Genotyping of Trichophyton tonsurans strains isolated between 2016 and 2020, and terbinafine susceptibility of the species in Japan.

Trichophyton tonsurans is the most prevalent fungus which causes dermatophytosis among contact sports players in Japan. We previously surveyed the epidemic of T. tonsurans in Japan from early 2000, and determined the genotypes of isolates by analysis of restriction enzyme fragment length polymorphisms in the non-transcription spacer (NTS) region of ribosomal RNA gene, which enabled discrimination of eight genotypes, namely NTS I to NTS VIII. In the present study, we performed genotyping of T. tonsurans isolated between 2016 and 2020, and investigated the trend of the epidemic and resistance of the pathogen to antibiotic terbinafine (TBF). Regardless of which contact sport they played, the genotype of all 123 strains of T. tonsurans isolated from athletes was NTS I. Genotypes NTS II and III, which were isolated in considerable numbers mainly from wrestlers between 2000 and 2015, were conspicuously absent. TBF susceptibility was screened in 237 T. tonsurans strains isolated between 2000 and 2020 with 28 of these further assessed for minimum inhibitory concentration of TBF and squalene epoxidase gene sequences. None of the strains showed TBF resistance. TBF may still be effective to control the epidemic of T. tonsurans.

Molecular Epidemiology of Trichophyton tonsurans, the Causative Dermatophyte of the Tinea Gladiatorum Epidemic in Japan between 2011 and 2015.

Trichophyton tonsurans, a major pathogen causing tinea capitis and tinea corporis, has been isolated from contact sports-players in Japan. The molecular types of 208 strains isolated between 2011 and 2015 were determined to understand the contemporary Japanese epidemic. Of these, 142 were isolated from practitioners of judo, 28 from wrestlers, 7 from sumo wrestlers, and 31 from individuals with unknown backgrounds. Based on length polymorphisms of the non-transcribed spacer (NTS) region of the ribosomal RNA gene, these 208 strains were divided into 3 subtypes: NTS I (204; 98.1%), II (3; 1.4%), and III (1; 0.5%). Single nucleotide polymorphisms (SNPs) and deletion/insertion profiles in the NTS region, length polymorphisms of the alkaline protease 1 gene, and a SNP in the carboxypeptidase Y gene were identified in 50 NTS I strains isolated between 2011 and 2015, and in 10 strains isolated before 2005. All 60 strains were classified as the same molecular type, with a profile identical to that of type Ib, a major type in the United States of America. These results indicate that NTS I strains isolated in Japan are clonal and independent of the type of sports activity.

A Case of Cutaneous Mycosis Caused by Scedosporium dehoogii on an Immunocompromised Patient.

This report describes a 77-year-old man with cutaneous mycosis caused by Scedosporium dehoogii while taking oral betamethasone and tacrolimus for the treatment of rheumatoid arthritis. At examination in our clinic, the patient had multiple cystic lesions and nodules with slight tenderness, varying in size up to 4 cm, on his left knee and shin. He had not noticed any traumatic injury at the site of the lesions. Fungal cultures of samples taken from the abscesses, scales, and crusts of the lesions yielded white, later grayish brown, fluffy surfaced colonies. Partial sequencing of the ß-tubulin gene confirmed the species of the isolate. The patient was initially treated with oral voriconazole and local hyperthermia, but experienced hepatic injury 2 weeks later. His treatment was changed to itraconazole (ITC) and local hyperthermia, followed by a combination of ITC and terbinafine. The patient recovered completely during the 12-month course of treatment.

Polyclonality of Trichophyton rubrum Isolates in aDermatophytosis Patient with Multiple Lesions.

We cultured 15 isolates of Trichophyton rubrum and one isolate of Trichophyton mentagrophytes from an 82-year-old male tinea patient with multiple lesions. To determine whether feet lesions were the source of dermatophytes of other tinea lesions, we extracted total cellular DNA from the T. rubrum isolates（13 from feet, two from right waist and buttock）. PCR targeting the non-transcribed spacer（NTS）region of ribosomal RNA gene was performed. Molecular polymorphisms were detected by length variation of amplicons.Four molecular types were found among the 15 isolates. The predominant type, which we previously named Type III, comprised seven isolates cultured from both feet and from left waist and buttock. This was followed by Type VI, five isolates; Type V, two isolates; and Type IV, one isolate. Apart from type III, which was cultured from both feet, isolates were cultured from one foot only. The patient was successfully treated for all types with a six-month course of oral terbinafine and topical luliconazole. The molecular typing supported the notion that tinea pedis was the source of tinea corporis in the patient.

Case of cutaneous phaeohyphomycosis caused by Phaeoacremonium sp. in a renal transplant recipient.

We describe a case of cutaneous phaeohyphomycosis in a 61-year-old man receiving re-dialysis treatment for renal failure of a transplanted kidney. He was immunocompromised with steroid and cyclosporin A at onset of an asymptomatic abscess on his right forearm. The abscess arose at the site of a skin injury approximately 1 year prior. Grayish molds isolated from the lesion were morphologically compatible with Phaeoacremonium sp. but nucleotide sequence data of internal transcribed spacer regions of ribosomal RNA gene, actin and ß-tubulin genes were unlike those of any described species. He was successfully treated with a total of 3 weeks of liposomal amphotericin B, but died of pneumonia approximately 3 months after cure of phaeohyphomycosis.

Simple identification of Trichophyton tonsurans by chlamydospore-like structures produced in culture media.

Trichophyton tonsurans is known to be the causative agent of a worldwide epidemic of dermatophytoses among contact sports practitioners, and is spreading among the general population of Japan. Prompt and simple identification of T. tonsurans in diagnostic laboratories is crucial to control infection. The present study evaluated the availability of observation of chlamydospore-like structures grown in culture media as a characteristic for identification of T. tonsurans. Twenty-five strains of T. tonsurans and five strains each of Trichophyton verrucosum, Trichophyton rubrum and Trichophyton mentagrophytes were inoculated on Mycosel agar plates and inoculated Petri dishes were observed by light microscopy from the reverse side. Twenty-three of 25 T. tonsurans strains showed chlamydospore-like structures within 5 days, and all strains at day 8. The numbers of chlamydospore-like structures were very abundant in most strains. The majority of strains of other species showed no chlamydospore-like structures, or very few when present. Positive for chlamydospore-like structures among 15 strains other than T. tonsurans was one strain at day 5 and six strains at day 8. As for the identification of T. tonsurans, presence of chlamydospore-like structures showed 92.0% sensitivity (23/25) and 93.3% specificity (14/15) at day 5, and 100% sensitivity (25/25) and 60.0% specificity (9/15) at day 8. Electron microscopic findings suggest chlamydospore-like structures are not true chlamydospores but are produced by inflation of actively growing hyphae by developing vacuoles in cells. In conclusion, observation of development of chlamydospore-like structures in culture media is the simplest method for identification of T. tonsurans.