Mycology – an update. Part 1: Dermatomycoses: Causative agents, epidemiology and pathogenesis

Abstract

Dermatomycoses are caused most commonly by dermatophytes. The anthropophilic dermatophyte Trichophyton rubrum is still the most frequent causative agent worldwide. Keratinolytic enzymes, e.g. hydrolases and keratinases, are important virulence factors of T. rubrum. Recently, the cysteine dioxygenase was found as new virulence factor. Predisposing host factors play a similarly important role for the development of dermatophytosis of the skin and nails. Chronic venous insufficiency, diabetes mellitus, disorders of cellular immunity, and genetic predisposition should be considered as risk factors for onychomycosis. A new alarming trend is the increasing number of cases of onychomycosis - mostly due to T. rubrum - in infancy. In Germany, tinea capitis is mostly caused by zoophilic dermatophytes, in particular Microsporum canis. New zoophilic fungi, primarily Trichophyton species of Arthroderma benhamiae, should be taken into differential diagnostic considerations of tinea capitis, tinea faciei, and tinea corporis. Source of infection are small household pets, particularly rodents, like guinea pigs. Anthropophilic dermatophytes may be introduced by families which immigrate from Africa or Asia to Europe. The anthropophilic dermatophytes T. violaceum, T. tonsurans (infections occurring in fighting sports clubs as "tinea gladiatorum capitis et corporis") and M. audouinii are causing outbreaks of small epidemics of tinea corporis and tinea capitis in kindergartens and schools. Superficial infections of the skin and mucous membranes due to yeasts are caused by Candida species. Also common are infections due to the lipophilic yeast fungus Malassezia. Today, within the genus Malassezia more than 10 different species are known. Malassezia globosa seems to play the crucial role in pityriasis versicolor. Molds (also designated non-dermatophyte molds, NDM) are increasingly found as causative agents in onychomycosis. Besides Scopulariopsis brevicaulis, several species of Fusarium and Aspergillus are found.

Dermoscopic features in 12 cats with dermatophytosis and in 12 cats with self‐induced alopecia due to other causes: an observational descriptive study

“…The hyphae then spread towards the upper part of the hair shaft and perforate the hair cuticle inducing breakage of damaged hairs. 10,11 Brown to yellow scales were also observed only in cats with dermatophytosis. However this finding is probably non specific and may only suggest a follicular and sebaceous inflammation that can be caused by an infectious or parasitic agent or by mechanical trauma.…”

Mechanical Properties of Healthy and ex vivo Onychomycosis Nails and the Influence of a Porphyrin-propylene Glycol Antifungal Formulation

“…In case of a14-day infection of human nail clippings with the dermatophyte T. mentagrophytes at 37°C and 6.4% CO 2 the fungal hyphae have been proven to penetrate the nail plate [6]. This fungal penetration starts from initial attachment of inoculated conidia to ventral and dorsal nail plate sides, subsequent germination and further hyphae development [16]. Infection conditions allow T. mentagrophytes hyphae to grow inside rather than outside the nail plate.…”

Infectious dermatological diseases findings of the wrestlers according to regions

“…Lower age average in the eastern (17.50) and coastal regions (16.40) where infectious skin diseases are commonly found compared to the inland region (18.80) shows that age factor can also be effective in infection incidence (35). Therefore, it would be more well-directed for young athletes to show more sensitivity to hygiene rules considering the fact that dermatologic problems can be encountered more commonly.…”