Protein synthesis inhibitors

Question 1

key difference between protein synthesis in prokaryotic + eukaryotic cells

Answer 1

• Ribosome structure

- Uptake of antibiotic molecules into cell (active uptake in bacteria; limited penetration into mammalian cells)

Question 2

Macrolides mode of action

Answer 2

inhibit protein synthesis by binding to 50s ribosomal subunit
Block translocation by preventing movement of peptidyl-tRNA from A to P
Exit tunnel from which peptide emerges

Question 3

Resistance mechanism of macrolides in gram-negative bacteria

Answer 3

The permeability of outer membrane

Question 4

Resistance mechanism of macrolides in gram-positive bacteria

Answer 4

Target modification involving adenine methylation of 23s + 5os ribosume
ATP binding cassette efflux pump through expression of
- mef (macrolides
Ribosomal mutation - small number of clinical isolates

Question 5

Tetracycline mode of action

Answer 5

Pass through porin proteins in outer membrane due to
Actively transported into bacterial cells
Bind to 30s ribosomal subunit at 16s rRNA involving ribosomal proteins + magnesium ions
- blocks aminoacyl-trna binding at A site
Enter mammalian cell
Bacteriostatic (not used with beta-lactams)

Question 6

Chloramphenicol

Answer 6

Inhibits protein synthesis by binding to ribosomal 50s subunit + inhibits peptidyl transferase
- normal aa-tRNA

Question 7

Treatment for conjunctivitis

Answer 7

Inflammation of membrane lining eyelids (staphylococcus aureus)
- Chloraphenicol

Question 8

Treatment of ear infection

Answer 8

Inflammation + infection of middle ear (Streptococcus pneumoniae)
- macrolides

Question 9

Treatment for sinusitis

Answer 9

Inflammation of nasal sinuses (streptococcus pneumoniae)

- Macrolides (clarithromycin, tetracycline