The growing prevalence of bacterial antibiotic resistance has led to a rediscovery of the antimicrobial properties of honey. This study investigated the antibacterial activity in aerobic and anaerobic conditions, the effect on bacterial antibiotic sensitivity, and the composition of four medical-grade honeys Medihoney®, Comvita® Antibacterial Wound Gel™, Revamil® gel, and Surgihoney™RO®.
A broth assay was used to assess the antibacterial activity of the honeys against Staphylococcus aureus and Pseudomonas aeruginosa in aerobic and anaerobic conditions. A disk diffusion test was used to investigate the effect of exposure to a subinhibitory concentration of the honeys to the sensitivity of bacteria to a range of antibiotics. The composition of each honey was characterised by measuring: sugar content, pH, hydrogen peroxide activity, total polyphenolic content and antioxidant capacity.
The honeys differed widely in antibacterial activity. Medihoney® was the most effective reducing the growth of both bacteria to < 1 compared to 9 log10 cfu/mL in the growth controls at all tested concentrations. Revamil® gel was the least active of the honeys only having a negligible effect on bacterial growth at the 25% honey concentration. All honeys were equally or more active in anaerobic conditions than in aerobic conditions. The polyphenolic content may influence the activity of honey. Various honey-antibiotic combinations were identified that enhanced antibiotic sensitivity in bacteria. More research is needed to clarify the role of polyphenols in honey activity and further explore the potential synergies between the honeys and antibiotics.
Honey, Antibacterial, Aerobic, Anaerobic, Antibiotic sensitivity, Compositional analysis.