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Skin, Culture for Fungi

Checking the skin and its components (nails and hair) for the presence of fungi involves direct microscopic observation of the specimen, culture of the specimen, and identification of the fungus in the event of a positive result.

Fungal infections of keratinized tissues (skin, hair and nails) can be caused by dermatophytes belonging to the genus Epidermophyton, Microsporum and Trichophyton. Opportunistic surface infections that resemble those caused by dermatophytes can be caused by yeasts or other fungi that are usually saprophytes.

Dermatophyta

Dermatophytes are fungi that can be divided into three groups: Human, Animal and Geophilic. Anthropophilic dermatophytes are transmitted from person to person and are the most common infections. Animal skin infections are usually sporadic. Infections with geophysical dermatophytes are more common after contact with the soil or with an infected animal. The diagnosis is made by observing the presence of fungal textures on the skin, hair or nails. However, it is important to cultivate the material in order to determine the genus and species of the fungus in order to ensure that the most appropriate treatment is selected.

Dermatophyte infections (also known as tinea) are commonly referred to as tinea dermatophytes followed by the Latin name of the area of ​​the body involved. The most common skin infections in adults are tinea pedis (athlete's foot) which can also include tinea unguium (tinea capitis) and in children tinea captis (scalp hair).

Dermatophyte infection is cutaneous and is generally confined to non-live keratinized layers in patients who are immunologically sufficient. This is because dermatophytes cannot penetrate tissues that are not fully keratinized (that is, deeper tissues and organs). However, reactions to such infections can range from mild to severe depending on the host's immune response, fungal infectivity, site of infection, and certain environmental factors. The group of cutaneous fungi is classified into three genera: Epidermophyton, Microsporum and Trichophyton.

Non-Dermal Fungi

There are some non-dermatological fungal species that can infect healthy skin and include: Scytalidium dimidiatum, Scytalidium hyalinum, Phaeoannellomyces werneckii and Piedraia hortae. Non-dermatological species, including those mentioned above, can infect nails that have been damaged by injuries, other diseases or pre-existing infection by dermatophytes. Non-dermatological fungi are responsible for less than 5% of onyx fungi. Candida species, Candida parapsilosis, Candida guilliermondii and Candida albicans have been reported as an important cause of onychomycosis.

The skin may be a target organ for the development of metastatic, possibly blood-borne infections from a variety of fungi that cause systemic fungi in immunosuppressed patients (filamentous fungi such as Aspergillus and Fusarium species, Candida species, Cryptococcus necrosis). Occasionally, fungi such as Sporothrix schenckii or Cryptococcus neoformans can penetrate the tissues through transdermal inoculation and subsequently cause local, or possibly even systemic, disease. Cryptococcosis in patients with kidney transplantation and HIV infection may occur with skin lesions.

Also, skin lesions can be contaminated by Aspergillus and Alternaria fungi as well as species of Scabies. In most cases, fungal growth is only local, but it can cause extensive tissue necrosis.

Clinical manifestations of superficial fungal infections

Tinea barbae

Gynecological infection can be mild to severe follicular fibrosis and which may resemble Staphylococcus aureus infection. Genital hair follicles are often associated with animal skin dermatophytes such as Trichophyton verrucosum, Trichophyton mentagrophytes var. mentagrophytes and rarely Trichophyton mentagrophytes var. erinacei. Sometimes it can be due to the anthropogenic Trichophyton rubrum.

Tinea capitis (scalp hair)

Infection of the scalp is usually caused by species of the genus Trichophyton or Microsporum. Infection can range from mild lesions to highly inflammatory reaction with folliculitis, scarring and alopecia. The surface of the skin and the hair can also be involved. The arrangement of the fungal spores on the hair stem may be diagnostic as to the type of fungus.

Tinea corporis

This dermatitis can include the skin of the torso, shoulders and limbs. The infection can range from mild to severe and is usually presented as annular scaly lesions with clear, elevated and erythematous borders.

Tinea cruris

Infections in the groin area, perineum and perineal area are more common in adult men. Trichophyton rubrum and Epidermophyton floccosum are the most common fungal species isolated from these lesions. The lesions are erythematous to brown and are covered by fine, dry scales. The lesions may extend downward to the inner side of the thigh and have elevated, defined borders that may have small vesicles.

Tinea favosa (Achora)

This is a serious and chronic condition that is more common in Africa and Asia. This condition is usually caused by Trichophyton schoenleinii.

Tinea imbricata

It is a chronic infection, which is a manifestation of tinea corporis and is found mainly in islands of the Pacific Ocean. It has a very distinctive appearance with concentric overlapping rings. The only known causative agent is Trichophyton concentricum.

Tinea manuum

The palms of the hands and the interdigital areas are affected. This condition is commonly referred to as diffuse hyperkeratosis and is most often caused by Trichophyton rubrum as well as other species of Trichophyton and Microsporum.

Tinea pedis (Athlete's foot)

Toes and soles are most often affected. In particular, the areas between the fourth and fifth toes may show moisture, scaling and cracks in the skin. Another form is the chronic, slender, hyperkeratotic type with thin gray scales covering the areas of the soles, heels and lateral parts of the foot. The most common agents of tinea pedis are Trichophyton rubrum, Trichophyton mentagrophytes var. interdigital and Epidermophyton floccosum.

Tinea unguium (Onychomycosis)

The term onychomycosis is accepted as a general term for any fungal infection of the nail (from Dermatophytes and Non-dermatophytes).

Tinea versicolor (Various dandruff)

It is an infection of the corneal layer of the skin with Malassezia furfur fungi. There is little tissue involvement and the disease mainly causes aesthetic changes in the color of the skin. In general, the diagnosis is made by clinical appearance as well as microscopic detection of fungi.

 
 
 
 
Important Note

Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".

Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.

At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.

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