Contents
Dermatophytosis is a fungal infection caused by dermatophytes (fungi that infect the epidermis, hair and nails). There are anthropophilic, zoophilic and geophilic infections. These mycoses are divided into superficial and deep. The most common of these are: tinea capitis (hairy scalp), tinea barbae (beard), tinea faciei (face), tinea corporis (torso), tinea inguinalis (groin), tinea manus (hand), tinea pedis (foot), tinea unguium (nail).
The causes of dermatophytosis
Dermatophytosis is a common disease. Out of several dozen known dermatophyte species, only some cause infections in humans. Due to their source, dermatophytes can be divided into three groups:
1) anthropophilic fungi (they can be infected from another person, they induce a slight immune response). The most common are: Trichophyton rubrum, Trichophyton mentagrophytes var. in-terdigitale, Trichophyton schoenleinii, Microsporum audouinii, Epidermophyton fl occosum;
2) zoophilic fungi (zoonotic infection; animals can be considered vectors due to the mild or asymptomatic course of the infection, they cause a pronounced inflammatory reaction in humans). The most common are: Microsporum canis, Trichophyton mentagrophytes var. granulosum, Trichophyton verrucosum;
3) geophilic fungi (they are found in the soil, they rarely cause disease) – Microsporum gypseum.
DIG. D-4. Skin scales – positive direct microscopic examination (DMSO + KOH).
DIG. D-5. Skin scales – positive direct microscopic examination (DMSO + KOH). Mushroom threads in a magnification.
DIG. D-6. Extracellular system of small spores in hair infection by Microsporum canis.
Age, sex, ethnicity and the capacity of the immune system play an important role in infection.
Additional factors favoring infection are:
- skin micro-injuries,
- maceration,
- occlusion,
- being in a humid and hot climate
The fungus produces enzymes that digest keratin. Iron-binding transferrin, necessary for fungal growth, may also play an important role (in persistent iron deficiency anemia there is a high level of transferrin and a relatively rare occurrence of dermatophytoses, e.g. feet)
The role of the cellular and humoral response is also important. After the ingress of trichophytin, a fungal antigen, a type I (immediate immune response) and a type IV (delayed immune response) immune reaction can be observed. Trichofityna – is a glycoprotein from fungal cells of the genus Trichophyton, the carbohydrate component of which is responsible for the immediate reaction, and the peptide component for the delayed reaction.
They play a significant role in antifungal immune processes neutrophils, macrophages, NK cells. In fungal infections, high antibody titers are not associated with immunity. Specific antibodies, on the other hand, are important in the serological diagnosis of fungal infections.
Symptoms of dermatophytosis
The most common localization of changes occurring in dermatophytosis are:
- ship,
- face,
- torso,
- hairy scalp,
- groin,
- hands,
- feet,
- nails.
Infection with dermatophytosis manifests itself in an asymmetrically located, usually single, flat, round or oval form skin lesionsperipherally with a scaly, more active and inflamed rim. The lesion center appears to be healing. Sometimes the lesion has a system of concentric circles resembling a “target”.
Dermatophiosis – diagnosis of the disease
In the case of mycosis, the elements of the fungus in the tissue can be identified by staining the preparation using the H + E method or the PAS test, or by impregnating with silver by the Gomori-Grocott method.
The direct microscopic preparation, lightened with KOH / DMSO, allows for quick detection of the fungus in the examined epidermal scrapings and / or hair and / or nails. 2-6 weeks of cultivation on Sabouraud’s or selective media enable the diagnosis of the fungus species (Figs. D-4 to D-9)
The disease should be differentiated from:
- psoriasis,
- eczema.
How do we treat dermatophytosis?
General treatment consists in taking itraconazole, fluconazole and terbinafine. Imidazole derivatives are used in local treatment.
What’s the prognosis?
Good for limited superficial infections. Infections are often recurrent and chronic, so it is important to remove predisposing factors.
DIG. D-7. Intra-hair spore system – infection of the hair by fungi of the species Trichophyton tonsurans.
DIG. D-8. Microsporum canis – microscopic image.
RYC. D-9. Trichophyton mentagrophytes var. granulosum – hodowla.
Lit .: [1] Elewski BE: Fungal skin infections. Alfa-Medica Press, Bielsko-Biała 2000. [2] Krajewska-Kułak E., Niczyporuk W .: Dermatophytoses imitating other skin diseases. Mikol Lek 1999, 6/2; 107-11. [3] Prochacki H .: Fundamentals of medical mycology. Ed. Bow. PZWL, Warsaw 1975. [4] Kowszyk-Gindifer Z., Sobiczewski W .: Grzybice and methods of combating them. Ed. Bow. PZWL, Warsaw 1986.
Source: A. Kaszuba, Z. Adamski: “Lexicon of dermatology”; XNUMXst edition, Czelej Publishing House