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Module 4 Week 3 > Antiobiotic Action > Flashcards

Antiobiotic Action Flashcards

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1
Q

Define antimicrobials/antibiotic
-2 types

A

Agents that kills microorganisms or stops their growth
2 types:
-antibiotic- microbial origin (commonly made by a bacteria)
-antimicrobial- chemically synthesised

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2
Q

Selective toxicity meaning
-how do bacteria exert selective toxicity

A

kill or inhibit the infecting organism without damaging the host
-targets something unique to bacteria e.g peptidoglycan of cell wall

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3
Q

2 types of actions of antimicrobials

A

Bactericidal
-kills bacteria
-is irreversible
-may or may not cause lyses of bacteria

Bacteriostatic
-suppresses bacteria but doesn’t kill it
-reversible

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4
Q

What are the sites of action of main antibiotics

A

Cell wall
Plasma membrane
Ribosomes
DNA synthesis
Metabolic pathways

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5
Q

Best target for selective toxicity

A

Cell wall

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6
Q

Peptidoglycan is made up of 2 components:

A

N-acetylglucosamine (NAG)
N-acetylmuramic (NAM)

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7
Q

Basic subunits of petidoglycan

A

NAG, NAM, peptide connected together

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8
Q

Describe process of biosynthesis of peptidoglycan

A

1.Subunit of peptidoglycan made in cytoplasm
2.Transported across cell membrane
3.Once in cell wall added to growing peptidoglycan chain
4.Strength and rigidity of structure provided by cross links of peptide bonds

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9
Q

Name antibiotics which inhibit each step of biosynthesis of peptidoglycan

A

1.Subunit of peptidoglycan made in cytoplasm—> cycloserine, fosfomycin
2.Transported across cell membrane—> bacitracin
3.Once in cell wall added to growing peptidoglycan chain —> glycopeptides
4.Strength and rigidity of structure provided by cross links of peptide bonds—> beta-lactams e.g penicillin (most important group)

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10
Q

4 types of beta-lactams antibiotics

A

Penicillin
Cephalosporin
Monobactam
Carbapenem

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11
Q

What do all b-lactams have in common?

A

All have a b-lactam ring (square shaped ring with double bonded oxygen and single bond nitrogen)

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12
Q

Which of the b-lactam antibiotics is only used in humans- shouldn’t be used in animals

A

Cephalosporin

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13
Q

B-lactam antibiotics only work on what kind of bacteria?

A

Growing bacteria

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14
Q

Steps of bacterial replication

A

-Bacterial cells chromosome replicates and cell elongates (stretches)
-chromosome separates and cytoplasmic membrane and cell wall invaginates
-cross wall formation complete
-daughter cells separate

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15
Q

How does b-lactam antibiotic work

A

For elongation of bacteria (during bacterial replication), it must make breaks in the peptidoglycan in order to add more peptidoglycan. Whilst it’s doing that peptidoglycan is weak, causing water to enter the cell which drives the elongation of bacteria. However this breakage in cell allows for b-lactam inhibition

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16
Q

Microscopic effect of b-lactam on bacteria

A

Normal Bacteria—> Cell growth—> bulging of cell—> lysis of cell

17
Q

Name the protein synthesis inhibitors (PSIs)

A

Aminoglycosides
Chloramphenicol
Macrolides & Lincosamides
Tetracyclines

18
Q

Protein synthesis inhibitors (PSI): Aminoglycosides
-what does it do

A

Inhibits initiation of bacterial protein synthesis
Causes misreading of mRNA

19
Q

Proetin synthesis inhibitors: Chloramphenicol, macrolides and lincosamides
-function

A

-All inhibit peptidoglycan transferase which transfers the amino acid from tRNA P site to A site during translation
-macrolides & lincosamides: inhibit translation of ribosome along mRNA

20
Q

Protein synthesis inhibitor: tetracyclines

A

Bind to A site and prevent binding of tRNA coming with amino acid

21
Q

Bacteria DNA must be tightly wound inside cell. Which enzymes activate the super coiling and Which antibiotics inhibit this super coiling of DNA

A

Topoisomerase II activates
Quinolones and 4-fluoroquinolones inhibit

22
Q

Antibiotic which disrupts gram negative bacterial membrane
-properties

A

Polymixins
-cyclic peptide, not made of ribosomes
-have a free fatty acid residue which acts like a detergent
-disrupt cytoplasmic membrane
-very toxic so not used when possible

23
Q

Antibiotic which disrupts gram positive bacterial membrane
-causes what

A

Daptomycin
-causes loss of ions from interior of bacteria

24
Q

3 types of interaction of antibiotics

A

Synergism- 2 o more drugs work together fora better effect against bacteria
Antagonism- drugs working together causes a worse effect on bacteria (want to avoid this one)
Indifference- drugs working together doesn’t make a difference

Module 4 Week 3 (8 decks)

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