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158 Cards in this Set
- Front
- Back
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What layer does superficial mycoses affect?
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outermost layer of skin and hair
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Do superficial mycoses induce a cellular response?
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generally do not
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Name the 4 superficial mycoses
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pityriasis versicolor - skin
tinea nigra - skin white piedra - hair black piedra - hair |
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What is pityriasis versicolor?
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fungal infection of the stratum corneum epidermidis
manifests as hypopigmented or hyperpigmented skin patches - usually on upper torso, arms and abdomen (may also cause a folliculitis w/ erythematous papules and pustules on upper trunk) caused by malassezia furfur - found in skin scales as short, curved, septate hyphae and yeast-like cells ("spaghetti & meatballs" appearance) |
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What fungus causes pityriasis versicolor?
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malassezia furfur (lipophilic yeast)
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Malassezia furfur causes what disease?
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pityriasis versicolor
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How is pityriasis versicolor diagnosed?
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KOH mount of skin scales - "spaghetti & meatballs" appearance from combined yeast and hyphal elements
lesions fluoresce yellow under Wood's light (longwave UV) |
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What is the treatment for superficial mycoses?
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hair infections: shave hair + good personal hygene
skin: keratolytics - sodium hyposulfite 25%, selenium sulfide 2.5% |
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Is malassezia furfur part of the normal skin flora?
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yes
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Malassezia furfur requires a medium supplemented with what?
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fatty acids
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What factors increase the incidence of pityriasis versicolor?
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location: tropics
activity: athletes medical: renal transplant pts. |
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Are cultures routine for malassezia furfur?
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no
not routine b/c of special media requirements |
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What is caused by malassezia furfur invasion?
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peritonitis in pts. on chronic ambulatory dialysis
chronic sinusitis pulmonary vasculitis fungemia on infants on IV fat emulsions - blood smears show yeast-like cells |
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What is tinea nigra?
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a superficial infection of the stratum corneum epidermidis
usually manifests as flat brown-black macular lesions on palms and soles (however, may occur in other areas) caused by exophiala werneckii (dimorphic melanin producing fungus) |
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How is tinea nigra diagnoses?
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KOH: darkly pigmented yeast-like cells w/ hyphal fragments
culture: two celled oval structures in early growth; older colonies w/ hyphae |
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What is black piedra?
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a fungal infection of the hair shaft that produces hair breakage
found as hard nodules on infected hair shafts, which house the asci containing spores caused by piedraia hortae - present in perfect state (sexual) when it colonizes the hair shaft and asexual state in culture (unusual) |
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How is black piedra diagnosed?
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microscopic examination of hair which includes the nits of pediculosis
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What disease is caused by exophiala werneckii?
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tinea nigra
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What disease causes flat brown-black lesions on the palms and soles?
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tinea nigra
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What disease causes hyper- or hypopigmented lesions on the upper torso, arms and abdomen?
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pityriasis versicolor
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Which fungi grows in the sexual state when causing disease and grows in the asexual state in culture?
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piedraia hortae - causative agent of black piedra
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What is white piedra?
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a fungal infection of the hair shaft that produces hair breakage
involves the scalp, mustache and beard causes a soft, pasty, cream-colored growth on th hair shafts (sleeve on hair shaft consisting of mycelia) caused by trichosporon asahii (dimorphic yeast-like fungus) |
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What is a bacterial infection that causes similar symptoms to white piedra?
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corynebacterium tenuis - found in people who do not bathe for 3-4 months
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What disease causes a cream colored growth on the hair shafts of the scalp, mustache and beard?
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white piedra
caused by trichosporon asahii |
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How is white piedra diagnosed?
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culture: grows as septate hyphae with arthroconidia, which readily round up to form blastoconidia
grows on all culture except those containing cycloheximide |
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What disease is caused by piedraia hortae?
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black piedra
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What disease is caused by trichosporon asahii?
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white piedra
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What is trichosporonosis?
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fungemia with cutaneous ocular lesions
caused by members of trichosporon (esp. T. beigelii) and blastoschizomyces capitatus |
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What is the DOC for trichospornosis?
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AMB + fluconazole
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What are the risk factors for trichosporonosis?
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neutropenia
corticosteroids |
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What fungi causes a false positive cryptococcal antigen test?
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trichosporon beigelii
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Neutropenia and corticosteroid use predisposes to what disease?
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trichosporonosis
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What fungi are part of the dermatophytes?
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eipdermophyton
microsporum trichophyton (filamentous fungi) |
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What are the two cutaneous mycoses?
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dermatophytosis - caused by dermatophytes (epidermophyton, microsporum, trichophyton)
candidiasis - caused by candida |
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Cutaneous mycoses involve what parts of the body?
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skin
hair nails |
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How are cutaneous mycoses acquired?
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zoophilic - from animals
anthropophilic - from humans |
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Which source of cutaneous mycoses causes less inflammation?
zoophilic or anthropophilic |
anthropophilic
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What is another name for cutaneous mycoses?
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ring worm
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Do cutaneous mycoses invoke an inflammatory response?
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yes
(unlike superficial mycoses) |
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Dermatophytes all possess what?
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keratinases
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Epidermonphyton floccosum commonly cause what disease?
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tinea pedis
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Does tinea pedis invade the hair?
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no
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What fungi exhibit large club-shaped macroconidia and no microconidia?
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epidermophyton floccosum
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Microsporum gypseum commonly cause what disease?
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tinea capitiis
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What occupation predisposes tinea capitiis infection?
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outdoor occupations
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What fungus genera exhibit thick walled, spindle shaped, spiny macroconidia?
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microsporum
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What is the most common dermatophyte?
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trichophyton rubrum
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What is tinea pedis?
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an acute to chronic fungal infection of the feet
aka athlete's foot most commonly caused by T. rubrum, T. mentagrophytes, or E. floccosum |
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How is tinea pedis differentiated from erythrasma?
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erythrasma fluoresces coral red w/ Wood's light
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What is tinea capitis?
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an infection of the skin and hair of the head
predominantly a disease of children predominantly caused by trichophyton tonsurans |
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What are the 3 types of tinea capitis?
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ectothrix - external infecton of the hair shaft
endothrix - internal infection of the hair shaft favus - internal infection of the hair shaft w/ gas bubbles (most serious) |
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What are the characteristics of ectothrix tinea capitis?
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spores surround shaft due to destruction of the cutivle
usally presents as areas of alopecia hairs break off just above the scalp leaving "gray patches" |
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What are the characteristics of endothrix tinea capitis?
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spores inside the shaft
produced by trichophyton species (mainly T. tonsurans) non-fluorescent hair breaks off at the follicle leaving a black dot kerion |
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What are the characteristics of favus?
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caused by trichophyton schoenleinii
thick yellow crusts on scalp composed of hyphal elements hyphae course through the hair shaft w/ air spaces may lead to alopecia w/ scarring |
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What disease does trichophyton schoenleinii cause?
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favus tinea capitis
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What is tinea cruris?
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an acute or chronic fungal infection of the groin
aka jock itch typically presents w/ a scalloped, erythematous, scaling border does not involve the scrotum (however, intertrigo of the groin by candidia albicans are much more common) |
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What is tinea barbae?
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an acute or chronic folliculitis of the beard, neck, or face
caused by trichophyton verrucosum presents w/ unilateral vesiculo-pustular eruption (side farmer turns toward cows when milking) |
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What disease is predominatly caused by trichophyton tonsurans?
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tinea capitis
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What disease is caused by trichophyton verrucosum?
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tinea barbae
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What is onychomycosis?
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fungal infection of the nails
90% caused by dermatophytes (esp. trichophyton rubrum, Epidermophyton floccosum, trichophyton mentagraophytes) |
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What are the 4 types of onychomycosis?
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distal subungal - 90%
proximal subungal - usually in immunocompromised white superficial candida - seen in pts. w/ chronic mucocutaneous candidiasis |
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What layer does subcutaneous mycoses effect?
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cutaneous and subcutaneous tissues of the skin
generally cause by traumatic implantation of normally saprobic fungi and remain localized in cutaneous and subcutaneous tissue chronic, indolent |
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What are the different types of subcutaneous mycoses?
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mycetoma
eumycotic mycetoma chromoblastomycosis sporothrichosis rhinosporidiosis lobomycosis phaeohyphomycosis |
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What are the characteristics of chromoblastomycosis?
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cauliflower-like appearance
caused by a variety of dematiaceous fungy (brown or black pigment in their cell walls) - fonsevaea pedrosi, cladosporium carrionii, phialpohora verrucosa |
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How is chromoblastomycosis diagnosed?
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skin biopsy:
pseudoepitheliomatous hyperplasia (overgrowth of epithelial cells) sclerotic (Medlar) bodies - copper colored cells |
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What is the DOC for chromoblastomycosis?
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flucytosine
itraconazole |
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What is chromoblastomycosis?
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slow development of verrcucous (warty) lesions -> progresses to cauliflower like appearance
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What is sporotrichosis?
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nodular and ulcerative lesions that develop along the lymphatics which drain the site of inoculation
caused by sporothrix schenckii (dimorphic fungus) associated w/ sphangnum moss, splinters from rotting tinbers, and rose thorns |
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What disease does sporothrix schenckii cause?
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sporothrichosis
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What disese does fonsecaea deprosi cause?
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chromoblastomycosis
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What disese does cladosporium carrionii cause?
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chromoblastomycosis
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What disese does phialophora verrucosa?
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chromoblastomybosis
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How is sporothrichosis diagnosed?
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normally not seen even w/ special stains
asteroid bodies (aka Splendore-Hoeppli phenomenon) grows as a budding cigar shaped yeast in culture grows as a branching hyphae w/ conidia at the ends of conidiospores in a rosette pattern diagnosis confirmed by converting the mycelial phase to the yeast phase |
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What fungi causes slow development of verrucous lesions which progress to a cauliflower-like appearance?
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fonsecaea pedrosoi
cladosporium carrionii phialophora verrucosa (chromoblastomycosis) |
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What fungi causes nodular ulcerative lesions that develop along the lymphatics which drain the side of inoculation?
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sporothrix schenckii
(sporothrixosis) |
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What is rhinosporidium seeberi?
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painless pedunculated polyps developing in the nasal area
caused by rhinosporidium seeberi (cannot be cultured) histologic spherules w/ endospores is diagnostic |
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Large spherules w/ endospores within polyps in the nasal area is diagnostic of what disease?
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rhinosporidiosis
(rhinosporidium seeberi) |
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What is the treatment of rhinosporidiosis?
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surgery
AMB dapsone |
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What is lobomycosis?
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keloidal nodules of the face, ears, and upper extremities
caused by loboa loboi (cannot be cultured) histology reveals 10-15 micrometer yeast in long chains |
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What fungi causes keloidal nodules of the face, ears, and upper extremities?
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loboa loboi
(lobomycosis) |
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What is the treatment of lobomycosis?
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surgery
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What is phaeohyphomycosis?
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caused by >40 differend dematiaceous fungi that forms a large subcutaneous cyst -> may cause disseminated disease in the immunocompromised
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What fungal diseases are endemic to the Ohio and Mississippi River Valleys?
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histoplasmosis
blastomycosis |
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Which geographic mycoses are usually asymptomatic?
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histoplasmosis
cocciodiomycosis |
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What fungal disease is endemic to Central and South America?
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paracoccidiomycosis
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What fungal disease is endemic to SW United States (California)?
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coccidiomycosis
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Which geographic mycoses can cause outbreaks in humans and animals together?
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blastomycosis
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What is the typical patient with blastomycosis?
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middle aged male w/ extensive outdoor exposure
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Which geographic mycosis causes mediastinal fibrosis?
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histoplasmosis
from immune rxn to fungus resulting in fibrous proliferation in the mediastinum |
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Which fungal disease causes oral, nasal, facial nodular ulcerative skin lesions?
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paracoccidiodomycosis
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What fungus causes TB like symptoms (upper lobe calcified cavities) and calcified granulomas in the liver and spleen?
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histoplasma capsulatum
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What fungus is diagnosed by a change from a slow-growing white mold at 25C to budding yeast at 37C?
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paracoccidiodomycosis brasiliensis
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What fungus forms painless, warty dome shaped papules that may ulcerate?
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histoplasma capsulatum var duboisii
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When does coccidiodomycosis most prevalent?
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dry summer and autumn, esp. after heavy rainy season
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Candidiasis is due mostly to which candida species?
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candidia albicans
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Which candidia is associated to a vascular line?
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candidia parapsilosis
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Which candidia is most common in leukemics receiving fluconazole?
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candidia krusei
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Candidia krusei is resistant to what antifungal?
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fluconazole
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Candidia lusitaniae is resistant to which antifungal?
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AMB
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Which candidia is confused with candidia albicans?
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candidia stellatoidea
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What factors predispose candidiasis?
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neutropenia
depressed CMI chemotherapy broad spectrum antibiotics IV catheters abdominal surgury (esp. upper GI) diabetes |
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What factors predispose to candidia skin infections?
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warm, moist skin
skin folds of the obese |
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What predisposes to candidia vulvovaginitis?
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antibiotics
steroids BCP pregnancy diabetes HIV |
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What factors predispose oral thrush?
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neonates
denture wearers asthmatics (due to inhaled steroids) AIDS pts. |
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What factors predispose chronic mucocutaneous candidiasis?
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problems w/ CMI against candidia
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What is chronic mucocutaneous candidiasis associated with?
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thymomas
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What factors predispose a patient to disseminated candidiasis?
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intense chemotherapy w/ profound neutropenia
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How is candidasis diagnosed?
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identification of candidia albicans by germ test tube test for production of hyphal outgrowths at 37C
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What is used to treat cutaneous or mucosal candidasis?
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topical azoles
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What fungi cause apsergillosis?
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aspergilla fumigatus
aspergilla flavus aspergilla niger |
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What causes episodic asthma, brown mucus plugs and elevated IgE?
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chronic bronchopulmonary aspergillosis
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Noninvasive allergic sinusitis is found in what type of patient?
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pts. w/ chronic pansinusitis and polyps
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What causes a greenish-black material with a peanut butter consistency?
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noninvasive allergic sinusitis (aspergillosis)
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What is allergic mucin composed of?
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eosinophils
charcot laden crystals cellular debris sparse fungal hyphae |
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Where is noninvasive sinus mycetoma generally locallized to?
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maxillary sinus
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How is aspergillosis diagnosed?
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biopsy of infected tissue w/ histologic examination for branching septate hyphae
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What fungi most commonly cause zygomycosis?
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rhizopus arrhizus
absidia corymbifera |
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What factors predispose zygomycosis?
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metabolic acidosis (diabetics w/ ketoacidosis)
hyperglycemia leukopenia deferroxamine therapy |
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What enzyme does fungi that cause zygomycosis carry?
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ketoreductase
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Which fungal disease causes perioribital edema, proptosis, epistaxis, and necrotic black eschars in the nares or on the hard palate?
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zygomycosis
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What genera are most frequently involved in phaeohyphomycosis?
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curvularia
bipolaris exserohilum alternaria exophiala |
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What protein is present in the cell wall of all fungi associated with phaeohyphomycosis?
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melanin
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How is phaeohyphomycosis diagnosed?
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tissue biopsy
Fontana Masson stain to detect melanin |
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What fungi genera are involved with hyalohyphomycosis?
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fusarium
scedosporium penicillium paecilomyces |
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What fungal disease is unresponsive to AMB or azoles?
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hyalohyphomycosis
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What fungi is characterized by intracellular yeast cells with clear central septation?
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penicillium marneffei
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What are the 3 stages of pneumocystis carinii?
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cyst
precyst trophozoite |
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What fungus causes a chronic skin infection in immunocompromised patients, often on corticosteroids, and commonly involves the olecranon bursa?
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protothecia wickerhamii
(protothecosis) |
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What type of fungus obtains nutrients from dead and decaying organic matter?
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saprobes
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What type of fungus lives together with another organism to mutal advantage?
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symbionts
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What type of fungus lives together to the benefit of one organism?
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commensals
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What type of fungus lives off another host?
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parasites
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What is a plasmalemma?
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the cell membrane
encloses the cytoplasm composed of glycoprotein, lipids and ergosterol |
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What is the fungal cell wall composed of?
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chitin
a polymer of N-acetyl glucosamine |
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What are mannans?
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glucans layered on top of the cell wall
may form a capsule |
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Sabouraud's medium contains what?
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D-glucose
peptone water |
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Why is Sabouraud's medium selective for fungi?
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b/c of acid pH and high sugar content
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What may be added to Sabouraud's medium to inhibit saprobic fungi?
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cycloheximide
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What are the symptoms of an acute fungal allergic reaction?
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fever
chills cough SOB (4-8 hours after exposure) |
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What are the symptoms of a chronic fungal allergy?
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insidious onset of cough, SOB, and weight loss
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What is mycetismus?
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mushroom poisoning
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What fungus is the most common cause of mycetismus?
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amanita phalloides
(the death cap mushroom) |
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What is the principal toxin of amanita phalloides?
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alpha amantin
(inhibitor of RNA pol. II, heat stable, water insoluable) |
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What is the mechanism of action of alpha amantin?
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inhibits RNA pol. II
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What are the symptoms in phase I of mycetismus?
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watery diarrhea w/ vomiting 6-24 hours after ingestion
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What are the symptoms in phase II of mycetismus?
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none
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What are the symptoms in phase III of mycetismus?
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acute hepatic and renal failure 3-6 days after ingestion
(50-90% mortality) |
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What is mycotoxicoses?
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ingestion of toxins of fungal origin in foods which have been damaged by molds
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Name the 3 mycotoxicoses toxins?
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ergot alkaloids
physhotrophics aflatoxins |
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Ergot alkaloids are produced by what fungus?
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claviceps purpurea
(when it infects grain, esp. rye) |
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What does claviceps purpurea infect?
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grains, esp. rye
(produces ergot alkaloids) |
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What do ergot alkaloids cause?
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intense peripheral vasoconstriction leading to gangrene
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What toxin is produced by aspergillus fumigatus?
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aflatoxins
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What fungus produces aflatoxins?
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aspergillus fumigatus
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What do aflotoxins cause?
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hemorrhage and liver necrosis
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What fungus produces trichothecene toxin (T-2)?
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fusarium sporotrichoides
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What does trichothecene toxin cause?
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leukopenia
mucositis |
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What is the lethal dose of tricothecene toxin?
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50 mg
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