Fungal Infections of the Skin Flashcards
Name the 3 most common superficial and cutaneous mycoses, caused by “ringworm”, Malassezia furfur, and Cladosporium werneckii.
Dermatophytosis, tinea versicolor, and tinea nigra, respectively.
What does “tinea” mean?
refers to fungal skin infections, most commonly ringworm/dermatophytes
Epidermophyton, trichophyton, and microsporum are the 3 main genera of what mycosis, and how are they most commonly spread?
Dermatophytosis; spread by direct contact, autoinnoculation, and fomites
What kind of body structures do dermatophytes infect, and where do they tend to form chronic infections?
superficial keratinized structures (ex. skin, hair, nails); chronic infections in warm, humid areas
What causes dermatophytid “id” vesicles to form on a patient’s fingers?
Hypersensitivity reaction to circulating fungal antigen
Name where the following infections occur: tinea capitis, tinea corporis, tinea cruris, tinea pedis.
head, body, groin, foot
What diagnostic test for dermayophytosis involves putting a drop of antigen under the patient’s skin and looking for a hypersensitivity reaction?
PPD with trichophytin
What is the predominant symptom of ringworm?
Itching
What skin infection involves overgrowth of a normal fungal flora on patients who are immunocompromised or have a genetic predisposition?
Tinea versicolor
What is the predominant symptom of tinea versicolor?
superficial hypo-pigmentation
Which cutaneous mycosis presents as a brown spot that may look like melanoma?
Tinea nigra
Which cutaneous mycosis grows shiny black colonies when cultured on Sabouraud’s agar at room temperature?
Tinea nigra
Why does the treatment of tinea nigra require both salicyclic acid and a topical azole?
The salicyclic acid is keratolytic - it breaks down the outer skin so that the azole can get to the fungus, which is growing between keratinized skin layers
How are tinea nigra, sporotrichosis, chromomycosis, and mycetoma introduced into the body?
via trauma that exposes subcutaneous tissue (or just keratizined tissue layers for tinea nigra)
Which subcutaneous mycosis, known as “rose-picker’s disease,” is thermally dimorphic?
Sporotrichosis
Which fungus, also known as chromoblastomycosis or dermititis verrucosa, can best be prevented by wearing shoes?
Chromomycosis
Which subcutaneous mycosis forms granulomas, dark wart-like lesions, and crusting abscesses?
Chromomycosis
Which subcutaneous mycosis forms abscesses, pus, colored granules, and granulomas that may extend to the bone?
Mycetoma
What fungus can be mistaken for the bacteria actinomycosis on both microscopic and physical examination, but does not usually affect the face?
Mycetoma
Which cutaneous mycosis can be diagnosed by PPD with trichophytin or by microsporum florescence under Wood’s lamp?
Dermatophytosis
Which cutaneous fungus appears as thick septate branching hyphae with dark pigment after KOH mount?
Tinea nigra
Which fungus appears as round or cigar-shaped budding yeasts in tissue biopsy, and as daisy-shaped conidia clusters in culture?
Sporotrichosis
Which fungus appear as gray or black septate hyphae or conidia after KOH mount, or as dark brown round fungal cells inside leukocytes and giant cells after biopsy?
Chromomycosis/Chromoblastomycosis
What rare infection can be caused by the soil fungi petriellidium or madurella?
Mycetoma
Which 3 fungal infections are caused by organisms that usually live in soil?
Tinea nigra, chromomycosis, and mycetoma
Which 2 subcutaneous mycoses are most likely to need surgical excision?
Chromoblastomycosis and mycetoma
Is miconazole a topical or oral azole? What about griseofulvin, itraconazole, flucytosine, and selenium sulfide?
miconazole and selenium sulfide are usually topical; griseofulvin, itraconazole, and flucytosine are usually oral
Which fungal infection often present as a painless, chronic ulcer that can develop into a pulmonary infection in a COPD patient, or meningitis in an immunosuppressed patient?
Sporotrichosis
