Microbio Week 7 - Mycology (Mini Exam) Flashcards
Study of fungi
Mycology
What does fungi include?
Yeast and mold
Are fungi prokaryotic or eukaryotic?
Eukaryotic
As eukaryotes, what type of environment do fungi require?
Aerobic or anaerobic
Are fungi plants?
NO, they don’t produce chlorophyll or energy via photosynthesis
Acquire nutrition from dead, decaying organic matter; aid in decomposition and recycling of carbon and nitrogen
Saprophytic
What do fungi breakdown in humans? What kind of people does this occur more often in?
Epithelial tissue (and spread into deeper tissue)
*occurs more often in immunocompromised people
What types of tissues are useful sources of nutrients for fungi?
Ischemic and necrotic
How many fungi are capable of causing infections in humans?
A few hundred
Why are fungi important to know clinically?
Can cause serious infections, may be resistant to antifungals
In what 3 ways are fungi diverse?
Appearance
Benefit/use
Ability to cause disease
How many morphologies can fungi display?
Some only display 1, others display combo
What are the clinically important morphological forms of fungi?
Yeast
Mold
Dimorphic fungi (display both yeast and mold forms)
Single-celled form of fungi; round or oval-shaped
Yeast
How do yeast reproduce?
Budding
Unequal asexual outgrowth from parent cell; produces genetically identical cells
Budding
What are the 2 routes that yeast can take when buds break off?
- Form single cell
- Elongate to become pseudohyphae
Chain of connected yeast cells that resemble hyphae, but constrict at the point of connection
Pseudohyphae
(think of a balloon animal)
What are 2 examples of yeast?
Candida
Cryptococcus
What is the multicellular, filamentous form of fungi?
Mold
What can mold filaments exist as?
- Hyphae
- Mycelium
Individual mold filaments
Hyphae
Masses/clusters of mold filaments
Mycelium
How does hyphae grow?
Lengthening filament and dividing nucleus
What may occur when hyphae grow?
Some branching
Cross walls
Septations
Mold with septations
Septate hyphae
Mold without septations
Aseptate/non-septate hyphae
Which type of hyphae in mold?
Majority of mold species; hyphae are smaller in diameter
Septate hyphae
Which type of hyphae in mold?
Mold species of the mucor group; hyphae are larger in diameter
Aseptate/non-septate hyphae
What is the branching pattern, presence/absence of septations, and hyphae in mold used for?
Distinguishing mold types
Can hyphae have pigment associated with them?
Yes!
What are 2 examples of mold?
Aspergillus
Mucor
What do dimorphic fungi alternate between?
Yeast form and mold form
What is the alternating between yeast form and mold form in dimorphic fungi based on?
Environmental conditions
Temperature
Yeast in the ________, mold in the _________
heat; cold
4 examples of dimorphic fungi
Candida
Histoplasma
Blastomyces
Coccidioides
Which is present with many nutrients, yeast or mold?
Yeast
Which is present with reduced nutrients, yeast or mold?
Mold
What makes fungal cells different form other eukaryotic cells? (ON EXAM)
Cell membrane contains ergosterol (instead of cholesterol)
What is the primary target of antifungals?
Ergosterol
The fungal cell wall is a thick, highly cross-linked layer with multiple long-chain ___________ and ___________ (both stimulate the immune system)
polysaccharides; glycoproteins
What is the fungal cell wall similar to?
Gram + cell wall
(except no peptidoglycan!!)
What are the polysaccharides present in the fungal cell wall? (ON EXAM)
a-glucan
B-glucan
Chitin
What are the glycoproteins present in the fungal cell wall? (ON EXAM)
Mannoproteins
Which cells phagocytose fungi for intracellular killing in the innate response?
*Neutrophils
Macrophages
What environment do fungal pathogens grow in?
Aerobic
What do fungi secrete that aid in survival and nutrient acquisition in the host?
Extracellular products (enzymes, mycotoxins, antibiotics)
Breakdown complex organic material for use in cells
Enzymes
Secreted substances that are toxic to humans and animals when ingested or inhaled
Mycotoxins
Produced in nature by some filamentous fungi (molds); may inhibit competing microbes
Antibiotics
How do fungi reproduce?
Sexual or asexual reproduction
Rapid; results in genetically identical offspring
Asexual reproduction
What type of reproduction do most pathogenic fungi seen in the clinical setting undergo?
Asexual reproduction
What does asexual reproduction of mold form?
Thick-walled asexual spores from hyphal filaments
What conditions do spores form in?
Unfavorable (ex: inadequate nutrients/water)
What conditions do spores germinate in?
Favorable
What are mold spores resistant to?
Drying
What are mold spores NOT resistant to?
Heat
Single-celled, smaller mold spores
Microconidia
Multi-celled, larger mold spores
Macroconidia
Fungal diseases may result from introduction of ______________ fungal spores into body, overgrowth of commensal _________, or exposure to ________ products produced by spores
environmental; flora; toxic
Mycoses meaning
Infections
Fungal diseases may present in the form of what 3 things?
Allergies
Mycotoxin exposure
Infections
What do fungal spores have which may stimulate allergic reactions and respiratory effects?
Surface antigens
What can allergic reactions/respiratory effects be from?
Inhaling mold spores due to growth in moist areas
What are 2 ways you could get a mycotoxin exposure?
Ingesting contaminated food
Inhaling spores (coated with mycotoxin)
What can you get an infection from?
Exposure to fungal spores
What are fungal infections typically characterized by?
Anatomic location
Epidemiology
Where can fungal infections be?
Superficial
Subcutaneous
Systemic (endemic + opportunistic)
Many fungi only cause serious disease in what types of people?
Immunocompromised
People with foreign devices
Where are superficial fungal infections localized to?
Outermost layers of skin, hair, nails
Where are subcutaneous/submucosal infections localized to?
Deeper skin structures
Submucosal tissue
What are subcutaneous/submucosal infections commonly associated with?
Trauma-related inoculation of spores from soil or vegetation
Cause infection in immunocompetent individuals
Endemic
Cause infection in immunocompromised individuals
Opportunistic
What 2 things can systemic infections be due to?
Commensal fungi that overgrows (candida)
Environmental fungi that is inhaled (mucor)
T/F: All pathogenic fungi have the ability to be opportunistic
True
The greater the degree of immunocompromise, the greater the likelihood of…
Severe infection