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52 Cards in this Set
- Front
- Back
The Fungi are members of what kingdom
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Myceteae
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What are the complex polysaccharides that made up the rigid cells walls of Fungi
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Chitin, glucans, mannans
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What are the four hereotrophic states of Fungi
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Saprobes, Symbionts, Commensals, Parasites
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What are saprobes
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Organisms that live on dead or decaying matter
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What are symbionts
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Organisms that live together and in which the association is of mutual advantage
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What are commensals
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Organisms living in a close relationship in which one benefits from the relationship and the other neither benefits nor is harmed
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What are parasites
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Organsims that live on or within a host, from which they derive benefits without making useful contribution in return; in the case of pathogens the relationship is harmful to the host
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How can yeasts be defined morphologically
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A cell that reproduces by budding or by fission, in which a progenitor or "mother" cell pinches off a portion of itself to produce a progeny or "daughter" cell. The daughter cells may elongate to form sausagelike pseudoyphae. Yeasts are usually unicellular and produce round, pasty or mucoid colonies on agar
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How can moulds be defined morphologically
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Multicellular organisms consisting of threadlike tubular structures call hyphae that elongate at their tips by a process known as apical extension. Hyphae are either coencoytic or septate. The hyphae form together to produce a matlike structure called a mycelium. The colonies formed by moulds are often described as filamentous, hairy, or woolly
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How do coenocytic hyphae look
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Hollow and multinucleate
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How do septate hyphae look
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Divided by partitions or cross-walls
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What is the name for the form of the fungus producing sexual spores
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Teleomorph
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What is the name for the fungus producing asexual spores
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Anamorph
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In what form are the fungi isolated from patient specimens
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Anamorph, the asexual form
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What are the two general types of asexual fungal spores
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Sporangiospores and conidia
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What are the characterisitcs of Zygomycetes
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Moulds with broad, coenocytic hyphae, rare septa, asexual sporangiospores; hyphae with rhizoids
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What are the characteristics of Ascomycetes
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Yeasts and moulds, septate hyphae; conidiophores produce asexual spores; sexual spores produced in ascus
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What are the characteristics of Deuteromycetes
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Imperfect fungi; sexual stage unknown; septate hyphae, conidia produced on conidiophores; yeasts reproduce by budding
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What organism produces the superficial disease Pityriasis versicolor
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Malassezia furfur
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What organisms produces Ringworm (tinea)
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Trichophyton species
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What two opportunistic fungal species produce Zygomycosis
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Mucor and Rhizopus
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Which fungi cause endemic mycoses
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Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, Penicilium marneffei
These are true virulent pathogens that can cause infection in healthy normal people. Primary infection in the lung, then may disseminate |
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What fungi cause opportunistic mycoses
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Aspergillus, Candida, Crytococcus neoformans, Pneumocystis jiroveci
These cause disease in immunocompromised individuals |
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How are fungal infections transmitted
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Respiratory inhalation of spores
Systemic spread by normal flora (Candida) or dissemination from the lungs Cutaneous/subcutaneous inoculation (sporothrix, dematiaceous molds) Direct contact with infected hosts (dermatophytoses) |
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What is the primary protective host response to fungal pathogens
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Cellular
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What fungus can produce chronic, local dermal inflammation
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Dermatophytes
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What funus can produce allergic hypersensitivity without tissue invasion
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Allergic bronchopulmonary aspergillosis
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Infection with what fungus can lead to acute pyogenic abscess
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Candida
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Infection with what fungus can lead to chronic granuloma formation
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Histoplasma (mimics TB)
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Infection with what fungus can lead to mixed pyogenic/granulomatous inflammation
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Blastomyces
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Infection with what fungi can lead to blood vessel invasion with thrombosis and infarction
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Mucor or Rhizopus
Aspergillus |
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India ink stains for what
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Cryptococcus capsule
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What does mucicarmine stain for
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Cryptococcus neoformans capsule
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What are the characteristics of Amphotericin B
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Binds to ergosterol; increases membrane permeability resulting in leakage of cytoplasmic contents, also causes cascade of oxidative reactions which generate toxic free radicals; fungicidal, IV
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What are the characteristics of azoles
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Inhibit ergosterol synthesis (at the lanosterol C14 a-demethylase, cytochrome P-450-dependent, enzymatic step). The depletions of ergosterol disrupts the permeability of the fungal cell membrane
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What are the three Triazoles
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Fluconazole, Itraconazole, Voriconazole
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What are the three Imidazoles
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Ketoconazole, Clotrimazole, Miconazole
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What type of infections are Clortimazole and Miconazole used for
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They are too toxic for systemic use, so they are primarily used for topical fungal infections, includings pityriasis versicolor, cutaneous candidiasis, and the dermatophytosis (tinea pedis, corporis, etc.)
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What is the drug of choice for chronic mucocutaneous candidiasis (Candida on every surface)
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Ketonazole. It is not used for systemic candidiasis (Amphotericin B is)
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What drug kills Candida albicans very well
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Fluconazole, one of the Triazoles
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Fluconazole is limited to what spectrum of fungi
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Yeasts, Cryptococcus, dermatophytes
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What is Itraconazole used for
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First line treatment for chromoblastomycosis, histoplasmosis, coccidioidomycosis, blastomycosis, and possible for invasive aspergillosis
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Voriconazole may be used with what
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Invasive aspergillosis
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How do the Echinocandins work
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They inhibit synthesis of B-(1,3)-glucans, a component of cell walls of specific fungi
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What is the Echinocandin drug Caspofungin (Cancidas) approved for
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IV use vs. invasive infections by Candidia (fungicidal) and Aspergillus (fungistatic)
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How does Flucytosine work
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It interferes with synthesis of DNA, RNA. It is used as a tag team partner with Amphotericin B, since resistance develops if used alone
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What does Flucytosine work against
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It is Fungistatic and narrow spectrum against Candidia species and Cryptococcus
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How do Allylamines work
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They inhibit squalene epoxidase, blocking ergosterol synthesis at the squalene to lanosterol step; Fungistatic
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What are the two Allylamine drugs
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Terbinafine and Naftifine
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How does Griseofulvin work
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It disrupts microtubules, resulting in inhibition of fungal mitosis
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What is Griseofulvin used against
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Visualize griseofulvin as a greasy fulcrum used to lever the dermatophyte plaques off the skin. The worker is peeling fungus off your "toe," sis
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Infection with what can lead to hypersensitivity without tissue reaction
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Allergic bronchopulmonary aspergillosis
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