Mechanisms of Action

Question 1

Penicillins

Answer 1

Cell wall synthesis (cross linking peptidoglycan strands)

Question 2

Cefalexin (Cephalosporins)

Answer 2

Cell wall synthesis (bind to PBPs) - use in cases of penicillin allergy

Question 3

Vancomycin (Carbapenams)

Answer 3

Cell wall synthesis

Question 4

Glycopeptides (vancomycin, -planins)

Answer 4

Cell wall synthesis (block peptidoglycan adding on)

Question 5

Ciprofloxacin (Fluroquinolone)

Answer 5

DNA gyrase (topoisomerase II and IV)

Question 6

Cefuroxime (Cephalosporins)

Answer 6

Cell wall synthesis (bind to PBPs) - penicillin allergy

Question 7

Metronidazole

Answer 7

DNA synthesis - (selectively reduced by anaerobic bacteria)

Question 8

Erythromicin (macrolide)

Answer 8

Inhibits 50S subunit assembly

Question 9

Clarithromycin (macrolide)

Answer 9

Inhibits 50S subunit assembly

Question 10

Gentamicin (Aminoglycosides)

Answer 10

Binds to 30S subunit - inability to recognise incorrect pairing, resulting in faulty protein sequences

Question 11

Streptomycin (Aminoglycosides)

Answer 11

Binds to 30S subunit

Question 12

Doxycycline (Tetracycline)

Answer 12

Binds to 30S subunit, preventing binding of tRNA

Question 13

Trimethoprim

Answer 13

Inhibits folate synthesis (therefore DNA synthesis) - don’t give in pregnancy

Question 14

Sulfonamides

Answer 14

Inhibits folate synthesis

Question 15

Clotrimazole - Canestan

Answer 15

Inhibits ergosterol biosynthesis, essential for fungal cell membranes

Question 16

Fluconazole (-azole)

Answer 16

Inhibitor of fungal cytochrome P450 dependant enzyme- converts lanosterol to ergosterol, essential for fungal cell membranes

Question 17

Nystatin

Answer 17

Binds to ergosterol in fungal cell membranes causing pores to form, intracellular contents (K+) leak out

Question 18

Aciclovir

Answer 18

Terminates viral DNA formation

Question 19

Clindamycin (Lincosamide)

Answer 19

Binds to 50S subunit

Question 20

Chloramphenicol

Answer 20

Binds to 50S subunit