6.6 Medical Mycology Flashcards
(42 cards)
Are fungi Eukaryotic or prokaryotic?
Eukaryotic with organelles and nucleus
What molecule is in the cell membrane of Fungi?
Sterols present (ergosterol)
What molecules are present in the cell wall of fungi?
- Polysaccharides including chitin
- Polymer of N-acetylglucosamine
- alpha-1,3 glucan (not in humans) Target for drugs
- beta-1,3-glucan (not in humans)
- Galactomannan
What is the 02 utilization methods for Fungi?
aerobic to obligate anaerobes
What is the doubling time of Fungi?
usually hours, more complex than bacteria that can double in minutes.
What are the functions and reproduction methods of spores in fungi?
- Mainly asexual, but can reproduce sexually
- Functions include survival and dissemination
What percent of infections are fungi related and why have the number of diagnosis increase over the recent years?
- 20% of infections are fungus related
- Increased diagnosis due to more immunosuppressed and better at diagnosis
What are risk factors for fungal infections?
- Living in a warm, humid climate
- Occupational (outdoor jobs, landscaper)
- CMI deficiency
- Cell mediated immune issues/defects
- Higher incidence more intractable
- Neutrophil, T-cell mediated response most important.
- Mostly environmental, not endogenous
- Some are normal microbicota
- Infections tend to be subacute to chronic, not usually acute
What are the three types of mycoses?
1) Superficial/cutaneous
2) Subcutaneous
3) Systemic
Describe Superficial/cutaneous fungi infections
- hair, skin, nails
- most common
Describe Subcutaneous mycoses
- beneath the skin
- Rare, tropical (Mexico)
Describe Systemic mycoses
- Deep within body
- Characteristic geographic regions (endemic mycoses)
- Coccidioides immitis, southwestern U.S., Mexico, Central and South America
Describe Opportunistic Fungi
- Only in immunocompromised, debilitated, or break in skin or mucous membrane
- Normal microbiota or environmental fungi
- Aspergillosis, candidiasis, cryptococcosis, mucormycosis
Describe Primary Pathogens Fugi
- Infects healthy individuals
- Examples: Histoplasmosis, blastomycosis, coccidioidomycosis, paracoccidioidomycosis
- Only environmental, soil, or vegetation
- Can be inhaled causing lung infections
- Conidia or hyphal fragments
Describe Unicellular Yeast
1) Unicellular eukaryotes
2) round/oval, look like bacterial colonies on agar plates.
3) ~10 times bigger than bacterial cells
4) Usually reproduce by budding
5) Divide asymmetrically
6) Buds= blastoconidia
7) May fail to detach or form a short chain of cells called pseudohypha
Describe multicellular molds
1) Multicellular, filamentous eukaryotes
2) Branching cylindric tubules called hyphae that can penetrate tissues. These grow from the tips and are multinucleate.
3) Mass of hyphae=mycelium
4) Part of mycelium involved in gaining nutrients=vegetative mycelium
5) Part of mycelium is involved in growth and reproduction
What is macroconidia?
Relatively large, complex conidia
What is microconidia?
Smaller, more simple conidia
What is a sporangium?
Sack that sporangiospores are in
Are conidia in a sack?
No
Conidiophore(stem) spores are called?
Conidiospores (no sack)
Sporangiophore(stem) spores are called?
Sporangiospores (sack surrounds spores)
Describe Dimorphic Fungi
- At low temperature in the soil the fungi grows as a filamentous fungus (mold)
- After being inhaled into the lungs the dimorphic fungi undergoes a morphological switch triggered by the change in temperature and become yeast like.
- can form hyphae in vivo and penetrate/spread
- Affects expression cell wall glycoproteins, proteolytic enzyme secretion, susceptibility to oxidative damage in neutrophils, adaptation to new environments.
- Makes harder for human immune system to fight due to switching.
What is a Blastoconidia?
Buds formed by yeast
