Antimicrobials

Question 1

Penicillin mechanism of action and resistance

Answer 1

Inhibits transpeptidases in gram-positive bacteria, inhibiting cell wall production in bacteria

Bacteria can quickly evolve to produce beta-lactamases, which breakdown the penicillin molecules (and other b-lactam based antibiotics)

Question 2

Ribosome as a drug target in bacteria, examples and mechanism and resistance

Answer 2

Tetracyclines (e.g., tetracycline, doxycycline), aminoglycosides (neomycin), and macrolides (erythromycin) target the ribosome, with many binding sites present in both the ribosome subunits

Tetracycline bind to both the RNA and protein sites in ribosome. This inhibits protein synthesis

As it has to act intracellularly, bacteria can develop efflux transporters that remove tetracycline form the bacteria. May also produce modifying enzymes that render the drug ineffective

Question 3

Drugs targeting DNA transcription

Answer 3

Quinolones (e.g., ciprofloxacin, levofloxacin), inhibits topoisomerase II and IV to inhibit DNA transcription/replication

Question 4

Experimental targets for bacteria

Answer 4

Inhibiting quorum sensing pathways to inhibit the accumulation of high density bacteria.

Bacteriophages, which insert viral RNA/DNA into bacteria as a way to kill bacteria, more interest now due to MRSA. Used to be used by USSR