Antibiotics and antifungals

Question 1

What are drugs that target proteinsyhthesis particularly useful for targeting and why?

Answer 1

Gram negative bacteria as no peptidoglycan hinderance

Question 2

Recall the pathway of nucleic acid synthesis and the enzymes involved

Answer 2

PABA–> DHOp (DHOp synthase)
DHOp –> DHF
DHF –> THF (DNA reductase)

Question 3

Recall examples of drugs that inhibit nucleic acid synthesis and their targets

Answer 3

Sulphonamides: DHOp synthase
Trimethoprim: DNA reductase

Question 4

Name the combination drug commonly used in inhibition of bacterial ucleic acid synthesis and what drugs it is made up of

Answer 4

Co-trimoxazole

= sulphonamides + trimethoprim

Question 5

Describe the process of bacterial DNA replication that can be inhibited by antibiotics and the enzymes involved

Answer 5

Tension released from DNA molecule so that it can be replicated
Enzymes: topoisomerase IV and DNA gyrase

Question 6

Recall the names of the antibiotic drugs that target bacterial DNA replication and their targets

Answer 6

Quinolones and fluoroquinolones

Target DNA gyrase and topoisomerase iv

Question 7

Recall the name of a drug that inhibits RNA synthesis in bacteria

Answer 7

Rifamycins

Question 8

How do bacterial and eukaryotic ribosomes differ?

Answer 8

Eukaryotes: 40s and 60s subunits
Prokaryotes: 30s and 50s subunits

Question 9

Recall 4 classes of antibiotics capable of inhibiting protein translation

Answer 9

Aminoglycosides
Chloramphenicol
Macrolides
Tetracylcines

Question 10

Give an example of an aminoglycoside antibiotic

Answer 10

Gentamycin

Question 11

Give an example of a macrolide antibiotic

Answer 11

Erythromycin

Question 12

Recall the components of peptidoglycan

Answer 12

N-acetyl muramic acid, N-acetyl glucosamine, pentapeptide

Question 13

What class of antibiotic is capable of inhibiting peptidoglycan synthesis? Give an example with its MOA

Answer 13

Glycopeptides
eg Vancomycin
Binds pentapeptide to prevent synthesis

Question 14

Recall the fate of a peptidoglycan molecule following synthesis

Answer 14

Transported across membrane by bactoprenol

Incorporated by PtG cross-links by transpeptidase

Question 15

Recall which antibiotic is capable of inhibiting trasnportation of PtG into the cell wall and its MOA

Answer 15

Bacitracin

Inhibits bactoprenol

Question 16

Recall the class of drugs capable of inhibiting peptidoglycan incorporation into the cell wall, and name examples

Answer 16

Beta-lactams:
Carbapenems
Cephalosporins
Penicillins

Question 17

Recall 2 classes of drug that interfere with cell stability, and their general MOA

Answer 17

Lipopeptides: disrupt G+ cell walls
Polymyxins: bind to LPS to disrupt G- membranes

Question 18

How do beta-lactamases destroy beta-lactam?

Answer 18

Hydrolyse the CN bond

Question 19

Recall 2 mechanisms by which a drug may become beta-lactam resistance

Answer 19

1. Production of beta-lactamase

2. Steric hinderence by production of molecules around beta-lactam ring

Question 20

What is amoxicillin co-administered with, and why?

Answer 20

Clavulanic acid

Conveys resistance to beta-lactamase

Question 21

Recall a bacteria that is resistant to trimethoprim, the mechanism by which it conveys resistance and which 2 general mechanisms of resistance this fulfils

Answer 21

E Coli
Can produce DHF reductase
= additional target and hyperproduction

Question 22

Recall a bacteria that is resistant to quinolones, and why

Answer 22

S aureus

Mutations in ParC region of topoisomerase iv

Question 23

Recall 5 mechanisms by which a bacteria may become antibiotic resistant

Answer 23

1. Production of destruction enzymes
2. Additional target
3. Alteration in target enzymes
4. Hyperproduction
5. Alteration in drug permeation

Question 24

Recall how a bacterium may alter antibiotic permeation to convey resistance

Answer 24

Reduce AQP expression

Increase efflux systems

Question 25

What are the 2 most common classes of anti-fungal drug? Give an example of each

Answer 25

Azoles: fluconazole
Polyenes: amphotericin

Question 26

Recall the MOA of azole drugs

Answer 26

Inhibit CYP450-dependent enzymes involved in ergosterol synthesis, destabilising the cell wall and reducing survival

Question 27

Recall the MOA of polyene drugs

Answer 27

Interact with cell membrane sterols to form membrane channels

Question 28

Why do polyene drugs have such a significant side effect profile?

Answer 28

Also “punches holes” in human cells

Question 29

What is the main indication for amphotericin?

Answer 29

Systemic fungal infection