anti fungals Flashcards
what are some key characteristics of fungi?
- cells contain nuclei like chromosomes (unlike bacteria)
- they cannot photosynthesis (they are heterotrophic, like animals)
- hyphae are key to growth (exude enzymes and absorb food)
- spores are important for reproduction (sexual and asexual)
what type of cell are fungi?
how do they reproduce ?
- they are single cells/ complex filamentous networks
- ‘dimorphic’ switching between Yeats and filaments
- sexual or asexual reproduction
- highly adaptable to their new environment
what are the key differences between fungi and bacteria?
- fungal walls contain polysaccharide not found in other micro-organisms
- CHITIN = this adds rigidity and support, this confers resistance to cell wall antibiotics (eg- penicillin)
- B- glucan = site of action of some anti fungals
- cell membranes consist of ergosterol rather than cholesterol (this is a good target for some anti funagls)
why will antibiotics not work against fungus?
because of the chitin protein in the cell wall - adding support and rigidity.
what type of pathogen are fungals
they are opportunistic pathogens - this means that they will target immunocompromised people
what fungus is going to cause superficial mycoses?
malassezia furfur
what fungus Is going to cause cutaneous mycoses?
- tinea capitus
- tinea cruris
- tinea pedis
what fungal pathogens are able to induce disease of an immunocompetent host?
- histoplasmosis
- coccoidomycosis
due to what, will most ‘opportunistic pathogens’ cause systemic disease in patients with compromised cell mediated immunity due to:
- HIV
- immunosuppressive medication
- concurrent illnesses/long term lines.
what type of yeast will cause meningitis
crytococcus neoformans
yeast?
single oval cells replicate by BUDDING or FISSION
(some are dimorphic, can be filamentous too)
disease entity:
candida spp.
thrush, fungaemia
disease entity:
cryptococcus neoformans
meningitis
pneumonia
fungaemia
disease entity:
systemic Yeasts
pulmonary or disseminated infections
disease entity:
aspergillus spp., mucor, rhizopius, absidia.
- allergic bronchopulmonary aspergillosis
- aspergilloma
- invasive aspergillois
disease entity:
dermatophytes; epidermophyton, microsporum, trichophyton
chronic infection of skin and nails, kerion
what are the 6 anti fungal drugs
- azoles
- terbinafine
- polyenes
- flucytosine
- griseofulvin
describe the ergosterol biosynthetic pathway?
- selective toxicity= key principle underpinning anti-infective therapy
- ergosterol biosynthetic pathway is essential to fungal but not to eukaryotic cell membranes
- anti fungal drugs can exhibit inhibitory mechanisms on ergosterol synthesis
what 2 drugs will act as ergosterol inhibitors?
azoles
terbinafine