31. ANTIBIOTICS + ANTIFUNGALS

Question 1

what do sulphonamides do

Answer 1

inhibits dihydropterate synthase

Question 2

Fluoroquinolones

Answer 2

inhibits bacterial DNA gyrase + topoisomerase IV

hence interfere with DNA replication

Question 3

how do drugs interfere with RNA synthesis

Answer 3

inhibits RNA polymerase

Question 4

what do 
Macrolides 
Chloramphenicol 
Aminoglycosides 
Tetracyclines 
do

Answer 4

interfere with ribosomes + protein synthesise

Question 5

how do drugs inhibit DNA synthesis

Answer 5

inhibits DHF reductase

this inhibits THF production

Question 6

how do drugs interfere with peptidoglycan synthesis

Answer 6

Glycopeptides (e.g. vancomycin) –

bind to the pentapeptides and inhibit peptidoglycan synthesis

This is used as a last resort for Gram-positive bacteria that are resistant to other antibiotics

Question 7

how do drugs prevent peptidoglycan transport

Answer 7

inhibits bactoprenol, hence preventing peptidoglycan transport

Question 8

Beta lactams

Answer 8

they bind covalently to transpeptidase, which inhibits peptidoglycan incorporation into the cell wall

Question 9

lipopeptides and polymyxins

Answer 9

interfere with cell wall stability

Lipopeptides – disrupt Gram-positive cell walls

Polymyxins – bind to lipopolysaccharide and disrupt Gram-negative cell membranes

Question 10

What are the two main groups of anti-fungals? Give an example ofeach.

Answer 10

Azoles (fluconazole)

Polyenes (amphotericin)

Question 11

Describe the mechanism of action of azoles.

Answer 11

They inhibit CYP51p (enzyme of the CYP450 system), which is involved in ergosterol production

Question 12

Describe the mechanism of action of polyenes.

Answer 12

These interact with membrane sterols and form channels (punching holes in the membrane)