RTI VIII Flashcards

1
Q

list the primary fungal pathogens

A
  • primary (healthy & immunocompetent)
    • Histoplasma capsulatum
    • Blastomyces dermatidis
    • Coccidiodes immitis
    • Paracoccidiodes brasiliensis
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2
Q

list the opportunistic fungal pathogens

A
  • opportunistic (immunocompromised individuals)
    • Cryptococcus neoformans
    • Aspergillus sp.
    • Pneumocystis jiroveci
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3
Q

all primary fungal RTIs are acquired via ____ and all are _____

A

all primary fungal RTIs are acquired via inhalation and all are dimorphic

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4
Q

____ & ____ are endemic in the area of the Mississippi River Valley and the Ohio River Valley

A

H. capsulatum & B. dermatitidis are endemic in the area of the Mississippi River Valley and the Ohio River Valley

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5
Q

____ is endemic in the area of Southwestern US and Northwestern Mexico

A

C. immitis is endemic in the area of Southwestern US and Northwestern Mexico

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6
Q

list the clinical features of fungal RTIs

A
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7
Q

fungi that cause RTIs are able to convert to form ____

A

fungi that cause RTIs are able to convert to form capable of replication at 37 C

  • mycelial → yeast form
  • may enhance survival of the fungi since yeasts aren’t killed as easily by phagocytes
  • colonize resp. mucosa
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8
Q

describe how H. capsulatum can grow inside macrophages

A
  • H. capsulatum
    • can increase phagolysosomal pH
    • interferes with enzyme activity and antigen processing
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9
Q

the composition of the ___ may be important in the pathogenesis of fungi

explain this

A

the composition of the cell wall may be important in the pathogenesis of fungi

  • certain components linked with virulence
    • e.g. virulence in P. brasiliensis is linked to presence of α-(1,3)-glucan in cell wall
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10
Q

describe obtaining samples and techniques used for diagnosing fungal RTIs

A
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11
Q

delayed hypersensitivity skin tests are useful for diagnosis of _____

A

delayed hypersensitivity skin tests are useful for diagnosis of Coccidiodomycosis

  • mycelial phase antigen: coccidioidin
  • spherule phase antigen: spherulin
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12
Q

describe the exoantigen test

A
  • exoantigen test:
    • basis = immunodiffusion
      • look for presence of specific cell free antigens produced by mycelial phase of the fungi
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13
Q

the natural habitat of Histoplasma capsulatum is _____, such as that enriched with ____

A

the natural habitat of Histoplasma capsulatum is soil with high nitrogen content, such as that enriched with bird or bat droppings

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14
Q

acquiring Histoplasmosis is dependent on… (2 things)

A
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15
Q

name the 2 clinically significant varieties of Histoplasma

A
  • H. capsulatum var capsulatum
    • pulmonary and disseminated infections
    • Eastern US and Latin America
    • thinner cell walls, smaller size
  • H. capsulatum var duboisii
    • _​​_skin and bone lesions
    • tropical Africa
    • thick walled; larger yeasts
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16
Q

describe what to look for when examining a tissue infected with Histoplasma

A
17
Q

Blastomyces is found in ____ and outbreaks are associated with contact with _____

A

Blastomyces is found in decaying organic matter and outbreaks are associated with contact with soil

18
Q

in Blastomycosis, look for ____

A

in Blastomycosis, look for skin lesions

19
Q

describe what to look for when examining a tissue infected with Blastomyces

A

look for single broad base bud in a yeast (B = Blastomyces)

20
Q

Coccidioides immitis is endemic to _____

A

clinical syndrome = Valley Fever

Coccidioides immitis is endemic to desert southwestern US, Nothern Mexico, certain areas of Central & South America

21
Q

____ is the most virulent of all the human mycotic pathogens

A

Coccidiodes immites is the most virulent of all the human mycotic pathogens

22
Q

____ protects Coccidioides from phagocytosis

A

spherules protects Coccidioides from phagocytosis

23
Q

opportunistic pathogens are usually (monomorphic/dimorphic)

A

opportunistic pathogens are usually monomorphic

24
Q

list the predisposing factor and the major pathogen associated with it

A
25
Q

Cryptococcus neoformans is the only fungus that is ____

A

Cryptococcus neoformans is the only fungus that is encapsulated

26
Q

describe CSF staining of Cryptococcus

A

India Ink staining is a negative stain of CSF, where the capsule creates a clear halo

27
Q

describe tissue staining of Cryptococcus

A
28
Q

Cryptococcus production of capsules is triggered by ____ and is composed of ____

A

Cryptococcus production of capsules is triggered by inhalation and is composed of glucuronoxylomannan (GXM)

29
Q

Cryptococci can oxidize exogenous _____ into ____ that prevents the fungi from phagocytic oxidative damage

A

Cryptococci can oxidize exogenous catecholamines into melanin that prevents the fungi from phagocytic oxidative damage

30
Q

Pneumocystis jirovecii is an unusual fungus because it lacks ____ in cell walls and has ____ instead

A

Pneumocystis jirovecii is an unusual fungus because it lacks ergosterol in cell walls and has cholesterol instead

31
Q

an AIDS patient is at risk of acquiring Pneumocystis jirovecii once the CD4 cell count drops below ____

A

an AIDS patient is at risk of acquiring Pneumocystis jirovecii once the CD4 cell count drops below 200 cell/uL

32
Q

describe the staining of Pneumocystis jirovecii

A
33
Q

a “branching, tree-like pattern” on staining is indicative of ____

A

a “branching, tree-like pattern” on staining is indicative of Aspergillus

34
Q

describe the 2 forms of aspergillosis

A
  • allergic: needs underlying asthma or CF
  • invasive: hyphae invade tissue (transplant patients – lung)
    • deadly, invasive pneumonia
    • hemoptysis
    • high mortality