Superficial, cutaneous, and subcutanoues mycoses Flashcards Preview

Micro/Immuno > Superficial, cutaneous, and subcutanoues mycoses > Flashcards

Flashcards in Superficial, cutaneous, and subcutanoues mycoses Deck (14):

Cutaneous mycoses include

dermatophytosis, tinea versicolor, tinea nigra


Dermatophytosis is; transmitted by; diagnose by; treat

very common, caused by three different genera of fungi (epidermophyton, trichophyton, microsporum) that infect only superficial keratinzed structures, produce keratinases, and symptoms called TINEA (jock itch, athlete's foot, ringworm);

fomites or autoinnoculation;

KOH mount after skin/nail scraping, culture on Sabouraud's agar at room temp, PPD with trichophyton, Wood's lamp exam (Microsporum fluorescing);

all affected sites simultaneously w/ topical antifungal cream, alt oral griseofulvin


Tinea versicolor is; diagnose; treat

common, hypo- or hyperpigmented areas on trunk, back, or abdomen, caused by overgrowth of normal flora Malassezia furfur or globosa;

KOH mount of skin scrapings (maybe examine with Wood Lamp or look microscopically for mix of budding yeasts and cigar butt hyphae: aside);

treat with selenium sulfide cream, alt oral azoles


Tinea nigra is; diagnose; treat with

uncommon infection of injured extremity by soil organism werneckii, appears as dark brown spot;

diagnose by KOH mount for thick septate branching hyphae with DARK PIGMENT in their walls, culture on Sabouraud's agar at room temp for shiny black colonies;

topical salicyclic acid (break down infected skin) and topical azole


Subcutaneous mycoses include

sporotrichosis, chromomycosis, mycetoma


Sporotrichosis is; diagnosis; treat with; prevention

caused by Sporothrix spp, thermally dimorphic (mold or yeast) fungi of vegetation that enters skin through small injuries (thorns, splinters); painless ulcer at site spreads up lymphatics over years and if COPD, could be pulmonary symptoms; if immunosuppressed could be disseminated, meningitis;

do biopsy (round or cigar-shaped budding yeasts) and culture at room temp from pus (hyphae and conidia resemble daisies);

normal type with oral azoles, more serious forms with Amphotericin B

Gardening gloves


Chromomycosis is; diagnose by; treat with; prevention

Chromoblastomycosis, caused by a variety of tropical soil fungi; enter by injuries with thorns or splinters to feet, form gradually spreading wartlike or plaque lesions with scattered black dots;

KOH mount for gray or black septate hyphae or conidia, biopsy dark spot for dark brown, round fungal cells inside leukocytes or giant cells;

combo of oral flucytosine, itraconazole, local surgery, heat



Mycetoma is; diagnose by, treat with

rare infection of wounds on extremities by Petriellidium or Madurella from soil; forms abscesses, granulomas, pus with granules; (aside: presentation similar to actinomycosis)

biopsy (see grains in pus; differentiate from actinomycosis with tissue gram stain for gram pos, branching filaments in actinomycetoma grain, and Gomori methenamine silver or PaS stain for larger hyphae of eumycetoma)

combo of surgery, IV amphotericin B; oral azole for home


Candida is

multimorphic: yeastlike, pseudohyphal, and hyphal forms may ALL be present at same disease site. C albicans is the most common normal flora but five other species are also major pathogens in disseminated disease


Candidiasis presents

commonly as thrush (steroid inhalers for asthma/AIDS), vaginitis, diaper rash; less common hand infections (dishwashers), folliculitis (boils), chronic mucocutaneous (genetic CMI deficiency), and full-GI infection (leukemia) appear with relevant predispositions


Candidemia and disseminated disease (organ abscesses)

are becoming major problems in hospitals as people with significantly impaired CMI survive long enough to develop them (chemo, transplants, complex surgeries, vascular devices, ICU)


Diagnose candida by

exam, biopsy (see three things), culture (germ tubes can form), and/or CT


Candida treatment

ramps up with severity: topical azoles and polyenes for superficial, oral azoles for more serious but not life-threatening, add AMPHOTERICIN B for life-threatening; add echinocandins and/or voriconazole for life-threatening drug-resistant


Candida develops

antifungal drug resistance; can and should be tested IN CULTURE!!