Introduction ot Mycology

Question 1

What are fungi?

Answer 1

eukaryotes found almost exclusively in soil, water, or on plants

Question 2

what does conidia mean?

Answer 2

asexual reproductive elemnts

Question 3

what are spores?

Answer 3

sexual reporductive elements

Question 4

what are the two was that fungi differ from animal cells that are exploited for medical use?

Answer 4

1) the contian a ridgid cell wall

2) fungal cell wall contains ergosterol instread of cholesterol

Question 5

what causes the cell wall to be rigid?

Answer 5

the chitin

Question 6

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)

Answer 6

10% KOH

Question 7

what are the two basic morpholoic forms of fungi?

Answer 7

yeast

molds

Question 8

How many cells do yeast have?

Answer 8

single cell

Question 9

How many cells do molds have?

Answer 9

multi-cellular

Question 10

what are hyphae and what type of fungi produce them?

Answer 10

they are tube-like projections, produced by molds, they can be septate or non-septate

Question 11

what is a mycelium?

Answer 11

an interwound mass of hyphe

Question 12

can fungi be dimorphis if so underwhat condictions?

Answer 12

YES; typically yeast in tissues at 37C in culture; molds form in culture at rm temp

Question 13

what are the three types of problems that fungi cause?

Answer 13

1) allergies
2) mycotoxicoses (mushroom poisioning)
3) mycoses (true infection)

Question 14

What is the working classification from least sever to most severe?

Answer 14

1) superficial mycoses
2) cutaneous mycoses
3) subcutaneous mycoes
4) systemic mycoses
5) opportunistic mycoses

Question 15

what is superficial mycoses?

Answer 15

only the outermost layer of skin

• often from poor hygiene
• mild discoloration

Question 16

what is cutaneous mycoses?

Answer 16

-tineas (ring worns; athlete’s foot)

Question 17

what is subcutaneous mycoses?

Answer 17

• often from wound to the skin

- can involve the lymphatics (spread systemically)

Question 18

waht is systemic mycoses?

Answer 18

• 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

Question 19

what is opportunisitic mycoses?

Answer 19

• cound predominantly in immunocompormised pts.
• severe infections that do not respond to antibotics
• fungal minigitis (blood stream infections)

Question 20

why have mycotic infections increased over the last decade?

Answer 20

1) predominatly nosocomial complication of at risk hospital pts.
- ^ survival times of AIDs, chemotherapy and transpoant pts.
- improved technologies; intravascular catherters, better immunosppressive drugs

Question 21

what ways can a fungis cross the inital barrier so they can infect?

Answer 21

1) mechanical breaks
2) inhalation of spores of conidia
3) invasive hyphe formation

Question 22

what are opportunistic molds sensitive to?

Answer 22

neutrophils

Question 23

____immunity is primary importance to a a fungal infection.

Answer 23

T-cell

Question 24

What plays a rold in preventing reinfection?

Answer 24

antibodies

Question 25

what leads to much of hte cellular harm seen in fungla infections?

Answer 25

the immune response

Question 26

what are the diagnostic characteristics for a fungal infection?

Answer 26

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

Question 27

What is sbouraud’s medium?

Answer 27

• 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)

Question 28

Why do you have to use antifungals for a long time?

Answer 28

becasue fungi grow very slow!!

Question 29

what are plyenes?

Answer 29

antifungals that bind to ergosterol and punch holes in the membrane

Question 30

what are azoles?>

Answer 30

antifungals tha tinhibit the synthesis of ergosterol

Question 31

why are there relatively few antifungals?

Answer 31

b/c fungi are eukaryotic cells and tx is fairly toxic

Question 32

how long are immunocompromised pts left on anaprophylaxis?

Answer 32

for life!! because their immune system is not helping much so trying to limit fungi form coming back