Trichophyton rubrum is the most common dermatophyte in the world with the highest prevalence in Korea. There are few reports about epidemiological and mycological characteristics of T. rubrum based on long-term, large-scale studies. The purpose of this study was to investigate the clinical and epidemiological characteristics of T. rubrum infections in Korea. We retrospectively investigated with patients' records about the epidemiological and mycological status of 115,846 cases with T. rubrum infection that was mycologically diagnosed at Catholic Skin Disease Clinic from 1979 to 2013. Direct microscopy in 15% KOH solution and culture was done in each case. The annual incidence of patients with T. rubrum infection had been increasing during the period; and of 131,122 patients with dermatophytosis, 115,846 patients (88.35%) had T. rubrum infection. Disease was most prevalent among patients in their twenties in the 1970s and 1980s; in their thirties in the 1990s; in their forties in the 2000s; and in their fifties in the 2010s. The sex ratio was 1.5:1. T. rubrum infection was most commonly seen in summer and was found predominantly in patients living in urban areas. Toe webs were most frequently involved, followed by toenails and groin. This epidemiologic findings provide useful information for prevention of T. rubrum infection and future dermatophytosis prospects.Graphical Abstract

Dear Editor: Dermatophytosis is common worldwide and is believed to affect more than 20%∼25% of the world's population 1 .The epidemiology of dermatophyte infection is influenced by the changing patterns of migration, growth in tourism, immunocompetence of the host, pathogenicity of the infectious agents, availability of medical treatment, and changes in socioeconomic conditions 2,3 . We investigated the epidemiology of fungal skin infections through a retrospective analysis of patient's medical records between 1979 and 2013. Of total 4,275,715 patients, 415,526 patients with clinically suspicious fungal infection were collected at Catholic Skin Clinic in Daegu. Most of the patients were enrolled from Daegu and Gyeongsangbuk-do province. Microscopic examination with 15% KOH preparation and culture using potato dextrose agar corn meal Tween 80 media were performed for fungal examination. Culture media maintained at 24 o C∼26 o C were examined after 2 to 4 weeks. Of 415,526 patients, 131,440 KOHand culture-proven patients were included in this study.

Trichophyton mentagrophytes is the second common dermatophyte in Korea. However, few reports have been issued on the epidemiological and mycological characteristics of T. mentagrophytes in Korea based on long-term, large-scale study. The purpose of this study was to elucidate the epidemiological and mycological characteristics of T. mentagrophytes in Korea. During the 21-yr-period from 1992 to 2012, 6,250 patients with T. mentagrophytes were surveyed to determine annual incidence and the distribution of subjects by age, sex, season, involved sites, and place of residence. T. mentagrophytes infections were confirmed by fungal culture. In addition, the colony appearance of T. mentagrophytes was classified as granular, persicolor, powdery, or downy. Epidemiological analysis showed that annual incidence reached a peak in 2005, and then gradually decreased. T. mentagrophytes infection was most common in July, and was found predominantly in middle-aged adults, especially in those in their forties. Mycological analysis showed a powdery colony appearance was the most common, followed by persicolor and granular colonies. Toewebs were most frequently involved. This investigation on T. mentagrophytes provides insights into its incidence and characteristics.Graphical Abstract

Since 1957, Microsporum (M.) canis has been one of the common causative agents of dermatophytosis in Korea. We analyzed 944 patients infected with M. canis who attended outpatient clinic over a 17-year period (1993-2009). M. canis infections were diagnosed by mycological examinations, including direct microscopic examinations with 15% KOH and cultures on potato dextrose agar complemented with 0.5% chloramphenicol. Mycological examinations confirmed 164,903 cases of dermatophytosis, 944 (0.6%) of which were M. canis infections. The annual prevalence of patients with M. canis infection was the highest in 2002 (91 cases). Then, the prevalence of patients with M. canis infection markedly decreased until 2008 (15 cases). The ratio of male to female patients was 0.65:1, but the ratio in children under the age of 15 was 1.14:1 and was 0.20:1 in adults. Seasonally, 274 cases occurred in winter, showing higher incidence than in other seasons. There was a difference in the clinical forms of M. canis infections between children and adults; tinea (T.) capitis was the most common form in children, but T. corporis was the most common in adults. We demonstrate that the decreasing prevalence of M. canis infections over the study period has been noted in Korea.

Since 1995, Trichophyton tonsurans has been one of the causative agents of dermatophytosis in Korea. Herein we evaluate 77 patients infected with T. tonsurans who visited an outpatient clinic between 2004 and 2014. Infections due to T. tonsurans were diagnosed by mycological examination, which included direct microscopic examination using 15% KOH and culture in potato dextrose agar complemented with 0.5% chloramphenicol. The annual prevalence of infection due to T. tonsurans was the highest in 2014 (15 cases) but remained constant in non-gladiators between 2004 and 2014. The ratio of male to female patients was 1:0.3. The spring season presented the highest incidence compared with other seasons, with 27 cases. The incidence of infections due to T. tonsurans among gladiators was highest in spring compared with the other seasons whereas the incidence in non-gladiators was the highest in the winter. The body site most commonly affected was the face. Tinea corporis was the most common subtype of dermatophytosis caused by T. tonsurans. Herein, we demonstrate that the prevalence of infection with T. tonsurans remain constant throughout the study period in Korea.