Epidermophyton floccosum is a species of fungus in the subgroup Eurotiomycetidae and the class Eurotiomycetes, classified in the Onygenales and below that in the fungal family Arthrodermataceae and genus Epidermophytes. The fungus is a dermatophyte and thus a possible causative agent of dermatophytosis. The infection is pathogenic to humans and manifests as skin and nail lesions.
What is epidermophyton floccosum?
The Eurotiomycetes represent a class of tubular fungi. In this class of fungi, the Eurotiomycetidae form a subclass. Below them is the order Onygenales, which includes the fungal family Arthrodermataceae. In this family, Epidermophyton forms a genus. Within this fungal genus, the species Epidermophyton floccosum is one of the best known species. The species is classified in the non-taxonomic group of dermatophytes, which includes filamentous fungi with carbohydrate and keratin nutrition. The species Epidermophyton floccosum is the only human pathogenic fungus within the fungal genus Epidermophytes. In microscopic image, the species consists of club-shaped smooth and thin-walled macroconidia that may have up to eight chambers. The chambers are usually located sporadically lateral to the septate hyphae. Sometimes they also sit terminally in groups of up to five and are thus arranged in clusters. Their width can be up to twelve micrometers. In length they reach up to 40 micrometers. Microconidia are not formed by Epidermophyton floccosum. Intercalary terminal chlamydospores are frequently observed.
Occurrence, distribution, and characteristics
Fungi of the species Epidermophyton floccosum have their growth optimum at temperatures of about 28 degrees Celsius, although they can also grow in an environment of 37 degrees Celsius. Thus, the constantly warm body of humans is a suitable growth environment. Unlike many other dermatophytes, the species Epidermophyton floccosum does not attack hair under any circumstances. The bacterial species grows moderately fast on Sabouraud glucose agar and Mycosel agar and initially appears white. Within days, the thalus takes on its characteristic olive-green coloration. In addition, purple and pink colored variations occur. The flat colonies usually have a central elevation that has a button shape. Radiating furrows or folds characterize the isolate. Within just one week, a colony of Epidermophyton floccosum can grow up to 25 millimeters in size. After about three weeks, white and cotton-wool-like aerial mycelial flakes form within the colonies. With age, the fungus becomes pleomorphic and is composed of white and cotton-wool sterile mycelium. Mycelium is the entirety of hyphae of a fungus or bacterium. Fungi of the species Epidermophyton floccosum are dermatophytes and possess the enzyme keratinase. In differentiation from other dermatophytes, they use it to break down keratin for growth purposes. The fungal species is transmitted from person to person. In most cases, transmission is not direct, but occurs via baths, showers, towels, shoes or other clothing such as underwear. In humans, the fungi most often colonize the groin area or the legs. However, colonization is also possible on the face, neck, back area, abdominal area, arms, backs of hands, palms, and finger interdigital spaces. In addition, the fungi feel at home on the soles of human feet, in the spaces between the toes and in the area of the nails. For infection with Epidermophyton floccosum, in addition to direct and indirect human-to-human transmission, transmission through contact with contaminated animals is also a possibility. In addition, the fungus can pass from the soil to the human host. Infection with Epidermophyton floccosum is always pathogenic for humans and leads, for example, to skin mycosis in the form of red and scaly efflorescences that spread to the periphery. Nail mycoses associated with the pathogen are known as onychomycoses (nail fungus), which cause the nails to become brittle and brownish.
Diseases and ailments
Dermatophytosis is the name given to all skin diseases caused by filamentous fungi in the sense of dermatophytes. Thus, the fungal species Epidermophyton floccosum also causes dermatophytosis. In most cases, the disease affects only the superficial layers of the skin. The dermis or subcutis is rather rarely colonized.The disease is also called tinea and affects the nails in addition to skin areas. In principle, dermatophytosis can also affect the hair. However, this is not the case with an infection with Epidermophyton floccosum. The most common symptom of Epidermophyton floccosum colonization is red pustules on the skin, which spread in a ring to radial pattern. In clinical practice, the pathogen is detected either by microscopic examination of the skin scales and affected nail parts or by culture. Locally, different agents are used to treat the patients. In addition to fluconazole and itraconazole, voriconazole has become established as an active agent against all dermatophytes. In addition, terbinafine and triazoles are also used, especially for more severe infestations. Griseofulvin is now only rarely used in the treatment of fungal diseases. The fungus Epidermophyton floccosum is a relatively common causative agent of dermatophytosis in Central Europe. Compared with other dermatophytes, infection with it occurs fourth most frequently. The detection of the pathogen is in any case considered a finding requiring treatment. External treatment of this pathogen is mainly carried out by means of antifungal creams and solutions of the above-mentioned active substances. In the case of an infestation of the nails, the therapy is systemic. Antifungal agents in the form of tablets and capsules are suitable for systemic therapy of nail infestation.
