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25 Cards in this Set
- Front
- Back
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Fungi are eukaryotic organisms that are usually localized rather than systemic. Some are thermally dimorphic meaning they form different structures at different temperatures.
Most exist as _____ in the cooler ambient temperatures and ______ at a warmer body temperature. |
molds
yeasts |
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The cell membrane of fungi contains _______. ( human cell membranes have cholesterol)
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ergosterol
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Cell wall of fungi contains ______(inner most layer), then ______, then ________.
Unlike bacteria it contains no peptidoglycan. |
Chitin
glucan mannoproteins |
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use etoh and then this type of prep to idenitfy branching hyphae or yeast cells for a diagnosis of a fungal infection
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KOH prep
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Dermal fungal infections can be classified in three ways. Tell me them and tell me if there is an immune response associated.
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Superficial mycoses- outermost layers of skin and hair (little immune response)
Cutaneous mycoses- deeper in the epidermis, hair, and nails (immune response) Subcutaneous- dermis, subQ tissues, muscle & fascia. (immune response) |
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The following 4 cases refer to this type of fungal infection which usually has only cosmetic pathology
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Superficial mycoses-
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Pt presents w/hypopigmented macular lesion on upper torso, arms, and abdomen. KOH smear shows a lipophilic yeast-like organism
•What is dz- •What is organism |
Pityriasis Versicolor-
-Malassezia furfur |
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Pt presents with a brownish-black, well demarcated lesion on the palm of his hand. He reports that it has been enlarging by peripheral extension. KOH smear shows a dimorphic fungus that produces melanin.
•What is the dz- •What is the organism- |
Tinea nigra
Exophiala werneckii |
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Pt presents with hard black nodules along his hair shaft which contains asci (spore-bearing container) that encases ascospores, the sexual phase of the fungus.
•What is the dz— •What is the organism -- |
Black Piedra
Piedra hortae |
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Pt presents with white “sleeves” growing around the hair of his scalp, mustache, and beard. KOH prep shows a yeast like organism
•What is the dz- •What is the organism - |
White Piedra-
Trichosporon beigelii |
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This classification of dermal fungal infections are caused by dermatophytes and are named “tinea followed by the location it occurs.”
They express keritinases that can break down keritin. Cell mediated immunity is very important in defence of these diseases and weak cell mediated can lead to chronic infxn. |
Cutaneous Mycoses
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18 y/o football player presnts w/ dry itchy feet
•What is the dx?-- •What is the organism -- |
Tinea pedis- athletes foot
Trichophyton rubrum, T. mentagrophytes, and Epidermophyton floccosum, |
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18 y/o football player presnts w/ dry itchy crotch
•What is the dx?-- •What is the organism -- |
Tinea Cruris- jock itch
T. rubrum and E. floccosum. |
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65 y/o male presents with infectionof the nail plate
•What is the dx? •What is the organism?-- |
--Tinea unguium
-- T. rubrum and T. mentagrophytes |
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7 y/o boy presents with a central round lesion with peripheral erythema?
•What is the dx? •What is the organism? |
Tinea corporis- (ring worm)
it can be caused by any dermatophyte. |
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65 y/o presents with infection of the palms of the hand
•What is the dx? •What is the organism? |
Tinea manuum
T. rubrum |
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45 y/o male presents with - infection of the beard hair.
•What is the dx? – •What is the organism? -- |
Tinea barbae
T. mentagrophytes and T. verrucosum |
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7 y/o boy presents with an infection of the scalp?
•What is the dx?-- |
Tinea capitis
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It is noted that hyphal elements and arthrospores surround the hair shaft. Hair breaks a few millimeters above the scalp.
•What type of Tinea capitis? –•What is the organism? -- |
Ectothrix
Microsporium audouinii, Microsporium canis and some trichophyton. |
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It is noted that there are arthrospores inside the shaft itself. Hair breaks AT the scalp
•What is the dx? •What is the organism? -- |
—Endothrix
-Trichophyton tonsurans |
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This classification of fungal infections usually occurs at sites of trauma where organism implanted. Infxn initially involves the deeper layers of the dermis, subcutaneous tissue, or bone. Most infections have a chronic insidious growth pattern that eventually extends into the epidermis and are expressed clinically as lesions on the skin surface.
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Subcutaneous Mycoses
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Rose gardener is pricked with a thorn and develops a small ulcer. Dimorphic fungus spreads through lymphatics.
•Dx - •Organism - |
Sporotrichosis
Sporothrix schenckii |
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After puncture incident pt presents with dark brown warty nodules that appear at the site of implantation.
•Dx-- |
Chromoblastomycoses
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Although this classification of fungal infection is rare it can occur with skin involvement with the following organisms:
Candida albicans Blastomyces dermatitides Cryptococcus neoformans Coccidioides immites |
Systemic infections:
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Obese pt with type II diabetes presents mid august with skin infection after a course of broad spectrum AB.
Or Baby with diaper rash presents with skin lesions •dx -- •organism -- |
Candidiosis or Candidiasis
Candida albicans |
