The Sensitivity of Dermatophytes to the Antimicrobial Activity of Manuka Honey and Other Honey

Abstract

Honey has been reported to have antifungal activity and so was tested against clinical isolates of the common dermatophyte species which cause tineas in man. A honey with an average level of hydrogen peroxide, and a manuka (Leptospermum scoparium J. R. and G. Forst, family Myrtaceae) honey with an average level of non-peroxide antibacterial activity were used. An agar well diffusion assay was used, the contents of the wells being replaced with freshly prepared honey solutions at 24-h intervals over the 3–4 days of incubation. The lowest concentrations (% v/v, in steps of 5%) of manuka honey with catalase added to remove hydrogen peroxide, and of the other honey (without catalase) showed that inhibition of growth around the wells were, respectively, Epidermophyton floccosum 25%, 10%; Microsporum canis 25%, 15%; Microsporum gypseum 55%, 20%; Trichophyton mentagrophytes var. interdigitale 45%, 15%; Trichophyton mentagrophytes var. mentagrophytes 25%, 15%; Trichophyton rubrum 20%, 5% and Trichophyton tonsurans 25%, 20%. No inhibitory activity was detected with the other honey at 50% (v/v) with catalase added. The results of this investigation show that the common dermatophytes are sensitive to the antimicrobial activity of honey, indicating that clinical evaluation of honey in the treatment of tineas is warranted. This would determine whether the hydrogen peroxide or the non-peroxide antifungal agent diffuses better into the skin.