Abstract
Specimens which are positive on microscopy sometimes fail to grow on culture, which may make evaluation of the efficacy of an antifungal drug difficult. A new method for evaluating the viability of fungal elements using neutral red staining in skin scales indicates that this discrepancy is mainly explained by the fact that some of the fungal elements are non-viable. The antifungal effect of drugs can be evaluated by this staining in vitro. The viability of dermatophytes was evaluated by the method in skin scales taken from tinea patients treated with antifungal drugs. The results showed that discrepancy between the positive neutral red stain rate and the positive fungal element rate was remarkable at the end of follow-up. These findings indicate that the efficacy of antifungal drugs should not be evaluated by the existence of fungal elements in scales using KOH direct microscopic examination alone, but should be evaluated by their viability. In this respect, neutral red staining is a useful and easily applicable method for evaluation of the efficacy of antifungal drugs clinically.
