Systemic Mycoses lecture Flashcards
What are 4 characteristics of Systemic Mycoses.
1) dimorphic 2) infection usually by inhalation 3) lesions tend to be pyogranulomatous 4) noncontagious
Coccidiodes is a dimorphic fungi, what are its environments for the saprophytic phase & parasitic phase
saprophytic phase: mold in soil parasitic phase: spherical structure in tissue
What are the two possible causes for Coccidiomycosis?
1) C. Immitis 2) C. Posadasii
Where would you find the two causes of Coccidiomycosis? (geographically)
Both found in western hemisphere ONLY. 1) C. Immitis found in Central Valley of Ca 2) C. posadasii found in Texas, New Mexico, Arizona, South America
What is the main species that is affected my Coccidiomycosis? 2nd common species infected?
Dogs are the main infected domestic animal. Horses are the second.
How do C. Immitis & C. Posadasii avoid the hosts immune response?
They stimulate a strong Th-2 response which down regulates the cell-mediated response.
What is the significance of Arthroconidias (associated w/ C. Immitis & C. Posadasii). (2)
1) resist drying & tolerate heat & salinity better than other competing organisms 2) has been bioweaponized
Transmission of C. Immitis & C. Posadasii?
mainly by inhalation of arthroconidia. cutaneous rare.
What is the Pathogenesis of C. Immitis & C. Posadasii?
1) inhalation of arthoconidias & rounding into spherical-shaped endospores 2) endospore differentiate into multinucleated spherules (contains hundreds of endospores) 3) spherules rupture & cycle starts 4) arthroconidia, spores and spherules trigger an inflammatory response in lungs & lymph nodes
What are the some common characteristics for when a Dog is infected with either C. Immitis or C. Posadasii?
1) disseminating disease is common 2) usually get pulmonary lesions & osteomyelitis 3) more common in male dogs 4-7yrs old 4) more common in young boxer dogs & doberman pinschers
What are the some common characteristics for when Horses & Cats are infected with either C. Immitis or C. Posadasii?
dissemination of disease occurs by less osseous & more visceral involvement
What are the some common characteristics for when Cattle, Sheep, & Swine are infected with either C. Immitis or C. Posadasii?
They are usually asymptomatic and it affects lungs & regional lymph nodes
What other disease is usually a possibility for Differential Dx when it comes to Systemic Mycoses cases?
Tuberculosis
What are some forms of Immunodiagnosis for C. Immitis & C. Posadasii?
1) complement fixation & immunodiffusion test 2) commercially available “exoantigen” test kit 3) coccidiodan skin test Tests deal with Type 4 Hypersensitivity
For a direct examination during a Lab Dx of C. Immitis or C. Posadasii, animal fluids and tissues are examined for spherules by wet mount in saline containing ______.
10% KOH
C. Immitis & C. Posadasii spores can be stained with _____.
periodic acid-Schiff (PAS)
When culturing C. Immitis & C. Posadasii ALL processing MUST be done under a microbiological ____ ____.
safety hood
What is Dr. Soto’s favorite molecular method of Lab Dx for C. Immitis & C. Posadasii?
PCR!
What do we use to Tx & Control C. Immitis & C. Posadasii for small animals
Ketoconazole & itraconazole (toxic effects are relatively minor)
What causes Histoplasmosis in mammals?
Histoplasma var. capsulatum & duboisii
Where can you find Histoplasma capsulatum? Histoplasma duboisii?
H. capsulatum: worldwide H. duboisii: Africa
How would you describe Histoplasma’s mold phase (saprophytic phase), appearance wise.
septate hyphae with spherical pyriform microconidia and tuberculate macroconidias
Where can you find H. capsulatum var. capsulatum in the host?
as a yeast inside macrophages, neutrophils, and/or dendritic cells
Why would H. capsulatum var. capsulatum (actual name? i might not always write it all out b/c im lazy) bind to neutrophils, macrophages, and dendritic cells?
allows the fungus to enter the cell without triggering an effective oxidative burst (basically so they can get avoid the immune system)
Whats the relationship between birds, bats, & Histoplasma?
birds are passive carriers of it and shed it. bats poop it out and get their intestines infected by it.
Where is H. capsulatum found in the environment?
topsoil layers, especially in the presence of birds or bats guano. its favored by an alkaline environment
Transmission of H. capsulatum & H. duboisii?
- mostly by inhalation of microconidias or hyphal fragments. - possible by ingestion & rarely by wound infection
What is the pathogenesis of H. capsulatum? (4)
1) microconidia, hyphal fragment, or yeast cell attach to macrophage in lungs 2) minimal respiratory burst occurs 3) microconidia & hyphal elements differentiate into yeast & survive phagolysosome 4) multiplication inside the cell eventually ruptures the phagocyte
What controls the multiplication of H. capsulatum’s yeast?
an effective cell-mediated immune response
In what animal is H. capsulatum more common? And what form do they usually get? What is the prognosis for it?
1) dogs 2-7 yrs old 2) usually get disseminated disease 3) disseminated disease have a grave prognosis with relapses being common
H. capsulatum develops primarily in what form in dogs.
primary pulmonary form
When culturing H. capsulatum microconidias & macroconidias are demonstrated in what kind of wet mounts?
lactophenol blue wet mounts
For H. capsulatum & Blastomycosis, what are some immunoDx & molecular methods for a Lab Dx?
1) ImmunoDx: commercially available “exoantigen” test kit 2) Molecular methods: PCR for ribosomal RNA or M protein genes
How do you Tx H. casulatum & Blastomyces dermatitidis?
itroconazole, ketoconazole, & amphotericin B
What does the reproducing Blastomyces dermatitidis yeast look like?
reproduces by single buds attached to a broad base
What disease does Blastomyces dermatitidis cause? And where is it found?
1) Blastomycosis 2) mainly in eastern third of N. America
What species does Blastomyces dermatitidis mainly affect?
humans & dogs (rarely horses & cats)
The lipid content in _____ (a fungi) is higher than in any other fungi.
Blastomyces
What does the yeast phase of Blastomyces produce? what is its purpose?
adhesin 1 (Bad-1) which binds to surface of phagocytic cells, triggering minimal respiratory burst. this down regulates the production of proinflammatory cytokines.
What is the pathogenesis of Blastomyces?
1) microconidia hyphal fragments are inhaled 2) conversion to the yeast form within the alveolar spaces 3) expression of Bad1 & phagocytosis w/ minimal respiratory burst & down regulation of cytokines 4) inflammatory response involving macrophages and neutrophils resulting in pyogranulomatous lesions in terminal bronchioles
____ is often more progressive than Histoplasmosis & coccidiomycosis.
blastomycosis
What are some signs of Blastomycosis? and describe what the nodular lesions are like.
skin lesions & respiratory distress. nodular lesions can be tubercle-like.
ID
C. immitis
ID
C. immitis
Left: arthrospore
Right: spherule
ID
C. immitis
ID
Blastomyces dermatitidis
ID
blastomyces dermatitidis
ID
Intracellular H. capsulatum
ID each one.
top: Histoplasma capsulatum
Bottom: Blastomyces dermatitidis
What is this?
This is a histological analysis of a typical endosporulating spherule of C. immitis
