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158 Cards in this Set

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What layer does superficial mycoses affect?
outermost layer of skin and hair
Do superficial mycoses induce a cellular response?
generally do not
Name the 4 superficial mycoses
pityriasis versicolor - skin
tinea nigra - skin

white piedra - hair
black piedra - hair
What is pityriasis versicolor?
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)
What fungus causes pityriasis versicolor?
malassezia furfur (lipophilic yeast)
Malassezia furfur causes what disease?
pityriasis versicolor
How is pityriasis versicolor diagnosed?
KOH mount of skin scales - "spaghetti & meatballs" appearance from combined yeast and hyphal elements

lesions fluoresce yellow under Wood's light (longwave UV)
What is the treatment for superficial mycoses?
hair infections: shave hair + good personal hygene

skin: keratolytics - sodium hyposulfite 25%, selenium sulfide 2.5%
Is malassezia furfur part of the normal skin flora?
yes
Malassezia furfur requires a medium supplemented with what?
fatty acids
What factors increase the incidence of pityriasis versicolor?
location: tropics
activity: athletes
medical: renal transplant pts.
Are cultures routine for malassezia furfur?
no

not routine b/c of special media requirements
What is caused by malassezia furfur invasion?
peritonitis in pts. on chronic ambulatory dialysis

chronic sinusitis

pulmonary vasculitis

fungemia on infants on IV fat emulsions - blood smears show yeast-like cells
What is tinea nigra?
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)
How is tinea nigra diagnoses?
KOH: darkly pigmented yeast-like cells w/ hyphal fragments

culture: two celled oval structures in early growth; older colonies w/ hyphae
What is black piedra?
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)
How is black piedra diagnosed?
microscopic examination of hair which includes the nits of pediculosis
What disease is caused by exophiala werneckii?
tinea nigra
What disease causes flat brown-black lesions on the palms and soles?
tinea nigra
What disease causes hyper- or hypopigmented lesions on the upper torso, arms and abdomen?
pityriasis versicolor
Which fungi grows in the sexual state when causing disease and grows in the asexual state in culture?
piedraia hortae - causative agent of black piedra
What is white piedra?
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)
What is a bacterial infection that causes similar symptoms to white piedra?
corynebacterium tenuis - found in people who do not bathe for 3-4 months
What disease causes a cream colored growth on the hair shafts of the scalp, mustache and beard?
white piedra

caused by trichosporon asahii
How is white piedra diagnosed?
culture: grows as septate hyphae with arthroconidia, which readily round up to form blastoconidia

grows on all culture except those containing cycloheximide
What disease is caused by piedraia hortae?
black piedra
What disease is caused by trichosporon asahii?
white piedra
What is trichosporonosis?
fungemia with cutaneous ocular lesions

caused by members of trichosporon (esp. T. beigelii) and blastoschizomyces capitatus
What is the DOC for trichospornosis?
AMB + fluconazole
What are the risk factors for trichosporonosis?
neutropenia
corticosteroids
What fungi causes a false positive cryptococcal antigen test?
trichosporon beigelii
Neutropenia and corticosteroid use predisposes to what disease?
trichosporonosis
What fungi are part of the dermatophytes?
eipdermophyton
microsporum
trichophyton

(filamentous fungi)
What are the two cutaneous mycoses?
dermatophytosis - caused by dermatophytes (epidermophyton, microsporum, trichophyton)

candidiasis - caused by candida
Cutaneous mycoses involve what parts of the body?
skin
hair
nails
How are cutaneous mycoses acquired?
zoophilic - from animals
anthropophilic - from humans
Which source of cutaneous mycoses causes less inflammation?

zoophilic or anthropophilic
anthropophilic
What is another name for cutaneous mycoses?
ring worm
Do cutaneous mycoses invoke an inflammatory response?
yes

(unlike superficial mycoses)
Dermatophytes all possess what?
keratinases
Epidermonphyton floccosum commonly cause what disease?
tinea pedis
Does tinea pedis invade the hair?
no
What fungi exhibit large club-shaped macroconidia and no microconidia?
epidermophyton floccosum
Microsporum gypseum commonly cause what disease?
tinea capitiis
What occupation predisposes tinea capitiis infection?
outdoor occupations
What fungus genera exhibit thick walled, spindle shaped, spiny macroconidia?
microsporum
What is the most common dermatophyte?
trichophyton rubrum
What is tinea pedis?
an acute to chronic fungal infection of the feet

aka athlete's foot

most commonly caused by T. rubrum, T. mentagrophytes, or E. floccosum
How is tinea pedis differentiated from erythrasma?
erythrasma fluoresces coral red w/ Wood's light
What is tinea capitis?
an infection of the skin and hair of the head

predominantly a disease of children

predominantly caused by trichophyton tonsurans
What are the 3 types of tinea capitis?
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)
What are the characteristics of ectothrix tinea capitis?
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"
What are the characteristics of endothrix tinea capitis?
spores inside the shaft

produced by trichophyton species (mainly T. tonsurans)

non-fluorescent

hair breaks off at the follicle leaving a black dot

kerion
What are the characteristics of favus?
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
What disease does trichophyton schoenleinii cause?
favus tinea capitis
What is tinea cruris?
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)
What is tinea barbae?
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)
What disease is predominatly caused by trichophyton tonsurans?
tinea capitis
What disease is caused by trichophyton verrucosum?
tinea barbae
What is onychomycosis?
fungal infection of the nails

90% caused by dermatophytes (esp. trichophyton rubrum, Epidermophyton floccosum, trichophyton mentagraophytes)
What are the 4 types of onychomycosis?
distal subungal - 90%

proximal subungal - usually in immunocompromised

white superficial

candida - seen in pts. w/ chronic mucocutaneous candidiasis
What layer does subcutaneous mycoses effect?
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
What are the different types of subcutaneous mycoses?
mycetoma
eumycotic mycetoma
chromoblastomycosis
sporothrichosis
rhinosporidiosis
lobomycosis
phaeohyphomycosis
What are the characteristics of chromoblastomycosis?
cauliflower-like appearance

caused by a variety of dematiaceous fungy (brown or black pigment in their cell walls) - fonsevaea pedrosi, cladosporium carrionii, phialpohora verrucosa
How is chromoblastomycosis diagnosed?
skin biopsy:

pseudoepitheliomatous hyperplasia (overgrowth of epithelial cells)

sclerotic (Medlar) bodies - copper colored cells
What is the DOC for chromoblastomycosis?
flucytosine
itraconazole
What is chromoblastomycosis?
slow development of verrcucous (warty) lesions -> progresses to cauliflower like appearance
What is sporotrichosis?
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
What disease does sporothrix schenckii cause?
sporothrichosis
What disese does fonsecaea deprosi cause?
chromoblastomycosis
What disese does cladosporium carrionii cause?
chromoblastomycosis
What disese does phialophora verrucosa?
chromoblastomybosis
How is sporothrichosis diagnosed?
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
What fungi causes slow development of verrucous lesions which progress to a cauliflower-like appearance?
fonsecaea pedrosoi
cladosporium carrionii
phialophora verrucosa

(chromoblastomycosis)
What fungi causes nodular ulcerative lesions that develop along the lymphatics which drain the side of inoculation?
sporothrix schenckii

(sporothrixosis)
What is rhinosporidium seeberi?
painless pedunculated polyps developing in the nasal area

caused by rhinosporidium seeberi (cannot be cultured)

histologic spherules w/ endospores is diagnostic
Large spherules w/ endospores within polyps in the nasal area is diagnostic of what disease?
rhinosporidiosis

(rhinosporidium seeberi)
What is the treatment of rhinosporidiosis?
surgery
AMB
dapsone
What is lobomycosis?
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
What fungi causes keloidal nodules of the face, ears, and upper extremities?
loboa loboi

(lobomycosis)
What is the treatment of lobomycosis?
surgery
What is phaeohyphomycosis?
caused by >40 differend dematiaceous fungi that forms a large subcutaneous cyst -> may cause disseminated disease in the immunocompromised
What fungal diseases are endemic to the Ohio and Mississippi River Valleys?
histoplasmosis
blastomycosis
Which geographic mycoses are usually asymptomatic?
histoplasmosis
cocciodiomycosis
What fungal disease is endemic to Central and South America?
paracoccidiomycosis
What fungal disease is endemic to SW United States (California)?
coccidiomycosis
Which geographic mycoses can cause outbreaks in humans and animals together?
blastomycosis
What is the typical patient with blastomycosis?
middle aged male w/ extensive outdoor exposure
Which geographic mycosis causes mediastinal fibrosis?
histoplasmosis

from immune rxn to fungus resulting in fibrous proliferation in the mediastinum
Which fungal disease causes oral, nasal, facial nodular ulcerative skin lesions?
paracoccidiodomycosis
What fungus causes TB like symptoms (upper lobe calcified cavities) and calcified granulomas in the liver and spleen?
histoplasma capsulatum
What fungus is diagnosed by a change from a slow-growing white mold at 25C to budding yeast at 37C?
paracoccidiodomycosis brasiliensis
What fungus forms painless, warty dome shaped papules that may ulcerate?
histoplasma capsulatum var duboisii
When does coccidiodomycosis most prevalent?
dry summer and autumn, esp. after heavy rainy season
Candidiasis is due mostly to which candida species?
candidia albicans
Which candidia is associated to a vascular line?
candidia parapsilosis
Which candidia is most common in leukemics receiving fluconazole?
candidia krusei
Candidia krusei is resistant to what antifungal?
fluconazole
Candidia lusitaniae is resistant to which antifungal?
AMB
Which candidia is confused with candidia albicans?
candidia stellatoidea
What factors predispose candidiasis?
neutropenia
depressed CMI
chemotherapy
broad spectrum antibiotics
IV catheters
abdominal surgury (esp. upper GI)
diabetes
What factors predispose to candidia skin infections?
warm, moist skin
skin folds of the obese
What predisposes to candidia vulvovaginitis?
antibiotics
steroids
BCP
pregnancy
diabetes
HIV
What factors predispose oral thrush?
neonates
denture wearers
asthmatics (due to inhaled steroids)
AIDS pts.
What factors predispose chronic mucocutaneous candidiasis?
problems w/ CMI against candidia
What is chronic mucocutaneous candidiasis associated with?
thymomas
What factors predispose a patient to disseminated candidiasis?
intense chemotherapy w/ profound neutropenia
How is candidasis diagnosed?
identification of candidia albicans by germ test tube test for production of hyphal outgrowths at 37C
What is used to treat cutaneous or mucosal candidasis?
topical azoles
What fungi cause apsergillosis?
aspergilla fumigatus
aspergilla flavus
aspergilla niger
What causes episodic asthma, brown mucus plugs and elevated IgE?
chronic bronchopulmonary aspergillosis
Noninvasive allergic sinusitis is found in what type of patient?
pts. w/ chronic pansinusitis and polyps
What causes a greenish-black material with a peanut butter consistency?
noninvasive allergic sinusitis (aspergillosis)
What is allergic mucin composed of?
eosinophils
charcot laden crystals
cellular debris
sparse fungal hyphae
Where is noninvasive sinus mycetoma generally locallized to?
maxillary sinus
How is aspergillosis diagnosed?
biopsy of infected tissue w/ histologic examination for branching septate hyphae
What fungi most commonly cause zygomycosis?
rhizopus arrhizus
absidia corymbifera
What factors predispose zygomycosis?
metabolic acidosis (diabetics w/ ketoacidosis)

hyperglycemia

leukopenia

deferroxamine therapy
What enzyme does fungi that cause zygomycosis carry?
ketoreductase
Which fungal disease causes perioribital edema, proptosis, epistaxis, and necrotic black eschars in the nares or on the hard palate?
zygomycosis
What genera are most frequently involved in phaeohyphomycosis?
curvularia
bipolaris
exserohilum
alternaria
exophiala
What protein is present in the cell wall of all fungi associated with phaeohyphomycosis?
melanin
How is phaeohyphomycosis diagnosed?
tissue biopsy
Fontana Masson stain to detect melanin
What fungi genera are involved with hyalohyphomycosis?
fusarium
scedosporium
penicillium
paecilomyces
What fungal disease is unresponsive to AMB or azoles?
hyalohyphomycosis
What fungi is characterized by intracellular yeast cells with clear central septation?
penicillium marneffei
What are the 3 stages of pneumocystis carinii?
cyst
precyst
trophozoite
What fungus causes a chronic skin infection in immunocompromised patients, often on corticosteroids, and commonly involves the olecranon bursa?
protothecia wickerhamii
(protothecosis)
What type of fungus obtains nutrients from dead and decaying organic matter?
saprobes
What type of fungus lives together with another organism to mutal advantage?
symbionts
What type of fungus lives together to the benefit of one organism?
commensals
What type of fungus lives off another host?
parasites
What is a plasmalemma?
the cell membrane
encloses the cytoplasm
composed of glycoprotein, lipids and ergosterol
What is the fungal cell wall composed of?
chitin
a polymer of N-acetyl glucosamine
What are mannans?
glucans layered on top of the cell wall
may form a capsule
Sabouraud's medium contains what?
D-glucose
peptone
water
Why is Sabouraud's medium selective for fungi?
b/c of acid pH and high sugar content
What may be added to Sabouraud's medium to inhibit saprobic fungi?
cycloheximide
What are the symptoms of an acute fungal allergic reaction?
fever
chills
cough
SOB

(4-8 hours after exposure)
What are the symptoms of a chronic fungal allergy?
insidious onset of cough, SOB, and weight loss
What is mycetismus?
mushroom poisoning
What fungus is the most common cause of mycetismus?
amanita phalloides
(the death cap mushroom)
What is the principal toxin of amanita phalloides?
alpha amantin
(inhibitor of RNA pol. II, heat stable, water insoluable)
What is the mechanism of action of alpha amantin?
inhibits RNA pol. II
What are the symptoms in phase I of mycetismus?
watery diarrhea w/ vomiting 6-24 hours after ingestion
What are the symptoms in phase II of mycetismus?
none
What are the symptoms in phase III of mycetismus?
acute hepatic and renal failure 3-6 days after ingestion
(50-90% mortality)
What is mycotoxicoses?
ingestion of toxins of fungal origin in foods which have been damaged by molds
Name the 3 mycotoxicoses toxins?
ergot alkaloids
physhotrophics
aflatoxins
Ergot alkaloids are produced by what fungus?
claviceps purpurea
(when it infects grain, esp. rye)
What does claviceps purpurea infect?
grains, esp. rye
(produces ergot alkaloids)
What do ergot alkaloids cause?
intense peripheral vasoconstriction leading to gangrene
What toxin is produced by aspergillus fumigatus?
aflatoxins
What fungus produces aflatoxins?
aspergillus fumigatus
What do aflotoxins cause?
hemorrhage and liver necrosis
What fungus produces trichothecene toxin (T-2)?
fusarium sporotrichoides
What does trichothecene toxin cause?
leukopenia
mucositis
What is the lethal dose of tricothecene toxin?
50 mg