Evaluation of antimicrobial activity of Italian honey for wound healing application in veterinary medicine

Comparing the antibacterial and healing properties of medical-grade honey and silver-based wound care products in burns

Burns are a major global healthcare concern, often complicated by the presence of bacteria such as Pseudomonas aeruginosa in the wounds. Silver-based dressings are commonly used in the treatment of burns but can cause skin irritation and delay healing time. Medical-grade honey (MGH) provides an interesting alternative. This study investigated the antimicrobial effects and possible cytotoxicity of L-Mesitran Soft (MGH-gel) and its individual components, Medihoney (Manuka), Flammazine (silver sulphadiazine), and silver nitrate (AgNO3) in an ex vivo human burn wound model. Bacterial survival and wound healing parameters, including re-epithelialization and keratinocyte proliferation were assessed. L-Mesitran, Flammazine, and AgNO3 reduced P. aeruginosa numbers below detection levels. L-Mesitran Soft exhibited a significantly stronger antimicrobial effect compared to Medihoney. The individual components of L-Mesitran contributed significantly to its antibacterial efficacy, thus suggesting synergistic activities. Moreover, L-Mesitran, Flammazine, and AgNO3 slightly inhibited re-epithelialization while Medihoney treatment resulted in a complete lack of re-epithelialization and keratinocyte proliferation. Furthermore, clinical cases illustrated the effectiveness of MGH therapy in infected burns. Overall, L-Mesitran Soft had similar effects as silver-based products on bacterial load and epidermal regeneration, but outperformed Medihoney. Therefore, supplemented MGH could be used as an effective alternative to silver-based dressings for P. aeruginosa-infected burns.

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

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

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.

Chemical Composition, Antioxidant and Antimicrobial Activity of Some Types of Honey from Banat Region, Romania

Honey is a natural product with multiple health benefits. The paper presents the chemical characterization and the antioxidant and antimicrobial potential of ten types of honey (knotweed, linden, wild cherry, acacia, honeydew, oilseed rape, sunflower, phacelia, plain polyflora and hill polyflora) from the Banat region, Romania. We studied the water content, dry matter, impurities, acidity and pH of honey. We also determined the content of reducing sugar, minerals and flavonoids and the total phenolic content. All honey samples analysed showed good nutritional characteristics according to the standard codex for honey. From the analysis of the mineral content of the honey samples, we observed a variability in the macro and microminerals, influenced by the botanical origin, ranging between 0.25% (wild cherry honey) and 0.54% (honeydew). The toxic metals’ (Cd and Pb) levels met the standard for almost all samples analysed except for knotweed. The flavonoid content of the samples ranged from 9.29 mg QE/100 g for wild cherry honey to 263.86 mg QE/100 g for linden honey, and for polyphenols between 177.6 mgGAE/100 g for acacia honey and 1159.3 mgGAE/100 g for honeydew. The best antioxidant capacity was registered in the case of linden honey (79.89%) and honeydew (79.20%) and the weakest in acacia (41.88%) and wild cherries (50.4%). All studied honey samples showed antimicrobial activity, depending on the type of honey, concentration and strain analysed. The novelty of this study is given by the complex approach of the study of honey quality, both from the perspective of chemical attributes and the evaluation of the antimicrobial potential on specific strains in correlation with the botanical and geographical origin of the analyzed area.

The effects of a proprietary Manuka honey and essential oil hydrogel on the healing of acute full-thickness wounds in dogs

OBJECTIVE

To evaluate the effect of a proprietary Manuka honey essential oil hydrogel on the healing of acute, full-thickness wounds in dogs.

STUDY DESIGN

Prospective, controlled, randomized, experimental study.

ANIMALS

Purpose-bred, adult, female beagles (n = 10).

METHODS

Two 2 × 2 cm surgical wounds were created bilaterally on the trunk of each dog; each side was randomized to receive HoneyCure® (HOC) or standard-of-care (CON) dressings. Cranial wounds were for histopathological analysis and the caudal wounds for culture and planimetry. Total and open wound areas were measured with digital image planimetry at 15 time points. From these data, percent contraction and percent epithelialization were calculated. Tissue biopsies were obtained at 7 time points and histologic features scored. Cultures were obtained at 2 time points.

RESULTS

Epithelialization was 11.7, 10.4, and 10.1 percentage points higher in HOC wounds compared to CON wounds at days 16, 18, and 21 respectively. Wound contraction and histological scores did not differ between groups. Cultures were positive in 7/40 (17.5%) wounds, with Staphylococcus pseudintermedius and Staphylococcus epidermidis isolated evenly. There was no difference of infection rate between the two groups; all infections were superficial and did not require treatment.

CONCLUSION

This study did not provide evidence to support the application of HoneyCure® in small, acute wounds in healthy dogs. However, application may be beneficial in the early proliferative stage of wound healing and in wounds that would benefit from early, robust epithelialization.

Medical grade honey: Hope for wounded white rhinos

South Africa is home to some of the world's most endangered wildlife, with the White rhinoceros (Cerathotherium simum) among its most threatened species due to its highly sought-after horn. Since the reproduction number is below the mortality rate, there is a decrease in rhinos year over year, urgently requiring changes and saving the survivors. In this study, the efficacy of medical grade honey (MGH) for wound care in rhinos was investigated. We presented a case series of seven rhinos with wounds of different etiologies, including gunshots and poaching. Four wounds were around the horns and three on the limbs. It was a challenge to take care and follow-up the wounds of these wild animals in their natural habitat. A well-balanced decision between the need of treatment and risk of immobilization is constantly evaluated. In the presented cases, MGH proved a novel tool with minimal intervention and maximal effectiveness. With the severity of the wounds taken into consideration, there was a rapid healing in all cases, while infection resolved when present. MGH creates a moist and anti-inflammatory wound environment, while promoting almost all aspects in the wound healing processes, such as autolytic debridement, angiogenesis and re-epithelialization. The efficacy of MGH has constantly been confirmed in other cases and literature as well. MGH forms a potent therapy for treating wounded rhinos, independent of the severity of the wound. The strong antimicrobial and healing properties make it an easy and versatile product that can be used in all kinds of wounds.

Medical-Grade Honey for the Treatment of Extravasation-Induced Injuries in Preterm Neonates: A Case Series

INTRODUCTION

Preterm neonates often depend on peripheral intravenous administration of nutrition and medication. Since their skin is not fully developed and very vulnerable, extravasation injury is a risk. Medical-grade honey (MGH) possesses antimicrobial activity and stimulates wound healing; although its use in neonatal patients is limited.

CLINICAL FINDINGS

We present a case series of 7 preterm neonates (28-36 weeks of gestation) with extravasation injuries secondary to peripheral intravenous administration of total parental nutrition and medication.

PRIMARY DIAGNOSIS

Extravasation injury following the unintentional leakage of total parenteral nutrition, and medication into the surrounding tissue. Signs of extravasation include local pain, erythema, burning, pruritus, and/or swelling.

INTERVENTIONS

All extravasation injuries were treated with daily cleaning and application of MGH. Some of the cases needed additional surgical intervention or assisted debridement.

OUTCOMES

After treatment, all extravasation injury wounds presented with granulation tissue formation progressed to normal epithelialization and closed in 7 to 67 days (median: 32 days). Upon initial application, peripheral edema and inflammation decreased. When present, necrotic tissue was effectively debrided, slough was removed, and no signs of infection were detected, irrespective of initial wound presentations. Cicatrization was minimal, and the full range of motion was preserved in all cases.

PRACTICE RECOMMENDATIONS

Continuous and thorough assessment of peripheral intravenous line placement for malposition, leaking, and signs of extravasation is needed for fast discovery and prevention of further damage.

CONCLUSION

Medical-grade honey possesses antimicrobial, anti-inflammatory, and antioxidative activity, enhancing wound healing. Medical-grade honey was safe and effective for treating extravasation-induced injuries, independent of location and severity. We recommend MGH for treating extravasation wounds and consideration for other types of wounds.

A Scoping Review of the Evidence for the Medicinal Use of Natural Honey in Animals

Honey has a history of medicinal use that predates written records. In recent decades, there has been renewed interest in the use of honey in human medicine, particularly for the treatment of burns and other wounds. Several recent systematic reviews in the human literature have demonstrated the efficacy of honey in the treatment of a number of conditions, including burns, wounds and oral mucositis. The goal of this scoping review was to describe the nature and extent of the current body of evidence addressing the medicinal use of natural honey and/or its derivatives in animals. Although the focus of this review was the veterinary literature, all animal species except insects and humans were eligible, including animals used for biomedical research. Electronic databases searched were MEDLINE, CAB Abstracts, AGRICOLA, Web of Science Core Collection, and Web of Science SciELO Citation Index. A total of 397 articles reporting 436 primary research studies were included in this review. The majority of the articles were biomedical research articles (n = 350); fewer veterinary research articles were identified (n = 47). Apart from one systematic review, all biomedical studies were challenge trials. Most veterinary studies were case reports/series (n = 23), followed by challenge trials (n = 18) and controlled trials (n = 8). The animal species examined within veterinary articles consisted primarily of dogs, horses, cats and cattle, whereas the majority of biomedical research articles examined rats and mice. Wound healing was the most common indication examined; other indications examined included the prevention or treatment of gastric ulcers, bacterial and parasitic infections, toxic exposures, metabolic conditions (e.g., diabetes) and neoplasia. The majority of interventions consisted of non-medical grade honey (n = 412/436), followed by medical-grade honey (n = 29/436) and derivatives of natural honey (n = 9/436). With much of the current veterinary literature consisting of case reports and case series, high-quality primary veterinary research in the form of controlled trials or challenge trials is needed to advance this field, as well as to provide sound data for evidence-based assessments of the efficacy of honey in clinical veterinary practise.

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.

Synergistic Antimicrobial Activity of Supplemented Medical-Grade Honey against Pseudomonas aeruginosa Biofilm Formation and Eradication

Biofilms hinder wound healing. Medical-grade honey (MGH) is a promising therapy because of its broad-spectrum antimicrobial activity and the lack of risk for resistance. This study investigated the inhibitory and eradicative activity against multidrug-resistant Pseudomonas aeruginosa biofilms by different established MGH-based wound care formulations. Six different natural wound care products (Medihoney, Revamil, Mebo, Melladerm, L-Mesitran Ointment, and L-Mesitran Soft) were tested in vitro. Most of them contain MGH only, whereas some were supplemented. L-Mesitran Soft demonstrated the most potent antimicrobial activity (6.08-log inhibition and 3.18-log eradication). Other formulations ranged between 0.89-log and 4.80-log inhibition and 0.65-log and 1.66-log eradication. Therefore, the contribution of different ingredients of L-Mesitran Soft was investigated in more detail. The activity of the same batch of raw MGH (1.38-log inhibition and 2.35-log eradication), vitamins C and E (0.95-log inhibition and 0.94-log eradication), and all ingredients except MGH (1.69-log inhibition and 0.75-log eradication) clearly support a synergistic activity of components within the L-Mesitran Soft formulation. Several presented clinical cases illustrate its clinical antimicrobial efficacy against Pseudomonas aeruginosa biofilms. In conclusion, MGH is a potent treatment for Pseudomonas biofilms. L-Mesitran Soft has the strongest antimicrobial activity, which is likely due to the synergistic activity mediated by its supplements.

Medical honey for canine nasal intertrigo: A randomized, blinded, placebo-controlled, adaptive clinical trial to support antimicrobial stewardship in veterinary dermatology

Intertrigo is a skin fold dermatitis often requiring recurrent treatment with topical antiseptics or antibiotics, which can select antimicrobial resistance. To minimize this risk, we tested the effectiveness of medical-grade Manuka honey at treating intertrigo as compared to a placebo hydrogel. We additionally characterized the culturable microbial flora of intertrigo and recorded any adverse effect with either treatment. During this randomized, placebo-controlled, double-blinded, adaptive group-sequential trial, the owners washed the affected sites on their dog with water, dried and applied a thin film of either the honey or the placebo product once daily for 21 days. Cytological and lesional composite scores, owner-assessed pruritus, and microbial cultures were assessed prior to treatment and on Day-22. The fixed effects of time, treatment, and animal-related variables on the pruritus and on each composite score, accounting for random dog effect, were estimated separately with generalized linear mixed models for repeated count outcomes (α = 0.05). The null hypothesis of equal treatment effects was rejected at the first interim analysis. The placebo (n = 16 dogs) outperformed the medical honey (n = 13 dogs) at improving both the cytological score (Treatment×Time = -0.35±0.17; P = 0.04) and clinical score (Treatment×Time = -0.28±0.13; P = 0.04). A microbial burden score higher than 4 increased the severity of the cytological score (dichotomous score: 0.29±0.11; P = 0.01), which in turn increased the severity of the clinical score and pruritus score. For every unit increase in cytological score, the linear predictor of clinical score increased by 0.042±0.019 (P = 0.03), and the one of pruritus score increased by 0.12±0.05 (P = 0.01). However, medical honey outperformed the placebo at alleviating the dog's owner-assessed pruritus after statistically controlling for masking effects (Time = -0.94±0.24; P = 0.002; and Treatment×Time = 0.80±0.36; P = 0.04). Unilateral tests of the least-square mean estimates revealed that honey only significantly improved the pruritus (Hommel-adjusted P = 0.003), while the placebo only improved the cytological and clinical scores (Hommel-adjusted P = 0.01 and 0.002, respectively). Taken together, these results question the value of Manuka honey at treating nasal intertrigo in dogs.

Data Mining a Medieval Medical Text Reveals Patterns in Ingredient Choice That Reflect Biological Activity against Infectious Agents

The pharmacopeia used by physicians and laypeople in medieval Europe has largely been dismissed as placebo or superstition. While we now recognize that some of the materia medica used by medieval physicians could have had useful biological properties, research in this area is limited by the labor-intensive process of searching and interpreting historical medical texts. Here, we demonstrate the potential power of turning medieval medical texts into contextualized electronic databases amenable to exploration by the use of an algorithm. We used established methodologies from network science to reveal patterns in ingredient selection and usage in a key text, the 15th-century Lylye of Medicynes, focusing on remedies to treat symptoms of microbial infection. In providing a worked example of data-driven textual analysis, we demonstrate the potential of this approach to encourage interdisciplinary collaboration and to shine a new light on the ethnopharmacology of historical medical texts.IMPORTANCE We used established methodologies from network science to identify patterns in medicinal ingredient combinations in a key medieval text, the 15th-century Lylye of Medicynes, focusing on recipes for topical treatments for symptoms of microbial infection. We conducted experiments screening the antimicrobial activity of selected ingredients. These experiments revealed interesting examples of ingredients that potentiated or interfered with each other's activity and that would be useful bases for future, more detailed experiments. Our results highlight (i) the potential to use methodologies from network science to analyze medieval data sets and detect patterns of ingredient combination, (ii) the potential of interdisciplinary collaboration to reveal different aspects of the ethnopharmacology of historical medical texts, and (iii) the potential development of novel therapeutics inspired by premodern remedies in a time of increased need for new antibiotics.

In vitro antimicrobial efficacy of two medical grade honey formulations against common high-risk meticillin-resistant staphylococci and Pseudomonas spp. pathogens

BACKGROUND

Antimicrobial resistance is a problem in human and animal healthcare. Honey may be used for its wound healing properties and antimicrobial effects.

OBJECTIVE

To investigate the antimicrobial activity of two commercially available medical grade honeys (MGHs) against Staphylococcus spp. and Pseudomonas spp. isolates.

METHODS AND MATERIALS

Two formulations, MGH1 (40% w/v honey) and MGH2 (80% w/v Manuka honey), were tested in vitro for minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) against 11 Staphylococcus and 11 Pseudomonas isolates at low [1.5 × 10⁴  colony forming units (cfu)/well] and high (1.5 × 10⁶  cfu/well) concentrations of inoculum, representing systemic and cutaneous bacterial loads during infection, respectively.

RESULTS

MGH2 showed a lower MIC against staphylococci than MGH1, although this was not statistically significant. MGH1 had stronger bactericidal effects against staphylococci than MGH2, although this effect was statistically significant only at the higher bacterial concentration (P < 0.01). For Pseudomonas spp., MGH1 had significantly higher antimicrobial activity (both MIC and MBC) than MGH2 against all isolates tested and at both bacterial concentrations (P < 0.05).

CONCLUSIONS AND CLINICAL IMPORTANCE

Both MGHs were effective in vitro against common cutaneous pathogens including meticillin-resistant staphylococci and Pseudomonas species. The higher efficacy of the MGH1 formulation against Pseudomonas and its consistent effects against staphylococci, while containing only half of the amount of honey compared to MGH2, invites further investigation of the mechanisms and clinical applications of MGH1.

Single and joint antibacterial activity of aqueous garlic extract and Manuka honey on extended-spectrum beta-lactamase-producing Escherichia coli

Background

Multidrug resistance and recent technological advances have renewed interest in natural product drug discovery from ancient remedies such as Allium sativum (garlic) and honey. This study assessed antibacterial activity of aqueous garlic extract (AGE) and Manuka honey on extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli.

Methods

Thirty clinical isolates of E. coli were collected and screened for ESBL production by double-disc synergy test. Single and joint antibacterial activity of AGE and Manuka honey against ESBL-producing E. coli were determined by agar well dilution and checkerboard methods, respectively.

Results

Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AGE ranged from 125-250 mg/mL and 250-500 mg/mL, respectively. MIC and MBC of Manuka honey ranged from 12.5-25% v/v and 25-50% v/v, respectively. The combination of AGE and Manuka honey exhibited different effects on selected ESBL-producing E. coli; synergism (1/4H+1/16G), additive (1/8H+1/2G, 1/2H+1/16G), indifference (1/16H+MICG, MICH+1/16G, 2MICH+1/32G) and antagonism (4MICH+1/32G).

Conclusions

Manuka honey exhibited greater antibacterial activity against ESBL-producing E. coli than AGE. Antibacterial activity, and the interaction of AGE and Manuka honey against ESBL-producing E. coli are dependent on their concentration. Studies assessing antibacterial activity of potent phytochemicals in AGE and honey would provide insights to mechanisms of interaction for development of new drug leads.

Phytochemicals-mediated production of hydrogen peroxide is crucial for high antibacterial activity of honeydew honey

Honeydew honey is increasingly valued due to its pronounced antibacterial potential; however, the underlying mechanism and compounds responsible for the strong antibacterial activity of honeydew honey are still unknown. The aim of this study was to investigate the inhibition of bacterial growth of 23 honeydew honey samples. Activity of bee-derived glucose oxidase (GOX) enzyme, the content of defensin-1 (Def-1) and hydrogen peroxide (H₂O₂), and total polyphenol content were determined in the 23 honey samples. Our results demonstrated that antibacterial activity of honeydew honey was equivalent to medical-grade manuka and kanuka honey and was abolished by catalase. Although H₂O₂ is an important factor in the inhibition of bacterial growth, polyphenolic compounds and their interaction with H₂O₂ are the key factors responsible for high antibacterial activity of honeydew honey. In addition, our results indicated that the antibacterial activity of honeydew honey is not dependent on GOX-mediated production of H₂O₂ or the presence of Def-1.

A new, easy-to-make pectin-honey hydrogel enhances wound healing in rats

BACKGROUND

Honey, alone or in combination, has been used for wound healing since ancient times and has reemerged as a topic of interest in the last decade. Pectin has recently been investigated for its use in various biomedical applications such as drug delivery, skin protection, and scaffolding for cells. The aim of the present study was to develop and evaluate a pectin-honey hydrogel (PHH) as a wound healing membrane and to compare this dressing to liquid honey.

METHODS

Thirty-six adult male Sprague-Dawley rats were anesthetized and a 2 × 2 cm excisional wound was created on the dorsum. Animals were randomly assigned to four groups (PHH, LH, Pec, and C): in the PHH group, the pectin-honey hydrogel was applied under a bandage on the wound; in the LH group, liquid Manuka honey was applied; in the Pec group, pectin hydrogel was applied (Pec); and in the C group, only bandage was applied to the wound. Images of the wound were taken at defined time points, and the wound area reduction rate was calculated and compared between groups.

RESULTS

The wound area reduction rate was faster in the PHH, LH, and Pec groups compared to the control group and was significantly faster in the PHH group. Surprisingly, the Pec group exhibited faster wound healing than the LH group, but this effect was not statistically significant.

CONCLUSION

This is the first study using pectin in combination with honey to produce biomedical hydrogels for wound treatment. The results indicate that the use of PHH is effective for promoting and accelerating wound healing.