白癬菌に対する木酢液の発育抑制･殺菌作用

足白癬は糖尿病患者で合併しやすく,高齢者にも多発する｡近年,白癬菌に対する木酢液の抗菌作用が知られており,この最適有効濃度を明らかにするため本研究を企画した｡白癬菌はTrichophyton mentagrophytesとTrichophyton rubrumの2菌種を用い,木酢液は市販品を用いた｡発育抑制テストは終濃度2,3,4,5%の木酢液を含んだ寒天平板希釈法で行った｡殺菌テストは2.5,5,10%溶液を胞子と接触後,寒天平板培地に接種し,菌の発育の有無を観察した｡発育抑制作用は,両菌種とも3%以上で7日培養後の菌糸の発育は見られなかった｡殺菌作用は, T. mentagrophytesでは10%,5%においては6時間接触で,2.5%においては24時間接触で菌糸の発育が見られず, T. rubrumでは,10%以上においては24時間接触で,5%においては48時間接触で菌糸の発育が見られなかった｡足浴等の看護ケアに木酢液を応用するためには,今後より短時間の接触で効果が得られる方法の検討が必要である｡

The Mokusaku-Eki is a kind of pyroligneous acid and a dark brown colored solution which obtained from the charcoal burner of Quercus spp. woods as a by-product. In Japan, the antifungal effects of this solution are well known in public. However, it is not clear that minimal inhibitory concentration (MIC) of Mokusaku-Eki against Trichophyton spp. In this study, we examined their antifungal activities in view of MIC and germicidal effect. To examine MIC of Mokusaku-Eki against Trichophyton spp, agar, dilution assay were used. Sabouraud agar plates containing 2%, 3%, 4%, or 5% of Mokusaku-Eki were prepared. Then the spores of T. mentagrophytes and T. rubrum inoculated onto each agar plate respectively and incubate the plates at 30℃. The growth of T. mentagrophytes and T. rubrum were completely inhibited on the agar plates contained more than 3% Mokusaku-Eki. Furthermore, we investigated the fungicidal effect of Mokusaku-Eki against these fungus. We exposed the spores of T. mentagrophytes and T. rubrum respectively to 2.5%, 4% or 10% Mokusaku-Eki for 20 min, 1 hr, 6 hr, 24 hr, and 48 hr, and then inoculated them onto Sabouraud agar plates. Exposures of the spores to 5% of the Mokusaku-Eki for 24 hr and 48 hr completely killed them and we could show that Mokusaku-Eki have also germicidation activity against both T. mentagrophytes and T. rubrum.