Antibiotics

Question 1

Describe the mechanism of action of penicillin

Answer 1

Inhibits DD-transpeptidase, this causes cross-linking of peptidoglycans in bacteria cell walls. This weakens the cell walls allowing water to enter > causing swelling and then cell lysis. (Penicillins have a B-lactam ring). WORKS FOR GRAM POSITIVE AND NEGATIVE.

Question 1

Describe the mechanism of action of vancomysin

Answer 1

Vancomycin (which is used for severe C. Diff) prevents formation of cross-links in the peptidoglycan cell wall by binding to proteins in the cell wall (preventing DD-transpeptidase from binding). Only works in GRAM POSITIVE.

Question 2

Describe the mechanism of Clarithromycin

Answer 2

Inhibits protein synthesis by binding to subunits of the ribosome and stopping translocation - useful for intra-cellular pathogens. WORKS FOR GRAM POSITIVE.

Question 3

Describe the mechanism of action of doxycycline

Answer 3

Stops bacteria by stopping bacteria from multiplying - useful against intracellular pathogens. WORKS ON GRAM NEGATIVE ONLY.

Question 4

Describe the mechanism of action of Ciprofloxacin

Answer 4

Inhibits DNA duplication and has broad spectrum of action. WORKS FOR BOTH.

Question 5

Describe the mechanism of action of trimethoprim

Answer 5

Resistance is common, used for non-severe UTI’s.