Mycology 01 Fungal Characteristics
Terms
undefined, object
copy deck
- The Fungi are members of what kingdom
- Myceteae
- What are the complex polysaccharides that made up the rigid cells walls of Fungi
- Chitin, glucans, mannans
- What are the four hereotrophic states of Fungi
- Saprobes, Symbionts, Commensals, Parasites
- What are saprobes
- Organisms that live on dead or decaying matter
- What are symbionts
- Organisms that live together and in which the association is of mutual advantage
- What are commensals
- Organisms living in a close relationship in which one benefits from the relationship and the other neither benefits nor is harmed
- What are parasites
- 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
- How can yeasts be defined morphologically
- 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
- How can moulds be defined morphologically
- 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
- How do coenocytic hyphae look
- Hollow and multinucleate
- How do septate hyphae look
- Divided by partitions or cross-walls
- What is the name for the form of the fungus producing sexual spores
- Teleomorph
- What is the name for the fungus producing asexual spores
- Anamorph
- In what form are the fungi isolated from patient specimens
- Anamorph, the asexual form
- What are the two general types of asexual fungal spores
- Sporangiospores and conidia
- What are the characterisitcs of Zygomycetes
- Moulds with broad, coenocytic hyphae, rare septa, asexual sporangiospores; hyphae with rhizoids
- What are the characteristics of Ascomycetes
- Yeasts and moulds, septate hyphae; conidiophores produce asexual spores; sexual spores produced in ascus
- What are the characteristics of Deuteromycetes
- Imperfect fungi; sexual stage unknown; septate hyphae, conidia produced on conidiophores; yeasts reproduce by budding
- What organism produces the superficial disease Pityriasis versicolor
- Malassezia furfur
- What organisms produces Ringworm (tinea)
- Trichophyton species
- What two opportunistic fungal species produce Zygomycosis
- Mucor and Rhizopus
- Which fungi cause endemic mycoses
-
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 - What fungi cause opportunistic mycoses
-
Aspergillus, Candida, Crytococcus neoformans, Pneumocystis jiroveci
These cause disease in immunocompromised individuals - How are fungal infections transmitted
-
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) - What is the primary protective host response to fungal pathogens
- Cellular
- What fungus can produce chronic, local dermal inflammation
- Dermatophytes
- What funus can produce allergic hypersensitivity without tissue invasion
- Allergic bronchopulmonary aspergillosis
- Infection with what fungus can lead to acute pyogenic abscess
- Candida
- Infection with what fungus can lead to chronic granuloma formation
- Histoplasma (mimics TB)
- Infection with what fungus can lead to mixed pyogenic/granulomatous inflammation
- Blastomyces
- Infection with what fungi can lead to blood vessel invasion with thrombosis and infarction
-
Mucor or Rhizopus
Aspergillus - India ink stains for what
- Cryptococcus capsule
- What does mucicarmine stain for
- Cryptococcus neoformans capsule
- What are the characteristics of Amphotericin B
- 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
- What are the characteristics of azoles
- 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
- What are the three Triazoles
- Fluconazole, Itraconazole, Voriconazole
- What are the three Imidazoles
- Ketoconazole, Clotrimazole, Miconazole
- What type of infections are Clortimazole and Miconazole used for
- 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.)
- What is the drug of choice for chronic mucocutaneous candidiasis (Candida on every surface)
- Ketonazole. It is not used for systemic candidiasis (Amphotericin B is)
- What drug kills Candida albicans very well
- Fluconazole, one of the Triazoles
- Fluconazole is limited to what spectrum of fungi
- Yeasts, Cryptococcus, dermatophytes
- What is Itraconazole used for
- First line treatment for chromoblastomycosis, histoplasmosis, coccidioidomycosis, blastomycosis, and possible for invasive aspergillosis
- Voriconazole may be used with what
- Invasive aspergillosis
- How do the Echinocandins work
- They inhibit synthesis of B-(1,3)-glucans, a component of cell walls of specific fungi
- What is the Echinocandin drug Caspofungin (Cancidas) approved for
- IV use vs. invasive infections by Candidia (fungicidal) and Aspergillus (fungistatic)
- How does Flucytosine work
- It interferes with synthesis of DNA, RNA. It is used as a tag team partner with Amphotericin B, since resistance develops if used alone
- What does Flucytosine work against
- It is Fungistatic and narrow spectrum against Candidia species and Cryptococcus
- How do Allylamines work
- They inhibit squalene epoxidase, blocking ergosterol synthesis at the squalene to lanosterol step; Fungistatic
- What are the two Allylamine drugs
- Terbinafine and Naftifine
- How does Griseofulvin work
- It disrupts microtubules, resulting in inhibition of fungal mitosis
- What is Griseofulvin used against
- Visualize griseofulvin as a greasy fulcrum used to lever the dermatophyte plaques off the skin. The worker is peeling fungus off your "toe," sis
- Infection with what can lead to hypersensitivity without tissue reaction
- Allergic bronchopulmonary aspergillosis