Immunology Week 4 - Fungi 1

Question 1

What is the mechanism of Azole?

Answer 1

interfere with ergosterol biosynthesis

Question 2

What are fungi cell walls made of?

Answer 2

carbohydrate polymers, chitin, a-glucan, B-glucan, a-mannon and mannoproteins

Question 3

What does coenocytic mean?

Answer 3

Multi-nuclei

Question 4

What makes up a mycelium?

Answer 4

multiple hyphae

Question 5

What is a hyphae?

Answer 5

branching cylindric tubules varying in diameter from 2-10 mM

Question 6

What is Chlamydoconidia?

Answer 6

A type of spore: thick walled single cells that are resistant to adverse conditions

Question 7

What is Arthroconidia?

Answer 7

A type of spore: single celled conidia that are formed by the disjoining of hypal cells

Question 8

What is Conidiospores? What are the two types?

Answer 8

A type of spore: medically important - borne naked on specialized structures

Two types:
macroconidia - large, multicelled conidia
Microconidia - small single celled conidia

Question 9

What is a Conidiophore?

Answer 9

The stalk that branch off from hyphae and have microconidia on them

Question 10

What is Sproangiospores?

Answer 10

A type of spore: medically important single celled spores formed within sacs called sporangia from the end of special hyphae

Essentially sporangiospores are held in a sac

Question 11

What causes allergic reactions?

Answer 11

inhalation of airborn spores

Question 12

What are the two most common methods to diagnose fungi infections?

Answer 12

1) direct microscopic observation of the fungi (KOH technique or staining)
2) biopsy

Question 13

What is the third most common technique to diagnose fungi infection?

Answer 13

cultivation on blood agar (at 37 degrees most commonly)

Question 14

What is cyclohexamide used for in agar?

Answer 14

to retard growth of many nonpathogenic fungi (need to be careful because C. neoformans is sensitive to cycloheximide)

Question 15

What are the targets of drugs against fungi? (4)

Answer 15

1) ergosterol
2) cell wall synthesis
3) nucleic acid synthesis
4) disruption of microtubules

Question 16

What do polyenes do?

Answer 16

Targets ergosterol

Question 17

What do azoles and allylamines do?

Answer 17

enzymatically interfere with the bio-synthetic pathway of ergosterol

Question 18

What do Echinocandins do?

Answer 18

Target cell wall synthesis

Question 19

What do antimetabolites do?

Answer 19

goes after nucleic acids synthesis

Question 20

What does Griseofulvin do?

Answer 20

goes after microtubules

Question 21

What is the problem with the drug flucytosine?

Answer 21

organisms often develop a resistance to it

Question 22

What are four possible strategies of combination therapy?

Answer 22

1) inhibition of different stages of SAME biochemcal pathway
2) Inhibition of different fungi cell targets
3) Increased penetration of one agent into the cell because of the permeabilizing activity of another agent
4) inhibiting the outward transport (efflux) of ANOTHER agent that is meant to be inside

Question 23

What are the drawbacks of combination therapy? (ways the drugs can antogonize each other)

Answer 23

1) action of one agent REDUCES CONCENTRATION of the target of another
2) action of one agent MODIFIES the target of another drug
3) action of one agent BLOCKS ACCESSIBILITY to target of another drug

Question 24

How do fungi develop resistance? (3 ways)

Answer 24

1) through efflux pumps
2) alterations
3) reduced access to drug targets

fungi DOES NOT destroy or modify the antifungal drug

Question 25

What is a primary resistance?

Answer 25

an organism that is resistant to a particular drug without prior exposure to the drug

Question 26

What is secondary resistance?

Answer 26

An organism develops resistance to a particular drug only AFTER exposure to the drug

Question 27

What is the eagle effect?

Answer 27

eagle effect is defined as an organism that is RESISTANT to high concentrations of the drug but SUSCEPTIBLE to low concentrations