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Flashcards in RTI VIII Deck (34):
1

list the primary fungal pathogens

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

2

list the opportunistic fungal pathogens

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

3

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

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

4

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

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

5

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

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

6

list the clinical features of fungal RTIs

7

fungi that cause RTIs are able to convert to form ____

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

8

describe how H. capsulatum can grow inside macrophages

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

9

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

explain this 

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

10

describe obtaining samples and techniques used for diagnosing fungal RTIs

11

delayed hypersensitivity skin tests are useful for diagnosis of _____

delayed hypersensitivity skin tests are useful for diagnosis of Coccidiodomycosis

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

12

describe the exoantigen test

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

13

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

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

14

acquiring Histoplasmosis is dependent on... (2 things)

15

name the 2 clinically significant varieties of Histoplasma

  • 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

16

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

17

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

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

18

in Blastomycosis, look for ____

in Blastomycosis, look for skin lesions

19

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

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

20

Coccidioides immitis is endemic to _____

clinical syndrome = Valley Fever

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

21

____ is the most virulent of all the human mycotic pathogens

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

22

____ protects Coccidioides from phagocytosis

spherules protects Coccidioides from phagocytosis

23

opportunistic pathogens are usually (monomorphic/dimorphic)

opportunistic pathogens are usually monomorphic

24

list the predisposing factor and the major pathogen associated with it

25

Cryptococcus neoformans is the only fungus that is ____

Cryptococcus neoformans  is the only fungus that is encapsulated

26

describe CSF staining of Cryptococcus

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

27

describe tissue staining of Cryptococcus

28

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

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

29

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

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

30

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

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

31

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

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

32

describe the staining of Pneumocystis jirovecii

33

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

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

34

describe the 2 forms of aspergillosis

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