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46 Cards in this Set
- Front
- Back
Agents of subcutaneous mycoses can cause extremely nasty disease with high morbidity and mortality but most present no problem at all unless...
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1. distrupction of skin barrier
2. underlying systemic condition |
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Where are the causitive agents of subcutaenous mycoses usually found in the environment
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-soil
-decaying organic matter -saprobically -plant pathogens |
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What are the three routes of infection for subcutaneous mycoses
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1. Direct sucutaneous inoculation
2. inhalation 3. iatrogenic |
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Describe the two ways that a subcutaenos infection could be directly innoculated
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1. traumatic implantation
2.exposure of subcutaneous tissue to air (burn, MVA, etc) |
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Where do fungal spores usually implant after inhalation
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paranasal sinuses or lungs
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Describe the general progress of infection for a subcutaenous mycoses
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-initial lesion at or nearsite of innoculation involving the deeper layers of the dermis and subcutaneous tissues
-extends out to the surface -may remain localized or spread by direct extension throug htissue or via lymphatics or hematogenosly |
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What agent causes sporotrichosis
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Sporothrix schenkii
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Where is sporotricosis distributed
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worldwide
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Describe the causitive agent of sporotrichosis
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Sporothrix schenkii
dimorphic fungus that exists as a mold in the environment/ room temp, yeast in tissues |
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What three clinical syndromes are caused by sprothrix schenkii
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1. lymphocutaneous sporotrichosis (most common)
2. pulmonary sporotrichosis 3. Fixed cutaneous, mucocutaneous and extracutaneous disseminated sporotrichosis |
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Describe lymphocutaneous sporotrichosis
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-caused by sporothrix schenkii
-most common manifestation of sporotrichosis -follows traumatic implantation of fungus by working with soil etc -initial lesion is small nodule which enlarges to an ulcer, more nodules develop along lymphatics -infection beyond region lymphatics is rare |
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spagnum moss is associated with which subcutaneous mycoses
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lymphocutaneous sporotrichosis
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Describe pumonary sporotrichosis
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-caused by sporothrix schenkii
-results from inhalation of spores -may be primary disase or secondary colonizer of cavitations caused by other diseases |
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Describe fixed cutaneous, mucocutaneous, and extracutaneous disseminated sporothrichosis
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possible maifestations of infection with sporothrix schenkii, disseminated is a problem in AIDS pts
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What histological sign may be indicative of sporotrichosis
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asteroid bodies- yeasts surrounded by radiating eosinophilic material
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What pathogens can cause zygomycoses
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Absidia, Conidiobolus, Mucor, Rhizopus
members of phylum zygomycota order mucorales |
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Zygomyotic infections usually result from
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direction implantation or inhalation of spores which are virtuall ubiquitous in the environment
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How does zygomycosis usually manifest
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-subcutaneous infection often with contiguous invasion
-generally seen after trauma or in burn pts -lungs and nasal sinuses are common sites of infection after inhalation |
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List 5 risk factors for zygomycosis
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1. neutropenia
2. immunosupressive therapy 3. iron chelation therapy with deferoxamine (sereves as iron source for fungus) 4. acidosis (iron aquisition) 5. diabetes mellitus (high glucose provides enhanced nutrition) |
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When is rhinocerebral zygomycosis usually seen
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acidotic induviduals particularly uncontrolled diabetics and neutropenic pts
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What usually causes rhinofacial zygomycosis and what population is at risk?
How does infection occur? What is the prognosis |
Caused by Conidiobolus coronatus which is found in soil and decaying vegetation in moist, warm regions. Typically a disease of adult males living or working in tropical rain forests.
infection occurs by inhalation or physical introduction on soiled fingers, implantation to paranasal sinues and spread to adjacent tissue -slow but progressive disfigurment over months to years |
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Which fungi cause mycetoma
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Madurella grisea, Pseudallescheria boydii, Scedosporium apiospermum
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Where is mycetoma aka eumycetoma commonly found
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tropical and subtropical regions
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Describe the typical presentation of mycetoma
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-chronic suppurative infection of cutaneous and subcutaneous tissues, fascia, bone
-usually affects hand or foot following traumatic implantation -characterized by initial localized nodule which ulcerates and drains black grains -can lead to bone erosin |
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Which is worse bacterial or fungal mycetoma
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bacterial
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Which agents of mycetoma would be found in tropical regions? Temperate?
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tropical-Madurella grisea
temperate- Pseudallescheria boydii and Scedosporium apiospermum |
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What are the caustive agents of Hyalohyphomycoses
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haline fungi like Fusarium and Acremonium
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Describe the typical presenation of Hyalohyphomycoses
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-pulmonary or disseminated infection in immunocomp hosts after inhalation or direct innoculation, similar to aspergillosis
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Describe the histopathological signs associated with hyalohyphomycoses
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-septate hyaline hyphae
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Describe the typical presenation of a phaeohyphomycoses
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-subcutaneous and deep infections
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What agents cause Phaeohyphomycoses
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deatiaceous fungi like Alternaria, Bipolaris, Cladosporium bantanum etc
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How is phaeohyphomycoses with alternaria obtained
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Alternaira from the soil are introduced by traumatic implantation, generally cause disease in neutropenic pts
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How is phaeohyphomycoses with Bipolaris obtained
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Bipolaris from soil or plants aquired by inhalation or traumatic implantation
-commonly associated with sinusitis in immunocomp or suppressed -can cause subcutaneous, invasive, or disseminated disease |
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What is unique about the presentation of phaeohyphomycoses with Cladosporium compared to other dematiaceous fungi in terms of tropism
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Cladosporium is neutropic, it is the most frequent cause of cerebral phaeohyphomycosis characterized by gradual onset and persistent headache which may occur in immunocompetent induviduals
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What are the caustive agents of Chromoblastomycosis
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dematiaceous fungi like Fosecaea pedrosoi and Wangiella dermattitidis
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Describe the typical presentation of Chromoblastomycoses
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-chronic progressive granulomatous infection of skin and subcutaneous tissue, usually of the extremities
-raised, crusted, verrucous lesions involve a granulomatous host response to the fungus |
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Where is Chromoblastomycosis found
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central and south america
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A histopathological findng of small, round, thick walled brown sclerotic bodies is indicative of which subcutaneous mycoses
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Chromoblastomycoses
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What is the caustive agent of Lobomycosis
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Loboa loboi aka Lacazia loboi
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Describe the typical presentation of a lobomycosis infection
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-rare
-slow progressive infection of skin and subcutaneous tissue -generally affects extremities, buttocks, face |
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Where can lobomycosis be found
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Central and South America
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A histopathological finding of round or oval cells in short chains in dermis is indicative of which subcutaneous mycoses
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lobomycosis
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What is the causitive agent of Rhinosporidiosis
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Rhinosporidium seeberi
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Describe the typical presentation of Rhinosporidiosis
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-chronic infection characterized by large nasal and other mucosal polyps
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Where is Rhinosporidiosis found
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Asia, South America, Africa
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A histopathological finding resembeling an endosporulating fungus is indicative of which subcutaenous mycosis
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Rhinosporidiosis
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