Dermatophytes

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:
  • Trichophyton 
  • Causes black dot ring worm
  • Microsporum
  • Epidermophyton
Distribution:
  • 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
Morphology
  • 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, 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.
Exam Question
 

Introduction

  • 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:
  • Trichophyton 
  • Causes black dot ring worm
  • Microsporum
  • Epidermophyton
Distribution:
  • M. distortum 
  •  Australia, USA
  • Not in India 
Morphology
  • 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 Manifestation

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.
Don’t Forget to Solve all the previous Year Question asked on Dermatophytes

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