Showing papers by "Yayoi Nishiyama published in 2000"

Inhibitory effect of essential oils on apical growth of Aspergillus fumigatus by vapour contact.

Abstract: The inhibitory effect of seven essential oils on the apical growth of hyphae of Aspergillus fumigatus was studied using a bio cell tracer by vapour contact in a sealed vessel. Based on the inhibitory pattern, these essential oils were classified into three groups. The first group, composed of citron, lavender and tea tree oils, stopped the apical growth in a loading dose of 63 micrograms ml-1 air, but allowed the regrowth of the hyphae after removal of the vapour, indicating fungistatic action. The second group, consisting of perilla and lemon-grass oils, stopped the apical growth in a loading dose of 6.3 micrograms ml-1 air, and did not allow the regrowth after gaseous contact at 63 micrograms ml-1 air, indicative of fungicidal action. The third group, consisting of cinnamon bark and thyme oils, retarded the growth in a dose of 6.3 micrograms ml-1 air, stopped it in a dose of 63 micrograms ml-1 air, and incompletely suppressed regrowth of the hyphae. Gas chromatographic analysis revealed that vapours of essential oils were absorbed on fungal mycelia and agar medium most abundantly by the first group, followed by the second and third groups, reflecting the volatility of the respective groups. Suppression of the apical growth by vapour contact was ascribed to the direct deposition of essential oils on fungal mycelia, together with an indirect effect via the agar medium absorbed.

In vitro antifungal activity of a novel lipopeptide antifungal agent, FK463, against various fungal pathogens.

Abstract: The antifungal activities of FK463 against various pathogenic fungi were tested by standard broth microdilution methods, and compared with the activities of five currently available antifungal agents; viz., fluconazole (FLCZ), itraconazole, miconazole, amphotericin B and flucytosine. Fourteen clinical isolates of Candida albicans categorized as FLCZ susceptible, FLCZ susceptible-dose dependent and FLCZ resistant were similarly susceptible to FK463 with geometric (GM) MIC values of 0.010, 0.011 and 0.015 microg/ml, respectively. All of 17 clinical isolates of Aspergillus fumigatus were inhibited by FK463 at 0.0078 microg/ml or lower concentrations. The antifungal activity of FK463 against a wider range of medically important yeasts and filamentous fungi were studied using stock fungal strains. While Cryptococcus, Trichosporon, Fusarium, Pseudallescheria and Alternaria species or zygomycetes were scarcely or not inhibited by 16 microg/ml of FK463, two Candida species (C. albicans, C. glabrata), as well as all species of Aspergillus, Paecilomyces and Penicillium, were highly susceptible with GM-MICs of < or = 0.008 microg/ml. The other fungal species including several non-albicans Candida were less susceptible with GM-MICs ranging between 0.016 and 2 microg/ml. MICs of the reference drugs were within the range thus previously reported. These results suggest that FK463 be of use in the treatment of serious fungal infections.