Antibiotics - Glycopeptide antibiotics

Question 1

How are we able to distinguish between gram positive and gram negative bacteria?

1 - shape of bacteria
2 - if they contain a cell membrane
3 - if they contain RNA or DNA
4 - if dye binds to bacterial wall

Answer 1

4 - if dye binds to bacterial wall
- gram negative cannot retain the dye as the walls are too thin

Question 2

Bacterial cell walls are composed of peptidoglycans, which are long amino polysaccharides. What 2 amino polysaccharides make up the peptidoglycan wall?

1 - N-acetylglucosamine (NAG) 2 - N-acetylmuramic acid (NAM)
3 - pili
4 - fimbraie

Answer 2

1 - N-acetylglucosamine (NAG)
2 - N-acetylmuramic acid (NAM)

• organised in an alternating pattern

Question 3

The 2 amino polysaccharides, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) that make up the peptidoglycan wall are connected at their tips by tetrapeptide and pentapeptide chains, protruding from NAM subunits.
These peptide chains can link to other peptide chains from the neighboring strands through a process known as transpeptidation. What enzyme is crucial for transpeptidation and the formation of a strong cell wall?

1 - B-lactamase
2 - penicillin binding protein
3 - deoxycholic proteins
4 - bacterial peptidase

Answer 3

2 - penicillin binding protein

Question 4

Which of the following is the core drug in the Glycopeptide antibiotics class that we need to know?

1 - Co-amoxicllav
2 - Flucloxacillin
3 - Vancomycin
4 - Cephalexin

Answer 4

3 - Vancomycin

Question 5

Vancomycin is the antibiotic in the Glycopeptide class that we need to know. What is the mechanism of action of this drug?

1 - binds to penicillin binding protein and renders it inactive
2 - prevents formation of the peptidoglycans (NAG and NAM) subunits
3 - inhibits DNA gyrase
4 - inhibits protein synthesis

Answer 5

2 - prevents formation of the peptidoglycans (NAG and NAM) subunits

• different to B-lactams though

Question 6

Vancomycin is the antibiotic in the Glycopeptide class that we need to know. Vancomycin can be used for complicated skin, soft tissue, bone and joint infections and infective endocarditis. BUT this medication should only be used in which of the following cases?

1 - penicillin allergy
2 - severe Gram + infections
3 - penicillin resistant (MRSA)
4 - all of the above

Answer 6

4 - all of the above

Question 7

Vancomycin is the antibiotic in the Glycopeptide class that we need to know. Vancomycin is the 1st line choice for which infection?

1 - infective endocarditis
2 - clostridioides difficile colitis
3 - hospital acquired pneumonia
4 - meningitis

Answer 7

2 - clostridioides difficile colitis

Question 8

Vancomycin is the antibiotic in the Glycopeptide class that we need to know. Is this a narrow or broad spectrum antibiotic?

Answer 8

• narrow
• only affective against Gram + organisms
• ineffective against Gram - bacteria

Question 9

Vancomycin is the antibiotic in the Glycopeptide class that we need to know. This a narrow spectrum antibiotic that is only affective against Gram + bacteria. But it is affective against 3 key bacteria, which one is NOT one of these 3 bacteria?

1 - Methicillin-resistant Staphylococcus aureus (MRSA)
2 - Streptococcus species
3 - Costridioides difficile
4 - Escherichia coli

Answer 9

4 - Escherichia coli
- this is a Gram - bacteria

Question 10

Vancomycin is the antibiotic in the Glycopeptide class that we need to know. Is the antibiotic bactericidal or bacteriostatic?

Answer 10

• bactericidal
• induces swelling, lysis and cell death

Question 11

All of the following are adverse events of vancomycin, but which 2 are the most common?

1 - pain
2 - thrombophlebitis (inflammation and blood clot formation)
3 - vancomycin flushing syndrome (red man syndrome)
4 - immune mediated allergy
5 - nephrotoxicity
6 - ototoxicity
7 - blood dyscrasia (neutropenia and thrombocytopenia)
8 - severe cutaneous adverse reactions

Answer 11

1 - pain
2 - thrombophlebitis (inflammation and blood clot formation)

• should be used with caution in patients with immune mediated hypersensitivities

Question 12

Why should vancomycin should be used with caution in patients with hearing impairment?

1 - induces otis media
2 - damages CN VIII
3 - induces systemic neural damage
4 - causes ototoxicity

Answer 12

4 - causes ototoxicity
- could impair heading further

Question 13

Patients with renal impairment, older age and neonates are at increased risk of nephrotoxicity when using vancomycin. Why is this?

1 - causes hypotension and reduces eGFR
2 - increases risk of renal calculi
3 - renally excreted and can become toxic
4 - induces inflammation of kidneys

Answer 13

3 - renally excreted and can become toxic

• linked with nephrotoxicity
• plasma concentrations of vancomycin are monitored to minimise the risk of toxicity

Question 14

Vancomyocin can induce nephrotoxicity and ototoxicity. This affect is accentuated when combined with which of the following?

1 - loop diuretics
2 - NSAIDS
3 - aminoglycosides
4 - all of the above

Answer 14

4 - all of the above

• acute tubular necrosis can be caused by aminoglycosides
• loop diuretics reduce blood flow, reduce eGFR and damage kidneys
• NSAIDs can induce acute tubular necrosis and vasoconstrict afferent arteriola

Question 15

How is vancomycin typically administered?

1 - orally
2 - IV
3 - IM
4 - suppository

Answer 15

2 - IV
- NOT absorbed in GIT

• dosing is based on weight
• 15-20mg/kg

DO NOT GIVE IM DUE TO MUSCLE NECROSIS

Question 16

Vancomycin typically administered parentally via IV. However, in what scenario is vancomycin given orally?

1 - infective endocarditis
2 - clostridioides difficile colitis
3 - hospital acquired pneumonia
4 - meningitis

Answer 16

2 - clostridioides difficile colitis

• the target tissue is the GIT, so doesn’t need to be absorbed

Question 17

When given via IV, vancomycin must be diluted to 5mg/ml and infused with sodium chloride 0.9% and 5% glucose and infused slowly to reduce the risk of flushing syndrome (red man syndrome). What rate should this be infused at?

1 - <10mg/min
2 - <20mg/min
3 - <30mg/min
4 - <40mg/min

Answer 17

1 - <10mg/min

• given over aprox 60 minutes

Question 18

For safety when prescribing vancomycin, which of the following should be monitored?

1 - hearing changes/ringing
2 - renal function
3 - platelet and leukocyte counts
4 - all of the above

Answer 18

4 - all of the above
- can induce otoxicity, agranularcytosis and induce acute tubular necrosis

Question 19

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 19

4 - all of the above

Question 20

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 20

3 - 48h

• not really the case with vancomycin though

Question 21

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 21

3 - microbiology results