Fungal infections of skin and soft tissue Flashcards
What are the superficial mycoses?
Pityriasis versicolor, tinea nigra, black piedra, white piedra
What is the cause of pityriasis versicolor?
Malassezia furfur
Where is pityriasis versicolor normally found?
Areas of the body rich in sebaceous glands (head, trunk, upper back)
What are the clinical symptoms of pityriasis versicolor?
Numerous irregularly shaped yelllow / brown scaly patches; failure to tan
What is the diagnosis for pityriasis versicolor?
Direct observation - KOH prep (“spaghetti and meatballs”)
What is the cause of tinea nigra?
Exophiala werneckii
How is tinea nigra transmitted?
Traumatic inoculation / contamination with soil, sewage, wood, compost
What is the clinical presentation of tinea nigra?
Distinct oval-shaped brown/black lesions on hands and feet
How is tinea nigra diagnosed?
KOH prep on skin scrapings reveal two-celled yeast forms containing dark pigment
Where is black piedra most common? White piedra?
- Black - tropics 2. White - southern US
What are the clinical symptoms of black piedra?
Hard, firmly attached gritty nodules on hair, primarily scalp
What are the clinical symptoms of white piedra?
Soft, loosely attached white / light brown nodules usually on pubic or axillary hair, beards, eyebrows
What is the cause of cutaneous mycoses?
Dermatophytes
What are the three most clinically relevant dermatophytes?
Microsporum, trichophyton, epidermophyton
What do the dermatophytes use as a nutrient source?
Keratin
What is used to treat tinea capitis?
Griseofulvin
Candida exists in which form in normal flora?
Yeast
Candida exists in which form in tissues?
Hyphal
What is the recommended treatment for disseminated candidiasis?
IV amphotericin B with or without fluconazole
What are the subcutaneous mycoses?
Sporotrichosis, chromoblastomycosis, mycetoma
How is sporotrichosis transmitted?
Traumatic inoculation via rose thorns, wood splinters, sphagnum moss
What are the clinical symptoms of sporotrichosis?
Inflammation at site of inoculation followed by development of painless granulomatous lesion which eventually ulcerates to create an open sore
How is sporotrichosis diagnosed?
Cultivation from tissue or pus - mold converts to yeast form at 37 C
How is sporotrichosis treated?
Oral potassium iodide, oral azoles (sever)
How is chromoblastomycosis transmitted?
Traumatic inoculation of darkly pigmented soil fungi
What is the clinical symptoms of chromoblastomycosis?
Initially presents as a wart like lesion and slowly develops to red/gray cauliflower like lesion (painless)
What are Medlar bodies?
Copper colored spherical cells seen in tissues during chromoblastomycosis infection
What is the diagnosis for chromoblastomycosis?
Brown pigmented hyphae in skin scrapings and presence of Medlar bodies
What is the replicating form of chromoblastomycosis?
Medlar bodies
What is the treatment for chromoblastomycosis?
Surgical removal, 5-fluorocytosine
How is mycetoma transmitted?
Traumatic inoculation of soil-inhabiting fungi
What is the clinical syndrome associated with mycetoma?
Slow growing papule at site of infection that ulcerates to release pus and blood - underlying bone becomes involved to create pitted lesions
What is the diagnosis for mycetoma?
Direct observation of colored “grains” in pus, tissue, or discharge - compacted hyphae and conidia
