Antibiotics - β-lactam antibiotic and β-lactamase

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

The principle of penicillin B-lactam antibiotics is that they resemble tetrapeptide chains that hold the cell wall together. Which of the following then happens if the penicillin binding protein (PBB) binds with the B-lactam molecule of the antibiotic?

1 - binds to PBB permanently
2 - PBB unable to perform transpeptidation
3 - cell wall becomes weak and unstable
4 - cell wall will fail when bacteria try to multiply
5 - all of the above

Answer 4

5 - all of the above

Question 5

The principle of penicillin B-lactam antibiotics is that they resemble tetrapeptide chains that hold the cell wall together. Which of the following then happens if the penicillin binding protein (PBB) binds with the B-lactam molecule of the antibiotic?

1 - binds to PBB permanently
2 - PBB unable to perform transpeptidation
3 - cell wall becomes weak and unstable
4 - cell wall will fail when bacteria try to multiply
5 - all of the above

Answer 5

5 - all of the above

Question 6

Some bacteria have developed a resistance to Penicillin B-lactam antibiotics. What do these bacteria possess that means they are resistant to B-lactam antibiotics?

1 - modified penicillin binding protein (PBB)
2 - pentapeptide chains only
3 - B-lactamase enzymes
4 - all of the above

Answer 6

3 - B-lactamase enzymes

• this enzyme can breaks down the B-lactam ring in the antibiotics

Question 7

Which common bacteria developed a resistance to penicillin B-lactam antibiotic resistance by developing B-lactamase?

1 - staphylococcus aureus
2 - streptococcus
3 - klebsiella
4 - escherichia coli

Answer 7

1 - staphylococcus aureus
- methicillin resistant staphylococcus aureus (MRSA)

Question 8

In an attempt to overcome the evolution of bacteria and inhibit the B-lactamases, what is added to penicillin B-lactam antibiotics?

1 - macrolides
2 - aminoglycosides
3 - quinolones
4 - clavulanic acid

Answer 8

4 - clavulanic acid

• able to inhibit B-lactamases

Question 9

Which of the following is an example of an penicillin B-lactam antibiotic with clavulanic acid attached?

1 - Amoxicillin
2 - Flucloxacillin
3 - Co-Amoxiclav
4 - Vancomycin

Answer 9

3 - Co-Amoxiclav

• the co means its two drugs
• amoxicillin + clavulanic acid

Question 10

Co-Amoxicillin is a B-lactamase antibiotic that we need to be aware of. Is this a broad or narrow spectrum antibiotic?

Answer 10

• broad
• especially used in hospital acquired infections

Question 11

In an attempt to overcome the evolution of bacteria and inhibit the B-lactamases, clavulanic acid was added to penicillin, which was able to inhibit B-lactamases. Methicillin used a different approach to combat B-lactamases, what was this?

1 - combine with quinolones
2 - combine with macrolides
3 - add side chain that B-lactamase don’t recognise
4 - remove the B-lactam ring

Answer 11

3 - add side chain that B-lactamase don’t recognise

• B-lactamase dont recognise B-lactam rings
• BUT this has led to methicillin resistant staphylococcus aureus (MRSA)

Question 12

Co-Amoxicillin is a broad spectrum penicillin B-lactamase antibiotic that we need to be aware of. Which of the following is this used to treat?

1 - intra-abdominal infection
2 - cellulitis
3 - bone and joint infections
4 - UTI
5 - pneumonia
6 - all of the above

Answer 12

6 - all of the above

• generally used against severe, resistant and hospital acquired infections

Question 13

Amoxicillin is a broad spectrum penicillin B-lactam that we need to be aware of. This drug is affective against Gram + and - cocci and bacilli (rods), but susceptible to penicillinases. Does combining amoxicillin with clavulanic acid have any affect on resistance?

Answer 13

• yes
• restores activity against many amoxicillin resistant strains

Question 14

Is co-amoxicillin bactericidal or bacteriostatic?

Answer 14

• bactericidal
• cells lysis and die

Question 15

All of the following are adverse events caused by co-amoxicillin, but which is the most common?

1 - GI upset
2 - antibiotic associated colitis
3 - anaphylaxis (1-10%) (IgE mediated)
4 - skin rash
5 - all of the above

Answer 15

1 - GI upset

• co-amoxicillin can also cause acute liver injury

Question 16

GI upset is the most common adverse event of Amoxicillin. Why 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 16

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

Question 17

The main contraindication for co-amoxicillin is severe allergy. Why should younger patients with severe throat be prescribed this drug?

1 - increases risk of resistance
2 - ineffective in younger adults
3 - increased risk of C. difficile
4 - induce a rash with glandular fever that mimics anaphylaxis

Answer 17

4 - induce a rash with glandular fever that mimics anaphylaxis

• wrongly labelled as a penicillin allergy

Question 18

Is amoxicillin bactericidal or bacteriostatic?

Answer 18

• bactericidal
• cells lysis and die

Question 19

All of the following are adverse events caused by Amoxicillin, but which is the most common?

1 - GI upset
2 - antibiotic associated colitis
3 - anaphylaxis (1-10%) (IgE mediated)
4 - skin rash
5 - all of the above

Answer 19

1 - GI upset

Question 20

The main contraindication for amoxicillin is severe allergy. Why should younger patients with severe throat be prescribed this drug?

1 - increases risk of resistance
2 - ineffective in younger adults
3 - increased risk of C. difficile
4 - induce a rash with glandular fever that mimics anaphylaxis

Answer 20

4 - induce a rash with glandular fever that mimics anaphylaxis

• wrongly labelled as a penicillin allergy

Question 21

Amoxicillin should be used with caution in all of the following EXCEPT which one?

1 - older adults at risk of C. difficile
2 - hospitalised patients at risk of C. difficile
3 - history of penicillin associated liver injury
4 - severe renal impairment
5 - all patients with community acquired pneumonia

Answer 21

5 - all patients with community acquired pneumonia

• caution in older adults, but not ALL patients

Question 22

Amoxicillin interacts with which drug to increase toxicity in the liver?

1 - paracetamol
2 - verapamil
3 - methotrexate
4 - bisoprolol

Answer 22

3 - methotrexate

• increases risk of toxicity

Question 23

In severe infections how are broad spectrum antibiotics typically administered?

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

Answer 23

2 - IV

• standard amoxicillin dose = 1g/8h

Question 24

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 24

4 - all of the above

Question 25

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 25

3 - 48h

Question 26

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 26

3 - microbiology results