Antifungals Flashcards
(31 cards)
How do antifungals work?
Cause fungal membrane to become deficient in ergosterol and toxic products accumulate
leads to cell death
Types of antifungals
Azoles - Most antifungal products
Allylamines
Polyene
Pyrimidine Analogues
Azoles Action
inhibit CYP450-dependent synthesis of ergosterol in cell membranes
Azoles Examples
Itraconazole
Ketoconazole
Miconazole
Allylamines action
Inhibits synthesis of ergosterol in fungal cells via inhibiting an enzyme (squalene epoxidase)
Allylamines example
Terbinafine
Polyene action
Binds to ergosterol in fungal cell membrane
Causes physical change in membrane and pores are created
Intracellular components leak out of pores leading to cell death
Polyene examples
Amphotericin B
Nyastatin
Pyrimidine analogue action
Anti-metabolite chemical used for some fungal conditions
5-flurocytosine is converted by fungal cell to 5-flurouracil
Inhibition of DNA and RNA synthesis
Doesn’t affect mammalian cells
Pyrimidine analogue action
Anti-metabolite chemical used for some fungal conditions
5-flurocytosine is converted by fungal cell to 5-flurouracil
Inhibition of DNA and RNA synthesis
Doesn’t affect mammalian cells
Pyrimidine analogue example
5-fluorocytosine
Cellular toxins
Not specific to fungi but have anti-fungal activity
Also kill bacteria and viruses
Cellular toxins examples and action
Silver sulfadiazine
Releases silver in concentrations that are toxic to bacteria and yeasts
Chlorhexidine (Hibiscrub)
Antiseptic
Binds to the skin and forms a protective layer preventing ingress of fungal cells
Can be applied as treatment in some conditions
Virkon
Disinfectant
Disrupts function of the cell membrane
By oxidising sulphur bonds in proteins and enzyme
What can be used to decontaminate environment and fomites
Virkon and chlorhexidine
Common Fungal diseases of cats/dogs
Malassezia - ears and skin
Ringworm (dermatophytosis)
Malassezia (otitis externa) Treatment in dogs
Nystatin
Miconazole
Clotrimazole - off licence in cats
Terbinafine - DO NOT USE IN CATS
Silver sulfadiazine - off licence
Used when Psuedomonas aeruginosa is cultured but no licenced products effective
Malassezia (skin infections) treatment in dogs
Miconazole - Prescription shampoo
Climbazole - Wipes
Ketoconazole – Off licence in cats, do NOT use in cats; oral, shampoo or skin spray
Chlorhexidine - Shampoo/foam/spray/otic solution/wipes
Ringworm (dermatophytosis) treatment in dogs
Ketoconazole - Do NOT use in cats (higher risk of side effects)
Oral
Systemic treatment
Enilconazole
Skin rinse
Miconazole - shampoo
Adjunctive treatment
Chlorhexidine - shampoo/foam/spray/otic solution/wipes
Synergistic with miconazole
Ineffective alone
Malassezia (otitis externa) treatment in cats
Nystatin
Miconazole
Malassezia (skin infection) treatment in cats
Miconazole - Prescription shampoo
Climbazole - Wipes
Itraconazole - Oral, systemic treatment
Chlorhexidine - Shampoo/foam/spray/otic solution/wipes
Ringworm (dermatophytosis) treatment in cats
Itraconazole
Oral
Systemic treatment
Miconazole - shampoo
Adjunctive treatment
Chlorhexidine - shampoo/foam/spray/otic solution/wipes
Synergistic with miconazole
Ineffective alone
Common fungal diseases in rabbits
Ringworm (dermatophytosis)
Ringworm (dermatophytosis) treatment in rabbits
All off licence
* Itraconazole – oral
Systemic treatment
* Enilconazole - skin rinse
* Miconazole - shampoo
Adjunctive treatment
* Chlorhexidine - shampoo/foam/spray/otic solution/wipes
Synergistic with miconazole
Ineffective alone
* Clotrimazole – cream
Adjunctive treatment
Common fungal diseases in horses
Ringworm (dermatophytosis)
Fungal keratitis (keratomycosis)
