treatment. We summarized the studies that have used this product and the technologies employed to study the antibacterial mechanisms that render MH a suitable agent for the management of problematic staphylococcal infections, including those involving staphylococcal SCVs. We also discussed the status of staphylococcal resistance development to MH and other factors that may impact its efficacy as an alternative therapy to help combat ABR.

Long-term stability and the physical and chemical factors predictive for antimicrobial activity in Australian honey

The growing burden of expired medicines contributes to environmental contamination and landfill waste accumulation. Medicinal honey, with its non-toxic nature and potentially long shelf-life, represents a promising and underutilised therapeutic that avoids some of these issues. However, limited knowledge on how its antimicrobial properties change over time combined with a lack of reliable processes in the honey industry for measuring antimicrobial potential, hinder its clinical adoption. Using a diverse selection of 30 Australian honey samples collected between 2005 and 2007, we comprehensively evaluated their antibacterial and antifungal activity and pertinent physical and chemical properties with the aims of assessing the effect of long-term storage on activity, pinpointing factors associated with antimicrobial efficacy, and establishing robust assessment methods. Minimum inhibitory concentration (MIC) assays proved superior to the standard phenol equivalence assay in capturing the full range of antimicrobial activity present in honey. Correlations between activity and a range of physical and chemical properties uncovered significant associations, with hydrogen peroxide, antioxidant content, and water activity emerging as key indicators in non-Leptospermum honey. However, the complex nature and the diverse composition of honey samples precludes the use of high-throughput chemical tests for accurately assessing this activity, and direct assessment using live microorganisms remains the most economical and reliable method. We provide recommendations for different methods of assaying various honey properties, taking into account their accuracy along with technical difficulty and safety considerations. All Leptospermum and fourteen of seventeen non-Leptospermum honey samples retained at least some antimicrobial properties after 15-17 years of storage, suggesting that honey can remain active for extended periods. Overall, the results of this study will help industry meet the growing demand for high-quality, medicinally active honey while ensuring accurate assessment of its antimicrobial potential.

Emerging Therapies in the Medical Management of Allergic Fungal Rhinosinusitis

A non-invasive type of chronic sinusitis named allergic fungal rhinosinusitis (AFRS), which is a variant of allergic bronchopulmonary aspergillosis with nasal obstruction, was first described in 1976. The goal of this article was to provide an overview of various treatment approaches and how they can be used to control AFRS. Since this is an inflammatory disease rather than an invasive fungal infection, the treatment tries to modulate inflammation and reduce disease burden. A comprehensive treatment strategy must incorporate medicinal, surgical, biological, and immunological techniques. Owing to the chronic nature of allergic fungal rhinosinusitis and its high propensity for flare-ups and recurrence, multiple procedures are frequently required. The most likely method of establishing a long-term disease control for AFRS is a comprehensive management strategy that integrates medical, surgical, and immunological care. However, there are still disagreements regarding the exact combinations. In this review, we have mentioned different modalities in the management of AFRS, such as monoclonal antibodies, probiotic Manuka honey, and aPDT among others, some of which are promising but require further research.

The impact of wound pH on the antibacterial properties of Medical Grade Honey when applied to bacterial isolates present in common foot and ankle wounds. An in vitro study

BACKGROUND

Diabetic foot ulcers (DFUs) and post-surgical wound infections are amongst the most troublesome complications of diabetes and following foot and ankle surgery (FAS) respectively. Both have significant psychosocial and financial burden for both patients and the healthcare system. FAS has been reported to have higher than average post-surgical infections when compared to other orthopaedic subspecialties. Evidence also indicates that patients with diabetes and other co morbidities undergoing FAS are at a much greater risk of developing surgical site infections (SSIs). With the growing challenges of antibiotic resistance and the increasingly high numbers of resilient bacteria to said antibiotics, the need for alternative antimicrobial therapies has become critical.

AIM

The aim of this study was to investigate the use of medical grade honey (MGH) when altered to environments typically present in foot and ankle wounds including DFUs and post-surgical wounds (pH6-8).

METHODS

MGH (Activon) was altered to pH 6, 7 and 8 and experimental inoculums of Pseudomonas aeruginosa (NCTC10782), Escherichia coli, (NCTC10418), Staphylococcus aureus (NCTC10655) and Staphylococcus epidermidis (NCTC 5955) were transferred into each pH adjusted MGH and TSB solution and the positive and negative controls.

RESULTS

MGH adjusted to various pH values had the ability to reduce bacteria cell survival in all pH variations for all bacteria tested, with the most bacterial reduction/elimination noted for Staphylococcus epidermidis. No correlations were noted among the pH environments investigated and the colony counts, for which there were small amounts of bacteria survived.

CONCLUSION

This research would indicate that the antibacterial properties of honey remains the same regardless of the pH environment. MGH could therefore potentially be considered for use on non-infected foot and ankle wounds to reduce the bacterial bioburden, the risk of infections and ultimately to improve healing outcomes.

Evaluation of bacterial attachment on mineralized collagen scaffolds and addition of manuka honey to increase mesenchymal stem cell osteogenesis

The design of biomaterials to regenerate bone is likely to increasingly require modifications that reduce bacterial attachment and biofilm formation as infection during wound regeneration can significantly impede tissue repair and typically requires surgical intervention to restart the healing process. Further, much research on infection prevention in bone biomaterials has focused on modeling of non-resorbable metal alloy materials, whereas an expanding direction of bone regeneration has focused on development of bioresorbable materials. This represents a need for the prevention and understanding of infection in resorbable biomaterials. Here, we investigate the ability of a mineralized collagen biomaterial to natively resist infection and examine how the addition of manuka honey, previously identified as an antimicrobial agent, affects gram positive and negative bacterial colonization and mesenchymal stem cell osteogenesis and vasculature formation. We incorporate manuka honey into these scaffolds via either direct fabrication into the scaffold microarchitecture or via soaking the scaffold in a solution of manuka honey after fabrication. Direct incorporation results in a change in the surface characteristics and porosity of mineralized collagen scaffolds. Soaking scaffolds in honey concentrations higher than 10% had significant negative effects on mesenchymal stem cell metabolic activity. Soaking or incorporating 5% honey had no impact on endothelial cell tube formation. Although solutions of 5% honey reduced metabolic activity of mesenchymal stem cells, MSC-seeded scaffolds displayed increased calcium and phosphorous mineral formation, osteoprotegerin release, and alkaline phosphatase activity. Bacteria cultured on mineralized collagen scaffolds demonstrated surfaces covered in bacteria and no method of preventing infection, and using 10 times the minimal inhibitory concentration of antibiotics did not completely kill bacteria within the mineralized collagen scaffolds, indicating bioresorbable scaffold materials may act to shield bacteria from antibiotics. The addition of 5% manuka honey to scaffolds was not sufficient to prevent P. aeruginosa attachment or consistently reduce the activity of methicillin resistant staphylococcus aureus, and concentrations above 7% manuka honey are likely necessary to impact MRSA. Together, our results suggest bioresorbable scaffolds may create an environment conducive to bacterial growth, and potential trade-offs exist for the incorporation of low levels of honey in scaffolds to increase osteogenic potential of osteoprogenitors while high-levels of honey may be sufficient to reduce gram positive or negative bacteria activity but at the cost of reduced osteogenesis.

Evidence for Natural Products as Alternative Wound-Healing Therapies

Chronic, non-healing wounds represent a significant area of unmet medical need and are a growing problem for healthcare systems around the world. They affect the quality of life for patients and are an economic burden, being difficult and time consuming to treat. They are an escalating problem across the developed world due to the increasing incidence of diabetes and the higher prevalence of ageing populations. Effective treatment options are currently lacking, and in some cases chronic wounds can persist for years. Some traditional medicines are believed to contain bioactive small molecules that induce the healing of chronic wounds by reducing excessive inflammation, thereby allowing re-epithelisation to occur. Furthermore, many small molecules found in plants are known to have antibacterial properties and, although they lack the therapeutic selectivity of antibiotics, they are certainly capable of acting as topical antiseptics when applied to infected wounds. As these molecules act through mechanisms of action distinct from those of clinically used antibiotics, they are often active against antibiotic resistant bacteria. Although there are numerous studies highlighting the effects of naturally occurring small molecules in wound-healing assays in vitro, only evidence from well conducted clinical trials can allow these molecules or the remedies that contain them to progress to the clinic. With this in mind, we review wound-healing natural remedies that have entered clinical trials over a twenty-year period to the present. We examine the bioactive small molecules likely to be in involved and, where possible, their mechanisms of action.

Effects of artificial honey and epigallocatechin-3-gallate on streptococcus pyogenes

Background

Streptococcus pyogenes is an important global human pathogen that causes pharyngitis, and antibacterial therapy has become an important part of the overall therapy for pharyngitis. As natural derivatives, honey and green tea are often recommended for patients with pharyngitis in traditional Chinese medicine without experimental theoretical basis on wether the combined effect of honey and green tea on pharyngitis is better than they alone. The aims of this study were to explore the effects of artificial honey (AH) and epigallocatechin-3-gallate (EGCG) on S. pyogenes and elucidate the possible mechanisms, which were investigated using MIC (the minimum inhibitory concentration), FIC (fractional inhibitory concentration) index, growth pattern, biofilm formation and RT-qPCR.

Results

The MIC of AH on S. pyogenes was 12.5% (v/v) and the MIC of EGCG was 1250 μg/ml. The FIC index of AH and EGCG was 0.5. The planktonic cell growth, growth pattern and biofilm formation assays showed that AH and EGCG mixture had stronger inhibitory effect on S. pyogenes than they alone. RT-qPCR confirmed that the expression of hasA and luxS gene were inhibited by AH and EGCG mixture.

Conclusions

AH and EGCG mixture can inhibit the planktonic cell growth, biofilm formation and some virulence genes expression of S. pyogenes, better than they alone. The combination of honey and green tea have the potential to treat pharyngitis as natural derivatives, avoiding drug resistance and double infection.

The Potential of Honey as a Prebiotic Food to Re-engineer the Gut Microbiome Toward a Healthy State

Honey has a long history of use for the treatment of digestive ailments. Certain honey types have well-established bioactive properties including antibacterial and anti-inflammatory activities. In addition, honey contains non-digestible carbohydrates in the form of oligosaccharides, and there is increasing evidence from in vitro, animal, and pilot human studies that some kinds of honey have prebiotic activity. Prebiotics are foods or compounds, such as non-digestible carbohydrates, that are used to promote specific, favorable changes in the composition and function of the gut microbiota. The gut microbiota plays a critical role in human health and well-being, with disturbances to the balance of these organisms linked to gut inflammation and the development and progression of numerous conditions, such as colon cancer, irritable bowel syndrome, obesity, and mental health issues. Consequently, there is increasing interest in manipulating the gut microbiota to a more favorable balance as a way of improving health by dietary means. Current research suggests that certain kinds of honey can reduce the presence of infection-causing bacteria in the gut including Salmonella, Escherichia coli, and Clostridiodes difficile, while simultaneously stimulating the growth of potentially beneficial species, such as Lactobacillus and Bifidobacteria. In this paper, we review the current and growing evidence that shows the prebiotic potential of honey to promote healthy gut function, regulate the microbial communities in the gut, and reduce infection and inflammation. We outline gaps in knowledge and explore the potential of honey as a viable option to promote or re-engineer a healthy gut microbiome.

Preparation and Characterisation of a Cyclodextrin-Complexed Mānuka Honey Microemulsion for Eyelid Application

Honey has been widely purported as a natural remedy due to its antimicrobial and anti-inflammatory effects. In recent years, several studies have suggested that the considerably high methylglyoxal (MGO) concentration in Mānuka honey (MH) makes it particularly effective to manage bacterial overload, such as that observed in blepharitis. However, the poor solubility, high viscosity, and osmolarity of aqueous honey solutions, especially at the high MGO concentrations studied in the literature, render the formulation of an acceptable dosage form for topical application to the eyelids challenging. Here, the antibacterial properties of raw MH and alpha-cyclodextrin (α-CD)-complexed MH were evaluated at relatively low MGO concentrations, and a liquid crystalline-forming microemulsion containing α-CD-complexed MH was formulated. After determining pH and osmolarity, ocular tolerability was assessed using human primary corneal epithelial cells and chorioallantoic membranes, while the antibacterial efficacy was further evaluated in vitro. The α-CD–MH complex had significantly greater antibacterial activity against Staphylococcus aureus than either constituent alone, which was evident even when formulated as a microemulsion. Moreover, the final formulation had a physiologically acceptable pH and osmolarity for eyelid application and was well-tolerated when diluted 1:10 with artificial tear fluid, as expected to be the case after accidental exposure to the ocular surface in the clinical setting. Thus, a safe and efficient MH dosage form was developed for topical application to the eyelids, which can potentially be used to support optimal eyelid health in the management of blepharitis.

A 4-Week Diet Low or High in Advanced Glycation Endproducts Has Limited Impact on Gut Microbial Composition in Abdominally Obese Individuals: The deAGEing Trial

Dietary advanced glycation endproducts (AGEs), abundantly present in Westernized diets, are linked to negative health outcomes, but their impact on the gut microbiota has not yet been well investigated in humans. We investigated the effects of a 4-week isocaloric and macronutrient-matched diet low or high in AGEs on the gut microbial composition of 70 abdominally obese individuals in a double-blind parallel-design randomized controlled trial (NCT03866343). Additionally, we investigated the cross-sectional associations between the habitual intake of dietary dicarbonyls, reactive precursors to AGEs, and the gut microbial composition, as assessed by 16S rRNA amplicon-based sequencing. Despite a marked percentage difference in AGE intake, we observed no differences in microbial richness and the general community structure. Only the Anaerostipes spp. had a relative abundance >0.5% and showed differential abundance (0.5 versus 1.11%; p = 0.028, after low- or high-AGE diet, respectively). While the habitual intake of dicarbonyls was not associated with microbial richness or a general community structure, the intake of 3-deoxyglucosone was especially associated with an abundance of several genera. Thus, a 4-week diet low or high in AGEs has a limited impact on the gut microbial composition of abdominally obese humans, paralleling its previously observed limited biological consequences. The effects of dietary dicarbonyls on the gut microbiota composition deserve further investigation.

Evaluation of consumer safety of Polish honey-the content of Cd and Pb in multifloral, monofloral and honeydew honeys

The paper aimed to evaluate the degree of contamination of honey available on the Polish market with cadmium (Cd) and lead (Pb). The analyses involved 49 samples of honey: monofloral (n = 24): linden, raspberry, goldenrod, bean, dandelion, buckwheat and rapeseed honey, multifloral honey (n = 17) and coniferous honeydew honey (n = 8). The content of Cd and Pb was determined using Inductively Coupled Plasma-Optical Emission Spectrometers (ICP-OES). The content of Cd and Pb was confirmed in all the analysed honeys, but in 18% of samples the level of Cd was < LOQ. The analysed honeys contained from < LOQ to ca. 0.09 mg Cd per 1 kg, on average 0.025 mg kg^-1. On average, they contained 0.193 mg Pb (range 0.014-1.007) per 1 kg of the raw product. The content of Cd and Pb can be presented as: honeydew honey > multifloral honey > monofloral honey. The content of Cd in monofloral honeys can be presented as follows: linden > other (raspberry, goldenrod, bean, linden + bean) > dandelion = buckwheat = rape, while the content of Pb as linden > other > rapeseed > buckwheat > dandelion honey. It should be emphasised that consuming 19 g of honey a week (mean honey consumption in Poland) is safe for human health, as it results in an intake of Cd at the level of 1.18E-04% PTWI and 0.553% PTWI for children and an intake of Pb at the level of 0.641% BMDL01 for adults and 5.916% BMDL for children. The obtained results lead to a conclusion that the risk of disorders related to chronic exposure to Cd and Pb ingested with honey is very low, which is demonstrated by the fact that both children and adults showed CDI, CR, THQ and HI that were lower than 1.

Treating (Recurrent) Vulvovaginal Candidiasis with Medical-Grade Honey-Concepts and Practical Considerations

Recurrent vulvovaginal candidiasis (RVVC) is a relapsing vaginal fungal infection caused by Candida species. The prevalence varies among age populations and can be as high as 9%. Treatment options are limited, and in 57% of the cases, relapses occur within six months after fluconazole maintenance therapy, which is the current standard of care. The pathogenesis of RVVC is multifactorial, and recent studies have demonstrated that the vaginal microenvironment and activity of the immune system have a strong influence on the disease. Medical-grade honey (MGH) has protective, antimicrobial, and immunomodulatory activity and forms a putative alternative treatment. Clinical trials have demonstrated that honey can benefit the treatment of bacterial and Candida-mediated vaginal infections. We postulate that MGH will actively fight ongoing infections; eradicate biofilms; and modulate the vaginal microenvironment by its anti-inflammatory, antioxidative, and immunomodulatory properties, and subsequently may decrease the number of relapses when compared to fluconazole. The MGH formulation L-Mesitran Soft has stronger antimicrobial activity against various Candida species than its raw honey. In advance of a planned randomized controlled clinical trial, we present the setup of a study comparing L-Mesitran Soft with fluconazole and its practical considerations.

Beehive Products as Antibacterial Agents: A Review

Honeybees are one of the most marvelous and economically beneficial insects. As pollinators, they play a vital role in every aspect of the ecosystem. Beehive products have been used for thousands of years in many cultures for the treatment of various diseases. Their healing properties have been documented in many religious texts like the Noble Quran and the Holy Bible. Honey, bee venom, propolis, pollen and royal jelly all demonstrated a richness in their bioactive compounds which make them effective against a variety of bacterial strains. Furthermore, many studies showed that honey and bee venom work as powerful antibacterial agents against a wide range of bacteria including life-threatening bacteria. Several reports documented the biological activities of honeybee products but none of them emphasized on the antibacterial activity of all beehive products. Therefore, this review aims to highlight the antibacterial activity of honey, bee venom, propolis, pollen and royal jelly, that are produced by honeybees.

Use of Honey Versus Standard Care for Hospital-Acquired Pressure Injury in Critically Ill Children: A Multicenter Randomized Controlled Trial

OBJECTIVES

To examine if the use of honey (medicated) for dressing is superior to standard care in terms of time to complete wound healing in stages 1-3 of pressure injuries in children admitted to the PICU.

DESIGN

Multicenter, open-label, parallel-group, randomized trial.

SETTING

Tertiary-care PICU from August 2017 to January 2019.

PATIENTS

Critically ill children, 2 months to 17 years old, who developed pressure injury (stages 1-3) were included; those on more than two inotropes or with signs of acute wound infection or wounds with greater than 5 cm diameter or known allergy to honey were excluded.

INTERVENTIONS

Children were randomized to receive either medicated honey dressing or standard (routine) wound care for the management of their pressure injury.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the time to complete wound healing. Manuka or active Leptospermum honey dressing/gel was used in the intervention group. Enrolled children were followed up until death or discharge from the hospital. A total of 99 children were enrolled: 51 in the intervention group and 48 in the standard care group. Baseline characteristics, including the nutritional status, were comparable between the groups. The most common sites of injury were bony prominences at face mask contact points. The median time to complete healing was 7 days (95% CI, 6-7 d) versus 9 days (7-10 d) in the intervention and standard care groups, respectively (p = 0.002; log-rank test). At any random time, children in the intervention group were about 1.9-fold more likely to have their pressure injury completely healed than those in the standard care group (hazard ratio 1.86; 95% CI, 1.21-2.87). There were no allergic reactions or secondary wound infections in the intervention group.

CONCLUSIONS

The use of medicated honey dressings decreased the time to wound healing in critically ill children with pressure injuries. There were no allergic reactions or secondary bacterial infections in any of these children.

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.

Honey as an Ecological Reservoir of Antibacterial Compounds Produced by Antagonistic Microbial Interactions in Plant Nectars, Honey and Honey Bee

The fundamental feature of "active honeys" is the presence and concentration of antibacterial compounds. Currently identified compounds and factors have been described in several review papers without broader interpretation or links to the processes for their formation. In this review, we indicate that the dynamic, antagonistic/competitive microbe-microbe and microbe-host interactions are the main source of antibacterial compounds in honey. The microbial colonization of nectar, bees and honey is at the center of these interactions that in consequence produce a range of defence molecules in each of these niches. The products of the microbial interference and exploitive competitions include antimicrobial peptides, antibiotics, surfactants, inhibitors of biofilm formation and quorum sensing. Their accumulation in honey by horizontal transfer might explain honey broad-spectrum, pleiotropic, antibacterial activity. We conclude that honey is an ecological reservoir of antibacterial compounds produced by antagonistic microbial interactions in plant nectars, honey and honey bee. Thus, refocusing research on secondary metabolites resulting from these microbial interactions might lead to discovery of new antibacterial compounds in honey that are target-specific, i.e., acting on specific cellular components or inhibiting the essential cellular function.

Manuka honey: A promising wound dressing material for the chronic nonhealing discharging wounds: A retrospective study

OBJECTIVES

To assess the efficacy and feasibility of topical manuka honey application in chronic nonhealing discharging extraoral wounds.

MATERIALS AND METHODS

The study includes 15 patients (9 males and 6 females, mean age: 38.06, range: 20-50 years), presenting with the complaint of chronic nonhealing discharging extraoral wounds from January 2018 to January 2020. After wound irrigation with normal saline, manuka honey in conjunction with the antibiotic treatment was directly applied onto the surface of the wound and was then covered by an absorbent layer to contain the honey. Dressings were changed every alternate day for a week till there was complete cessation of pus discharge. Henceforth, the interval between dressings was increased to 1 week subsequently and was continued for 4 weeks. Assessment was done on the basis of discharge and depth of the wound before the procedure and weekly for 4 weeks.

RESULTS

The average depth of wound as seen at 15 sites after a week was 5.72 mm, and decrease in the average depth of wound seen at the end of the 4th week was 0.88 mm with complete wound epithelization. This was found to be statistically significant (P = 0.0001). No cases were reported with allergy, pain, infection, inflammation, and swelling on 1st, 2nd, 3rd, and 4thweek.

CONCLUSION

Hence, the use of manuka honey as a wound dressing material in our study has proved to promote the growth of tissues for wound repair, suppress inflammation, and bring about rapid autolytic debridement.

Manuka Honey: Feasibility and Safety in Postoperative Neurosurgical Wound Care

OBJECTIVE

To date, no reports have been published on active Leptospermum manuka honey (ALH) feasibility as a postoperative topical wound supplement in neurosurgical patients. The objective of the study is to present the authors' initial experience with using ALH in postoperative neurosurgical patients.

METHODS

A single-surgeon retrospective case series review of cranial and spinal operations between 2018 and 2020 was performed in patients with nonhealing wounds or wounds deemed "at risk" as defined by grade 1 Sandy surgical wound dehiscence grading classification. An ALH gel or ointment was applied to these incisions once a day for 2 to 4 weeks. Patients were followed up in the clinic every 2 weeks until incisions had healed.

RESULTS

Twenty-five postoperative patients (12 cranial, 13 spinal) were identified to be at high risk of operative debridement. All 25 patients were prescribed a topical application of ALH, which was easily adopted without patient-related adverse events. Seven (four cranial, three spinal) patients required operative debridement and treatment with long-term antibiotic therapy.

CONCLUSIONS

In this small case series of neurosurgical patients who were at risk of poor wound healing, the application of medical-grade ALH was well tolerated without patient-reported adverse events. The ALH may have prevented the need for operative debridement in the majority of patients. Further prospective studies are necessary to establish its efficacy in wound healing in the neurosurgical population.

Nectar antimicrobial compounds and their potential effects on pollinators

Nectar is a sugary, aqueous solution that plants offer as a reward to animal mutualists for visitation. Since nectars are so nutrient-rich, they often harbor significant microbial communities, which can be pathogenic, benign, or even sometimes beneficial to plant fitness. Through recent advances, it is now clear that these microbes alter nectar chemistry, which in turn influences mutualist behavior (e.g. pollinator visitation). To counteract unwanted microbial growth, nectars often contain antimicrobial compounds, especially in the form of proteins, specialized (secondary) metabolites, and metals. This review covers our current understanding of nectar antimicrobials, as well as their interplay with both microbes and insect visitors.

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.

Portuguese honeys as antimicrobial agents against Candida species

BACKGROUND AND AIM

Honey has been recognized worldwide for its antioxidant, anti-tumor, anti-inflammatory and antimicrobial properties. Among them, the antifungal properties associated to honey make it an attractive alternative treatment for Candida-associated infections, particularly for topical application to the mucous membranes and skin. In this sense, the main purpose of this work was to evaluate physicochemical properties of five Portuguese honeys and Manuka honey (an Australian honey with well recognized medical proprieties, used as control) and to evaluate the antifungal activity in Candida species planktonic and biofilm assays.

EXPERIMENTAL PROCEDURE

Pollen analysis, pH determination, color, concentration of protein and methylglyoxal, conductivity, total phenolics and flavonoids, hydrogen peroxide concentration, and characterization by differential scanning calorimetry in honey samples were determined. Additionally, the effect of honeys on planktonic growth of Candida was initially evaluated by determination of the minimum inhibitory concentrations. Then, the same effect of those honeys was evaluated in biofilms, by Colony Forming Units enumeration.

RESULTS AND CONCLUSION

It has been shown that Portuguese heather (Erica cinereal) honey presented the most similar physicochemical properties to manuka honey (specially phenolic and flavonoids contents). The five Portuguese honeys under study, presented in general a potent activity against planktonic multi-resistant yeast pathogens (several clinical isolates and reference strains of Candida species) and S. aureus and P. aeruginosa bacteria cultures. Additionally, it was also concluded that Portuguese heather honey (50% and 75% (w/v)) can also act as a good Candida species biofilm reducer, namely for C. tropicalis.

Overcoming bacterial resistance to antibiotics: the urgent need – a review

The discovery of antibiotics is considered one of the most crucial breakthroughs in medicine and veterinary science in the 20th century. From the very beginning, this type of drug was used as a ‘miraculous cure’ for every type of infection. In addition to their therapeutic uses, antibiotics were also used for disease prevention and growth promotion in livestock. Though this application was banned in the European Union in 2006, antibiotics are still used in this way in countries all over the world. The unlimited and unregulated use of antibiotics has increased the speed of antibiotic resistance’s spread in different types of organisms. This phenomenon requires searching for new strategies to deal with hard-to-treat infections. The antimicrobial activity of some plant derivatives and animal products has been known since ancient times. At the beginning of this century, even more substances, such as antimicrobial peptides, were considered very promising candidates for becoming new alternatives to commonly used antimicrobials. However, many preclinical and clinical trials ended without positive results. A variety of strategies to fight microbes exist, but we are a long way from approving them as therapies. This review begins with the discovery of antibiotics, covers the modes of action of select antimicrobials, and ends with a literature review of the newest potential alternative approaches to overcoming the drug resistance phenomenon.

Usefulness of Honey as an Adjunct in the Radiation Treatment for Head and Neck Cancer: Emphasis on Pharmacological and Mechanism/s of Actions

BACKGROUND

In the treatment of head and neck cancer (HNC), ionizing radiation is an important modality in achieving curative objectives. However, the effective use of radiation is compromised by the side effects resulting from the damage to the adjacent normal tissue. Preclinical studies carried out in the recent past have shown that the age old dietary agent honey, which also possess myriad medicinal use is beneficial in mitigating diverse radiation-induced side effects like mucositis, xerostomia, fatigue, weight loss and to promote healing of refractory wounds.

OBJECTIVE

The objective of this memoir is to review the beneficial effects of honey in mitigating radiation-induced side effects in HNC and to emphasize on the underlying mechanism of action for the beneficial effects Methods: Two authors searched Google Scholar, PubMed, Embase, and the Cochrane Library for publications up to December 2019 to assess the ability of honey in reducing the severity of radiation-induced ill effects in the treatment of HNC. Subsequently, the adjunct pharmacological effects and mechanism/s responsible were also searched for and appropriately used to substantiate the underlying mechanism/s of action for the beneficial effects.

RESULTS

The existing data is suggestive that honey is beneficial in mitigating the radiation-induced mucositis, xerostomia, healing of recalcitrant wounds in radiation exposed regions and multiple pathways mediate the beneficial effects especially, free radical scavenging, antioxidant, wound healing, anticancer, analgesic, anti-inflammatory, anabolic, anti-fatigue and anti-anaemic effects that add additional value to the use of honey as an adjunct in cancer therapy.

CONCLUSION

For the first time this review addresses the underlying pharmacological effects related to the beneficial effects of honey in radiation-induced damage, and attempts at emphasizes the lacunae that need further studies for optimizing the use of honey as an adjunct in radiotherapy of HNC. The authors suggest that future studies should be directed at understanding the detail molecular mechanisms responsible for the beneficial effects using validated cell culture and animal models of study. Large multi centric clinical trials with standardised honey is also needed to understand the clinical use of honey.

Manuka honey versus saline sinus irrigation in the treatment of cystic fibrosis-associated chronic rhinosinusitis: A randomised pilot trial

OBJECTIVES

Manuka honey attacks biofilms, which contribute to bacterial persistence in cystic fibrosis sinusitis. The primary objective was to determine feasibility of investigating manuka honey as an irrigation treatment for cystic fibrosis sinusitis and secondarily to assess the treatment's preliminary effectiveness.

DESIGN

Prospective, single-blinded (clinician only), randomised, parallel two-arm pilot trial.

SETTING

Tertiary rhinology clinic.

PARTICIPANTS

Subjects had recalcitrant cystic fibrosis sinusitis and previous sinus surgery. They received manuka honey or saline sinus irrigations twice daily for 30 days.

MAIN OUTCOME MEASURES

Main outcomes were recruitment/retention rates and tolerability. Preliminary effectiveness was assessed based on quality-of-life Sinonasal Outcome Test-22 and Lund-Kennedy endoscopic change scores and post-treatment culture negativity.

RESULTS

Over 10 months, 13 subjects were enrolled, and 77% (10/13) were included in the analysis. Manuka honey irrigations were well-tolerated. The quality-of-life change score was clinically significant for manuka honey (-9 [-14,-6]) but not saline (-5 [-9,-1]), although the difference was not statistically significant (P = .29). Lund-Kennedy endoscopic change score was significantly better for manuka honey (-3 [-5,-3]) versus saline (0 [0,0]) (P = .006). There was no difference in post-treatment culture negativity between manuka honey (1/5, 20%) and saline (0/5, 0%) (P = 1.00).

CONCLUSIONS

Manuka honey irrigations were well tolerated, and retention rates were high. Preliminary data showed that manuka honey achieved a clinically important difference in quality-of-life score and a significantly better endoscopic outcome. Microbiological control was difficult to achieve. A future definitive trial would require multi-institutional recruitment.

The Antibacterial Potential of Honeydew Honey Produced by Stingless Bee (Heterotrigona itama) against Antibiotic Resistant Bacteria

Scientific studies about the antibacterial effects of honeydew honey produced by the stingless bee are very limited. In this study, the antibacterial activities of 46 blossom and honeydew honeys produced by both honey bees and stingless bees were evaluated and compared. All bacterial isolates showed varying degrees of susceptibility to blossom and honeydew honeys produced by the honey bee (Apis cerana) and stingless bee (Heterotrigona itama and Geniotrigona thoracica) in agar-well diffusion. All stingless bee honeys managed to inhibit all the isolates but only four out of 23 honey bee honeys achieved that. In comparison with Staphylococcus aureus, Escherichia coli was found to be more susceptible to the antibacterial effects of honey. Bactericidal effects of stingless bee honeys on E. coli were determined with the measurement of endotoxins released due to cell lysis. Based on the outcomes, the greatest antibacterial effects were observed in honeydew honey produced by H. itama. Scanning electron microscopic images revealed the morphological alteration and destruction of E. coli due to the action of this honey. The combination of this honey with antibiotics showed synergistic inhibitory effects on E. coli clinical isolates. This study revealed that honeydew honey produced by H. itama stingless bee has promising antibacterial activity against pathogenic bacteria, including antibiotic resistant strains.

Honey: Another Alternative in the Fight against Antibiotic-Resistant Bacteria?

Antibacterial resistance has become a challenging situation worldwide. The increasing emergence of multidrug-resistant pathogens stresses the need for developing alternative or complementary antimicrobial strategies, which has led the scientific community to study substances, formulas or active ingredients used before the antibiotic era. Honey has been traditionally used not only as a food, but also with therapeutic purposes, especially for the topical treatment of chronic-infected wounds. The intrinsic characteristics and the complex composition of honey, in which different substances with antimicrobial properties are included, make it an antimicrobial agent with multiple and different target sites in the fight against bacteria. This, together with the difficulty to develop honey-resistance, indicates that it could become an effective alternative in the treatment of antibiotic-resistant bacteria, against which honey has already shown to be effective. Despite all of these assets, honey possesses some limitations, and has to fulfill a number of requirements in order to be used for medical purposes.

Topical Antimicrobial Agents for Burn Wound Care: History and Current Status

Background: Infection is the leading cause of death after thermal injury. Optimal prevention and treatment of burn wound infection is enabled by an in-depth understanding of burn wound treatment modalities not only from a technical standpoint, but also from the standpoint of the clinical context in which these modalities were originally developed. Methods: A review of the historical literature on the topical antimicrobial care of burn wounds was performed. Results: As our understanding of post-burn infection evolved, and as new products were developed for the prevention of post-burn wound infection, major advances in post-burn survival occurred. Ultimately, improvements in anesthetic, surgical, and critical care management have permitted early excision and grafting of the burn wound, decreasing but not eliminating the importance of topical antimicrobial care, and shifting much of the burden of wound infection prevention to the post-operative period. Conclusions: The development of effective topical antimicrobial agents for wound care was, arguably, the single most important advance in the care of the burn patient. Still, many gaps in our ability to treat complicated burn wounds remain. Fungal infection is an unusual but daunting challenge. Patients with impaired wound healing and those with advanced age or medical comorbidities may not benefit from early excision, and the benefits of early excision may not be available in austere or remote locations. For these reasons, research on optimal topical treatment continues.

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.

Detrimental effect on the gut microbiota of 1,2-dicarbonyl compounds after in vitro gastro-intestinal and fermentative digestion

This study investigated the stability of dicarbonyl compounds (DCs), 3-deoxyglucosone (3-DG), glyoxal (GO) and methylglyoxal (MGO) during simulated gastrointestinal digestion processes and the impact these compounds have on the gut microbiota. DCs pass almost unaltered through the in-vitro gastrointestinal digestion phases (concentration loss: 11% for 3-DG, 24% for GO and MGO) and have an effect on the fermentative digestion process, reducing the total gut bacterial population up to 6 Log₁₀ units. Previous studies have shown no antimicrobial activity for 3-DG, however, for the first time it has been shown that when incubated with faecal bacteria 3-DG strongly depressed this microbial community. The influence of dicarbonyl compounds on the anaerobic fermentation processes was confirmed by the reduced production of short-chain fatty acids. Considering the modern Western diet, characterised by high consumption of ultra-processed foods rich in dicarbonyl compounds, this could lead to a reduction of bacteria important for the microbiome.

Optimal Management of Allergic Fungal Rhinosinusitis

Introduction

Allergic fungal rhinosinusitis (AFRS) is a chronic disorder with significant morbidity and a high recurrence rate needing long-term follow-up. Even after its first description many decades ago, there is still considerable uncertainty about the management of this condition.

Description

In this chapter, we breakdown the topic “Optimal management of allergic fungal rhinosinusitis” into sub-headings in order to discuss the latest research and available literature under each topic in great detail. Every attempt has been made to incorporate the highest level of evidence that was available at the time of writing.

Summary

Pre-operative diagnosis and further management prior to surgery is important. Steroids help in reducing inflammation and help improve the surgical field. Surgery remains the mainstay in the management of this condition along with long-term medical management. Oral steroids are reserved for acute flare-ups in the background of associated lung concerns. Oral and topical antifungal agents have no role in the control of the disease. Biological agents are being prescribed predominantly by respiratory physician colleagues, mainly for the control of the chest-related issues rather than for sinus disease. Immunotherapy as an adjunct with surgery is promising.

Conclusion

AFRS is a disease with many variables and a wide range of symptomatic presentation. It takes a keen clinician to identify the disease and subsequently manage the condition. Treatment involves long-term follow-up with early detection of recurrence or flare-ups. Any of the mentioned modalities of management may be employed to effectively control the condition, and treatment protocols will have to be tailor-made to suit each individual patient. Various medications and drugs such as Manuka honey, antimicrobial photodynamic therapy, hydrogen peroxide and betadine rinses appear to be promising. More robust studies need to be undertaken to ascertain their routine use in clinical practice.

Exposure to a Manuka Honey Wound Gel Is Associated With Changes in Bacterial Virulence and Antimicrobial Susceptibility

The use of manuka honey for the topical treatment of wounds has increased worldwide owing to its broad spectrum of activity towards bacteria in both planktonic and biofilm growth modes. Despite this, the potential consequences of bacterial exposure to manuka honey, as may occur during the treatment of chronic wounds, are not fully understood. Here, we describe changes in antimicrobial susceptibility and virulence in a panel of bacteria, including wound isolates, following repeated exposure (ten passages) to sub-inhibitory concentrations of a manuka honey based wound gel. Changes in antibiotic sensitivity above 4-fold were predominantly related to increased vancomycin sensitivity in the staphylococci. Interestingly, Staphylococcus epidermidis displayed phenotypic resistance to erythromycin following passaging, with susceptibility profiles returning to baseline in the absence of further honey exposure. Changes in susceptibility to the tested wound gel were moderate (≤ 1-fold) when compared to the respective parent strain. In sessile communities, increased biofilm eradication concentrations over 4-fold occurred in a wound isolate of Pseudomonas aeruginosa (WIBG 2.2) as evidenced by a 7-fold reduction in gentamicin sensitivity following passaging. With regards to pathogenesis, 4/8 bacteria exhibited enhanced virulence following honey wound gel exposure. In the pseudomonads and S. epidermidis, this occurred in conjunction with increased haemolysis and biofilm formation, whilst P. aeruginosa also exhibited increased pyocyanin production. Where virulence attenuation was noted in a passaged wound isolate of S. aureus (WIBG 1.6), this was concomitant to delayed coagulation and reduced haemolytic potential. Overall, passaging in the presence of a manuka honey wound gel led to changes in antimicrobial sensitivity and virulence that varied between test bacteria.

Effect of manuka honey on biofilm-associated genes expression during methicillin-resistant Staphylococcus aureus biofilm formation

Methicillin-resistant Staphylococcus aureus (MRSA) are among the most important biofilm-forming pathogens responsible for hard-to-treat infections. Looking for alternatives to antibiotics that prevent biofilm formation, we investigated the effects of manuka honey on the transcriptional profile of genes essential for staphylococcal biofilm formation using qRT-PCR. mRNA from two hospital MRSA strains (strong and weak biofilm producer) were isolated after 4, 8, 12 and 24 h from cells grown in biofilm. Manuka honey at 1/2 minimum biofilm inhibition concentration (MBIC) significantly reduced MRSA cell viability in biofilm. Manuka honey downregulated the genes encoding laminin- (eno), elastin- (ebps) and fibrinogen binding protein (fib), and icaA and icaD involved in biosynthesis of polysaccharide intercellular adhesin in both weakly and strongly adhering strain compared to the control (untreated biofilm). Expression levels of cna (collagen binding protein) and map/eap (extracellular adherence protein—Eap) were reduced in weakly adhering strain. The lowest expression of investigated genes was observed after 12 h of manuka honey treatment at 1/2 MBIC. This study showed that the previously unknown mechanism of manuka honey action involved inhibition of S. aureus adhesion due to reduction in expression of crucial genes associated with staphylococcal biofilm.

Characterizing the Mechanism of Action of an Ancient Antimicrobial, Manuka Honey, against Pseudomonas aeruginosa Using Modern Transcriptomics

Manuka honey has broad-spectrum antimicrobial activity, and unlike traditional antibiotics, resistance to its killing effects has not been reported. However, its mechanism of action remains unclear. Here, we investigated the mechanism of action of manuka honey and its key antibacterial components using a transcriptomic approach in a model organism, Pseudomonas aeruginosa We show that no single component of honey can account for its total antimicrobial action, and that honey affects the expression of genes in the SOS response, oxidative damage, and quorum sensing. Manuka honey uniquely affects genes involved in the explosive cell lysis process and in maintaining the electron transport chain, causing protons to leak across membranes and collapsing the proton motive force, and it induces membrane depolarization and permeabilization in P. aeruginosa These data indicate that the activity of manuka honey comes from multiple mechanisms of action that do not engender bacterial resistance.IMPORTANCE The threat of antimicrobial resistance to human health has prompted interest in complex, natural products with antimicrobial activity. Honey has been an effective topical wound treatment throughout history, predominantly due to its broad-spectrum antimicrobial activity. Unlike traditional antibiotics, honey-resistant bacteria have not been reported; however, honey remains underutilized in the clinic in part due to a lack of understanding of its mechanism of action. Here, we demonstrate that honey affects multiple processes in bacteria, and this is not explained by its major antibacterial components. Honey also uniquely affects bacterial membranes, and this can be exploited for combination therapy with antibiotics that are otherwise ineffective on their own. We argue that honey should be included as part of the current array of wound treatments due to its effective antibacterial activity that does not promote resistance in bacteria.

Manuka honey modulates the release profile of a dHL-60 neutrophil model under anti-inflammatory stimulation

Manuka honey, a wound treatment used to eradicate bacteria, resolve inflammation, and promote wound healing, is a current focus in the tissue engineering community as a tissue template additive. However, Manuka honey's effect on neutrophils during the inflammation-resolving phase has yet to be examined. This study investigates the effect of 0.5% and 3% Manuka honey on the release of cytokines, chemokines, and matrix-degrading enzymes from a dHL-60 neutrophil model in the presence of anti-inflammatory stimuli (TGF-β, IL-4, IL-4 +IL-13). We hypothesized that Manuka honey would reduce the output of pro-inflammatory signals and increase the release of anti-inflammatory signals. The results of this study indicate that 0.5% honey significantly increases the release of CXCL8/IL-8, CCL2/MCP-1, CCL4/MIP-1β, CCL20/MIP-3α, IL-4, IL-1ra, and FGF-13 while reducing Proteinase 3 release in the anti-inflammatory-stimulated models. However, 3% honey significantly increased the release of TNF-α and CXCL8/IL-8 while reducing the release of all other analytes. We replicated a subset of the most notable findings in primary human neutrophils, and the consistent results indicate that the HL-60 data are relevant to the performance of primary cells. These findings demonstrate the variable effects of Manuka honey on the release of cytokines, chemokines, and matrix-degrading enzymes of this model of neutrophil anti-inflammatory activity. This study reinforces the importance of tailoring the concentration of Manuka honey in a wound or tissue template to elicit the desired effects during the inflammation-resolving phase of wound healing. Future in vivo investigation should be undertaken to translate these results to a physiologically-relevant wound environment.

Efficacy of Honey-based Ophthalmic Formulation in Patients with Corneal Ulcer: A Randomized Clinical Trial

AIM

The aim of this study was to evaluate the efficacy of honey-based ophthalmic drop in patients with foreign body induced corneal ulcer.

BACKGROUND

Honey is traditionally used for skin, mucosal and corneal ulcers. Its use is well studied in human skin and mucosal ulcers and animal model of corneal ulcer with promising effects.

METHODS

In this randomized clinical trial, 50 patients with foreign body induced corneal ulcer were allocated to receive 70% sterile honey-based ophthalmic formulation or 0.3% ophthalmic ciprofloxacin, as the standard treatment every 6 hours. All the patients were examined for the size of corneal epithelial defect, corneal infiltration and depth and followed on a daily basis until complete healing. Duration for complete healing was considered as the outcome measure. Smear, culture, antibiogram and minimum inhibition concentration (MIC) tests were performed for honey and ciprofloxacin in all patients.

RESULTS

The average durations of complete healing of corneal epithelial defect in the honey and ciprofloxacin groups were 3.88 ± 3.44 vs. 6.32 ± 3.69days, respectively (p=0.020). No significant difference was observed between two groups regarding an average duration of healing of corneal infiltration (8.12 ±1.94 days vs. 8.64±2.15 days, p=0.375). MIC of honey for pseudomonas aeruginosa was 60%w/w, for E.Coli 40% w/w, and for staphylococcus aureus 30% w/w.

CONCLUSION

Honey based ophthalmic drop can acceleratethe corneal epithelial defect healing in patients with foreign body induced corneal ulcer, compared to ophthalmic ciprofloxacin as a standard treatment. The study was registered in Iranian registry of clinical trial center (IRCT) with registration number IRCT2015020120892N1.

Antibacterial potential of Swiss honeys and characterisation of their bee-derived bioactive compounds

BACKGROUND

Antibacterial activity of honey is not only crucial characteristic in selection of honey for medical usage but also an important honey quality marker. The aim of the study was to characterise the antibacterial potential of 29 honey samples representing the main types of multi-floral blossom and honeydew honeys produced in Switzerland. Antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa was expressed as a minimum inhibitory and bactericidal concentrations (MIC and MBC). Furthermore, the content of bee-derived glucose oxidase (GOX) and its enzymatic product, H₂ O₂ , were also evaluated.

RESULTS

All honey samples successfully met basic defined criteria (moisture and hydroxymethylfurfural (HMF)) tested in this study. Honeydew honeys were the most effective honey samples and generated the highest levels of H₂ O₂ . A strong significant correlation was found between the overall antibacterial activity and the level of H₂ O₂ among all honey samples. Interestingly, the content of GOX in honey samples did not correlate with their antibacterial activity as well as H₂ O₂ production capacity. A weak antibacterial activity was determined in five floral honeys, most likely due to increased enzymatic activity of pollen-derived catalase.

CONCLUSION

This study showed that antibacterial effect of Swiss honey samples is associated mainly with H₂ O₂ . © 2019 Society of Chemical Industry.