Antibiotics - Macrolides Flashcards
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
1 - copying of specific part of DNA to create mRNA
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
2 - converting mRNA into proteins using the ribosome
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
3 - drugs can be targeted against prokaryotes ribosome specifically
- prokaryotes - 50 and 30S = 70S
- eukaryotes - 60 and 40S = 80S
Which of the following is NOT a step in translation (protein synthesis)?
1 - elongation
2 - transcription
3 - initiation
4 - termination
2 - transcription
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
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
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)
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.
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.
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
2 - 1st tRNA binds to P site and begins adding further tRNA at site A
- this repeats until protein is finished
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
2 - 1st tRNA binds to P site and begins adding further tRNA at site A
- this repeats until protein is finished
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
1 - codon signalling termination is recognised by P site
Which 2 of the following are the core macrolids that we need to be aware of?
1 - Doxycycline
2 - Clarithromycin
3 - Erythromycin
4 - Gentamicin
2 - Clarithromycin
3 - Erythromycin
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
3 - binds to 50S ribosome inhibiting translocation
Clarithromycin and Erythromycin are the core Macrolides that we need to be aware of. Is this a bactericidal or bacteriostatic?
- bacteriostatic
- suppress growth of bacteria, keeping them in the stationary phase of growth
Clarithromycin and Erythromycin are the core Macrolides we need to be aware of. Are these broad or narrow spectrum antibiotic?
- 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)
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
1 - able to get into the cell as no or thin cell wall
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
1 - Penicillins (β-lactam antibiotics)
- generally due to allergies
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
5 - Clostridium difficile colitis
- vancomyocin is 1st line for this
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
1 - Penicillins (β-lactams)
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
1 - amoxicillin or metronidazole
2 - omeprazole
Clarithromycin and Erythromycin are the core Macrolides. Which of the 2 has the worst adverse events profile?
- Erythromycin
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
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
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
3 - healthy flora are killed causing C. difficile and colitis
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
1- retinopathy
If a patient is allergic to penicillin, does this mean they are also allergic to macrolides?
- no
- no cross sensitivity
- good alternative if patient allergic to penicillin
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?
- no, ok to use
- BUT should be used with caution
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
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
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
1 - prolonged QT interval
- increases the risk of arrhythmias
- other drugs that do similar include amiodarone, quinine, quinolone antibiotics and SSRIs
Does Clarithromycin or Erythromycin have a longer half life?
- 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
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
2 - >60 minutes
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
4 - all of the above
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
3 - 48h
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
3 - microbiology results
