Lesson 3.1.2

• Dermatophytoses


  -fungal infections of the skin, hair, and nails

  -invades the dermis of the skin and deeper layer of the hair
• Characteristics of Dermatophytoses

  • Agents of tinea or ringworm
  • Keratinophilic (infects the skin or stratum corneum, nails, and hairs)
  • Arthroconidia (main means of dissemination)
  • Culture (macro and microconidia)
  • Ectothrix
  • Endothrix
• 3 genera, ~30 species are recognized, 10 species

  1. Microsporum spp
  2. Epidermophyton spp
  3. Trichophyton spp
• Microsporum spp

  • Macroconidia - numerous, thick- and rough-walled
  • Microconidia - rare
  • Infects the skin and hair
• Epidermophyton spp

  • Macroconidia - numerous, smooth-walled
  • Microconidia - absent
  • Infects the skin and nails
• Trichophyton spp

  • Macroconidia - rare, thin- and smooth-walled
  • Microconidia - Abundant
  • Infects the skin, hair, and nails
• Types of Tinea or Ringworm

  1. Tinea capitis
  2. Tinea corporis
  3. Tinea cruris
  4. Tinea pedis
  5. Tinea manuum
  6. Tinea unguium/ onchomycosis
• Tinea capitis


  -scalp hair and scalp skin

  -favus: NA, ME, SEE

  • specimen include hair roots, hair brush sampling
• Tinea corporis


  -trunk, legs, arms (excluding groin, hands, and feet)

  -collect from raised border of lesion

  -submit entire top of vesicles
• Tinea cruris


  -groin, perianal, pubic region

  -spread from another infected site
• Tinea pedis

  -athlete's foot

  -one or both feet
• Tinea manuum


  -one (more common) or both hands

  -often coexist with tinea pedis: two feet, one hand
• TInea unguium/onchomycosis


  -fingernails (unilateral) or toenails (first and fifth): very rare to see fingernail infection without toenail involvement

  -may be caused by Candida spp

  -Tinea pedis is a risk factor
• Genus Microsporum

  1. Microsporum canis
  2. Microsporum gypseum
  3. Microsporum audouinii
• Genus Epidermophyton

  1. Epidermophyton floccosum
• Genus Trichophyton

  1. Trichophyton concentricum
  2. Trichophyton mentagrophytes
  3. Trichophyton rubrum
  4. Trichophyton tonsurans
  5. Trichophyton schoenleinii
  6. Trichophyton verrucosum
• Microsporum canis


  -zoophilic

  -macrocoinidia: spindle-shaped with tapered ends

  -Rice medium (+)

  -Florescence in UVL
• Microsporum gypseum


  -Geophilic

  -Macroconidia: ellipsoidal/oblong with pointed ends

  -Rice medium (+)

  -does NOT fluoresce UVL
• Microsporum audouinii


  -anthropophilic

  -Macroconidia: rarely seen, bizaar/mutant-shaped

  -Hyphae: pectinate bodies/ hyphae

  -Rice medium (-)

  -formerly #1 agent of tinea capitis
• Epidermophyton floccosum


  -anthropophilic

  -macroconidia: club-shaped/spatulate/beaver tail/ Dutch pants fuseaux

  -KOH: hyaline, septate hyaline

  -fluoresce in UVL
• Trichophyton concentricum


  -anthropophilic

  -endemic to Pacific Islands and Melanasia; SEA

  -only agent producing Tinea imbricata
• Trichophyton mentagrophytes


  -zoophilic

  -hairbaiting (+); Urease (+)

  -Macroconidia: cigar-shaped

  -Microconidia: grape-like

  -Hyphae: spiral

  -NOT fluoresce in UVL
• Trichophyton rubrum 


  -anthropophilic

  -hair baiting (-); Urease (-)

  -Macroconidia: pencil-shaped

  -Microconidia: teardrop/peg shaped

  -Culture: red pigment in SDA w/ 1% glucose (reverse)
• Trichophyton tonsurans


  -anthropophilic

  -agent of black-dot tinea capitis

  -Macroconidia: balloon-shaped

  -Microconidia: teardrop/peg shaped

  -NOT fluoresce under UVL
• Trichophyton schoenleinlii


  -causes favus/ t. favosa

  -Hyphae: favic/chandelier/deer antlers
• Trichophyton verrucosum


  -zoophilic

  -require thiamine and inositol for growth

  -Macroconidia: rat tail/string beans

  -Microconidia: clavate/pyriform