Mycology and Antifungals Flashcards
what are the general structures of mould and their classification. (6)
Sporangium - enclosed unit where spores are found.
Spores - reproduction structures.
Sporangiphore - hypha as stalk of sporangium.
Hyphae - filamentous structure formed together as a network called mycelium.
Rhiziod - ‘roots’ to absorb nutrients.
Mould → multicellular
what are the general structures of yeast and their classification. (7)
Cytoplasm
Ribosome
Mitochondrion
Nucleus
Cell wall
Cell membrane
Yeast → unicellular
what is an example of a superficial fungal disease
pityriasis versicolor
what are common dermatophyte cases (3)
- Tinea cruris (groin infection)
- Tinea pedis (athlete’s foot)
- Tinea unguium (nail bed, discolouration and thickening) - hard to treat as medicine has to penetrate the nail. Treatment normally lasts weeks - months.
why is cryptococcosis C. neoformans dangerous and what is it treated with (5)
- mould within the soil
- yeast within the human host.
- polysaccharide capsule inhibits phagocytosis
- affects the lung, brain and meninges.
- treated with amphotericin B and 5-fluorocytosine combination.
what are the cellular targets of fungal cell walls and how is this achieved (4)
- Glucans
- Mannans
- Chitans
achieved by administering polyoxins.
what is the cellular target of fungal cell membrane, and how is this achieved
Ergosterol is the cellular target of the CELL MEMBRANE
this can be achieved by administering polyenes.
what is the cellular target of fungal nucleus and how is this achieved (3)
- Nucleic acid and DNA and RNA synthesis
- 5-fluorocytosine inhibits the synthesis of nucleic acid synthesis of DNA and RNA.
- griseofulvin stops the fungi from multiplying by affecting microtubule formation.
what is the cellular target of fungal cytoplasm and how is this achieved
squalene
Azoles and Allylamines work by inhibiting squalene.
What are the differences in fungal eukaryotic and animal eukaryotic cells. (4)
- fungal cell wall is 80-90% polysaccharides made up of glucans, mannans and chitins.
- Mannan linkages & side chains give antigen specificity and aid classification.
- Membrane contains lipids & proteins, traces of nucleotides, carbohydrates glucan and mannan.
- Contains the sterol ergosterol in fungi, which is mechanically stronger than cholesterol, which is present in animal cells.
What are examples of antifungals (9)
- amphotericin B and 5-fluorocytosine combination → Cryptococcosis C. neoformans
- Terbinafine (allylamine) → dermatophytes
- Imidazole → systemic fungi and dermatophytes.
- Itraconazole (Azole) → histoplasmosis and aspergillosis
- Fluconazole (triazole) → cryptococcal meningitis, candidiasis and coccidioidomycosis.
- Voriconazole → Has interaction at CYP450 affecting drug breakdown. Inducers = griseofulvin & rifampicin, which increase the breakdown of the drug. Inhibitors = ketoconazole & fluconazole which decrease the breakdown of the drug.
- Nystatin → GI use against candida and dermatophytes.
- Griseofulvin → dermatophytosis
- 5-flucytosine (antimetabolite) → systemic fungal infection, mainly candida and cryptococcus. Used with amphotericin B and itraconazole to treat long-term fungal skin infections.
What are the cellular targets of fungal cells (4)
- DNA, RNA & nucleic acid synthesis - nucleus
- Ergosterol - Cell membrane
- Glucans, mannans, chitons - Cell wall
- Squalene - cytoplasm