Antibiotics - Macrolides

Question 1

What is transcription?

1 - copying of specific part of DNA to create mRNA
2 - converting mRNA into proteins using the ribosome
3 - adding molecules to proteins
4 - packaging proteins into vesicles

Answer 1

1 - copying of specific part of DNA to create mRNA

Question 2

What is translation (also called protein synthesis)?

1 - copying of specific part of DNA to create mRNA
2 - converting mRNA into proteins using the ribosome
3 - adding molecules to proteins
4 - packaging proteins into vesicles

Answer 2

2 - converting mRNA into proteins using the ribosome

Question 3

Ribosomes in prokaryotes (bacteria) is smaller in eukaryotes (human cells). Why is this important for drug development?

1 - means bacteria are limited to how they replicate
2 - drugs can inhibit mRNA
3 - drugs can be targeted against prokaryotes ribosome specifically
4 - bacterial wall production can be inhibited

Answer 3

3 - drugs can be targeted against prokaryotes ribosome specifically

• prokaryotes - 50 and 30S = 70S
• eukaryotes - 60 and 40S = 80S

Question 4

Which of the following is NOT a step in translation (protein synthesis)?

1 - elongation
2 - transcription
3 - initiation
4 - termination

Answer 4

2 - transcription

Question 5

Which of the following described initiation?

1 - codon signalling termination is recognised by P site
2 - 1st tRNA binds to P site and begins adding further tRNA
3 - 50S and 30S subunits bind to mRNA forming ribosome-mRNA complex
4 - tRNA bind to the A, P and E binding sites of ribosome

Answer 5

3 - 50S and 30S subunits bind to mRNA forming ribosome-mRNA complex

• mRNA is the blueprint for protein synthesis
• composed of 3 nucleotide sequences called codons
• tRNA binds to codons with matching anti-codon sequence

Question 6

The ribosome complex has 3 specific sites where the mRNA can bind. Which of the following is NOT one of these sites?

1 - A site (aminoacyl site)
2 - B site (binding site)
3 - P site (peptidyl site)
4 - E site (exit site)

Answer 6

2 - B site (binding site)

• correct codons are added at sites A and P, building a protein, once finished a stop codon is recognised and the mRNA is then detached and a protein is formed.

Question 7

The ribosome complex has 3 specific sites where the mRNA can bind, A site (aminoacyl site), P site (peptidyl site) and E site (exit site). Once the correct codons have been added at site A and P, the mRNA is then detached and a protein is formed.

Question 8

Which of the following described elongation?

1 - codon signalling termination is recognised by P site
2 - 1st tRNA binds to P site and begins adding further tRNA at site A
3 - 50S and 30S subunits bind to mRNA forming ribosome-mRNA complex
4 - tRNA bind to the A, P and E binding sites of ribosome

Answer 8

2 - 1st tRNA binds to P site and begins adding further tRNA at site A

• this repeats until protein is finished

Question 9

Which of the following described elongation?

1 - codon signalling termination is recognised by P site
2 - 1st tRNA binds to P site and begins adding further tRNA at site A
3 - 50S and 30S subunits bind to mRNA forming ribosome-mRNA complex
4 - tRNA bind to the A, P and E binding sites of ribosome

Answer 9

2 - 1st tRNA binds to P site and begins adding further tRNA at site A

• this repeats until protein is finished

Question 10

Which of the following described termination?

1 - codon signalling termination is recognised by P site
2 - 1st tRNA binds to P site and begins adding further tRNA at site A
3 - 50S and 30S subunits bind to mRNA forming ribosome-mRNA complex
4 - tRNA bind to the A, P and E binding sites of ribosome

Answer 10

1 - codon signalling termination is recognised by P site

Question 11

Which 2 of the following are the core macrolids that we need to be aware of?

1 - Doxycycline
2 - Clarithromycin
3 - Erythromycin
4 - Gentamicin

Answer 11

2 - Clarithromycin
3 - Erythromycin

Question 12

Clarithromycin and Erythromycin are the core Macrolides that we need to be aware of. What is the mechanism of action of this class of antibiotics?

1 - binds to penicillin binding protein
2 - interfere with NAG and NAMs
3 - binds to 50S ribosome inhibiting translocation
4 - binds to A site on the 30S ribosome

Answer 12

3 - binds to 50S ribosome inhibiting translocation

Question 13

Clarithromycin and Erythromycin are the core Macrolides that we need to be aware of. Is this a bactericidal or bacteriostatic?

Answer 13

• bacteriostatic
• suppress growth of bacteria, keeping them in the stationary phase of growth

Question 14

Clarithromycin and Erythromycin are the core Macrolides we need to be aware of. Are these broad or narrow spectrum antibiotic?

Answer 14

• broad spectrum
• good effect against Gram + (e.g. Streptococcus pyogenes and pneumococcal)
• some effect against Gram -
• VERY effective against haemophilus influenza

Similar to Flucloxacillin
S. pyogenes (sore throat, skin infections)
Pneumococcal infections (resp. tract)
Coliform infections (urinary tract infections)
(patients with penicillin allergy)

Question 15

Clarithromycin and Erythromycin are the core Macrolides can be used to treat Chlamydia trachomatis. Why are macrolides good for this?

1 - able to get into the cell as no or thin cell wall
2 - no LPS so easy to enter the cells
3 - lopophilic so can enter the cells easily
4 - all of the above

Answer 15

1 - able to get into the cell as no or thin cell wall

Question 16

Clarithromycin and Erythromycin are the core Macrolides that can be used to treat respiratory, skin and soft tissue infections as an alternative to which antibiotic class?

1 - Penicillins (β-lactams)
2 - Nitroimidazole
3 - Glycopeptide antibiotics
4 - Quinolones

Answer 16

1 - Penicillins (β-lactam antibiotics)

• generally due to allergies

Question 17

Which of the following are macrolides NOT indicated in the use of?

1 - Cellulitis
2 - Mild diabetic foot infection
3 - Community acquired pneumonia
4 - Hospital-acquired pneumonia
5 - Clostridium difficile colitis
6 - H-pylori eradication in combination with other drugs

Answer 17

5 - Clostridium difficile colitis

• vancomyocin is 1st line for this

Question 18

Clarithromycin and Erythromycin are the core Macrolides can be used to treat severe pneumonia to treat bacteria including legionella pneumophila and mycoplasma pneumonia. They are typically combined with what other antibiotic class?

1 - Penicillins (β-lactams)
2 - Nitroimidazole
3 - Glycopeptide antibiotics
4 - Quinolones

Answer 18

1 - Penicillins (β-lactams)

Question 19

Clarithromycin and Erythromycin are the core Macrolides can be used to eradicate Helicobacter pylori that can cause peptic ulcers. They are typically combined with which 2 of the following?

1 - amoxicillin or metronidazole
2 - omeprazole
3 - antacids
4 - Hydrocortisone

Answer 19

1 - amoxicillin or metronidazole
2 - omeprazole

Question 20

Clarithromycin and Erythromycin are the core Macrolides. Which of the 2 has the worst adverse events profile?

Answer 20

• Erythromycin

Question 21

Macrolides are irritants and can therefore cause which of the following?

1 - diarrhoea
2 - nausea/vomiting
3 - abdominal pain
4 - thrombophlebitis (given IV)
5 - all of the above

Answer 21

5 - all of the above

• thrombophlebitis = inflammatory process that causes a blood clot to form and block one or more veins, usually in the leg

Question 22

Macrolides can cause antibiotics induced colitis. How does this occur?

1 - irritates mucosal membrane
2 - has osmotic effect inducing diarrhoea
3 - healthy flora are killed causing C. difficile and colitis
4 - stimulates serotonin receptors and induces nausea and vomiting

Answer 22

3 - healthy flora are killed causing C. difficile and colitis

Question 23

Macrolides can cause all of the following adverse events, EXCEPT which one?

1- retinopathy
2 - allergy
3 - ototoxicity
4 - cholestatic hepatitis
5 - prolonged QT interval (increased risk of arrhythmias

Answer 23

1- retinopathy

Question 24

If a patient is allergic to penicillin, does this mean they are also allergic to macrolides?

Answer 24

• no
• no cross sensitivity
• good alternative if patient allergic to penicillin

Question 25

Macrolides are predominantly eliminated by the liver, with a small portion of renal excretion. Are they contraindicated in patients with severe hepatic and renal impairment?

Answer 25

- no, ok to use - BUT should be used with caution

Question 26

Clarithromycin and Erythromycin are the core Macrolides. Which enzyme are these antibiotics able to inhibit? 1 - pancreatic lipase 2 - pepsin 3 - cytochrome P450 4 - plasminogen

Answer 26

3 - cytochrome P450 - drugs are not metabolised and can increases risk of adverse events from other drugs - i.e. increased risk of bleeding warfarin - i.e. increased risk of myopathy in statins

Question 27

What affect do macrolides have on the conduction in the heart? 1 - prolonged QT interval 2 - prolonged PR interval 3 - inverted T waves 4 - AV node suppression

Answer 27

1 - prolonged QT interval - increases the risk of arrhythmias - other drugs that do similar include amiodarone, quinine, quinolone antibiotics and SSRIs

Question 28

Does Clarithromycin or Erythromycin have a longer half life?

Answer 28

- Clarithromycin - concentrated in tissues, so doesn't need to be given as often - Clarithromycin standard dose = 250-500mg/12 hours - Erythromycin standard dose = 250-500mg/6 hours

Question 29

As macrolides are an irritant, if given as an infusion they should be diluted in 0.9% sodium chloride (500mg in 250ml). How long does it typically take to infuse to reduce the risk of arrhythmias? 1 - >30 minutes 2 - >60 minutes 3 - >2 hours 4 - >5 hours

Answer 29

2 - >60 minutes

Question 30

When prescribing any antibiotics, in accordance with antibiotic stewardship, which of the following must be document on the prescription and in the patients notes? 1 - indication 2 - review date 3 - treatment duration 4 - all of the above

Answer 30

4 - all of the above

Question 31

If prescribed as IV, how long should it be before the antibiotics are switched to oral where appropriate? 1 - 12h 2 - 24h 3 - 48h 4 - 72h

Answer 31

3 - 48h

Question 32

Broad spectrum antibiotics are prescribed empirically, when we do not know the specific cause of the infection. However, what is the main driver to switch antibiotics to a narrow spectrum antibiotic? 1 - cost 2 - patients request 3 - microbiology results 4 - allergies

Answer 32

3 - microbiology results