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Cutaneous Mycoses

Microconidia of Trichophyton mariatii
Microconidia of Trichophyton mariatii

Cutaneous mycoses are the diseases caused by fungi and involving the skin, hair and nails. They are different from superficial mycoses as evoke cellular immune response.

Classifications: 

Based on Anatomic Location
1.    Tinea pedis
2.    Tinea capitis
3.    Tinea corporis
4.    Tinea cruris

Based on Ecologic location       
1.    Geophilic
2.    Zoophilic
3.    Anthrophilic

Microsporum persicolor macroconidia
Microsporum persicolor macroconidia

Dermatophytosis

Dermatophytosis are caused by fungi belonging to following genera:

  1. Trichophyton
  2. Epidermophyton
  3. Microsporum

 

They infect only superficial keratinized tissue(skin, nails, hair) and are classified as geophilic, zoophilic or anthropophilic. They are acquired by contact with contaminated soil, animals or humans.

Clinical Name Site Most frequent organisms
Tinea capitis (epidemic) scalp Trichophyton tonsuruns, Microsporum audouinii
Tinea capitis (non-epidemic) scalp Microsporidium canis, Trichophyton verrucosum
Tinea pedis interdigital space T. rubrum, T. mentagrophytes, Epidermophyton floccosum
Tinea barbae beard Trichophyton rubrum, T. verrucosum
Tinea corporis arms, legs,torso T. rubrum, M. canis, T. mentagrophytes
Tinea cruris groin T. rubrum, T. mentagrophytes, Epidermophyton floccosum
Tinea manus hands T. rubrum, T. mentagrophytes
Tinea unguium nails T. rubrum, T. mentagrophytes, E. floccosum
Tinea unguium, dermatophytosis involving nail bed
Tinea unguium, dermatophytosis involving nail bed

Clinical Findings

  • Raised circular lesions
  • Tinea pedis is the chronic infection of toe webs, other varieties are vesicular, ulcerative and of moccasin type with hyperkeratosis
  • Tinea unguium with yellow, brittle, thickened and crumbled nails
  • Tinea corporis containing annular lesions with a clearing, scaly center surrounded by red advancing border, vesicle formation and pruritis

Diagnosis

1.    Scrapings from skin, nails and hair
2.    Microscopic examination of specimen on slide in a drop of 10-20% KOH
3.    Branching hyphae or chains of arthroconidia
4.    Culture on Sabouraud’s dextrose agar and Sabouraud’s dextrose agar with chloramphenicol. Dermatophyte test medium (DTM) may be used as well.

Identification on basis of colonial morphology, growth rate, surface texture, microscopic morphology and nutritional requirements.

Macroconidia of Epidermophyton floccosum and filamentous hyphae
Macroconidia of Epidermophyton floccosum and filamentous hyphae

Treatment:

Treatment consists of topical antifungal agents.

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Superficial Mycoses

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