fungal infections Flashcards
what are fungi?
Eukaryotic
Chitinous cell wall
Heterotrophic
how do fungi move?
Move by means of growth or through the generation of spores, which are carried through air or water
describe yeasts
Yeasts are small single celled organisms that divide by budding
Account for <1% of fungal species but include several highly medically relevant ones
what do moulds form?
Moulds form multicellular hyphae and spores
what are dimorphic fungi?
Some fungi exist as both yeasts and moulds switching between the two when conditions suit
how is it that only a few hundred species can cause human infection?
Inability to grow at 37 degrees
Innate and adaptive immune response
what does the eukaryotic feature of fungi limit?
limits options for selective toxicity
what is fungi cell wall made up of?
mannoproteins
Β1,3 glucan
Β1,6 glucan
chitin
Doesn’t exist in humans
what does the plasma membrane of fungi made up of?
ergosterol
what drugs affect the fungi cell wall?
Echinocandins
what drugs affect the fungi plasma membrane?
ergosterol
Polyenes e.g. amphotericin
Azoles
Allylamines e.g. terbinafine
what drugs affect DNA/rna synthesis?
Flucytosine
Griseofulvin
which fungal infections are very common?
superficial fungal infection
which fungal infections are very rare?
Invasive fungal infection
what is the aim of antimicrobial drug therapy?
to achieve inhibitory levels of agent at the site of infection without host cell toxicity
what does antimcrobial drug therapy rely on?
Relies upon identifying molecules with selective toxicity for organism targets
Target does not exist in humans
Target is significantly different to human analogue
Drug is concentrated in organism cell with respect to humans
Increased permeability to compound
Modification of compound in organism or human cellular environment
Human cells are ‘rescued’ from toxicity by alternative metabolic pathways
what are risk factors for mucosal commensal
immunosuppression, diabetes antibacterial therapy and mucosal disruption
what is used to treat mucosal candidiasis?
Treatment with topical or oral azoles
what is common in recurrant cases?
Resistant disease common in recurrent cases
Acquired resistance in normally susceptible species
Selection for intrinsically resistant species
how can dermatophytes spread?
human-human
animal-human
how are dermatophytes treated?
Treatment is usually with topical or oral azoles or terbinafine
is ringworm a worm
NO
What does tines capitis look like?
plucked hair
scalp scraping
what does tinea corporis look like?
Scraping of scaled edge of lesion
