Fungi
function of mannan in the cell wall of dermatophytes
(-) immune response
where is cryptococcus gattii native to
Australia and part of South America
does aspergillus reproduce sexually or asexually
asexually
what does amphotericin B do
binds to ergosterol and makes a WS pore in the plasma membrane
spores that are easy to breathe in from aspergillus
conidiophores
where is ergosterol found in the fungal cell
it makes up the fungal plasma membrane
2 main forms of dimorphic yeasts, which is more pathogenic?
1. Yeast (Y) form - this is more pathogenic 2. Mycelia (M) form
2 main pathogenic yeast species
1. candida species (candida albicans) 2. cryptococcus neoformans
2 overarching concepts that are targeted by antifungals
1. fungal cell wall 2. nucleic acid synthesis
3 types of dimorphic yeasts
1. histoplasma 2. blastomyces 3. coccidioides
3 major components of the fungal cell wall and their functions
1. mannan - outermost protective layer 2. glucan - acts as the scaffold 3. chitin - rigid to give the cell wall strength
what 3 diseases does candida albicans cause
1. oral candidiasis (thrush) 2. diaper rash 3. vulvovaginal candidiasis
cytosine analog that (-) DNA and RNA synthesis and takes up cytosine permease, which converts the drug to 5-FU
5-flucytosine
are fungi usually aerobic or anaerobic
aerobic, although some yeasts are fermentative
tumor made of fungus that is found in pts with previous lung damage (usually TB pts)
aspergilloma
species of fungi that is associated with seasonal allergies and lung infections that can become invasive if previous lung damage exists
aspergillus
how long do we usually treat cryptococcus neoformans for, why?
at least 6 months due to slow replication of the yeast
tinea pedia
athlete's foot
dimorphic yeast that is found in moist soil with decomposing leaves and organic matter native to the Southeast and Midwest
blastomyces
the most common candida species that is part of the normal flora
candida albicans
candida species that is MDR and has therefore caused numerous outbreaks in healthcare facilities
candida auris
candida species that is seen in pediatric pts with bloodstream infections and is increasing in resistance to azoles
candida glabrata
candida species that has inherent resistance to fluconazole and acquired resistance to other antifungals
candida krusei
candida species with a high mortality rate and is seen in pts with blood cancers and prolonged azole tx
candida krusei
common cause of local infections, although some can get into the bloodstream and cause serious illness
candida species
candida species that forms biofilms and is resistant to fluconazole
candida tropicalis
common infection in immunocompromised pts and is the most common cause of nosocomial candidiaemia
candida tropicalis
which component of the fungal cell wall makes up the majority of it
chitin
what does nikkomycin target
chitin synthesis
dimorphic yeast that is found in the Southwest US and Washington state because it is kicked up during dust storms
coccidioides
new strain of cryptococcus that causes lethal disease in healthy people
cryptococcus gattii
is able to cause meningitis and pneumonia and is increasing in prevalence among HIV pts and those on immunosuppressive meds
cryptococcus neoformans
cause of common superficial skin infections because they thrive in warm and moist areas
dermatophytes
describe phase transition for dimorphic yeasts
dimorphic fungi can move back and forth between both the yeast (Y) form and mycelial (M) form
main target for antifungals that is a part of the cell wall
ergosterol
what do the azoles target
ergosterol synthesis
is the structure of fungal cells more eukaryotic or prokaryotic
eukaryotic - they have a nucleus, mitochondria, and linear chromosomes
t/f: aspergillus is easy to dx
false - it is hard to dx because sx are not specific
t/f: tinea infections can be invasive if left untreated
false - these are not invasive :)
where is cryptococcus neoformans found, and is it dimorphic?
found in soil/bird droppings throughout the world it is NOT dimorphic
what is the main difference between fungal cell and human cells and is, therefore, the main target with antifungals
fungal cell wall
uncommon form of aspergillus but was cause of a 2012 outbreak due to contaminated lots of preservative-free methylprednisolone
fungal meningitis
principal decomposers in the ecosystem that obtain their nutrients by absorption
fungi
what do the echinocandins target
glucan synthesis
is there a high or low incidence of resistance to flucytosine
high - it is limited to mild yeast infections or in combination therapy for severe infections
dimorphic yeast that is found in bird and bat droppings and is common in Mississippi and Ohio River valleys
histoplasma
multicellular filamentous structures that are formed by molds
hyphae
in which pts is aspergillus resistant
in those with previous antifungal tx
tinea cruris
jock itch
extracellular enzymes produced by dermatophytes that hydrolyze keratin in the skin and break down the outer skin layer
keratinases
what is mycelia
mass of hyphae
are dermatophytes molds or yeasts
molds
multiple cells connected together that form hyphae
molds
do fungal cell walls contain peptidoglycan, LPS, and teichoic acids
no
structure of cryptococcus
prominent polysaccharide capsule that allows the fungi to be invasive since the capsule is thick and protective
what do dimorphic yeasts present as in pts
respiratory infections
tinea corporis
ringworm
tinea capitis
scalp/hair follicles
what do fungal cell walls form
spores
potential future for antifungal drug research
target phase transition of dimorphic yeasts
t/f: mycelial (M) form of dimorphic yeasts form hyphae and resemble molds
true
most common cause of yeast infections and is caused by changes in the vaginal environment that disrupt growth of lactobacilli
vulvovaginal candidiasis
round or oval single cells that reproduce by budding to create daughter cells called blastoconidia
yeasts
do dimorphic yeasts occur in heat or cold, how about dimorphic molds?
yeasts in the heat, molds in the cold
2 forms that fungi can be
yeasts or molds