| Term | Definition |
|---|
| Are fungi eukaryotes or prokaryotes? | Eukaryotes |
| Do fungi have chlorophyll | No-- no photosynthesis |
| Are fungi aerobes or anaerobes? | Aerobes |
| What are yeasts? | Single cellular form of fungi, can be spherical or ellipsoidal, reproduce by budding |
| What are pseudohyphae? | Long chains of yeast cells produced when budding is incomplete |
| What are molds/mycelia? | Multicellular colonies of fungi composed of clumps of intertwined hyphae. Molds grow by longitudinal extension and produce spores |
| What are spores? | The reproducing bodies of molds; rarely seen in skin scrapings |
| What are dimorphic fungi? | Fungi that can exist as either yeast or molds |
| What are saprophytes? | Fungi that live in and use organic matter as an energy source (sapro means rotten) |
| Describe the cell membrane of fungi | Double-layered membrane, has cholesterol |
| Kind of cholesterol unique to fungi cell membranes? | Ergosterol |
| Other organisms that have sterols in their cell membranes? | Mycoplasma (only bacteria to have cholesterol and other sterols); human cells have cholesterols in them |
| Amphotericin B | Antifungal agent; binds to ergosterol and punches holes into the cell membrane, forming a transmembrane channel that leads to K+ leakage and fungal cell death |
| Nystatin | Antifungal agent; binds to ergosterol and punches holes into the cell membrane. treatment for oral thrush |
| The "azoles" | Antifungal agent;inhibits ergosterol synthesis by binding to cytochrome P-450 14 alpha demethylase, block it from converting lanosterol to ergosterol |
| Echinocandins | Antifungal agent; inhibits ergosterol synthesis, inhibit synthesis of 1,3-beta-D-glucan important for fungal cell wall |
| What is the cell wall of fungi composed of? | Carbohydrates and some protein |
| What is the capsule of fungi made of? | Polysaccharide |
| What fungi use the antiphagocytic capsule to its benefit | Cryptococcus neoformans |
| How do you visualize the capsule of Cryptococcus neoformans? | India ink stain |
| Fungal diseases classification | superficial mycoses, cutaneous mycoses, subcutaneous mycoses and systemic mycoses. |
| superficial mycoses | pityriasis versicolor, tinea nigra, black piedra and white piedra. |
| subcutaneous mycoses penetrate the dermis, subcutaneous tissue, muscle and fascia | sporotrichosis, chromoblastomycosis and mycetoma |
| Fungi are most commonly cultured on | Sabouraud's agar(low pH) or Mycosel agar(selective for pathogenic fungi because it has chloramphenicol and cycloheximide) |
| pyrimidine analogs such as flucytosine | incorporate into RNA and/or DNA thus blocking protein synthesis or DNA synthesis. |
| pityriasis versicolor | Malazessia furfur and Malazessia globosa |
| how do unicellular fungi/yeast reproduce | asexually by blastoconidia/budding formation |
| coenocytic vs septate hyphae | molds without cross walls vs those with cross walls |
| aflatoxin | carcinogen produced by Aspergillus flavus |
| triazole family | fluconazole, itraconazole, voriconazole |
| side effects of fluconazole | headache, liver toxicity, alopecia from long term treatment. GI effects. also fetal damage in pregnancy |
| which medications are contraindicated for itraconazole | antacids or H2 inhibitors(cimetidine), since it requires acid pH for capsules to dissolve |
| imidazole family | ketoconazole, clotrimazole, miconazole. inhibit CP450 alpha demethylase |
| toxicitiy associated with ketoconazole | gynecomastia due to inhibition of estrogen metabolism, thrombocytopenia, photophobia |
| how does flucytosine work | converted to 5-fluorouracil in fungal cells and is antimetabolite. does not kill humans since we lack cytosine deaminase enzyme for this conversion |
| flucytosine toxicity | leukopenia, thrombocytopenia |
| what drugs should be used with caution with fluconazole | drugs causing bone marrow suppression (ganciclovir, zidovudine etc) |
| how does terbinafine work | inhibits squalene epoxidase, enzyme required for ergosterol. use terbinafine for dermatophye infections |
| mechanism of action of griseofulvin | binds polymerized microtubules |
| Histoplasma capsulatum | Darling's disease, reticuloendotheliosis, reticuloendothelial cytomycosis, Ohio Valley disease, tingo, and Maria fever |
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