Paper I — 2023 July (Supplementary) (2019 Scheme)

Paper I

2023 July (Supplementary) (2019 Scheme) · 100 marks · 180 min

Question

Name four mechanisms of antimicrobial resistance in bacteria.

Q124 marksShort Answers

Four mechanisms of antimicrobial resistance in bacteria:

Enzymatic inactivation of the drug — e.g., beta-lactamases hydrolysing the beta-lactam ring of penicillins/cephalosporins.
Alteration of the drug target — e.g., altered penicillin-binding proteins (PBP2a in MRSA), altered DNA gyrase (fluoroquinolone resistance), altered ribosomal binding sites (macrolide/aminoglycoside resistance).
Reduced drug uptake/permeability — e.g., porin loss or downregulation in the outer membrane of Gram-negative bacteria, limiting antibiotic entry.
Efflux pumps — active pumping of the antibiotic out of the bacterial cell before it can reach its target, conferring resistance to multiple drug classes simultaneously.

(Other valid mechanism: bypass pathways, e.g., alternative folate-synthesis enzymes conferring sulfonamide/trimethoprim resistance.)