Antibiotics

Question 1

1. Know and describe the mechanisms of action of the most common antibiotics used to treat dental infections.

Erythromycin, Clindomycin, Tetracyclines,
Metronidazole, Quinolones

Answer 1

Inhibition of cell wall synthesis: Beta-Lactams (penicillins and Cephalosporins)
Inhibit enzymes responsible for transpeptidation for 3D cell wall.

Inhibition of Ribosomal Protein Synthesis:
Clindamycin, Erythromycin, Tetracyclines

Suppression of nucleic acid synthesis: Metronidazole, Quinolones

Question 2

Erythromycin

Answer 2

bind to 50s ribosomal subunit to inhibit peptidyl transferase

Question 3

Clindomycin

Answer 3

50 S ribosomal subunit inhibit RNA-dependent protein synthesis

Question 4

Tetracyclines

Answer 4

Binds to 30S ribosomal subunit to inhibit binding of tRNA to rRNA

Question 5

Metronidazole

Answer 5

microbial reduction of 5’ nitro group by nitroreductase to cell toxic metabolites that damage the DNA and interfere with DNA synthesis

Question 6

Quinolones

Answer 6

inhibit DNA supercoiling by DNA gyrase resulting in abnormal DNA growth

Question 7

2. Know the difference between bacteriostatic and bactericidal antibiotics.

Answer 7

Bacteriostatic: Inhibition of growth or multiplication

Bactericidal: Microbial cell death

Bacteriostatic agents that effect protein synthesis and cell membrane function work better with pulse dosing because their activity is less dependent on drug concentration.

Bactericidal agents that effect cell wall synthesis function better with continuous dosing because their activity is more drug concentration dependent.