Abstract: Objective To compare the in vitro antifungal susceptibility of germinated, ungerminated conidia and hyphae of some filamentous fungi and dermatophytes to terbinafine. Methods The MICs of terbinafine for 7 isolates of Aspergillus spp., 5 isolates of dematiaceous fungi, 4 isolates of Pseudallescheria boydii, 4 isolates of Scedosporium apiospermum and 5 isolates of dermatophytes were examined using the NCCLS M38-P microdilution method. The isolates were inoculated in three different forms, ungerminated conidia, germinated conidia and hyphae respectively, in the tests. Results The MICs of terbinafine for the isolates of Aspergillus spp., dematiaceous fungi, Pseudallescheria boydii, Scedosporium apiospermum, and dermatophytes were ≤0.03~0.5 μg/mL, ≤0.03~0.06 μg/mL, >16 μg/mL, >16 μg/mL, and ≤0.03 μg/mL, respectively. The MICs did not show significant differences among the ungerminated conidia and the germinated conidia for all the isolates tested except A.versicolor and Phialophora verrucosa. Conclusions Terbinafine is effective against the isolates of Aspergillus spp., dematiaceous fungi and dermatophytes in vitro except Pseudallescheria boydii and Scedosporium apiospermum. The MIC of terbinafine obtained with ungerminated conidia may reflect the antifungal activity of terbinafine against germinated conidia and hyphae of some filamentous fungi in vitro.

Key words: Antibiotics, antifungal, Microbial sensitivity tests, Fungi, Hyphae, Spores, fungal