Mycology Flashcards
What are the features of fungi?
- eukaryotic (nuclei)
- widely distributed in environment
- most are saprophytic (eat dead material)
- grow aerobically
How many species of fungi are there?
- >250,000
- (150 pathogenic to man/animals)
What are the 4 main groups of fungi?
- Ascomycota- (yeasts, truffles)
- Basidiomycota (mushrooms)
- Zygomycota (bread moulds)
- Deuteromycetes (fungi imperfecti)
What are the 2 main morphological forms of fungi?
- filamentous- branches, spreads
- yeast - little granules
- some can be both (dimorphic)
What do fungi produce when they reproduce?
- spores (germinate when environmental conditions favourable)
- asexually or sexually
Describe fungal sexual and asexual reproduction
What kind of fungi can change shape/size and what are the triggers? Examples?
- in order to survive- DIMORPHIC fungi change
- triggers:
- pH
- temp
- water levels
- Examples:
- Candida albicans (yeast ->filamentous)
- Histoplasma (filamentous ->yeast)
At what temp will a fungus be in mold/ yeast form?
What are the 3 mechanisms involved in fungal disease?
- tissue invasion (mycosis)
- toxin production (mycotoxicosis)
- induction of hypersensitivity)
What are the types of mycosis?
- superficial (incl. mucous membranes and subcutaneous)
- systemic (respiratory/ GIT)
List the predisposing factors that increase the risk of fungal disease
- immunosuppression (after steroids)
- persistent moisture
- prolonged antibiotics
- immunological defects
- young/old
- malnutrition
- large infective dose
- breed/genetics
- trauma to tissues
What are the 3 groups of dermatophytes (ringworm)?
- Zoophilic- obligate pathogens- mainly infect animals
- Anthropophilic - obligate pathogens - only humans
- Geophilic - occur naturally in soil (with decomposing hair/ feathers) - animals/ peiple
What is the main species of dermatophytes?
- microsporum
- trichophyton
How is Dermatophytosis spread/ what does it invade?
- transmission via direct (or indirect) contact with spores
- m.canis- cats most common source
- t.mentagrophyte- (rodent/ hedgehogs source to dog)
- t.verrucosum- calves
- m.gypseum- soil (digging dogs)
- invades superficial keratinised structures (skin, hair, claws)
How long can ringworm spores remain viable for?
- >12m in suitable environments
What clinical signs would you see in dermatophytosis?
- hyphae grow out from original lesion -> normal skin
- alopecia, dermatitis, epidermal hyperplasia, hyperkeratosis, onchomycosis (nail infection)
What is this?
- dermatophytosis
What is Aspergillus?
- saprophytic
- wide distribution
- A.fumigatus most common species
- respiraotry pathogen- aquired by spore inhalation
- most common source: poor quality hay and compost heaps, contaminated bedding
In what animals is aspergillus most commonly found?
- poultry
What clinical signs would you see in Aspergillus (aspergillosis)?
- poultry - yellow nodules in lungs/airsacs = gasping, emaciation, death
- horses - guttoral pouch mycosis = epistaxis, nasal discharge, dysphagia, laryngeal hemiplegia
- dogs - nasal aspergillosis = sanguinopurulent nasal discharge, sneezing, epistaxis
What type of infections do yeasts cause and where are they found?
- opportunistic infections (live undetected until microbiome is affected)
- found in environment, on plants or as commensals on skin/ mucous membranes
Species of yeast?
- Candida (C.albicans)
- Cryptococcus neoformans
- Malassezia pachydermatis
- Trichosporon- rare
What type of yeast has caused this and what are its features?
- candida albicans
- commensal of GIT and urogenital tracts
- yeast form -> hyphal form in body
- overgrowth causes clinical signs
- e.g. thrush, stomatitis, enteritis, cystitis
