Antimicrobial Properties of Honey

Abstract

Background: Many countries and cultures worldwide use honey as a medicinal remedy to treat a variety of burns and wound infections. Over the years, research has provided evidence of the increasing antimicrobial properties exerted from specific honeys. A number of factors such as pH, colour, polyphenol and antioxidant levels, % sugar content and H2O2 content are all believed to contribute to these antimicrobial properties, as well as the floral and geographical origins of the honey. As such, the most widely researched honey, Manuka honey, has been highlighted as a prime example of a honey that exerts powerful antimicrobial properties in inhibiting the growth of infectious bacteria. Aims and Objectives: In the present study, the aim was to investigate he antimicrobial properties of a selection of honeys against wound infecting bacteria Staphylococcus aureus. The biochemical composition would also be investigated alongside the antibacterial properties of honey in combination with antibiotics. Finally, the antibacterial properties of a recently discovered diacid isolate from honey would also be explored. Methods: The antimicrobial properties of the honeys were investigated after 24 and 48 hours incubation through the use of a serial broth dilution assay. Viable counts were then made. The compositional analysis of honey was carried out using the appropriate measures - pH strips for pH, Ciocalteau and Folin method for polyphenol content, FRAP assay for antioxidant capacity and Refractometer for sugar content. A qualitative analysis was carried out for the levels of H2O2 produced. Results: Initial screening identified Chestnut and Kashmir honey as the most antimicrobial out of the six samples tested. Manuka honey remained in the study as a positive control. Significant reduction in bacteria growth was observed with the three honeys after both 24 and 48 hours incubation (P<0.0001) compared to a TSB growth control. Chestnut honey was identified as the strongest honey out of the three and it was included in further investigation compared to a negative sugar control. After 24 hours and 48 hours incubation, Chestnut honey caused significant decrease in bacteria growth compared to the sugar control (P<0.05). Conclusion: Many factors contribute to the antimicrobial properties of honey and the importance of all factors has been indicated throughout this study. A synergistic relationship is suggested between honey and antibiotics and the inhibitory action of the diacid isolate is also apparent. Further investigation can be carried out on different honeys against different strains of bacteria. The opportunity for further investigation into the action of antibiotics with honey and the action of the diacid isolate is also open. Keywords: Honey, bacteria, antioxidants, polyphenols, antimicrobial, growth inhibition.