Antifungal activity of Origanum vulgare essential oil against Malassezia pachydermatis

The aim of this study was to evaluate the in vitro antifungal activity of essential oil of Origanum vulgare against clinical isolates of Malassezia pachydermatis. The dried leaves of O. vulgare were purchased from a commercial distributor with certified quality and origin and referred for essential oil extraction and chromatography. The technique for in vitro testing was microdilution (CLSI M27A3) with modifications to phytochemicals and M. pachydermatis. The essential oil of O. vulgare was tested at concentrations from 28 to 0.87mg/mL in Sabouraud broth diluted with 1% of tween 80. All isolates were tested in duplicate. In the chromatographic analysis of the essential oil 12 compounds were identified, and thymol, alpha-terpinene, 4-terpineol were the major compounds. The MIC and the MFC of the 42 isolates of M. pachydermatis ranged from <= 0.87 to 7mg/mL with MIC50 and MIC90 values of 1.18 and 3.28 mg/mL, respectively. With this study it was concluded that M. pachydermatis is sensible to O. vulgare essential oil even at low concentrations. Thus, the essential oil of O. vulgare is presented as bioprospecting in the promising new drugs for the treatment of otitis and dermatitis in small animal clinic.