Introduction ot Mycology Flashcards
What are fungi?
eukaryotes found almost exclusively in soil, water, or on plants
what does conidia mean?
asexual reproductive elemnts
what are spores?
sexual reporductive elements
what are the two was that fungi differ from animal cells that are exploited for medical use?
1) the contian a ridgid cell wall
2) fungal cell wall contains ergosterol instread of cholesterol
what causes the cell wall to be rigid?
the chitin
what can you use to tx fungi to only see the hyphae and remove all the animal cells and fungal cell wall? (preceptor wet slides)
10% KOH
what are the two basic morpholoic forms of fungi?
yeast
molds
How many cells do yeast have?
single cell
How many cells do molds have?
multi-cellular
what are hyphae and what type of fungi produce them?
they are tube-like projections, produced by molds, they can be septate or non-septate
what is a mycelium?
an interwound mass of hyphe
can fungi be dimorphis if so underwhat condictions?
YES; typically yeast in tissues at 37C in culture; molds form in culture at rm temp
what are the three types of problems that fungi cause?
1) allergies
2) mycotoxicoses (mushroom poisioning)
3) mycoses (true infection)
What is the working classification from least sever to most severe?
1) superficial mycoses
2) cutaneous mycoses
3) subcutaneous mycoes
4) systemic mycoses
5) opportunistic mycoses
what is superficial mycoses?
only the outermost layer of skin
- often from poor hygiene
- mild discoloration
what is cutaneous mycoses?
-tineas (ring worns; athlete’s foot)
what is subcutaneous mycoses?
- often from wound to the skin
- can involve the lymphatics (spread systemically)
waht is systemic mycoses?
- mostly from inhalation of conidia or spores
- can cause mild to sever disease in healthy individuals
- most virulent of hte fungi
- can cause chronic infections resembling tuberculosis
what is opportunisitic mycoses?
- cound predominantly in immunocompormised pts.
- severe infections that do not respond to antibotics
- fungal minigitis (blood stream infections)
why have mycotic infections increased over the last decade?
1) predominatly nosocomial complication of at risk hospital pts.
- ^ survival times of AIDs, chemotherapy and transpoant pts.
- improved technologies; intravascular catherters, better immunosppressive drugs
what ways can a fungis cross the inital barrier so they can infect?
1) mechanical breaks
2) inhalation of spores of conidia
3) invasive hyphe formation
what are opportunistic molds sensitive to?
neutrophils
____immunity is primary importance to a a fungal infection.
T-cell
What plays a rold in preventing reinfection?
antibodies
what leads to much of hte cellular harm seen in fungla infections?
the immune response
what are the diagnostic characteristics for a fungal infection?
1) clinical apperance
2) microscopic examination (10% KOH looking for hyphae)
3) culture on Sabouraud’s medium
4) yeast frow at 37C
5) molds grow at rm temp, mycelium’s apperance fro identification
6) serology for systemic infections but cross-reactivity can be a problem
What is sbouraud’s medium?
- low pH, high glucose, which inhibits bacterial growth
2) antibiotics are somtimes incorporated to furterh inhibit bacterial growth
3) necessary b/c fungi are slow growing, bacteria would over whelm cultures in dish (have to grow for a long time)
Why do you have to use antifungals for a long time?
becasue fungi grow very slow!!
what are plyenes?
antifungals that bind to ergosterol and punch holes in the membrane
what are azoles?>
antifungals tha tinhibit the synthesis of ergosterol
why are there relatively few antifungals?
b/c fungi are eukaryotic cells and tx is fairly toxic
how long are immunocompromised pts left on anaprophylaxis?
for life!! because their immune system is not helping much so trying to limit fungi form coming back
