Lecture 19 11/13/23 Flashcards
Where can fungi be found?
-practically everywhere in the environment
-skin and mucous membranes
What are the general characteristics of fungi?
-free-living eukaryotes
-majority are saprophytes and non-pathogens
-heterotrophs
-most reproduce asexually
-cell membrane contains sterols
-plant-like cell wall
What is the unicellular form of fungi?
yeast
What is the multicellular form of fungi?
mold
What structures are found in mold?
-hyphae
-fruiting bodies containing spores
What is a mycelium?
groups of tangled hyphae
What are the visual characteristics of yeast?
-opaque, creamy, and smooth
-round single cells that undergo budding
What are the visual characteristics of mold?
-woolly/fluffy colonies
-hyphae/tube-like structures intermeshed
What are dimorphic fungi?
fungi exhibiting characteristics of both yeast and molds
What are the two fungi classifications based on hyphae arrangement?
-septate (septa dividing the hyphae)
-non-septate
What are the potential pigmentations of hyphae?
-dark pigmented (dematiaceous)
-non-pigmented (hyaline)
What are the general characteristics of fungal infections?
-invade tissue and induce pathogenic effects
-opportunistic
-cause chronic, granulomatous infections
-antimicrobials are limited
What is mycotoxicosis?
fungal contamination of food material, leading to toxin accumulation and severe disease if ingested
What happens when fungal spores are inhaled?
hypersensitivity/allergic reaction
What is a superficial infection?
infection limited to outermost skin/hair layers
What is a cutaneous infection?
-infection extending deeper into dermis
-invasive hair and nail diseases
What is a subcutaneous infection?
infection involving the dermis, subcutaneous tissues, muscle, and fascia
What is a systemic infection?
infection originating in lung that spreads to many other organs
How can fungi be diagnosed?
-cytology
-histopath.
-wet mounts
-Beta D-glucan assay
-agar gel immunodiffusion
-ELISA
-culture and ID
-PCR
What are the characteristics of a calcofluor stain?
-requires UV microscope
-stain binds to chitin in fungal cell walls
What are the characteristics of fungal culture?
-requires special media and growth conditions
-best grown at ambient environmental temps
-aerobic
Which media can be used for fungal culture?
-Sabouraud Dextrose agar
-Sabouraud Dextrose agar w/ Cycloheximide
-Dermatophyte test media
How can fungi be definitively identified following culture?
-DNA probes/sequencing
-serotyping
-mating studies
-virulence testing
What is the Beta D-glucan assay?
general screening of invasive fungal disease
What is the latex agglutination test?
qualitative/semi-quantitative test for detection of capsular polysaccharide antigens in serum or CSF
Which fungus can the latex agglutination test identify?
Cryptococcus neoformans
Which fungal species can be detected using antigen detection tests?
-histoplasma
-blastomyces
-coccidioides
-aspergillus
-cryptococcus
Which anti-fungal drugs inhibit ergosterol?
-polyenes
-azoles
-allylamines
Which anti-fungal drug inhibits nucleic acid synthesis?
flucytosine
Which anti-fungal drug binds to mitotic spindles and inhibits mitosis?
griseofulvin
What are the characteristics of fungal infection immunity?
-cell-mediated
-antibodies produced but not protective
-most lesions are granulomatous
