Mycology (Skin) Part 2 Flashcards
What are the 3 types of skin fungi?
Superficial mycoses, Cutaneous mycoses, and Subcutaneous mycoses.
What is the causitive agent of Pityriasis versicolor?
Malassezia furfur; A lipophilic yeast that is found worldwide. Infection is common in people with oily skin.
How is Pityriasis versicolor transmitted?
Direct transfer of infected keratinous material; Causes hypo/hyperpigmented patches of discoloration due to interfering with melanin production.
How is Pityriasis versicolor diagnosed?
They have a ‘spaghetti and meatball’ apperance in a microscope; Treat with topical azoles.
Name the dermatophytes
Tichonphyton, Epidermophyton, and Microsporum; They all invade the skin, hair or nails resulting in indolent lesions of skin and appendages.
Describe the dermatophytes
Keratinophilic and keratinolytic; skin infections only affect the outer layer of epidermis. Found worldwide.
Explain the habitats of the dermatophytes.
Can be Geophilic, Zoophilic or Anthrophilic; Appear clinically as ringworms.
How are dermatophytes diagnosed?
Centripetal raised ring of inflammatory scaling with lesion center; Treat with azoles
What are the main subcutaneous mycoses?
Sporotrichosis, Chromoblastomycosis, Subcutaneous phaeohyphomycosis; Sourced from soil and decaying vegetation.
Describe Sporotrichosis.
A subcutaneous infection caused by the dimorphic Sporothrix schenckii; Acquired by traumatic inoculation. Disease spreads by lymph. Found in warm climates
How does Sporothrix schenckii present clinically?
Chronic nodular/ulcerative lesions appear 2 weeks post exposure; Develops along lymphatics that drain site of infection.
How is Sporothrix schenckii diagnosed?
Splendore-Hoeppli material (asterioid body) surrounds yeast form of fungus; Non-specific. A sporotrichin skin test or latex agglutination procedure is done. Treat with potassium iodide.
Discuss Chromoblastomycosis.
Slow growing verrucous (warty) nodules or plaques; Fonsecaea pedrosoi in the Americas. Found in the tropics
How does Chromoblastomycosis present clinically?
Direct traumatic inoculation required; No person-to-person transmission. Presents with cauliflower like nodules.
How is Chromoblastomycosis diagnosed?
Pigmented hyphae; Sclerotic bodies in infected tissues. Treat with Itraconazole.
