DERMATOPHYTES

Introduction

• Filamentous fungi
• Infect only superficial keratinized tissue
  • Skin(stratum corneum), hair and nails.
• Cause a variety of clinical conditions, collectively known as dermatophytoses, tinea or ring worm.

Classification:

Three genera:

1. Trichophyton 
   • Causes black dot ring worm
2. Microsporum
3. Epidermophyton

• Epidermophyton floccosum
  • Worldwide
• Trichophyton mentographytes
  • Worldwide
• T. rubrum
  • Worldwide
• T. Tonsurans
  •  Europe america
• M. distortum 
  •  Australia, USA
• M. canis
  • Worldwide
• M. nanum
  • Worldwide
• T. equinum
  • • Worldwide
• T. verrucosum
  • Worldwide
• T. simii 
  •  India 

In lesions appear as :

• Hyphae
• Arthrospores

On sabouraud’s agar form :

• Septate hyphae
• Asexual spores (micro and macroconidia)
• Differentiation is based mainly on macroconidia.

	Trichophyton	Microsporum	Epidermophyton
Site	Hair, Skin Nail	Hair Skin	Skin Nail
Microconidia	Abundant Arranged in clusters along hyphae	Single (multicellular)	Absent
Macroconidia	Relatively scanty Elongate Blunt ends Pencil/Cylindrical shaped	Single Multicellular Spindle shaped	Groups of 2 or 3 Club shape/pear shaped

Clinical Manifestations 

• Local inflammation is due to irritation by fungal products and hypersensitivity reaction.

Transmission:

• Occurs from infected to uninfected persons often by brushes, combs, and towels.

Dermatophytoses	Causative agent
Tinea capitis	Microsporum, Trichophyton most species
Favus	T. schoenleinii T. violaceum, M. gypseum
Tinea barbae	T. rubrum, T. mentagrophytes, T. verrucosum
Tinea imbricata	T. concentricum
Tinea corporis	T. rubrum and any other dermatophyte
T. cruris (Tock itch)	E. floccosum, T.rubrum
T pedis (Athlete’s foot)	E. floccosum, T rubrum
Ectothrix  hair infection	Microsporum species, T. rubrum
Endothrix hair infection	T. schoenleinii, T. tonsurans, T. violaceum(INDIA)

 Treatment

• Topical antifungal agents
• Oral griseofulvin is DOC.
• 3 months duration for fingure nail dermatophytosis.

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