Fungi Flashcards
What can Malassezia furfur cause?
Pityriasis versicolor
What is the morphology of Malassezia furfur?
“Spaghetti and meatballs”
What happens in Pityriasis versicolor?
Hypo or hyperpigmented patches on the skin.
Surrounding skin darkens with sunlight while the patches remain white.
How do we diagnose Malassezia furfur infection?
KOH prep:
Reveals short, curved, unbranched hyphae, with spherical yeast cells (looks like spaghetti with meatballs).
What is the location of the Malassezia furfur infection?
Superficial
What is the morphology of Exophiala werneckii?
Brown-pigmented, branched, septate hyphae and budding yeast cells.
What can Exophiala werneckii cause?
Tina nigra
What happens in tinea nigra?
Dark brown to black patches on the soles of the hands and feet.
How do we diagnose Exophiala werneckii?
KOH prep:
Brown pigmented, branched septate hyphae and budding yeast cells.
What is the location of Exophiala werneckii infection?
Superficial
Where are Microsporum, Trichophyton species, and Epidermophyton floccosum found?
Depending on the particular species:
- Soil
- Animals
- Humans
What can Microsporum, Trichophyton, and Epidermophyton floccosum cause?
Dermatophytosis. Tinea corporis - ringworm Tinea cruris - jock itch Tinea pedis - athlete's foot Tinea capitis - scalp Tinea unguium - Onychomycosis
How do we diagnose Microsporum, Trichophyton, and Epidermophyton floccosum species?
- KOH: branched hyphae.
2. Wood’s light: certain species of Microsporum will fluoresce under UV light.
What do Microscporum, Trichophyton, and Epidermophyton floccosum secrete?
Keratinase
What is the location of Microsporum, Trichophyton, and Epidermophyton floccosum infection?
Cutaneous
Where is Sporothrix schenckii found?
On rose thorns.
What can Sporothrix schenckii cause?
Sporotrichosis
What happens in sporotrichosis?
- Subcutaneous nodule gradually appears at site of thorn prick.
- This nodule becomes necrotic and ulcerates.
- This ulcer heals but new nodules pop up nearby along the lymphatic tracts.
How do we diagnose Sporothrix schenckii?
Dimorphic:
Culture at 25C –> branching hyphae.
Culture at 37C –> yeast cells.
What is the location of Sporotrhix schenckii infection?
Subcutaneous
Where are Phialophora verrucosa, Cladosporium carrionii, Fonsecaea species found?
These copper-colored soil saprophytes can be found on rotting wood.
What is the morphology of Phialophora verrucosa, Cladosporium carrionii, and Fonsecaea species?
Sclerotic bodies: copper colored cells.
What can Phialophora verrucosa, Cladosporium carrionii, and Fonsecaea species?
Chromoblastomycosis
What happens in chromoblastomycosis?
Following a puncture wound, a small violet wart-like lesion develops.
With time, clusters of these skin lesions can develop. (Resembling cauliflower)
How do we diagnose Phialophora verrucosa, Cladosporium carrionii, and Fonsecaea species?
Skin scrappings with KOH prep reveal copper-colored cells, called sclerotic bodies.
What is the location of Phialophora verrucosa, Cladosporium carrionii and Fonsecaea species infection?
Subcutaneous
Where is Coccidioides immitis found?
- Desert areas of the southwestern US and northern Mexico.
2. Respiratory transmission.
What is the morphology of Coccidioides immitis?
Dimorphic:
- Mycelial forms with spores at 25C.
- Yeast forms at 37C.
What happens in Coccidioidomycosis?
- Asymptomatic (in most persons)
- Pneumonia
- Disseminated –> affects lung, skin, bones, meninges.
What is useful to keep in mind about coccidioidomycosis?
A small percentage of individuals with this infection will develop painful erythematous nodular lesions called erythema nodosum.
How do we diagnose Coccidioides immitis infection?
- Biopsy of affected tissue: lung biopsy, skin biopsy etc.
a. Silver stain or KOH prep.
b. Culture on Sabouraud’s agar. - Serology
- Skin test
What is the location of Coccidioides immitis infection?
Systemic