C / 8 - penicillins

Question 1

What is the MOA of penicillins?

Answer 1

• They are beta lactams : they inhibit cell wall synthesis by binding to PBP and inhibit the synthesis of the peptidoglycan layer (no cross-links).
• This causes activation of autolysins, which degrade the cell wall and cause death.

Question 2

How can a bacteria develop betam lactam resistance?

Answer 2

• Production of beta-lactamase
• Altered PBPs
• Decreased permeability so penicillin cannot enter the cell

Question 3

Narrow spectrum penicillins (5)

Answer 3

• Penicillin G
• Penicillin V
• Benzathine-penicillin
• Flucloxacillin
• Ampicillin

Question 4

Penicillin G, Penicillin V
- Spectrum (5)
- Toxicity
- ROA

Answer 4

• Streptococcal infection / Gram positive rods / Clostridium perfringens /enterococci / neisseria
• Hypersensitivity or allergy + nephritis + Jarish Herxheimer reaction
• G : IV, V : oral

Question 5

Benzathine-penicillin
- Spectrum
- ROA
- Toxicity

Answer 5

• Syphilis
• IM depot injection
• Same as natural penicillins

Question 6

Broad and extended spectrum penicillins

Answer 6

• Broad : amoxicillin
• Extended : piperacillin

Question 7

Amoxicillin
- Spectrum
- Special indication
- Toxicity
- Dose

Answer 7

• Same as basic penicillins + H influenzae / S pneumoniae / H pylori
• High risk patients prior to dental procedures
• Skin rash, GI disturbances, hepatotoxicity
• 3 x 500-1000mg