RTI VIII Flashcards
list the primary fungal pathogens
- primary (healthy & immunocompetent)
- Histoplasma capsulatum
- Blastomyces dermatidis
- Coccidiodes immitis
- Paracoccidiodes brasiliensis
list the opportunistic fungal pathogens
- opportunistic (immunocompromised individuals)
- Cryptococcus neoformans
- Aspergillus sp.
- Pneumocystis jiroveci
all primary fungal RTIs are acquired via ____ and all are _____
all primary fungal RTIs are acquired via inhalation and all are dimorphic
____ & ____ 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
____ is endemic in the area of Southwestern US and Northwestern Mexico
C. immitis is endemic in the area of Southwestern US and Northwestern Mexico
list the clinical features of fungal RTIs
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
describe how H. capsulatum can grow inside macrophages
- H. capsulatum
- can increase phagolysosomal pH
- interferes with enzyme activity and antigen processing
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
describe obtaining samples and techniques used for diagnosing fungal RTIs
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
describe the exoantigen test
- exoantigen test:
- basis = immunodiffusion
- look for presence of specific cell free antigens produced by mycelial phase of the fungi
- basis = immunodiffusion
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
acquiring Histoplasmosis is dependent on… (2 things)
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
describe what to look for when examining a tissue infected with Histoplasma
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
in Blastomycosis, look for ____
in Blastomycosis, look for skin lesions
describe what to look for when examining a tissue infected with Blastomyces
look for single broad base bud in a yeast (B = Blastomyces)
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
____ protects Coccidioides from phagocytosis
spherules protects Coccidioides from phagocytosis
opportunistic pathogens are usually (monomorphic/dimorphic)
opportunistic pathogens are usually monomorphic
list the predisposing factor and the major pathogen associated with it
Cryptococcus neoformans is the only fungus that is ____
Cryptococcus neoformans is the only fungus that is encapsulated
describe CSF staining of Cryptococcus
India Ink staining is a negative stain of CSF, where the capsule creates a clear halo
describe tissue staining of Cryptococcus
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)
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
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
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
describe the staining of Pneumocystis jirovecii
a “branching, tree-like pattern” on staining is indicative of ____
a “branching, tree-like pattern” on staining is indicative of Aspergillus
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
