Question
(
- (a) Penicillin. ( 4 mark(s)
- (b) Aminoglycosides. 4 mark(s)
Answer
a) Penicillin The prototype beta-lactam. MOA: binds penicillin-binding proteins (transpeptidases), inhibiting peptidoglycan cross-linking, causing bactericidal cell wall failure. Uses: Streptococcus pyogenes infections, syphilis, meningococcal infections. Adverse effects: hypersensitivity reactions (including anaphylaxis), Jarisch-Herxheimer reaction when treating syphilis.
b) Aminoglycosides Bactericidal, active mainly against aerobic Gram-negative organisms. MOA: bind the bacterial 30S ribosomal subunit, causing misreading of mRNA and blocking translocation, inhibiting protein synthesis. Examples: Gentamicin, Amikacin, Streptomycin. Uses: severe Gram-negative infections (often combined with a beta-lactam for synergy), tuberculosis (streptomycin, second-line). Adverse effects: nephrotoxicity (reversible), ototoxicity (often irreversible), neuromuscular blockade at high doses.

