L3 Cushman

Question 1

easily penetrated by drugs
A. GP
B. GN

Answer 1

A

Question 2

beta-lactmases are secreted extracellularly
A. GP
B. GN

Answer 2

A

Question 3

thin peptidoglycan layer
A. GP
B. GN

Answer 3

B

Question 4

beta-lactamases localized in periplasmic space
A. GP
B. GN

Answer 4

B

Question 5

how do transpeptidases cross-link peptidoglycan strands? what does this do?

Answer 5

connects the terminal D-Ala of one strand to the L-Lys of another through an AA bridge. this strengthens the bacterial cell wall

Question 6

penicillin MOA

Answer 6

bind to transpeptidases (PBPs) which inhibits cross-linking of peptidoglycan strands. this weakens the cell wall and causes osmotic lysis

Question 7

when talking about the peptidoglycan fragments, what do beta-lactams mimic to allow them to bind to transpeptidases and “trick” the enzyme into forming an inactive complex?

Answer 7

the D-Ala-D-Ala structure *

Question 8

4 resistance mechanisms for penicillin

Answer 8

• production of beta-lactmases
• altered PBPs (reduced affinity for b-lactams)
• presence of efflux pump that pumps antibiotics out
• porin mutations (in GN bacteria)

Question 9

why/how does penicillin allergenicity occur?

Answer 9

penicillins act as “haptens” which acetylate (form covalent bonds) host proteins, which causes an immune response

Question 10

how does penicillin degrade under basic conditions?

Answer 10

undergoes hydrolysis which forms inactive penicilloic acid

Question 11

T or F:
hydrolysis of beta-lactams is a reversible process through re-acetylation of the penicillin

Answer 11

false, irreversible

Question 12

T or F:
Pen V is more stable to hydrolysis in the stomach than Pen G

Answer 12

true

Question 13

which is the oral version?
Pen V or Pen G

Answer 13

Pen V, it is less nucleophilic than G

Question 14

T or F:
Penicillins with more lipophilic side chains are more highly protein bound

Answer 14

true