Mycology Flashcards
what type of micro organisms are fungi?
eukaryotic
what is the cytoplasm enclosed within in fungi?
a cell wall
what is found within the cell wall of fungi?
chitin
how do fungi gain nutrients?
absorption of organic molecules from the immediate surroundings
how do fungi reproduce?
sexual (meiosis) and asexual (mitosis) spores
what is the most common way that fungi reproduces?
asexual spores
what are the 2 main morphological forms of fungi?
moulds and yeasts
what is the basic cell unit of moulds?
hypha
what is the structure of hyphae?
a cylinder which elongates from the tip and is capable of branching
what strengthens the tubular wall?
cross walls (septa)
what is a feature of the cross wall which means that nutrients can be shared with the whole organism?
they have a central pore which cytoplasm can stream through
what makes hypha acellular?
the central pores in the cross wells
what are mycelium?
network of hyphae forming the body of the mould
what two layers can mycelium consist of?
submerged vegetative mycelium and aerial mycelium
what is found on the aerial mycelium?
asexual spores
what are yeasts?
an alternative growth form of hypha
what do yeasts consist of?
discrete, ovoid cells
how does yeast reproduce?
budding
what can some yeasts produce?
yeasts and hyphae depending on the environmental conditions
what is the name for yeasts which produce both yeasts and hyphae?
dimorphic
what is pseudo-mycelium?
intermediate form of growth between hyphae and yeasts in which elongated budding cells form pseudohyphae
define colony
in a culture, a mycelium or mass of yeast cells usually grown from a single hyphal fragment or yeast cell
what are phylum deuteromycota?
an assemblage of fungi which only produce conidia as there is no sexual reproductive state
what group do most pathogenic species fit into?
phylum deuteromycota
what are arthrospores?
conidia (spores) formed by simple fragmentation of hyphae in dermatophytes (skin loving bacteria)
what does fungi cause as a pathogen?
mycosis (infection)
allergy (inhaled spores)
toxicosis (usually mycotoxicosis)
what are the 2 sources of infection?
endogenous and exogenous
where does endogenous infection come from?
commensal flora
where does exogenous infection come from?
free living saprophytes in the environment or parasites on another animal host
what are the 3 types of infection?
superficial mycoses
sub-cutaneous mycoses
deep mycoses
where are superficial mycoses found?
epidermis
where are deep mycoses found?
within the body
what can sub-cutaneous mycoses be caused by?
introduction through trauma in the skin
what can ringworm cause in cattle?
loss of growth rate
lower milk yield
scarring which affects hide value
contamination will persist for years
what are the two ways that fungal infection must be treated?
topically and systemically
what stops spores from continuing to reinfect the animal from the environment?
radical approach including thorough cleaning and burning/disposal of animal bedding etc
at what temperature do deep mycoses grow best?
blood temperature
are deep mycoses contagious?
no
when do deep mycoses continue to arise?
when the immune system is compromised or commensals are reduced as they are opportunistic
what can cause predisposition to fungal infection?
immune suppression (natural or induced)
age
trauma
exposure to heavy spore loads
what are the 3 types of deep mycoses caused by mould?
aspergillosis
Mucoromycosis
mycotic abortion
what are the 2 types of deep mycoses caused by yeast?
candidosis
cryptococcosis
what is the main source of aspergillosis?
hay/straw
what size are aspergillosis spores?
2-3 micro metres
what are the 2 types of aspergillosis?
acute and chronic
when is acute aspergillosis seen?
neonates
what is a key way of diagnosing chronic aspergillosis in dogs?
uni/bilateral depigmentation of the nose and discharge
what does bovine mycotic abortion result in?
infection of placenta and foetus
how does bovine mycotic abortion present?
thickened cotyledons, amnion and foetal skin
is bovine mycotic abortion contagious?
no
where are hyphae found in bovine mycotic abortion?
in tissues and in foetal stomach contents
where can the most reliable culture of bovine mycotic abortion be taken from?
foetal stomach contents
what are the 2 main types of yeast infections?
candidosis and cryptococcosis
where is candidosis often found?
normal gut flora
where is cryptococcosis found?
in bird/bat faeces
what does cryptococcosis cause?
nasal granuloma, skin ulcers, brain infection
when do most fungal infections arise?
during immunosuppression
can cryptococcosis be identified by the body?
no as it is surrounded by a capsule
what is the most dangerous element of cryptococcosis?
it can be dormant for a number of years and is walled off by the body where it will continue to grow until it bursts
what is key when cryptococcosis is being treated?
it is kept moist as the spores can’t be shed so easily
how can fungal infection be diagnosed normally?
from a skin scrape: direct microscopy, culture and visual ID
how can deep mycosis be diagnosed?
serology: checking for antibodies and antigens (e.g. chitin), presence of alcohol and molecular identification using PCR
