Katzung 12th ed - Chapter 43 - Vancomycin (2)

Question 1

Classify vancomycin.

Answer 1

Glycopeptide.

Question 2

What is the mechanism of action of vancomycin?

Answer 2

Vancomycin targets cell wall synthesis: it binds to peptidoglycan and inhibits transglycosylase, therefore preventing peptidoglycan elongation and cross-linking that confers rigidity. It is only active against gram-positive species.

Question 3

Vancomycin is active against which bacteria?

Answer 3

Only gram positive. MRSA (particularly endocarditis, sepsis). Vancomycin is synergistic with gentamicin in activity against enterococcus.

Question 4

By what mechanism can bacteria be resistant to vancomycin?

Answer 4

By altering its binding site on D-ala D-ala.

Question 5

Describe the administration and absorption of vancomycin.

Answer 5

Vancomycin is poorly absorbed from the GIT, and the only reason for giving it orally would be to treat Clostridium difficile in the gut.

Question 6

What is the half-life of vancomycin?

Answer 6

6hrs. Can be 6 days in renal impairment.

Question 7

How is vancomycin excreted?

Answer 7

90% is filtered at the glomerulus. Dose adjustment required in renal impairment.

Question 8

Describe the distribution of vancomycin in tissues.

Answer 8

After IV administration, vancomycin is distributed widely throughout the body, including into CSF. Volume of distribution is medium (27L /70kg)

Question 9

Describe the adverse effects of vancomycin.

Answer 9

In about 10% of individuals, there will be minor reactions such as phlebitis at the site of injection, or “red man syndrome” which involves flushing due to histamine release (treatable by slowing the infusion rate and giving an antihistamine). Rarely, there can be ototoxicity and nephrotoxicity, especially if co-administered with gentamicin.