Effectiveness of essential oils against Malassezia spp.: comparison of two in vitro tests.

ABSTRACT Objective of the study: The aim of this work was to compare two in vitro methods to evaluate the activity of some essential oils on Malassezia spp. Material and methods: Twenty-three essential oils were tested toward 12 strains of Malassezia spp. (8 M. pachydermatis and 4 Malassezia lipid dependent strains) from different sources. A microdilution method, inspired to the document of the Clinical Laboratory Standard Institute CLSI M38-A, was performed using mDixon broth as medium. Parallel, a disk diffusion method in Petri dishes containing mDixon agar was carried out. Results: The effect of the essential oils tested was highly variable depending to the oil tested (Cymbopogon flexuosus, Origanum vulgare, Thymus vulgaris, Satureja montana and Cinnamomum verum \u2013 cortex were the most effective) and the different Malassezia strains. No statistically significant correlation was found between micro dilution test and the disk diffusion test