Effects Of Dexamethasone On The Biological Characteristics Of Trichophyton Rubrum

Objective: 1. To observe the effects of dexamethasone to the phenotype of Trichophyton rubrum such as the growth, tippled pigment on the colony and the antifungal susceptibility to terbinafine. 2. To analyse if the dexamethasone could change the genetype of Trichophyton rubrum.Methods: 1. The strains of Trichophyton rubrum were cultured on sabouraud' agar, which included different concentration of dexamethasone. The diameter of the colony was recorded everyday, and a growth curve was drawn based on growth time and avervage diameter of the colony. Furthermore, the optical density (OD) and minimum inhibitory concentration (MIC) were detected in Trichophyton rubrum strains by spectrophotometer and NCCLS 38-A microdilution method respectively. 2. The total DNAs of Trichophyton rubrum were extracted by using mini-preparation, then the ITS region of rDNA were amplified by using the fungi-universal primers ITS1, ITS4. Moreover, two novel tandem repeat subelements (TRSs), TRS-1 and TRS-2, located in the Trichophyton rubrum rDNA nontranscribed spacer (NTS), were amplified from Trichophyton rubrum.Results: 1. When the concentrations of dexamethasone are 0.05%, 0.1% and 0.2%, there is no significant difference in the growth of Trichophyton rubrum between the dexamethasone-absent group and the dexamethasone-present group. However, there is significant difference in the growth of Trichophyton rubrum when the concentrations of dexamethasone are 0.4% and 0.8%. When the concentration of dexamethasone is 1.0%, there isn't almost growth about the colony of Trichophyton rubrum. 2. The geometry mean of OD and MIC of dexamethasone-absent group are...