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The unusual antibacterial activity of medical-grade Leptospermum honey: antibacterial spectrum, resistance and
S E Blair1, N N Cokcetin, E J Harry
1School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW, Australia.
Abstract:
There is an urgent need for new, effective agents in topical wound care, and selected honeys show potential in this regard. Using a medical-grade honey, eight species of problematic wound pathogens, including those with high levels of innate or acquired antibiotic resistance, were killed by 4.0-14.8% honey, which is a concentration that can be maintained in the wound environment. Resistance to honey could not be induced under conditions that rapidly induced resistance to antibiotics. Escherichia coli macroarrays were used to determine the response of bacterial cells to a sub-lethal dose of honey. The pattern of gene expression differed to that reported for other antimicrobial agents, indicating that honey acts in a unique and multifactorial way; 78 (2%) genes were upregulated and 46 (1%) genes were downregulated more than two-fold upon exposure to the medical-grade honey. Most of the upregulated genes clustered into distinct functional regulatory groups, with many involved in stress responses, and the majority of downregulated genes encoded for products involved in protein synthesis. Taken together, these data indicate that honey is an effective topical antimicrobial agent that could help reduce some of the current pressures that are promoting antibiotic resistance.
Insights
Medical-grade honey effectively kills antibiotic-resistant wound pathogens at concentrations achievable in wounds. Unlike antibiotics, bacterial resistance to honey could not be induced, suggesting a unique mechanism of action.
Area of Science:
- Microbiology
- Wound Care
- Antimicrobial Agents
Background:
- There is a critical need for novel topical wound care agents.
- Selected honeys demonstrate potential as effective antimicrobials.
- Antibiotic resistance in wound pathogens poses a significant clinical challenge.
Purpose of the Study:
- To evaluate the efficacy of a medical-grade honey against problematic wound pathogens.
- To investigate the potential for developing resistance to honey compared to antibiotics.
- To elucidate the mechanism of action of honey at a molecular level using gene expression analysis.
Main Methods:
- Testing the antimicrobial activity of a medical-grade honey against eight wound pathogen species.
- Attempting to induce resistance to honey and antibiotics in Escherichia coli.
- Utilizing Escherichia coli macroarrays to analyze gene expression changes in response to sub-lethal honey exposure.
Main Results:
- Honey concentrations of 4.0-14.8% were effective in killing tested wound pathogens, including antibiotic-resistant strains.
- Resistance to honey could not be induced under conditions that rapidly induced antibiotic resistance.
- Honey exposure resulted in differential gene expression in E. coli, with upregulated genes involved in stress responses and downregulated genes related to protein synthesis, indicating a unique multifactorial mechanism.
Conclusions:
- Medical-grade honey is a potent topical antimicrobial agent against challenging wound pathogens.
- Honey's unique mechanism of action and lack of induced resistance suggest its value in combating antibiotic resistance.
- Honey represents a promising therapeutic option for topical wound care, potentially alleviating pressure on antibiotic use.
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