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Trichophyton interdigitale, an anthropophilic species, is one of the main causative agents of tinea unguium and tinea pedis. T. interdigitale and the zoophilic species T. mentagrophytes are morphologically and physiologically very similar. Isolates of the T. interdigitale/T. mentagrophytes complex from around the world have been classified into more than 10 internal transcribed spacer (ITS) genotypes. In this study, we isolated T. interdigitale from Japanese patients and investigated which ITS type was more common. The ITS regions of 29 clinical isolates of T. interdigitale and one clinical isolate of T. mentagrophytes were sequenced. The phylogenetic analysis of the ITS region sequences revealed that the 29 isolates of T. interdigitale belong to ITS type II of T. interdigitale. The one clinical isolate of T. mentagrophytes was in the same cluster with ITS type II* of T. mentagrophytes. One terbinafine-resistant strain of T. interdigitale also belonged to ITS type II of T. interdigitale.

Efinaconazole is a topical antifungal drug approved in Japan for tinea unguium. Although topical treatments generally have low cure rates with a prolonged therapy period, a Cochrane review confirmed that high‐quality evidence supports the effectiveness of efinaconazole for the complete cure of tinea unguium. Combination therapy is a way to improve the cure rate of onychomycosis. In this study, topical efinaconazole was administrated to 12 patients who had been treated with oral terbinafine (125 mg daily) for more than 20 weeks with little expected effect. Because terbinafine accumulates for a long time in the nail, treatment immediately followed by other drugs can be considered sequential combination therapy. During terbinafine monotherapy, the percentage involvement decreased from 53.5% to 44.0% after 37.4 weeks and the effective and cure rates were 16.7% and 0%, respectively. During sequential topical efinaconazole therapy combined with lasting terbinafine in the nail, the percentage involvement decreased from 44.0% to 18.7% after 28.4 weeks, and the effective and cure rates were 66.7% and 16.7%, respectively. The improvement rate per month of combination therapy (12.6%) was higher than that with monotherapy (2.1%) (p = 0.002). There were no serious side‐effects. This sequential combination therapy with efinaconazole was effective in poor terbinafine responders, making it a promising regimen for improving the cure rate of tinea unguium.

Fusarium onychomycosis is uncommon in the temperate climate zone of Japan. Based on the morphological characteristics and a gene analysis, we diagnosed a patient with ungual hyalohyphomycosis caused by Fusarium cugenangense belonging to the F oxysporum complex. This intractable disease was cured by 6‐month treatment with efinaconazole 10% solution.

Fosravuconazole is a novel oral antifungal drug developed in Japan and used to treat tinea unguium since 2018. Its excellent oral absorbability and systemic bioavailability has enabled short-duration therapy of 3 months. Furthermore, no concomitant drugs are contraindicated due to the presence of the mild inhibitor of cytochrome P450 enzyme which is responsible for polypharmacy adverse effects. Therefore, it can be safely administrated to elderly patients. Elderly patients (≥65 years old) with severe onychomycosis (≥50% nail involvement) were treated with oral fosravuconazole 100 mg once daily for 12 weeks. The rate of involvement improved from 86.6% to 28.1% (P < 0.01). The efficacy (i.e. percentage of those rated as "improved" and better) and cure rate was 83.8% (31/37) and 29.7% (11/37), respectively. Furthermore, when focusing on the thin nail group (

We encountered two cases of phaeohyphomycosis caused by Exophiala jeanselmei and E. oligosperma that were treated with fosravuconazole and terbinafine, respectively. Our cases were successfully treated with empiric therapy before the pathogen's species or antifungal sensitivity had been determined. We summarized 32 cases of cutaneous and subcutaneous phaeohyphomycosis caused by Exophiala species in Japan. The patients received antifungals, including itraconazole, terbinafine, voriconazole, and fosravuconazole, and the treatment success rates of these monotherapies were 77% (17/22), 67% (8/12), 100% (5/5), and 50% (1/2), respectively. Although the broad-spectrum azole antifungal itraconazole is the first choice for treatment, terbinafine at 125 mg/day might exert the same efficacy. Fosravuconazole is a novel broad-spectrum azole and a moderate inhibitor of Cyp3A4 that causes fewer drug interactions than itraconazole and voriconazole, indicating a promising drug for this disease.

Trichophyton rubrum is an anthropophilic dermatophyte that is most frequently isolated from onychomycosis (tinea unguium) worldwide. T. rubrum strains showing resistance to the anti-fungal drug terbinafine (TRF) have also been isolated from human patients worldwide.In this study, we isolated a TRF-resistant strain (N99-2) of T. rubrum from a patient with recurrent tinea unguium. In vitro susceptibility of the clinical isolate to TRF, itraconazole (ITZ), ravuconazole (RVZ), and luliconazole (LCZ) was investigated using the ClinicalLaboratory Standards Institute M38-A2 test. To identify mutations, we compared the gene sequence of N99-2 to that of a TRF-susceptible strain of T. rubrum. Results; In N99-2, the minimum inhibitory concentrations were 32 mg/L for TRF,0.03 mg/L for ITZ,0.03 mg/L for RVZ, and0.03 mg/L for LCZ. The squalene epoxidase (SQLE) gene sequence in N99-2 was determined to be 1467 bp in length, and it encoded a protein of 488 amino acids, beginning with a putative initiating methionine (ATG). The following mutations were identified from the SQLE of N99-2: L393F and Y394del.This is the first report of the detection of a deletion mutation in SQLE in a TRF-resistant strain. The protein of SQLE is the target of TRF, and it is essential for cell membrane synthesis in dermatophytes. However, dermatophyte cells were found to undergo gene mutations to escape the effects of antifungal agents.

Ravuconazole (RVCZ) is a new human anti-fungal azole drug available in Japan since 2018 and is a broad-spectrum agent that exhibits excellent activity against dermatophytes. In the present study, the in vitro RVCZ susceptibility of clinical isolates of anthropophilic dermatophytes, including Trichophyton interdigitale strains with either low susceptibility to itraconazole (ITCZ) or resistance to terbinafine (TEBR), was investigated using the Clinical & Laboratory Standards Institute M38-A2 test. The MICs of RCVZ for 20 clinical isolates of T. interdigitale were < 0.03125-0.125 mg/L; for 4 clinical isolates of T. rubrum, < 0.03125-0.0625 mg/L; and for 20 clinical isolates of T. tonsurans, < 0.03125 mg/L. Similarly, the MICs of RCVZ for the T. interdigitale strains with either low susceptibility to ITCZ or resistance to TEBR were also < 0.03125 mg/L. To our knowledge, this is first study to investigate the in vitro RVCZ susceptibility of T. interdigitale strains with either low susceptibility to ITCZ or resistance to TEBR. Our results indicated that RVCZ was the most effective drug against these strains.

Terbinafine (TRF)-resistant Trichophyton interdigitale and Trichophyton rubrum have been isolated from human patients. These strains have missense mutations (Leu393Ser/Phe or Phe397Leu) in the squalene epoxidase-encoding gene, SQLE. We developed a PCR detection method to identify hotspot mutation sites in SQLE genes of dermatophytes. To sequence hotspots in isolates, we prepared primers based on conserved sequences of T. rubrum and T. interdigitale SQLEs. Approximately 390-bp long DNA bands for T. rubrum, T. interdigitale, and Trichophyton indotineae strains were sequenced. Hotspots were detected only in TRF-resistant strains. This PCR-based method is simpler and more rapid than the conventional test.

Terbinafine (TRF) has been used in the treatment of fungal infections for more than 20 years. Recently, TRF-resistant Trichophyton interdigitale and T. rubrum strains have been isolated from human patients worldwide. However, an epidemiological study of TRF-resistant strains in Japanese patients has not been investigated. In the present study, antifungal susceptibility testing was performed on clinical isolates from Japanese patients to assess TRF-resistance patterns of T. interdigitale and T. rubrum strains. We also sequenced the squalene epoxidase (SQLE) encoding gene of TRF-resistant T. rubrum strains. Two hundred and ten T. interdigitale and T. rubrum clinical isolates were obtained from 210 human cases of tinea pedis, tinea corporis, tinea unguium, tinea cruris, tinea manuum, tinea faciei and tinea capitis in Tokyo, Saitama, Chiba, Hyogo and Kumamoto, Japan, in 2020. Five T. rubrum isolates (N74, N79, N99, H30 and K2) grew on Sabouraud's dextrose agar (SDA) containing 1 mg/L of TRF. All five strains exhibited TRF minimum inhibitory concentrations (MICs) ≥32 mg/L but remained susceptible to azoles. We determined SQLE sequences in these TRF-resistant T. rubrum strains and found that all strains harbored missense mutations (L393F) in the SQLE-encoding gene.

The incidence of non-dermatophyte mould onychomycosis has been increasing worldwide for the past several decades, but it is not well recognized in Japan. Recent molecular techniques and phylogenetic analyses contributed to the identification of uncommon and emerging species. We came across 13 (0.5%) cases of non-dermatophyte onychomycosis among a total of 2,591 onychomycosis cases in 106,703 outpatients during the past 5 years (January 2015-December 2019). The cases included 5 patients with Aspergillus species, 4 patients with Fusarium species, and one patient each with Scopulariopsis brevicaulis and Botryosphaeria dothidea, respectively. Botryosphaeria dothidea is closely related phylogenetically to Neoscytalidium dimidiatum. In Japan, at the time of writing this report, there are 26 reported cases of ungual aspergillosis and 18 cases of hyalohyphomycosis caused by Fusarium species. We summarize these cases and report the symptoms and mycological features.

Hand eczema (HE) is a common skin disease that impairs health-related quality of life (HRQOL). Impairments in HRQOL have already been reported in Japanese HE patients using the Skindex-16. Recently, an instrument to measure disease-specific HRQOL in HE patients was developed by an international expert group, consisting of domains for: (i) symptoms; (ii) emotions; (iii) functioning; and (iv) treatment and prevention. The objective of this study is to translate the English-language version of the Quality of Life Hand Eczema Questionnaire (QOLHEQ) to Japanese and then to validate the Japanese version. The Japanese version of the QOLHEQ, the Dermatological Life Quality Index (DLQI) and a questionnaire regarding basic demographic information, including patient ratings of HE severity, were distributed to Japanese HE patients. Additionally, a dermatologist evaluated patients' HE severity using the Physician Global Assessment. A total of 124 patients with a mean age of 43.7 years were included in the analysis, and 78% of the sample was female. Cronbach's alphas for the domains symptoms, emotions, functioning, and treatment and prevention were 0.76, 0.89, 0.88 and 0.81, respectively. The total QOLHEQ score showed a strong correlation with the DLQI, a moderate correlation with patient-rated severity and weak correlations with dermatologist-rated severity and the number of consultations. The Japanese version of the QOLHEQ showed excellent reliability and high validity. The Japanese version of the QOLHEQ is ready for use in epidemiological studies to evaluate HRQOL impairments in HE patients.

We describe a case of a 23-year-old female patient with no apparent underlying diseases. She showed a discoloration of the proximal portion of the left big toenail with paronychia. Direct microscopy revealed septate hyphae with conidiophores, and a periodic acid-Schiff-stained nail specimen revealed septate hyphae branching at angles of approximately 45°. On the basis of phylogenetic analysis, we finally arrived at the diagnosis of ungual aspergillosis caused by Aspergillus subramanianii. After p.o. administration of terbinafine and topical application of 10% efinaconazole solution, the disease resolved in 6 months. A. subramanianii is one of the new species in the genus Aspergillus section Circumdati. Reported clinical isolates have been isolated from lung tissue, wounds and feet. This is the first documented case of onychomycosis caused by A. subramanianii. Onychomycosis due to Aspergillus species is uncommon. We summarized the reported cases of ungual aspergillosis in Japan.

We treated tinea unguium (onychomycosis caused by dermatophytes) patients with efinaconazole 10% solution. All patients with tinea unguium who tested positive for fungi in fingernails and toenails, regardless of age or severity, were eligible for the treatment. The number of patients was 106, consisting of 43 men and 63 women with a mean age of 66.7 years. The patients were treated with efinaconazole for a mean treatment duration of 38.1 weeks. Therapeutic efficacy was rated on a 5-point scale as follows: "cured", "markedly improved", "improved", "slightly improved" or "no change". A single nail was selected in each patient as the target nail. Selected nails were the big toenails with less than 50% involvement in 25 patients, the big toenails with 50% or more involvement in 52 patients, the fingernails in 10 patients and the second to fifth toenails in 19 patients with a mean treatment duration of 43.9, 38.1, 38.7 and 33.7 weeks, respectively. All groups showed an improvement in the percentage involvement from 30.6% to 9.8%, 77.6% to 35.7%, 82.7% to 17.6% and 80.3% to 15.5%, respectively (P < 0.01). The improvement rate (i.e. percentage of those rated as improved and better) was 76.0%, 65.4%, 80.0% and 89.5%, respectively. Efinaconazole 10% topical solution is beneficial for patients, regardless of age, severity or clinical type.

An 85-year-old Japanese woman presented with infiltrative erythema and ulceration on the extensor surface of her right forearm. Direct microscopic examination demonstrated spherical and morula-like sporangia, while histopathology revealed numerous microorganisms with a mulberry-like appearance in the dermis. Staining of the microorganisms also showed mulberry-like sporangia that resembled the spokes of a wheel. The isolated yeast-like microorganism had been identified as Prototheca wickerhamii genotype 2 in another independent study on the basis of its morphological, biochemical and genetic analysis. This case of protothecosis was recorded in Kyushu, Japan, and oral treatment with itraconazole 200 mg/day for 2 months was effective. Herein, we also summarize and analyze 39 cases of human protothecosis reported in Japan since the first record in 1983.

Cutaneous cryptococcosis is classified either as primary or secondary based on the route of infection. The disease can also be classified either as localized cutaneous cryptococcosis or cutaneous manifestations of disseminated cryptococcosis. However, from a physician's point of view, whether lesions are localized to the skin or are disseminated/systemic is more important than the route of infection. The Clinical Practice Guidelines for Diagnosis and Treatment of Cryptococcosis, which was established in 2019 by the Japanese Society for Medical Mycology, adopted the latter classification. Localized cutaneous cryptococcosis is defined as a condition in which lesions are confined within a limited part of the skin, not systemically disseminated at the same time, and are associated with neither cryptococcal fungemia nor antigenemia. This type of cutaneous cryptococcosis is uncommon in Japan. Only 65 cases were reported during the 50-year study period from 1968 to August 2018, with the patients divided into two groups: immunocompromised patients (n=44, 68%) and immunocompetent patients (n=21, 32%). None of the patients were infected with the human immunodeficiency virus (HIV). Localized cutaneous cryptococcosis can also occur in non-HIV-infected patients and well-appearing individuals, therefore, it is considered an important infection in routine dermatology practice. Here, we outline the classification, diagnosis, and treatment of cutaneous cryptococcosis and present a summary of cutaneous cryptococcosis cases reported in Japan.

A 73-year-old healthy woman noticed black pigmentation on both thumbnails for 6 years. Upon her visit to our clinic, she had pigmented onychomycosis with onycholysis in the distal area. There was no evidence of paronychia. Direct microscopy using Zoomblue™ and histopathological examination showed aggregated blastoconidia. Fontana-Masson staining confirmed fungal melanin production. A combination of morphological features and genetic testing identified the isolates as Candida parapsilosis. Fungal melanonychia due to C. parapsilosis is rare, with only six cases reported since 1979. The minimum inhibitory concentration of the isolates was 0.25 μg/mL for itraconazole, less than 0.03 μg/mL for ravuconazole and 2.0 μg/mL for terbinafine. Both oral terbinafine treatment and itraconazole pulse therapy performed for 6 months were unsuccessful. The disease was ultimately cured with a 3-month treatment of oral fosravuconazole.

A 68-year-old male plasterer with no history of trauma presented to our clinic in March 2012 with a 16×14-mm ulcer that developed following a crushed small papule on the right anterior chest. In April 2012, the patient was referred to another hospital, where cutaneous cryptococcosis was diagnosed based on discharge culture results. The patient was treated with oral itraconazole at a dose of 150 mg/day for 10 weeks; however, the ulcer remained unchanged and he discontinued the treatment. In May 2014, when he revisited our clinic, the ulcer with crust had grown to 29×13 mm. No regional lymph node swelling was noted. India ink staining showed a yeast-like fungus with a thick, clear capsule. A cream-colored, viscous yeast-like colony was observed on Sabouraud dextrose agar. Genetic testing identified the isolate as Cryptococcus neoformans serotype A. The patient was negative for serum cryptococcal antigen. Neither chest radiography nor computed tomography revealed any abnormalities. The patient had no underlying disease. Oral fluconazole (400 mg/day for 12 weeks) was prescribed, resulting in scar formation. The patient has remained free of relapse for one year to date, since the end of treatment. Localized cutaneous cryptococcosis is not a commonly used disease name overseas. However, 36 cases of this disease have been reported in Japan (since in 1968). We herein report a new case with localized cutaneous cryptococcosis and summarize previously reported cases in Japan.

A 56-year-old woman on insulin therapy for diabetes visited our clinic due to whitish discoloration on the right index finger. Despite topical application of 1% lanoconazole solution, the lesion grew, causing paronychia. Direct microscopy revealed non-dermatophyte molds. Based on the morphological features and genetic analysis of the isolate, the pathogen was identified as Aspergillus flavus. The patient was diagnosed with proximal subungual onychomycosis due to A. flavus. Following itraconazole pulse therapy, she was cured in 6 months. To our knowledge, this is the first reported case of fingernail onychomycosis due to A. flavus in Japan.

Trichophyton interdigitale is an anthropophilic species that is frequently isolated from tinea unguium and tinea pedis throughout the world. In the present study, antifungal susceptibility testing was performed on T. interdigitale isolates from Japanese patients (isolated in 2017-2018; 24 strains) to assess itraconazole (ITZ) and terbinafine (TRF) susceptibility of these strains. E-test determinations revealed that the mean ITZ minimum inhibitory concentration (MIC) of the 24 strains was 0.023 mg/L (range, 0.064-1). Clinical Laboratory Standards Institute M38-A2 determinations revealed that the mean TRF MIC of 23 of the 24 strains was less than 0.03125 mg/L. Among these strains, one (NUBS18016) had a TRF MIC of 2 mg/L, confirming its resistance to TRF. The predicted amino acid sequences of the squalene epoxidase (SQLE) gene from the TRF-resistant strain (NUBS18016) was 100% identical to the SQLE gene sequence of the reference strain T. interdigitale, indicating that no gene mutations were present in NUBS18016. Therefore, the TRF-resistance mechanism of our TRF-resistant strain NUBS18016 has not been defined. Dermatologists should be cautious about the prevalence of foot dermatophytosis due to antifungal drug-resistant strains.