Background: Antifungal activity of micafungin (MICA) against Aspergillus has been supposed, however, the standard antifungal susceptibility test in vitro was not still established because determining the MIC of the echinocandins for Aspergillus is not possible. Although, instead of MIC, minimum effective concentration (MEC) has been suggested, its usefulness to determine antifungal activity was unknown. This study focused on the evaluation of fungicidal activity of MICA evaluated with transmission electron microscope (TEM). Methods: We used Aspergillus niger TIMM2921 and A. fumigatus isolated from a patient with invasive pulmonary aspergillosis. The fungal inocula and antifungal agents were prepared in accordance with M38-A recommendation of CLSI. MEC of MICA and MICs of 5 other antifungal agents (amphotericin-B, miconazole, fluconazole, itraconazole, and voriconazole) were determined. Based on the morphological changes under TEM, the concentrations with prominent fungicidal features (Fungicidal Activity: AC) were determined in each agent. Results: The MEC, MIC and AC values, were determined (Fig). In case of MICA concentration > 1 μg/ml, AC (disruption of the cell wall, expansion of endoplasmic reticula) were more prominent, whereas MECs were 8804;0.015μg/ml. In other agents, MIC and AC values were distributed within 0.5-2.0 folds. Conclusions: These findings suggest that MICA shows high concentrations to kill Aspergillus, although MEC were low. Observation with electron microscope is useful to evaluate the fungicidal activities.
Full conference title:
47th Interscience Conference on Antimicrobial agents and Chemotherapy
- ICAAC 47th