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106 Cards in this Set
- Front
- Back
Define where in the body the superficial mycoses are found
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Occur in outer dead layers of skin and hair
- do not penetrate living tissue |
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Explain why a patient would seek medical attention for a superficial mycoses
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usually because infection is unsightly, not because lesions are painful
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define the term keratinophyllic.
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enzymes capable of breaking down keratin found in skin and hair
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List the genus and species that are causes of superficial mycoses
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Piedraia hortae
Trichosporon beigelii Phaeoannellomyces werneckii Malassezia furfur |
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Describe the types of infections caused by superficial mycoses
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Causes;
Piedras and Tineas |
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Describe Piedras
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means stone
hair infection where the nodules of fungal elements surrounds hair shaft. no discomfort or hair loss. does not involve the base of the shaft or follicle |
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Describe black piedra
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-caused by Piedraia hortae
- occurs on scalp and forms nodules on hair |
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Lab ID of Piedraia hortae
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Macroscopic- dark brown colonies
Microscopic- dematiaceous septate hyphae |
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Treatment of Piedraia hortae
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removal of infected hair shafts with topical fungicides
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Describe white piedra
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caused by Trichosporon Beiglii
- occurs on facial and genital hair - occasionally part of normal skin flora - nodular swellings that weaken hair and cause it to break off |
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Lab ID of Trichosporon Beiglii
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-causes white piedra
- presence of blastoconidia and arthroconidia - produces creamy white yeast-like colonies on standard lab media |
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Treatment of Trichosporon Beiglii
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shave area
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Describe tineas
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-infections of hair, nails, skin
-outermost cornified laryers of epidermis |
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Explain tinea nigra
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-caused by Phaeoannellomyces werneckii
- palms of hands and soles of feet have brown to black nonscaly macules - non inflammatory - mold morphology |
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Lab ID of Phaeoannellomyces werneckii
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-causes tinea nigra
- skin scraping in 10-20% KOH - older mycelial portion of colony showing; hyphae with annellides in clusters |
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Explain tinea versicolor
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caused by Malassezia furfur
- common skin flora - parch lesions or scaling skin of varying pigments - also described as fawn colored liver spots - may have correlation between sun tan lotion and infections with yeast - in light skinned people causes pink to dark brown patches - in dark skinned people results in depigmentation - yeast morphology |
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list Four infections caused by Malassezia furfur
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pityriasis
Folliculitis Seborrheic dermatitis dandruff |
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Lab ID of Malassezia furfur
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-causes tinea versicolor
- KOH preps of skin scrapings and with Wood's lamp- flourescence budding conidia (resembling yeast) along with septate hyphae - in skin scrapings described as SPAGHETTI AND MEATBALLS FUNGI |
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Treatment for Malassezia furfur
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Selsen Blue: 0.1% selenium sulfide
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Define where in the body the cutaneous mycoses are found
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Involves infection of skin, hair, nails, but also can penetrate to a deeper level
- involves the keratinized portion - group of fungi called dermatophytes - host defenses cause inflammation and discomfort |
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Name the Latin words used to define the location of the cutaneous mycoses and their meaning
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Tinea pedis- athletes foot
Tinea cruris- jock itch Tinea capitis- head Tinea corporis- body |
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Describe Microsporum canis
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-causes dermatophytoses
-Infection acquired from house hold pets |
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What three genera are responsible for most dermatophytoses
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Trichophyton
Miscrosporum Epidermophytom floccosum |
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Describe the the structures of the macroconidia and microconidia for Microsporum
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Macroconidia- fusiform or spindle shaped (They taper out from center to both ends). Echinuluate- means prickly
-Microconidia- few, club shaped |
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Describe Microsporum gypseum
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-causes dermatophytoses
- acquired from soil - called a geophilic dermatophyte |
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Describe Microsporum audouini
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-causes dermatophytoses
- common cause of tinea capitis in children - called anthrophilic dermatophyte |
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Describe Epidermophyton floccosum
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- causes athletes foot
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Describe the structures of the macroconidia and microconidia for Epidermophyton
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Macroconidia- paddle-like, beaver's tail, or snow shoe
Microconidia- never present |
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Describe the the structures of the macroconidia and microconidia for Trichophyton
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Macroconidia- Rare, cylindrical, pensil shaped
Microconidia- numerous- comes in single (en thryses), clusters of grapes (en grappe), or spread out |
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Describe Trichophyton mentagrophytes
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- most commonly encountered dermatophyte
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describe T. tonsurans
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LEADING CAUSE OF tinea capitis in children
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three diseases that are caused by subcutaneous infections.
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Sporotrichosis
Chromoblastomycosis Eumycotic mycetoma |
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Define phaeohyphomycosis
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general term referring to miscellaneous subcutaneous infections caused by dematiaceous fungi
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For the fungus Sporothrix schenckii, give the common name for the disease and how it is acquired,
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-Rose gardeners diseas
- resides in soil and is introduced by thorn pricks or wood splinters - typically found in sphagnum moss |
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Explain why Sporothrix schenckii is a dimorphic fungus
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- has two colony types at different temps
Room temp (25 C)- mold-form colony - produces colonies initially white, glabrous (resembling pressed felt), and yeast like- as they grow older they turn darker - Microscopically they have septate hyphae with conidia in shape of rosette Body Temp (37 C)- yeast-form colony - cigar shaped yeast like cells |
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For the fungi Phialophora, Fonsecaea, and Cladosporium, give the name of the disease they cause and the symptoms,
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Cause Chromoblastomycosis
-verrucous (wart-like) dermatitidis - may become elevated 1-3cm above surrounding tissue - may spread to surrounding tissues through lymphatic system - almost always on extremeties - not painful unless there is a secondary bacterial infection |
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Descirbe Phialophora
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flask shaped phialides with balls of conidia (tight bunch of flowers)
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Describe Fonsecaea
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various arrangements of conidia,
-primary secondary tertiary conidia |
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Describe Cladosporium
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conidia resemble a wheat head
- only one that produces conidia in chains |
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For the fungus Pseudallescheria boydii, give the name of the disease it causes and the symptoms
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-most common cause of eumycotic mycetoma in U.S.
- produces hyaline (white) granules in drainage from infection - unique among fungi pathogenic for humans because its able to produce both sexually and asexually on culture media |
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Name two bacteria that can cause the same disease as Pseudallescheria boydii
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-causes Actinomycotic mycetoma
- caused by Nocardia, Actinomyces, Streptomyces, and Actinomadura |
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Describe Eumycotic mycetoma
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-swollen tumor-like areas with sinuses that drain through multiple sinus tracts
- pus contains "granules" composed of compact mycelia masses with white and black grains |
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Explain the term Perfect Fungi
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- capable of sexual reproduction
- male nucleus and female cell fuse to form zygote called and ASCUS and walls itself off - |
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Define Fungi Imperfecti
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-only capable of asexual reproduction
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What are the sexual spores within the ascus
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Ascospores
-the nucleus in the ascus divides and produces these - the ascus is now a sac containing ascospores |
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What are ascocarps
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-Big sacs within a fungal structure that contain a number of asci
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Define Ascomycota (ascomyces)
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- A division of fungi that contains about 32,000 known species of molds and yeasts that are characterized by the formation of HAPLOID ASCOSPORES within sacs called ASCI
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Define cleistothecium
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a special type of ascocarp in Psuedallescheria boydii
- sealed off sac full that ruptures and spills out ascopores |
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Define systemic mycoses and at what temperatures cultures should be incubated
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Pathogen usually inhaled into lungs which can spread to circulatory system
- infection involves organs and organ systems - suspected material should be cultured at 37 C and 25 C since they are dimorphic fungi |
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List four fungi that cause systemic mycoses and the general term used to describe infection by each of the organisms.
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1- Coccidoides immitis: Coccidioidmycosis
2- Histoplasma capsulatum: Histoplasmosis 3- Blastomyces dermatitidis: North American Blastomycosis 4- Paracoccidioides brasiliensis- South American Blastomycosis |
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For the fungus Coccidioides immitis, list three common names for the infection
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- Valley fever
- Desert rheumatism - San Joaquin Valley in California causes "Desert Bumps" |
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Symptoms for the fungus Coccidioides immitis
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60% of time are asymptomatic and self-limiting
- more sever in dark skinned people and pregnant women -severe cases cause progressive pulmonary disease |
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For the fungus Coccidioides immitis list areas of the U.S. where infection with the organism is endemic
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-found in low rainfall and semi arid conditions
- California, Arizona, southern Utah, and New mexico - 90% of population in endemic areas give a positive skin test |
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Describe the virulence of Coccidioides immitis
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-Most virulent of all human mycotic agents
- Arthroconidia in the dust get inhaled where they convert to spherules that produce endospores - the endospores ruture and produce spherules |
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For the fungus Histoplasma capsulatum, what is the common name for the disease, list where it is endemic and the symptoms of the infection
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- histoplasmosis AKA "caves diesase" or "spelunkers disease"
endemic along the Mississippi river valley - immunocompetent host is asymptomatic - heavy exposure causes acute/chronic pulmonary disease - potentially fatal disseminated disease |
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For the fungus Histoplasma capsulatum what are the zoophilic hosts
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-pigeons and bats
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For the fungus Histoplasma capsulatum explain how an individual acquires the fungus
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-acquired by inhaling microconidia which once in lungs convert to yeast stage
- when phagocytized by macrophages in lungs the yeast becomes an intracellular parasite living in the macrophage |
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Lab ID for the fungus Histoplasma capsulatum
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sample is a direct sputum or bronchial washing
- microscopically there are tiny yeast seen in monocytes |
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For the fungus Blastomyces dermatitidis, list where it is endemic and the symptoms of the infection
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- North American Blastomycosis
-Endemic in Mississippi and Ohio river basins May be manifested as - disseminated disease from inhalation of conidia where flu like symptoms may progress to progressivve pulmonary disease - Skin disease- where organism spreads and causes ulcerative lesions |
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Lab ID of Blastomyces dermatitidis
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Candida that resemble lollipops
"blastomyces lollipops" |
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For the fungus Paracoccidioides brasiliensis, list where it is endemic and the symptoms of the infection
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-South American Blastomycosis
- Rarely seen in North America -causes cutaneous and mucosal lesions |
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Lab ID of Paracoccidioides brasiliensis
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Budding yeast with multiple budding buds around central yeast cell
- looks like a "MARINERS WHEEL" |
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Define opportunistic mycoses
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fungi that can cause infections that affect individuals who are significantly injured or debilitated
- these are the fungi that are most frequently isolated in the clinical lab |
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list three general groups of fungi that are involved in opportunistic mycoses
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Yeasts
Zygomyces Hyaline molds |
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List four genus and species that cause yeast infections
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Candida albicans
Candida krusei Candida tropicalis Cryptococcus neoformans |
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Define blastoconidium
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conidium produced by budding
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Define pseudohyphae
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blastoconidium that are connected and constricted at the ends
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define chlamydospore
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swollen cells which help yeast survive under harsh conditions
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Explain carbohydrate assimilation method
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detects oxidative and anaerobic fermentation
- commercial ID systems used like API 20C are specific for yeast ID |
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What is the plating media for fungi
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Cornmeal Tween 80 Agar (CMT)
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What structures will you see with Candida
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Pseudohyphae, blastoconidia, and chlamydospores
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What genus will lack pseudohyphae
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Cryptococcus
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What structures will you see with trichosporon
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Arthroconidia, blastoconidia, and pseudohyphae
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Explain the germ tube test
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-A rapid test with one colony of yeat to 0.5 ml of sheep, horse, or human serum
- incubate at 35 C for 3 hours - give accurate ID of C. albicans - no constriction at base of germ tube= C. albicans - constriction at base of germ tube= C. tropicalis |
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Name 3 diseases caused by Candida albicans
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Thrush
vaginitis localized skin infections, dissemination and septicemia |
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Describe vaginitis
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-can follow antibiotic therapy since lactobacillus normally inhibits Candida
- produces a thick yellow discharge |
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Describe Thrush
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Candida albicans infection of the oropharynx
- white creamy patches on tongue forming a pseudomembrane that looks like cottage cheese - the material consists of masses of pseudohyphae - removal of pseudomembrane leaves a raw, red base |
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For Cryptococcus neoformans, explain how an individual would contract the organism
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Infection by inhalation of pigeon fecal flora
- causes pulmonary infection and can cause meningitis in immunocompromized - very common in AIDS patients |
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List two laboratory identification methods for detecting Cryptococcus neoformans
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Capsular crytococcal antigen
- this is a latex agglutination test - test of choise since it's the only pathogenic yeast that has a capsule India Ink and microscopic exam - previously used and showed a contrast of the capsule |
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List the characteristics of the Zygomycetes.
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-Aseptate hyaline molds
- rapid growing - Perfect fungi; capable of sexual and asexual reproduction |
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Explain the asexual and sexual repro of zygomycetes
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Asexual -sporangial sporulation
Sexual- occurs between compatible mating strains with produciton of zygospores by fusing together |
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Most commonly encountered genus of fungi in the clinical lab?
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Aspergillus fumigatus
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List 3 genera of zygomycetes
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Absidia
Mucor Rhizopus |
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What does Penicillium resemble
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paint brush
- has branched conidiohphore at the base of the "brush head" |
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Define saprobes or saprophytes
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organism that lives on dead organic material and are enriched by the nitrogenous matter
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What are fungal cell walls made of
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Chitin
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What gives molds their fuzzy or woolly appearance
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mycelium which is made of hyphae
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What are hyphae
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tube like structures that have an optimum growth temp of 20-30 C
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Define pseudohyphae
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chains of budding yeast
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define hyaline
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light pigment
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Dematiaceous
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dark pigment due to presence of melanin
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septate hyphae
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have frequent cross walls between cells
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define wet mount
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a suspension of the specimen on a slide with a cover slip
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What does KOH do
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dissolves most cellular debris, like keratin, without affecting chitinous cell wall of fungus
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What does KOH with calcoflour white do
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binds to chitin and flouresces making fungal elements appear as "apple green" or white with reddish background
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What is SDA
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Sabouraud Dextrose Agar
- medium most often used, supports growth of almost any fungus |
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What antibiotics are in some SDAs
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Chloramphenicol
Cyclohexamide |
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What is BHIA
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Brain-Heart Infusion Agar
- supports growth of the yeast phase of the dimorphic fungi |
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What is LPCB
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Lactophenol-Cotton Blue
- preferred stain for microscopic examination of mold-form colonies |
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Conidia
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Conidium (singular)
Asexual reproductive structures found in phialides or annellides |
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Phialide
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vase-like structures that produce and contain many conidia located on a conidiophore
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annellide
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ringed structure that produce and contain a single conidium
- looks kind of like a bowling pin - located on an annellophore |
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arthroconidia
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fragmented hyphae produced by asexual repro
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sporangiospores
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asexual spores formed only is aseptate fungi
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Sporangium
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saclike structure in which sporagniospores are formed
- located on a sporangiophore |
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What 2 fungi make up the Hyaline Molds
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Aspergillus fumigatus
Penicillium species |