Background: Dermatophytes are usually identified on the basis of macroscopic characteristics and microscopic examination of the cultures. Identification of dermatophytes often remains difficult or uncertain because there are variations from one isolate to another and overlapping characteristics between species. Objective: To identify dermatophyte species producing numerous microconidia and resembling Trichophyton mentagrophytes by DNA sequence analysis. Methods: The complete ITS1 + 5.6s + ITS2 rDNA region of various dermatophytes isolated in culture was amplified by PCR and sequenced. Results: Nine isolates of a fast-growing dermatophyte species were identified as Arthroderma benhamiae by DNA sequencing. Retrospective investigations revealed that the isolates were from 8 children and 1 adult suffering from inflammatory dermatophytosis. Eight of the 9 patients had had previous contact with rodents, mostly guinea pigs. Conclusion: It is the first time that A. benhamiae is reported in Switzerland. In cases of dermatophytosis attributed to A. benhamiae, a rodent is the most likely cause of infection.

Background: Tinea capitis is a worldwide-spread infection of the scalp caused by dermatophytes and is predominantly seen in children. The clinical manifestations range from mild scaling lesions to widespread alopecia or highly inflammatory suppurating lesions. Terbinafine and itraconazole seem to be promising therapies with shorter treatment durations than griseofulvin. Objective: The objective of the present study was to test the sensitivity of different species of dermatophytes towards terbinafine and itraconazole, and to compare the results with a retrospective study on 35 immunocompetent patients with tinea capitis who were treated with terbinafine (Lamisil^®). Methods: Minimal inhibitory concentrations (MIC) were measured with an agar dilution method. Results: Each tested species of dermatophyte was sensitive to terbinafine and itraconazole at different concentration ranges. The MIC for terbinafine ranged from 0.005 to 0.5 μg/ml and for itraconazole from 40 to 80 μg/ml. Microsporum canis was the dermatophyte least sensitive to terbinafine. Our retrospective study showed that the cure rate was excellent for Trichophyton violaceum and T. soudanense, variable for T. mentagrophytes and poor for M. canis and M. langeronii. Conclusions: (i) Regarding the results of susceptibility tests obtained with species involved in tinea capitis, clinical efficacy is not related to MIC measured in vitro; (ii) identification of the isolated dermatophyte from tinea capitis seems to be important for choosing the appropriate treatment.