SUPERFICIAL MYCOSES

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SUPERFICIAL MYCOSES
By
Dr. Emad AbdElhameed Morad
Lecturer of Medical Microbiology and Immunology
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Superficial mycoses
1- Pityriasis versicolor Skin 2-
Tinea nigra Skin 3- Black piedra
Hair 4- White piedra Hair
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Pityriasis versicolor

• Causative agent
• Malassezia furfur is the causative agent.
• Malasseszia furfur is a lipophilic fungus living
  on the skin as part of the normal flora.
• So, it is cultivated on media containing fatty
  substances like olive oil.

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• Diseases caused by Malassezia furfur
• Pityriasis versicolor is associated with
  hyperpigmented or hypopigmented macules usually
  on the chest and upper back of the patients.
• Pityriasis folliculitis.
• Catheter acquired fungemia in patients receiving
  total parenteral nutrition containing lipid
  emulsion.

Pityriasis versicolor
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• Laboratory diagnosis
• Woods lamp
• Woods light is ultraviolet light at wave length
  365 nm.
• The lamp is held four or five inches from the
  affected skin. If pityriasis versicolor is
  present on the skin, the affected skin will
  appear yellowish green in color.
• Specimen
• Skin scrapings from the lesions.
• Direct Microscopy
• The skin scrapings are mounted in 10-20 KOH.
• It will show spherical budding cells and short
  unbranched angular septate hyphae (spaghetti and
  meat balls).
• These microscopic features are diagnostic for
  Malassezia furfur and culture is not necessary.

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• Treatment
• Daily application of selenium sulfide.
• Topical or oral azoles are very effective.

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Tinea nigra

• Causative agent
• Exophiala (Hortae) werneckii is the causative
  agent.
• It is a saprophytic fungus which occurs in the
  soil.
• It is a dematicaeous fungus (contains melanin in
  its cell wall and appear dark in color under the
  microscope).

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• Clinical picture
• Brown to black discoloration of the palm of the
  hand.
• So, Tinea nigra is also called Tinea palmaris.
• But, it may affect the sole of the foot.

Tinea nigra
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• Laboratory diagnosis
• Specimen
• Skin scrapings from the lesions.
• Direct Microscopy
• The skin scrapings are mounted in 10-20 KOH.
• It will show brown to black two celled yeast
  cells branched septate hyphae.

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• Treatment
• Keratolytic solutions like salicylic acid.
• Azoles are also effective.

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Black piedra

• Piedraia hortai is the causative agent.
• It is a dematicaeous mold.
• It affects the hair like beard, moustache and
  scalp pubic hair.
• It causes brown to black hard nodules around the
  hair shaft.
• It is treated by removal of infected hairs
  topical antifungal drugs.

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White piedra

• Trichosporon beigelii is the causative agent.
• It is a mold.
• It affects the hair.
• It causes large, white to yellow soft nodules
  around the hair shafts.
• It is treated similar to black piedra.

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