Inhibitors of protein synthesis

Question 1

Protein synthesis must continue even when cells are dormant. True or false?

Answer 1

True

Question 2

Which drug is biosynthesised from acetate by several species of streptomyces?

Answer 2

Tetracycline

Question 3

Tetracycline binding to nucleic acid inhibits cellular function. True or false?

Answer 3

False - only ribosome binding does

Question 4

Tetracycline is contraindicated in children. Why?

Answer 4

Stain tooth enamel

Question 5

Oxytetracycline is used to treat conjunctivitis in cats. True or false?

Answer 5

False - used to treat acne

Question 6

Which tetracycline is used to treat lyme disease?

Answer 6

Demeclocycline

Question 7

Which tetracycline is an antibacterial also used in prophylaxis of malaria?

Answer 7

Doxycycline

Question 8

Minocycline is broader spectrum than other tetracyclines and can treat Neisseria meningitidis. True or false?

Answer 8

True

Question 9

Streptomycin, gentamycin, kanamycin and neomycin belong to which group of drugs?

Answer 9

Aminoglycosides

Question 10

Which ribosomal subunit does streptomycin bind?

Answer 10

30S

Question 11

Aminoglycosides are active against gram negative bacteria. True or false?

Answer 11

True

Question 12

Aminoglycosides show nephrotoxicity. True or false?

Answer 12

True

Question 13

Gentamicin is derived from streptomyces. True or false?

Answer 13

False - derived from micromonospora

Question 14

Which aminoglycoside binds to both ribosomal subunits, preventing them combining?

Answer 14

Tobramycin

Question 15

Amikacin is arrived from which other aminoglycoside?

Answer 15

kanamycin

Question 16

Paramomycin is used to treat a protozoal infection. Which ribosomal subunit does is interact with?

Answer 16

30S

Question 17

What is the name of the only clinically available oxazolidinone?

Answer 17

Linezolid

Question 18

Linezolid is not active against MRSA. True or false?

Answer 18

False

Question 19

Linezolid is used against hospital acquired gram positive infections. True or false?

Answer 19

True

Question 20

Which ribosomal subunit does linezolid bind to?

Answer 20

50S

Question 21

Linezolid is toxic to mitochondria. True or false?

Answer 21

True

Question 22

What is the soil bacterium that produces erythromycin?

Answer 22

Saccharopolyspora erythraea

Question 23

Structure of erythromycin A is based on proprionate. True or false?

Answer 23

True

Question 24

In what way are the structures of erythromycin and tetracycline similar?

Answer 24

both polyketides

Question 25

Erythromycin is a macrolide. True or false?

Answer 25

True

Question 26

Macrolides are first-line treatment in patients that are allergic to ______

Answer 26

penicillin

Question 27

Macrolides are gut motilide agonists. What is meant by this?

Answer 27

Sensitised patients find that erythromycin and food do not sit well - taste and bitter is foul and cannot be masked

Question 28

Macrolides give rise to a number of DDI. What is the reason for this?

Answer 28

They are metabolised by CYP450 3A4 in the liver

Question 29

What is the mode of action of erythromycin?

Answer 29

Blocks protein synthesis after several rounds and oligopeptides are released from the ribosome. It blocks the exit tunnel of the bacterial ribosome

Question 30

What is the paediatric erythromycin that is used called and how does it work?

Answer 30

Erythromycin ethyl succinate - taste-free prodrug which hydrolyses in the blood.

Question 31

Paediatric erythromycin needs to be stored in the fridge. True or false?

Answer 31

True - hydrolyses in the bottle

Question 32

Are second generation macrolides more or less stable than erythromycin A?

Answer 32

More stable - so better in the stomach

Question 33

Second generation macrolides are more hydrophilic than erythromycin A. True or false?

Answer 33

False - more hydrophobic

Question 34

What is the half life of clarithromycin at pH 2.5 and 37 degrees?

Answer 34

310 mins

Question 35

What is the half life of erythromycin at pH 2.5 and 37 degrees?

Answer 35

<10 mins

Question 36

What is the only ketolide that is clinically used at the moment?

Answer 36

Telithromycin

Question 37

What are some mechanisms of macrolide resistance?

Answer 37

Modification of ribosomal proteins Efflux pumps, pumping macrolides out of cell Methylation of adenine 2058 in 23S RNA

Question 38

Chloramphenicol is only used to treat gram positive bacteria. True or false?

Answer 38

False - gram positive and gram negative

Question 39

How many chiral centres does chloramphenicol have?

Answer 39

2 - but only one is active

Question 40

Why is chloramphenicol not usually given internally and how is it mainly given?

Answer 40

Because it can cause aplastic anaemia. | It is typically found in eye drops

Question 41

Of the four possible stereoisomers of chloramphenicol, how many are active?

Answer 41

One

Question 42

Lincomycin is a natural product. True or false?

Answer 42

True

Question 43

How is resistance to lincomycin and clindamycin induced?

Answer 43

Methylation of adenine 2058 in 23S RNA - so assumed that mode of action is similar to macrolides

Question 44

Clindamycin is generally superior to lincomycin. True or false?

Answer 44

True

Question 45

Clindamycin can be used to treat both aerobic and anaerobic infections. True or false?

Answer 45

True

Question 46

Clindamycin is used in the treatment of toxic shock syndrome, often in combination with ________

Answer 46

vancomycin

Question 47

Fusidic acid is a fungal product. True or false?

Answer 47

True

Question 48

Fusidic acid is used to treat gram negative infections. True or false?

Answer 48

False - gram positive

Question 49

Fusidic acid is most commonly seen in eye drops. It cannot be given as tablets. True or false?

Answer 49

False - can be given as tablets

Question 50

What is the mode of action of fusidic acid?

Answer 50

Binds to EFG.GTP the ternary complex binds to ribosome as normal GTP is hydrolysed EFG.GDP is unable to leave the ribosome and protein synthesis is therefore stalled