Feb 28 - Antifungals and Mycology Flashcards
How do Amantidine and Rimantidine fxn?
They block uncoating by M2 protein, a membrane protein, through a viral proton channel
How do Zanamivir and Oseltamivir fxn?
They inhibit neuramidase
What do Amantidine and Rimantidine treat?
Influenza, Type A
What do Zanamivir and Oseltamivir treat?
Influenza, Type A and B
What drug(s) would you give to a pregnant woman with the flu?
Zanamivir or Oseltamivir
How is Rimantidine eliminated?
Hepatic
How is Amantidine eliminated?
Renally
Generally, what would you use to treat HSV I, II, VZV, or CMV?
Acyclovir, Valacyclovir, Gancyclovir, or Docosanol
How do Acyclovir, Valacyclovir, and Gancyclovir fxn?
They inhibit a virus-specific polymerase
Which has good oral absorption, Acyclovir or Valacyclovir?
Valacyclovir
What is necessary for (Val)Acyclovir to be converted to its active form?
A viral thymidine kinase (which also grants these drugs their selectivity)
How does Docosanol fxn?
It disallows viral envelope coating - it is a long-chain saturated alcohol
Abreva = (generic?)
Docosanol
What is the biggest concern for a Pt with CMV?
Retinitis
What do you give a Pt with active CMV?
Gancyclovir or Valgancyclovir
What are the adverse effects of (Val)gancyclovir?
Nephrotoxicity, myelosuppression, hypocalcemia
What drug could treat both HepC and RSV?
Ribiviron
How does yeast classically present on histological slide?
Arranged in cell-to-cell chains with hypochromic cytoplasm
Are fungi unicellular or multicellular? Sexual or asexual?
Yes. Yes to all the above
What is fungal cell wall made of? Why do we care?
Chitin (very rigid), and provides a drug target with excellent selectivity
What do fungi use instead of cholesterol? Why do we care?
Ergosterol - provides a drug target with excellent selectivity
What are pseudohyphe?
Elongated, linked yeast forms that kind of look like worms of slides
Tell me a little about yeast species
Unicellular balls, with fission/budding reproduction that are creamy/pasty in appearance - vary in size
What are true hyphe?
Tubular, filament-like fungal structures with BRANCHING - not unicellular, but can be septate or aseptate.
What are your dimorphic fungal species of note?
"Some Can Have Both Phases" Sporothrix Colcidioides Histoplasmosis Blastomyces Paracoccydiosis
Define Pleomorphic:
The culture plate has several different growth types at the same time
Define aerial hyphe
Hyphe that grow up and down
Define vegetative hyphe
Hyphe that spread laterally on the surface of the medium
Define rhizoids
Root-like structures on the bottom of the hyphe
Define septate
cells in a hyphe-like chain that are divided by cell walls
Define spore
The asexual form of reproduction - resistant to temp, pH, H2O change
What is a conidiospore?
A pine-cone looking spore
What is a microconidiae?
A spore that looks like a sparsely-branched tree
What is a sporangiophore?
A structure that contains developing spores, looks like a tiny bag of fish-eyes
What is a chlamydospore?
Hardy, resistant balls interspersed on hyphe that are made when the fungus is under environmental stress
What is an arthrospore?
An asexual spore that develops on the hyphe - looks like lumpy string
What is a spherule?
A large asexual spore, typically seen outside the body
What is a blastoconidia?
A small bud on a single-celled yeast
What is a thallus?
A cultured colony (can be wooly, smooth, cottony)
When preparing a sample, what do you add to remove the human tissue but leave the fungal?
KOH
What is the difference between Sabouraud’s agar, Mycocol agar, and Dermatophyte test medium?
Sabouraud’s agar = non selective
Mycocol agar = some antiB
Dermatophyte test medium = antiB + pH gradient
How does Amphoterecin fxn?
“Polyenes punch holes!” FungiCIDAL drug that inhibits erosterol synthesis
How does Imidazole/Fluconazole/Triazoles fxn?
They inhibit 1,4-dimethylase - inhibits general ergosterol synthesis. Fungistatic, will go into the CSF
How do Allylamines/Benzylamine fxn?
They block squalene epoxidase, which blocks 1,4-dimethylase, which inhibits general ergosterol synthesis. FungiCIDAL
How do Echinocandins fxn?
They inhibit 1,3-glucan synthase (good for Candidae/Aspergillis infection)
How does Griseofulvan fxn?
Inhibits the MT/spindle complex - good for ringworm of the scalp (take with ice cream yum)
How does Flucytosine fxn?
Blocks the addition of more bp’s in DNA synthesis
How does Ciclopirox olamine fxn?
It chelates metals needed for fungal development
What is a common side effect from improper use of an asthma inhaler? What organism causes this?
Oral thrush - Candidae
What are our two opportunistic fungi?
Candidae and Aspergillis
Are deep fungal infections better or worse than superficial ones?
Deep fungal infections are super nasty
How do Amphotericin B and Nystatin work? Route of admin?
They are polyene ergosterol inhibitors.
Amphotericin B = IV
Nystatin = topical
What is an adverse rxn to Amphotericin B or Nystatin?
Red Man Syndrome: chills, fever, shaking, hypotension, anemia due to kidney EPO depression, BM depression
What would you use Terbinafine for?
Keratin (finger/toenail) fungal infections
What is the difference between worms and parasites?
Worms develop in humans, but do not replicate. Parasites can replicate in humans
Some ways parasites evade host immune responses?
Encapsulation, Immunosuppression Intraluminal location
Three stages of Schistomiasis?
1) Swimmer’s Itch
2) Febrile response/HSM 3 wks later
3) Cirrhosis, Bladder cancer, chronic inflammation
How to treat schistomiasis?
Praziquantel
How do shistosomes spread around?
Their eggs are excreted in the urine (s. haematobium) and feces
What cell does malaria infect first/most readily?
Hepatocytes
What is the lethal species of plasmodium?
P. falciferum:
RBC lysis leading to rapid acute anemia
Makes “nobs” that cling to vasculature - brain death via hypoxia
