Dermatomycoses.
Dermatomycoses are infections of the skin, hair or nails by fungi. The principal causative agents are dermatophytes, which are subdivided into three groups (genera): Microsporum spp., Trichophyton spp. and Epidermophyton floccosum. The three genera are distinguished by the form of the spores, or macroconidia.
- Trichophyton: thin-walled, smooth, four to six septa
- Microsporum: thick-walled, with projections five to more septa
- Epidermophyton: thick-walled, pear to oval shaped four or fewer septa
Examples of dermatomycoses are tinea and cutaneous candidiasis.
Tinea infections: Red, scaly or blister-like lesions; often a raised red ring; “ringworm”
- Tinea pedis
- Tinea corporis
- Tinea capitis
- Tinea favosa
- Tinea barbae
- Tinea cruris
- Tinea unguium
❖ Etiology:
- Dermatophytons of 3 genera: Trichophyton, Microsporum and Epidermophyton
- Keratophytons of some yeast species: Pityrosporum ovale, Pityrosporum orbiculare, Malassezia furfur.
- Candida genus (Candida albicans).
- Pseudofungi (Corynebacterium minutissimum and Actinomyces israelii).
- Moulds (Scopulariopsis, Aspergillus, Penicillium, etc.)
❖ Mode of transmission:
Dermatophytes are transmitted by direct contact with infected host (human or animal). By direct or indirect contact with infected exfoliated skin or hair in clothing, combs, hair brushes, theatre seats, caps, furniture, bed linens, shoes, socks, towels, hotel rugs, bathhouse and locker room floors.
❖ Signs and symptoms:
T. rubrum is the most common fungi, and it causes majority of the cases. It produces a non-inflammatory type of dermatophytosis characterized by:
- Dull erythema
- Pronounced scaling involving the entire sole and sides of feet
Tinea symptoms:
- Itching and stinging.
- Red scaly rash that is shaped like a ring (annular)
- Cracking, splitting and peeling in the toe web spaces.
- Blisters.
- Yellow or white discoloration of the nails.
- Bald spots on the scalp.
❖ Diagnosis:
- microscopic detection of fungus
- culture of the pathogen from clinical material
- EUROArray Dermatomycosis - reliable, accurate and sensitive method for molecular genetic direct detection of dermatophytes, yeasts and moulds.
❖ Treatment:
- topical agents - miconazole, terbinafine, clotrimazole, ketoconazole, or tolnaftate applied twice daily
- in severe cases - systemic treatment with oral medications
- imidazole cures the infection (t.rubrum is often resistant to therapy)