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Semester 3: BacT > Systemic Mycoses lecture > Flashcards

Systemic Mycoses lecture Flashcards

1
Q

What are 4 characteristics of Systemic Mycoses.

A

1) dimorphic 2) infection usually by inhalation 3) lesions tend to be pyogranulomatous 4) noncontagious

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2
Q

Coccidiodes is a dimorphic fungi, what are its environments for the saprophytic phase & parasitic phase

A

saprophytic phase: mold in soil parasitic phase: spherical structure in tissue

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3
Q

What are the two possible causes for Coccidiomycosis?

A

1) C. Immitis 2) C. Posadasii

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4
Q

Where would you find the two causes of Coccidiomycosis? (geographically)

A

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

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5
Q

What is the main species that is affected my Coccidiomycosis? 2nd common species infected?

A

Dogs are the main infected domestic animal. Horses are the second.

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6
Q

How do C. Immitis & C. Posadasii avoid the hosts immune response?

A

They stimulate a strong Th-2 response which down regulates the cell-mediated response.

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7
Q

What is the significance of Arthroconidias (associated w/ C. Immitis & C. Posadasii). (2)

A

1) resist drying & tolerate heat & salinity better than other competing organisms 2) has been bioweaponized

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8
Q

Transmission of C. Immitis & C. Posadasii?

A

mainly by inhalation of arthroconidia. cutaneous rare.

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9
Q

What is the Pathogenesis of C. Immitis & C. Posadasii?

A

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

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10
Q

What are the some common characteristics for when a Dog is infected with either C. Immitis or C. Posadasii?

A

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

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11
Q

What are the some common characteristics for when Horses & Cats are infected with either C. Immitis or C. Posadasii?

A

dissemination of disease occurs by less osseous & more visceral involvement

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12
Q

What are the some common characteristics for when Cattle, Sheep, & Swine are infected with either C. Immitis or C. Posadasii?

A

They are usually asymptomatic and it affects lungs & regional lymph nodes

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13
Q

What other disease is usually a possibility for Differential Dx when it comes to Systemic Mycoses cases?

A

Tuberculosis

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14
Q

What are some forms of Immunodiagnosis for C. Immitis & C. Posadasii?

A

1) complement fixation & immunodiffusion test 2) commercially available “exoantigen” test kit 3) coccidiodan skin test Tests deal with Type 4 Hypersensitivity

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15
Q

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 ______.

A

10% KOH

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16
Q

C. Immitis & C. Posadasii spores can be stained with _____.

A

periodic acid-Schiff (PAS)

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17
Q

When culturing C. Immitis & C. Posadasii ALL processing MUST be done under a microbiological ____ ____.

A

safety hood

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18
Q

What is Dr. Soto’s favorite molecular method of Lab Dx for C. Immitis & C. Posadasii?

A

PCR!

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19
Q

What do we use to Tx & Control C. Immitis & C. Posadasii for small animals

A

Ketoconazole & itraconazole (toxic effects are relatively minor)

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20
Q

What causes Histoplasmosis in mammals?

A

Histoplasma var. capsulatum & duboisii

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21
Q

Where can you find Histoplasma capsulatum? Histoplasma duboisii?

A

H. capsulatum: worldwide H. duboisii: Africa

22
Q

How would you describe Histoplasma’s mold phase (saprophytic phase), appearance wise.

A

septate hyphae with spherical pyriform microconidia and tuberculate macroconidias

23
Q

Where can you find H. capsulatum var. capsulatum in the host?

A

as a yeast inside macrophages, neutrophils, and/or dendritic cells

24
Q

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?

A

allows the fungus to enter the cell without triggering an effective oxidative burst (basically so they can get avoid the immune system)

25
Q

Whats the relationship between birds, bats, & Histoplasma?

A

birds are passive carriers of it and shed it. bats poop it out and get their intestines infected by it.

26
Q

Where is H. capsulatum found in the environment?

A

topsoil layers, especially in the presence of birds or bats guano. its favored by an alkaline environment

27
Q

Transmission of H. capsulatum & H. duboisii?

A
  • mostly by inhalation of microconidias or hyphal fragments. - possible by ingestion & rarely by wound infection
28
Q

What is the pathogenesis of H. capsulatum? (4)

A

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

29
Q

What controls the multiplication of H. capsulatum’s yeast?

A

an effective cell-mediated immune response

30
Q

In what animal is H. capsulatum more common? And what form do they usually get? What is the prognosis for it?

A

1) dogs 2-7 yrs old 2) usually get disseminated disease 3) disseminated disease have a grave prognosis with relapses being common

31
Q

H. capsulatum develops primarily in what form in dogs.

A

primary pulmonary form

32
Q

When culturing H. capsulatum microconidias & macroconidias are demonstrated in what kind of wet mounts?

A

lactophenol blue wet mounts

33
Q

For H. capsulatum & Blastomycosis, what are some immunoDx & molecular methods for a Lab Dx?

A

1) ImmunoDx: commercially available “exoantigen” test kit 2) Molecular methods: PCR for ribosomal RNA or M protein genes

34
Q

How do you Tx H. casulatum & Blastomyces dermatitidis?

A

itroconazole, ketoconazole, & amphotericin B

35
Q

What does the reproducing Blastomyces dermatitidis yeast look like?

A

reproduces by single buds attached to a broad base

36
Q

What disease does Blastomyces dermatitidis cause? And where is it found?

A

1) Blastomycosis 2) mainly in eastern third of N. America

37
Q

What species does Blastomyces dermatitidis mainly affect?

A

humans & dogs (rarely horses & cats)

38
Q

The lipid content in _____ (a fungi) is higher than in any other fungi.

A

Blastomyces

39
Q

What does the yeast phase of Blastomyces produce? what is its purpose?

A

adhesin 1 (Bad-1) which binds to surface of phagocytic cells, triggering minimal respiratory burst. this down regulates the production of proinflammatory cytokines.

40
Q

What is the pathogenesis of Blastomyces?

A

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

41
Q

____ is often more progressive than Histoplasmosis & coccidiomycosis.

A

blastomycosis

42
Q

What are some signs of Blastomycosis? and describe what the nodular lesions are like.

A

skin lesions & respiratory distress. nodular lesions can be tubercle-like.

43
Q

ID

A

C. immitis

44
Q

ID

A

C. immitis

Left: arthrospore

Right: spherule

45
Q

ID

A

C. immitis

46
Q

ID

A

Blastomyces dermatitidis

47
Q

ID

A

blastomyces dermatitidis

48
Q

ID

A

Intracellular H. capsulatum

49
Q

ID each one.

A

top: Histoplasma capsulatum

Bottom: Blastomyces dermatitidis

50
Q

What is this?

A

This is a histological analysis of a typical endosporulating spherule of C. immitis

Semester 3: BacT (4 decks)

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