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Microbiology Test 2 > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

Define selective toxicity

A

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

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2
Q

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

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

What are the Abx that target bacterial cell walls

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

What are the 2 classes of beta lactams

A
  1. Penicillins 2. Cephalosporins
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5
Q

What does a bet lactam ring look like

A
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6
Q

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

A

the abx properties can be changed

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7
Q

What is the principle of action of beta lactams

A

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

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8
Q

What are the major characteristics of beta lactams

A
  1. bactericidial
  2. low toxicity
  3. most effective against gram positive bacteria
  4. only effective against activelygrowing bacteria
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9
Q

What is the mode of action for Vancomycin

A

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

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10
Q

What is the mode of action for Bacitracin

A

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

-not beta lactam

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11
Q

What is Isoniazid

A

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

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12
Q

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

A
  1. Chlorampheniol
  2. Clindamycin
  3. Linezolid
  4. erythromycin/Macrolides
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13
Q

What is the mode of action for Chlorampheniol and Clindamycin

A

inhibits polypeptide elongation by inhibiting peptide bond formation

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14
Q

True or False Chlorampheniol and Clindamycin are bactercidal

A

False, they are bacteristatic

-think of their mechanism

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15
Q

True or False Chlorampheniol and Clindamycin board spectrum Abx

A

True, think of their mschanism

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16
Q

What is the mode of action for macrolides

A

binds to 50S ribosomal subunit and prevents translocation of mRNA

17
Q

What is a type of macrolide

A

erythromycin

18
Q

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

A
  1. Streptomycn

2 . Aminoglycosides

3 Tetracyline

19
Q

What is the mode of action of Aminoglycosides

A

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

20
Q

How does resistance occur in beta-lactams

A
  1. entrance of Abx is not allowed into bacteria
  2. Chnage in PBP structure so Abx cannot bind
  3. Beta-lactamases hydrolysize the Abx
21
Q

What is the mode of action of Tetracyclines

A

Blocks tRNA from binding to 30S mRNA complex

22
Q

Are the 30S abx board or narrow spectrum

A

Board, think mech of action

23
Q

How is resistance acheived against aminoglycosides

A

enzymatic modifiction of Abx

24
Q

How is resistance acheived against Tetracylines

A

efflux of Abx out of the cell by bacteria

25
Q

What is the mode of action of Polymixins

A

disrupts fxnal integrity of cytoplasmic membrane

26
Q

Where are polymixins used and why

A

external use only, because they are nephrotoxic

27
Q

True or False polymixins are affective against gram positive bacteria

A

False, they are only affect against gram negatives

28
Q

What is the mode of action of Amphotericin B

A

antifungal, binds ergosterol in fungal membranes disrupting them

29
Q

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

A
  1. Quinolones=Blocks DNA gyrase
  2. Rifampin = Bloock RNA polermerase
  3. Metronidazole =Breaks DNA bonds
30
Q

True or False, nuleoside analogues are antivirals

A

True

31
Q

What is an example of a viral nuceloside analogue

A

Acyclovir

32
Q

What class of Abx inhibits bacterial metabolism

A
  1. Sulfonamides
  2. Trimethoprim

They both work by interfering with folic acid synthesis

33
Q

What is the mechanism of action for Azoles

A

inhibit synthesis of ergosterol in fungal cells

34
Q

What are the points of antiviral action

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

Microbiology Test 2 (5 decks)

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