Antibiotics Target: Protein Synthesis

Question 1

Chloramphenicol

Answer 1

Emergency antibiotic for H. Influenzae, N. Meningitidis, Rikketsia
Targets 50S ribosomal subunit and prevents tRNA P site binding
Toxicity issues with bone marrow suppression

Question 2

Tetracycline

Answer 2

Broad spec four carbon polyketide - mysteriously also effective against some protozoa
Inhibits 30S subunit by inhibiting aminoacyl-tRNA to A site
Toxicity associated with intracellular sequestration by magnesium and removal of calcium from teeth and bones
Used against mycoplasma and cholera

Question 3

Streptomycin

Answer 3

Aminoglycoside narrow spec antibiotic - gram negative rods and some gram positives
Potentiates β lactams
Freezes pre initiation complexes by binding near A site on 30S

Question 4

Fusidic acid

Answer 4

Inhibits elongation factor G
Active selectively against gram negative skin and eye infections
Less toxicity than most antibiotics

Question 5

Erythromycin

Answer 5

Macrolide gram positive antibiotic. Used where allergy contraindicates penicillin
Acid labile, short half life
Blocks exit tunnel on 50s subunit -> only short, 6αα peptides -> ribosomal disassembly
Clarithromycin + azithromycin = improved versions