Pharmacology of antibiotics

Question 1

What are the targets for antibiotics

Answer 1

Bacterial cell wall
Bacterial ribosomes
Bacterial folate metabolism
Bacterial DNA gyrases

Question 2

What does Amoxicillin contain

Answer 2

Beta-lactam ring

Question 3

What do penicillins target and how

Answer 3

Bacterial cell wall synthesis

-By binding irreversibly to a transpeptidase which cross-links peptidoglycans in the bacterial cell wall

Question 4

What are penicillins only effective against

Answer 4

Dividing organisms (because division requires cell wall synthesis)

Question 5

What are penicillins

Answer 5

Bacteriacidal (cause lysis of bacteria)

Question 6

What are some penicillins inactivated by and what are these secreted from

Answer 6

Beta-lactamases secreted by resistant bacteria

Question 7

What inhibits beta lactamases

Answer 7

Clavulanic acid

Question 8

Where is clavulanic acid included and why

Answer 8

With some agents like amoxicillin to inhibit the beta lactamases

Question 9

Another example of beta lactam antibiotics

Answer 9

Cephalosporins

Question 10

how do cephalosporins work

Answer 10

Inhibit transpeptidases which cross link the peptidoglycan chains

Question 11

Whom should you be cautious about giving cephalosporins to

Answer 11

Those with a penicillin allergy because they show cross-reactivity with penicillins

Question 12

How do glycopeptides work

Answer 12

Inhibit bacterial cell wall synthesis by inhibiting the growth of the peptidoglycan chain

Question 13

What are glycopeptides usually used to manage

Answer 13

Severe infections due to superbugs (e.g. MRSA)

Question 14

How do tetracyclines work

Answer 14

inhibit protein synthesis by binding to the 30s subunit of the bacterial ribosome and preventing tRNA from binding at the acceptor site

Question 15

Are tetracyclines bacteriostatic or bactericidal

Answer 15

Bacteriostatic

Question 16

What do macrolides do

Answer 16

Prevent the translocation of the 50s subunit of the bacterial ribosome along the mRNA (so stop protein synthesis)

Question 17

Are macrocodes bacteriostatic or bactericidal

Answer 17

Bacteriostatic

Question 18

What is used as an alternative to penicillin in those with a penicillin allergy

Answer 18

Macrolides

Question 19

Which drug is associated with a range of drug interactions and why

Answer 19

Macrolides

-They are cytochrome P450 inhibitors and so are increase concentrations of interacting drugs

Question 20

How do aminoglycosides act

Answer 20

Bind irreversibly to the 30s subunit of bacterial ribosomes which leads to the misreading of mRNA and therefore interferes with protein synthesis

Question 21

What are aminoglycosides used to manage

Answer 21

Gram negative bacteria

Question 22

What drug can be mixed with penicillin to form a synergy and what effect does this have

Answer 22

Aminoglycosides

-Breakdown of cell wall and so increases uptake of aminoglycosides

Question 23

What do quinolones do

Answer 23

Inhibit bacterial DNA gyrase (topoisomerase 2) and topoisomerase IV

Question 24

What do quinolones do to gram negative bacteria

Answer 24

Inhibit DNA gyrase and they inhibit the supercoiling of bacterial DNA which is essential for DNA repair and replication

Question 25

What is trimethoprim structurally related to

Answer 25

Folate

Question 26

What does trimethoprim do

Answer 26

Folate antagonist and inhibit the bacterial dihydrofolate reductase which converts folate to tetrahydrofolate

Question 27

Drugs which inhibit folate

Answer 27

Sulphonamides and trimethoprim

Question 28

What do sulfonamides do and what does this mean

Answer 28

Inhibit growth of bacteria by competitively inhibiting enzyme dihydropteroate synthase which is involved in the synthesis of folate

-The availability of DNA and RNA precursors are reduced

Question 29

What drug is used against anaerobic bacteria

Answer 29

Metronidazole