Purpose: The purpose of the current study was to evaluate antimicrobial properties of 42 Florida honeys from different floral sources and geographical locations in their ability to inhibit growth of Staphylococcus aureus compared to commercially available Manuka honey and phenol standards.
Methods: The agar well diffusion method was used, and dilutions (50%) with deionized water (DI) or buffered peptone water (BPW), as well as treatment with catalase or autoclaving (to eliminate peroxide-based activity), were evaluated.
Results: Manuka honey antimicrobial activity was influenced by diluent, with inhibition zones of 8.7 ± 0.3 mm and 14.4 ± 0.7mm, for DI water (pH 4.18) and BPW (pH 5.82), respectively. Some Florida honeys (16/42) showed no inhibition, while 21/42 had activity equal to or superior compared to Manuka, with the rest showed less activity compared to Manuka control. Ten Florida honeys showed an average inhibition zone above 18 mm with standard deviations not exceeding ± 0.9 mm. Antimicrobial activity of Florida honeys was completely diminished after addition of catalase. Similarly, autoclaving reduced antimicrobial activity of all Florida honeys.
Significance: To summarize, we showed that significant fraction of Florida honeys possessed antistaphylococcal activity similar to or exceeding activity of commercially available Manuka honey, though the results of the catalase addition and autoclaving suggest the activity was possibly solely related to the presence of glucose oxidase.