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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...
1. distrupction of skin barrier
2. underlying systemic condition
Where are the causitive agents of subcutaenous mycoses usually found in the environment
-soil
-decaying organic matter
-saprobically
-plant pathogens
What are the three routes of infection for subcutaneous mycoses
1. Direct sucutaneous inoculation
2. inhalation
3. iatrogenic
Describe the two ways that a subcutaenos infection could be directly innoculated
1. traumatic implantation
2.exposure of subcutaneous tissue to air (burn, MVA, etc)
Where do fungal spores usually implant after inhalation
paranasal sinuses or lungs
Describe the general progress of infection for a subcutaenous mycoses
-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
What agent causes sporotrichosis
Sporothrix schenkii
Where is sporotricosis distributed
worldwide
Describe the causitive agent of sporotrichosis
Sporothrix schenkii
dimorphic fungus that exists as a mold in the environment/ room temp, yeast in tissues
What three clinical syndromes are caused by sprothrix schenkii
1. lymphocutaneous sporotrichosis (most common)
2. pulmonary sporotrichosis
3. Fixed cutaneous, mucocutaneous and extracutaneous disseminated sporotrichosis
Describe lymphocutaneous sporotrichosis
-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
spagnum moss is associated with which subcutaneous mycoses
lymphocutaneous sporotrichosis
Describe pumonary sporotrichosis
-caused by sporothrix schenkii
-results from inhalation of spores
-may be primary disase or secondary colonizer of cavitations caused by other diseases
Describe fixed cutaneous, mucocutaneous, and extracutaneous disseminated sporothrichosis
possible maifestations of infection with sporothrix schenkii, disseminated is a problem in AIDS pts
What histological sign may be indicative of sporotrichosis
asteroid bodies- yeasts surrounded by radiating eosinophilic material
What pathogens can cause zygomycoses
Absidia, Conidiobolus, Mucor, Rhizopus
members of phylum zygomycota order mucorales
Zygomyotic infections usually result from
direction implantation or inhalation of spores which are virtuall ubiquitous in the environment
How does zygomycosis usually manifest
-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
List 5 risk factors for zygomycosis
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)
When is rhinocerebral zygomycosis usually seen
acidotic induviduals particularly uncontrolled diabetics and neutropenic pts
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
Which fungi cause mycetoma
Madurella grisea, Pseudallescheria boydii, Scedosporium apiospermum
Where is mycetoma aka eumycetoma commonly found
tropical and subtropical regions
Describe the typical presentation of mycetoma
-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
Which is worse bacterial or fungal mycetoma
bacterial
Which agents of mycetoma would be found in tropical regions? Temperate?
tropical-Madurella grisea
temperate- Pseudallescheria boydii and Scedosporium apiospermum
What are the caustive agents of Hyalohyphomycoses
haline fungi like Fusarium and Acremonium
Describe the typical presenation of Hyalohyphomycoses
-pulmonary or disseminated infection in immunocomp hosts after inhalation or direct innoculation, similar to aspergillosis
Describe the histopathological signs associated with hyalohyphomycoses
-septate hyaline hyphae
Describe the typical presenation of a phaeohyphomycoses
-subcutaneous and deep infections
What agents cause Phaeohyphomycoses
deatiaceous fungi like Alternaria, Bipolaris, Cladosporium bantanum etc
How is phaeohyphomycoses with alternaria obtained
Alternaira from the soil are introduced by traumatic implantation, generally cause disease in neutropenic pts
How is phaeohyphomycoses with Bipolaris obtained
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
What is unique about the presentation of phaeohyphomycoses with Cladosporium compared to other dematiaceous fungi in terms of tropism
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
What are the caustive agents of Chromoblastomycosis
dematiaceous fungi like Fosecaea pedrosoi and Wangiella dermattitidis
Describe the typical presentation of Chromoblastomycoses
-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
Where is Chromoblastomycosis found
central and south america
A histopathological findng of small, round, thick walled brown sclerotic bodies is indicative of which subcutaneous mycoses
Chromoblastomycoses
What is the caustive agent of Lobomycosis
Loboa loboi aka Lacazia loboi
Describe the typical presentation of a lobomycosis infection
-rare
-slow progressive infection of skin and subcutaneous tissue
-generally affects extremities, buttocks, face
Where can lobomycosis be found
Central and South America
A histopathological finding of round or oval cells in short chains in dermis is indicative of which subcutaneous mycoses
lobomycosis
What is the causitive agent of Rhinosporidiosis
Rhinosporidium seeberi
Describe the typical presentation of Rhinosporidiosis
-chronic infection characterized by large nasal and other mucosal polyps
Where is Rhinosporidiosis found
Asia, South America, Africa
A histopathological finding resembeling an endosporulating fungus is indicative of which subcutaenous mycosis
Rhinosporidiosis