Flashcards in Mycology Deck (66):
What are saprophytes?
Eating dead matter
What are the three ways in which fungi can adversely affect us?
2. Toxin producers
3. infectious agents
Does the development of fungal allergies require colonization?
What are mycotoxins?
Toxins produced by fungi
What are ergot alkaloids?
Fugal mycotoxin that produces hallucinations
What are alfaltoxins?
Hepatotoxins from fungus that grows on peanuts
What is stachybotrys?
A mycotoxin produced by household mold. Brain effects
What are the two typical targets of antifungal therapies?
Fungal cell wall
Membrane sterol composition (ergosterol)
What is the lipid component of fungal membranes that is analgous to cholesterol, and serves as a target for antifungal therapy?
Will abx that affect bacterial cell walls have any effects on fungal cell walls?
What are the three major components of the fungal cell wall?
Are fungal cells wall very or poorly immunogenic?
Is the capsule that some fungi produce immunogenic?
What are the two categories of fungi?
What is the term that describes fungi that can transition from a yeast form to a mold form?
How many cells do yeast have? What shape are they?
Unicellular spheres or ellipsoids
How do yeasts reproduce?
A germ tube is diagnostic for what fungi?
What are the small buds that are produced from the process of budding?
What are pseudohyphae?
Long extensions of fungi "chains of buds that never broke off"
What are hyphae?
a long, branching filamentous structure of a fungus. In most fungi, hyphae are the main mode of vegetative growth.
What is a mass of hyphae?
Molds that are infectious (and dimorphic) grow in what form: yeast or mold?
Reproductive fungi units produced *Asexually* are known as what?
Reproductive fungi units produced *sexually* are known as what?
Where on existing molds do conidia form?
along hyphae or on stalk like structures known as conidiophores.
What are the two forms of hyphae, that are distinguished by the presence/absence of cell walls?
What are the three different forms of conidia?
What are arthrocanidia?
Spores that form in the center of a hyphae
What is the main diagnostic procedure for identifying fungi?
Conidia which form within a hyphal element are known as what?
chlamydoconidia or arthroconidia.
What are superficial mycoses?
Infections of the outermost layer of the skin/hair
What are cutaneous mycoses?
infection which extends deep into the epidermis as well as invasive hair and nail infections.
What are subcutaneous mycosis?
infections involving the dermis, subcutaneous tissues, muscle, and fascia.
What are systemic mycoses?
infections that originate primarily in the lung but may spread to any organ in the body.
What are opportunistic mycoses?
infection associated primarily with immunosuppressed individuals.
What is characteristic of fungi that can cause systemic mycoses?
Intact skin, pH, competition with normal bacterial flora, epithelial turnover rate, desiccated nature of the stratum corenum, and mucous membranes are all examples of what type of immunity?
What role do antibodies play in our immune response to fungi?
Antibodies are sometimes produced, but there is little evidence for a role of humoral immunity in resistance or resolution of infection.
What is the main immune defense against fungi?
The severity of a disease caused by fungi is dependent on what factors? (4)
Size of innoculation
magnitude of tissue destruction
ability of fungi to multiply in tissue
Immuologic status of host
What do macrophages have to do in order to get rid of persistent fungi?
Become activated by IFN-gamma
When is topical therapy indicated for a fungal infection?
When the infection is superficial or cutaneous
When is systemic therapy of antifungals indicated?
When the fungi are at the subcutaneous level or beyond
What is the origin of systemic fungal infections?
What are the four examples of systemic mycoses given in class?
What are the major targets of antifungal drugs? (5)
Cell wall synthesis
Inhibit protein syn
Inhibit nucleic acid syn
What are the antifungal targets in the cell wall of a fungus?
What is the class of drugs that directly target the cell membrane of a fungus? How do these work?
Polyenes--binding to fungal-specific membrane sterols (ergosterol)
What are the classes of drugs that inhibits ergosterol synthesis?
What is the class of antifungals that inhibit both RNA and DNA synthesis? What is the scope of fungi that these drugs target?
Nucleoside analogs (like 5-fluorocytosine!)
Target yeasts (little effect on dimorphic fungi)
What are allyalmines effective in killing? Ineffective?
Effective against dermatophytes
Ineffective against yeast
What is the MOA of echinocandins?
Inhibit the synthesis of beta-glucans, an important component of the fungal cell wall.
What is KI used to treat? How does it work?
Subcutaneous infections caused by sporothrix schencki
What is the class of drugs that inhibits cell wall synthesis?
What is the MOA of grisans?
Inhibits microtubule assembly
What type of drug is amphotericin B? What is the MOA?
Polyene, binds to ergosterol and causes pore fomation
What is the KOH prep used in the lab to identify fungal infections?
Add KOH to tissue scrapings--will dissolve skin tissue at a faster rate than the fungus, and thus allows for visual identification
All fungi are gram (positive or negative)?
What is the black stain used in the lab that specifically stains chitin?
What is the whtie stain used in the lab that specifically fungal cell walls?
The india ink stain is used to identify what fungus? What is the target here?
Cryptococcus neoformans--stain targets the capsule
What is the germ tube test diagnostic of?
If an india ink test is positive, what is the infectious agent?
What is the commonly used agar in culturing fungi?
Sabouraud dextrose agar