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
