Micafungin (FK463) is a new water-soluble antifungal of the candin family that inhibits the synthesis of 1,3-beta-glucan, an essential component of the cell walls of medically important fungi. The effect of the drug on the morphology of growing hyphae of Aspergillus fumigatus in a liquid medium was examined by scanning and transmission electron microscopy. When cultures were grown with the drug in a concentration range between from 1 to 100 ng/ml, hyphal growth was markedly inhibited and several morphological changes were observed. They were characterized by formation of short branching, deformation of hyphae, and swelling or bursting of the hyphal tip. In thin sections abnormal septum formation, accumulation of electron dense vesicular structures within the space between the cell wall and cytoplasmic membrane, and degeneration of cytoplasmic membrane and intracellular organelles were visible. The morphological changes increased in severity with increasing drug concentrations and were most prominent after 24 hours of exposure to the drug. These results suggest that morphological changes caused by micafungin lead to lysis and death of fungal hyphae.
Full conference title:
The 15 th Congress of the International Society for Human and Animal Mycology
- ISHAM 15th (2003)