Dermatophytes (Superficial Mycoses)

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Dermatophytes(Superficial Mycoses)

• (Skin Plants)

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Tinea

• Ringworm (moth)

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Tinea corporis(the body)
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Tinea pedis(feet)
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Tinea unguium(nails)
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Tinea capitis(scalp)
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Tinea cruris(jock itch)
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Tinea barbae(bearded area)
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Tinea versicolor (Spaghetti and meatballs)
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Ecology of Dermatophytes

• To determine the source of infection

• Anthropophilic
• Zoophilic
• Geophilic

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Anthropophilic

• Associated with humans only. Person -to-person
  transmission through contaminated objects (comb,
  hat, etc.)

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Zoophilic

• Associated with animals. Direct transmission to
  humans by close contact with animals.

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Geophilic

• Usually found in soil. Transmitted to humans by
  direct exposure.

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Geographic Distribution

• Worldwide

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Dermatophytes3 Genera

• Trichophyton
• Microsporum
• Epidermophyton

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Trichophyton (19 species)

• Hair
• Skin
• Nails

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Trichophyton species
Large, smooth, thin wall, septate, pencil-shaped
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Trichophyton rubrum

• Causes a chronic infection in patients with a
  cell-mediated immune defect.
• (most common in SC blacks)

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Microsporum(13 species)

• Skin
• Hair

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Microsporum species
Thick wall, spindle shape, multicellular
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Microsporum canis

• .
• Most common etiologic agent of tinea in SC whites

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Epidermophyton floccosum

• Skin
• Nails

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Epidermophyton floccosum
Bifurcated hyphae with multiple, smooth, club
shaped macroconidia (2-4 cells)
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Therapy

• Griseofulvin
• Tinactin
• Clotrimazole
• Miconazole
• Ketoconazole
• Itraconazole
• Terbinafine

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Dermatophytid Reaction(ID)

• Dermatophyte infection on feet
• (not clinically evident)
• Ringworm Lesion on hand
• (usually the dominant side)

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Dermatophytid Reaction(ID)

• Culture skin scrapings from feet
• Treat the tinea pedis
• The hand lesion (ID phenomenon) will respond to
  therapy of the foot.

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Dermatophyte Culture
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Dermatophyte Culture
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Dermatophyte Culture
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Dermatophytes

• It is not necessary to be an athlete to get
  athletes foot.
• A tinea (moth) does not cause skin lesions
• There are no worms in ringworm

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• The end