Antibiotics

Question 1

Define selective toxicity

Answer 1

when the Abx will only affect the target organism w/o harming the host (mild toxicity of host and side effects are ok )

Question 2

What are the 6 primary sites of actions of Abx on bacterial cells

Answer 2

1. Cell wall 2. 50 S subunit of ribosome 3. 30 S subunit of ribosome 4. Cell membrane 5. DNA 6 Metabolism

Question 3

What are the Abx that target bacterial cell walls

Answer 3

1. Beta lactams 2. Vancomycin 3. Bacitracin 4. Monobactams

Question 4

What are the 2 classes of beta lactams

Answer 4

1. Penicillins 2. Cephalosporins

Question 5

What does a bet lactam ring look like

Question 6

What happens when you change the side changes of a beta-lactam ring

Answer 6

the abx properties can be changed

Question 7

What is the principle of action of beta lactams

Answer 7

inhibits peptidoglycan synthesis at penicillin binding proteins, by inhibiting formation of cross links between NAM and NAG

Question 8

What are the major characteristics of beta lactams

Answer 8

1. bactericidial
2. low toxicity
3. most effective against gram positive bacteria
4. only effective against activelygrowing bacteria

Question 9

What is the mode of action for Vancomycin

Answer 9

Binds to cross link peptide of NAM/NAG so that the link cannot be completed the polymer cannot be elongated

Question 10

What is the mode of action for Bacitracin

Answer 10

Blocks the phosolipid carrier that helps carries subunits of peptidoglycan across the cell membrane to the cell wall

-not beta lactam

Question 11

What is Isoniazid

Answer 11

Abx that blocks the formation of mycolic acid in mycobacterium (TB) cell walls

Question 12

What are the 4 class of Abx that work on the 50S subunit of bacterial ribosomes

Answer 12

1. Chlorampheniol
2. Clindamycin
3. Linezolid
4. erythromycin/Macrolides

Question 13

What is the mode of action for Chlorampheniol and Clindamycin

Answer 13

inhibits polypeptide elongation by inhibiting peptide bond formation

Question 14

True or False Chlorampheniol and Clindamycin are bactercidal

Answer 14

False, they are bacteristatic

-think of their mechanism

Question 15

True or False Chlorampheniol and Clindamycin board spectrum Abx

Answer 15

True, think of their mschanism

Question 16

What is the mode of action for macrolides

Answer 16

binds to 50S ribosomal subunit and prevents translocation of mRNA

Question 17

What is a type of macrolide

Answer 17

erythromycin

Question 18

What are the 3 classes of Abx that work on the 30S bacterial ribosomal subunit

Answer 18

1. Streptomycn

2 . Aminoglycosides

3 Tetracyline

Question 19

What is the mode of action of Aminoglycosides

Answer 19

inhibt translation by causing misreading of mRNA at 30s ribosomal subunit

Question 20

How does resistance occur in beta-lactams

Answer 20

1. entrance of Abx is not allowed into bacteria
2. Chnage in PBP structure so Abx cannot bind
3. Beta-lactamases hydrolysize the Abx

Question 21

What is the mode of action of Tetracyclines

Answer 21

Blocks tRNA from binding to 30S mRNA complex

Question 22

Are the 30S abx board or narrow spectrum

Answer 22

Board, think mech of action

Question 23

How is resistance acheived against aminoglycosides

Answer 23

enzymatic modifiction of Abx

Question 24

How is resistance acheived against Tetracylines

Answer 24

efflux of Abx out of the cell by bacteria

Question 25

What is the mode of action of Polymixins

Answer 25

disrupts fxnal integrity of cytoplasmic membrane

Question 26

Where are polymixins used and why

Answer 26

external use only, because they are nephrotoxic

Question 27

True or False polymixins are affective against gram positive bacteria

Answer 27

False, they are only affect against gram negatives

Question 28

What is the mode of action of Amphotericin B

Answer 28

antifungal, binds ergosterol in fungal membranes disrupting them

Question 29

What are the classes of Abx that inhibit nucleic acid synthesis and modes of action ?

Answer 29

1. Quinolones=Blocks DNA gyrase 2. Rifampin = Bloock RNA polermerase 3. Metronidazole =Breaks DNA bonds

Question 30

True or False, nuleoside analogues are antivirals

Answer 30

True

Question 31

What is an example of a viral nuceloside analogue

Answer 31

Acyclovir

Question 32

What class of Abx inhibits bacterial metabolism

Answer 32

1. Sulfonamides 2. Trimethoprim They both work by interfering with folic acid synthesis

Question 33

What is the mechanism of action for Azoles

Answer 33

inhibit synthesis of ergosterol in fungal cells

Question 34

What are the points of antiviral action

Answer 34

1. Block attachement and entry 2. Blocking release of genome from viral capsid (uncoating) 3. Inhibit replication of viral genome 4. Inhibit protein