A survey of non-manuka New Zealand honeys for antibacterial and antifungal activities
N Brady, P Molan and L Bang
To assess the variation in antibacterial and antifungal activity of non-manuka honeys, a study was undertaken using 179 unifloral, unpasteurized honey samples obtained from commercial beekeepers throughout New Zealand. The honeys were tested against Staphylococcus aureus and Candida albicans, Escherichia coli and the dermatophyte Trichophyton mentagrophytes using agar well diffusion, measurement of minimum inhibitory concentration and modified agar well diffusion methods, respectively. Of the 179 non-manuka honey samples assessed, none showed non-peroxide or anti-yeast antimicrobial activities. By contrast, 50% of the samples tested showed antibacterial activity against S. aureus, with activity ranging from 5.0-27.9% phenol equivalent. Approximately 30% of the samples tested showed antibacterial activity against E. coli; however honey concentrations required for inhibition were, with one exception, in excess of 19%. Similarly, 35% of samples showed antifungal activity although the levels of activity measured were low.