The Electron Microscopic Study of Normal Structures and Post-exposed Structural Changes to Antifungal Agents in Dermatophytes / 대한피부과학회지

ABSTRACT

BACKGROUND: Dermatophytes are common pathogens of cutaneous fungal infections. Although antifungal agents have been used widely on the dermatophyte infections, the ultrastructural changes of dermatophytes caused by drugs have not been described in detail elsewhere. OBJECTIVE: We compared the ultrastructures of common dermatophytes and their changes after exposure to three antifungal agents, itraconazole, terbinafine and creosote, to inform the effectiveness of drugs on ultrastructures of dermatophytes. METHODS: Two strains of Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis were cultivated on Sabouraud dextrose agar(SDA). Conventional electron microscopic specimen preparation was performed and examined by transmission electron microscope. After 24-hour exposure of each strain with 100 microgram/ml of itraconazole, 50 microgram/ml of terbinafine and 100 microgram/ml of creosote on SDA, the ultrastructural changes of their hyphae were investigated. RESULTS: The ultrastructural findings of each dermatophyte were similar. Tube-like hyphae and simple septal pores with Woronin bodies were typical findings. There were one or more than one nuclei and various intracellular organelles between the septa. A greater density of cytoplasm and organelles could be seen in the younger hyphae. Microscopically, destruction of the cell wall, edema and necrosis of intracellular organelles, and an increase in the number and size of vacuoles could be seen after drug exposure. After exposure to itraconazole and terbinafine, edema and necrosis of the cell wall and membranous structures were found, as well as, membranous bodies that represented destructive changes in the cell wall. The hyphae exposed to terbinafine showed various sized of lipid globule in the cytoplasm. Creosote exposure lead to a more non-specific and severer necrotic pattern of the intracellular structures. CONCLUSION: There seemed to be similar features of normal hyphae of dermatophytes. Antifungal agents, itraconazole and terbinafine, affected membranous structures of dermatophytes, whereas creosote acted on internal structures by a nonspecific direct toxic effect. Transmission electron microscope was a useful tool to investigate the changes of internal ultrastructure of dermatophyte by antifungal agents.