Tinea imbricata and tinea pseudoimbricata are variant types of tinea corporis characterized by annual-ring-shaped erythema. Although the skin lesions manifest similar symptoms, these two diseases are classified based on causative fungi. The former is caused by Trichophyton concentricum, an anthropophilic dermatophyte, and the latter is caused by dermatophytes other than T. concentricum, commonly zoophilic fungi such as Trichophyton mentagrophytes complex. Here, we report a 27-year-old Japanese male diagnosed with tinea pseudoimbricata attributed to Trichophyton tonsurans, an anthropophilic dermatophyte. We suspected that application of steroid ointment caused the annular pattern of his skin lesions. After three months use of topical luliconazole cream, treatment was finished. We also summarize the knowledge about tinea pseudoimbricata through previous reports with bibliographical consideration.

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Aspergillus fumigatus-related species are responsible for causing aspergillosis, which is a fatal infectious disease. Recently, there has been a series of reports of A. fumigatus-related species that are resistant to azole drugs used in clinical practice for the treatment of fungal infections. Some of these species have been isolated from outdoor environments. Testing the drug susceptibility of the strains from outdoor environments, therefore, is important. In this study, we isolated and cultured 72 strains of A. fumigatus-related species from the outdoor environment in Japan. The isolates identified via morphological observation and molecular phylogenetic analysis were Aspergillus felis, Aspergillus lentulus, Aspergillus pseudoviridinutans, Aspergillus udagawae, and Aspergillus wyomingensis. The results of the drug susceptibility testing revealed that A. felis (6 of 14 strains) and A. pseudoviridinutans (13 of 17 strains) were resistant to itraconazole (ITCZ), with 4 mg/L or higher minimum inhibitory concentrations (MICs). The voriconazole (VRCZ)-resistant strains with 4 mg/L or higher MICs were A. felis (14 of 14), A. lentulus (4 of 4), A. pseudoviridinutans (15 of 17), A. udagawae (23 of 34), A. wyomingensis (1 of 3), and A. pseudoviridinutans (1 of 3). Among them, A. felis (1 of 14) and A. pseudoviridinutans (7 of 17) demonstrated 8 mg/L or higher MICs for ITCZ and VRCZ. These results indicate that A. fumigatus-related species resistant to ITCZ and VRCZ are widely distributed in outdoor environments in Japan.

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We postulated that disinfection of viable Trichophyton species in shoes would help reduce the number of patients with tinea pedis in Japan and that this might be accomplished safely using volatile components of essential oils. As vapor of lemongrass (Cymbopogon citratus) oil and citral have strong antimicrobial activities against Trichophyton, we examined the conditions under which lemongrass oil or citral show optimal antimicrobial activity in shoes. First, we investigated whether or not a strong antimicrobial effect could be obtained by combining with terpene aldehydes or aromatic aldehydes. When combined with citral, perillaldehyde showed superior antimicrobial activity to citronellal, cinnamaldehyde, cuminaldehyde, hydroxycitronellal, and vanillin. The combined effects of citral and perillaldehyde against Trichophyton mentagrophytes, Bacillus subtilis, and Candida albicans as volatile components dotted on filter paper placed away from the petri dish inoculated with fungi or bacteria were examined. Citral (2.5 mg/mL) and perillaldehyde (2.5 mg/mL) showed a greater inhibitory effect on growth of C. albicans than either solution alone in the aromatogram (disc diffusion) descent method (fractional inhibitory concentration [FIC] index of 0.58). Citral (2.5 mg/mL) and perillaldehyde (1.25 mg/mL) vapors in a closed box synergistically inhibited growth of B. subtilis and T. mentagrophytes (FIC indexes of 0.5 and 0.38, respectively). These results suggested that this combination would be safe and useful for disinfection of shoes.

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A 57-year-old male patient with >10-year history of type 2 diabetes presented with a left big toenail deformity and pain. A physical examination revealed a white and yellow-to-brown patch on the nail as well as thickening and ingrowth of the nail plate. The nail plate was opened using nippers, and a fungal culture revealed Trichophyton interdigitale with yellow yeast. The yeast isolate was identified as Kocuria koreensis, a Gram-positive aerobic coccoid with keratinolytic properties that is part of the normal flora of the skin. We created an ex vivo onychomycosis model of T. interdigitale infection of the human nail by placing a sterilized normal nail on the cultured slant. K. koreensis initially spread over the normal nail, and T. interdigitale then penetrated the nail plate. After one year and six months, a spiral ingrown nail developed. A histopathological examination of the spiral revealed onychomycosis with superficial and deep abscesses of Gram-positive cocci infection. We performed PCR from paraffin-embedded material, and the sequences obtained were identical to those of T. interdigitale and K. koreensis. These results suggest that the development of onychomycosis by T. interdigitale is introduced and accelerated by K. koreensis, and the symbiosis of these microorganisms is suspected in the nail. This ex vivo model has a number of limitations. Therefore, further research on co-infected cases is needed to confirm this hypothesis.

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