Fungal Structure, Function, and Antifungals Flashcards
Which of the following are defining properties of fungi: eukaryotic, 70S ribosome, peptidoglycan cell wall, ergosterol in cell membrane, LPS in cell membrane
Eukaryotic and ergosterol in cell membrane.
Fungi have 80S ribosomes and chitin + beta-glucan in their cell walls. These 2 features make them resistant to most antibiotics! They also lack endotoxin.
Are most fungi obligate aerobes, obligate anaerobes, or facultative anaerobes; and are they autotrophs or heterotrophs?
Obligate aerobes, some are facultative anaerobes; heterotrophs
Name the only commensal fungus.
Candida albicans
Name 3 environments in which fungi survive better than bacteria.
Dry, acidic, and high-osmotic pressure environments
How do yeasts and molds reproduce?
Yeasts - budding; molds - spores (can be sexual or asexual)
What kind of fungi reproduce by budding, and how does the size of the daughter cell compare to the mother’s?
Yeast; daughter cell is smaller than mother
What term describes the filamentous, long multinucleated cells that make up molds?
Hyphae
What term describes the mat-like appearance of some molds?
Mycelium
Zygospores, ascospores, and basidiospores are what kind of fungi, and how do they reproduce?
Molds; reproduce by forming sexual spores
What are conidia, and what kind of fungi reproduce by this method?
Asexual spores; fungi imperfecti
What does it mean to say that yeast reproduce by “closed mitosis”?
The nuclear envelope doesn’t disappear during yeast mitosis
In thermal dimorphism, what form do fungi take at 37°C vs. 24°C?
37°C - yeasts, 24°C - molds
Describe the 2 main immune responses to fungi.
Granuloma formation and acute suppuration
Immune review: what cells are involved in granuloma vs. pus formation?
Granulomas: T cells and macrophages
Pus: mainly neutrophils
PPD-type skin tests can sometimes be used to detect what kind of fungal reaction?
Delayed hypersensitivity
What is mycotoxicosis?
Toxigenic disease caused by ingestion - not an infection (ex. eating amanita mushrooms)
What condition is caused by eating grain contaminated with Claviceps purpura, which produces LSD?
Ergotism
What fungus, found in spoiled grains, produces aflatoxins, which may be linked to p53 mutation and hepatic carcinoma?
Aspergillus flavus
Immediate hypersensitivity leading to asthmatic reaction (bronchoconstriction), eosinophilia, and “wheal and flare” reactions (like mosquito bites) can all be caused by what kind of response to fungi?
Allergic response
What is a KOH mount?
A method of breaking down human tissue with KOH while leaving the fungi intact for microscopy
What fungus, which may be isolated from CSF, has a characteristically thick capsule and can be stained with India ink?
Cryptococcus
What fungus, also know as the cause of “valley fever,” can be detected by spherules in the sputum?
Coccidioidomycosis
Fungi can be cultured on what type of low pH, antibiotic-containing agar?
Sabouraud’s agar
Name 2 other methods of fungal identification besides direct microscopy and culture.
DNA probe tests/PCR and serology
