Antibacterial Therapy

Question 1

How do penicillin & cephalosporin work?

Answer 1

• Disrupts 2 polysacchrides in peptidoglycan structure from binding via Glycine & penultimate Alanine
• as a result, breaks up peptidoglycan cell wall
• Penicillin has a betalactam structure
• These drugs look like 2 alanines and therefore binds to peptide transferase and inhibits it

Question 2

Resistance to penicillin and cephalosporin due to

Answer 2

• Enzymes that cleave the beta-lactam structure via betalactamase
• Renders penicillin and cephalosporin inactive

Question 3

Insertion Elements

Answer 3

Result in antibiotic resistance

Question 4

Betalactam

Answer 4

Enters bacteria via porin channel and binds to pencillin-binding protein preventing formation of more bonds

Question 5

Vancomycin compared to penicillin

Answer 5

A much more complex structure, different mechanism to disrupt peptidoglycan structure
-works by preventing polymerization of polysaccharide chain

Question 6

Vancomycin Resistance

Answer 6

1. Prevent vancomycin penetration of bacteria (gram negative are intrinsically better at this)
2. Alter target: so instead of D-ala-D-ala, make D-ala-D-lactate

Question 7

Aminoglycoside Resistance

Answer 7

1. Decrease penetration to target (active transport of aminoglycoside depends on ETC)
2. Alter target of antibiotic (mutate RNA)
3. Inactivate drug with enzyme

Question 8

Drug Resistance Mechanisms

Answer 8

1. Change permeability of bacterial cell
2. Make enzymes that destroy the drug
3. Make enzyme that resists the drug
4. Modify the drug (cleave it)
5. Prevent drug binding/alter the binding protein

Question 9

Drugs in combination

Answer 9

Work in synergy (better together), indifference (no change when used together), antagonism (oppose one another)

Question 10

Antibiotics & FDA

Answer 10

Decreased approved drugs over the past couple of years