Antibiotics - Antibiotics - Penicillins (β-lactam 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

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

B-lactam antibiotics are the most widely used antibiotics that contain a B-lactam ring and are able to inactivate penicillin binding protein (PBB), causing lysis of the cell. Which 2 of the following are the core penicillin B-lactam antibiotics we need to know?

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

Answer 5

1 - Amoxicillin
2 - Flucloxacillin

Question 6

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

Answer 6

• broad spectrum
• susceptible to B-lactamase
• increased risk of resistance

Question 7

Flucloxacillin is a penicillin B-lactam that we need to be aware of. Is this a broad or narrow spectrum antibiotic?

Answer 7

• narrow spectrum
• resistant to penicillinases and B-lactamases due to acyl side chain

Question 8

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

1 - sinusitis
2 - otis media
3 - community acquired pneumonia
4 - UTI (oliform infection)
5 - eradication of H.pylori in peptic ulcer disease
6 - RTI (Pneumococcal infections)
7 - sore throat or skin infections (Streptococcus pyogenes)
8 - all of the above

Answer 8

6 - all of the above

Question 9

Flucloxacillin is a narrow spectrum penicillin B-lactam that is resistant to penicillinases that we need to be aware of. Which of the following is this used to treat?

1 - skin
2 - soft tissue injuries
3 - bone and joint infections
4 - otis externa
5 - endocarditis
6 - all of the above

Answer 9

6 - all of the above

• typically prescribed with other antibiotics as narrow spectrum

Question 10

Amoxicillin is a broad spectrum penicillin B-lactam that we need to be aware of. Which 2 of the following is it useful in treating?

1 - Gram + cocci and bacilli (rods)
2 - Gram - cocci and bacilli (rods)
3 - Gram + spirilla
4 - Gram - spirilla

Answer 10

1 - Gram + cocci and bacilli (rods)
2 - Gram - cocci and bacilli (rods)

• BUT susceptible to penicillinases

Question 11

Flucloxacillin is a narrow spectrum penicillin B-lactam that is resistant to penicillinases that we need to be aware of. Which of the following bacteria is it especially affective against?

1 - staphylococcus aureus
2 - streptococcus
3 - clostridium dificill
4 - klebsiella

Answer 11

1 - staphylococcus aureus
- common on skin
- this is why it can be used for otis externa

Question 12

Are amoxicillin and flucloxacillin bactericidal or bacteriostatic?

Answer 12

• bactericidal
• cells lysis and die

Question 13

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 13

1 - GI upset

Question 14

All of the following are adverse events caused by Flucloxacillin: GI upset (most common), antibiotic associated colitis, anaphylaxis (1-10%) (IgE mediated), skin rash. Which 2 other of the following can Flucloxacillin also cause?

1 - renal toxicity
2 - cardiac toxicity
3 - neurological toxicity
4 - liver toxicity

Answer 14

3 - neurological toxicity
- convulsion and coma in high concentrations due to renal failure

4 - liver toxicity

Question 15

GI upset is the most common adverse event of Amoxicillin and Flucloxacillin. 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 15

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

• also causes diarrhoea
• may cause Candida Albicans infections

Question 16

GI upset is the most common adverse event of Amoxicillin as healthy flora are killed causing C. difficile and colitis. This can increase the anticoagulant effect and bleeding risk of which drug?

1 - heparin
2 - enoxaparin
3 - edoxaban
4 - warfarin

Answer 16

4 - warfarin

• healthy gut flora are important for vitamin K absorption

Question 17

The main contraindication for amoxicillin is severe allergy. Why should younger patients with severe throat infections NOT 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

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 18

5 - all patients with community acquired pneumonia

• caution in older adults, but not ALL patients

Question 19

If allergic to one type of penicillin, does that mean you are allergic to all penicillins?

Answer 19

• yes
• basic structure causes the allergy
• this includes cephalosporins

Question 20

Amoxicillin and Flucloxacillin interact with which drug to increase toxicity in the liver and kidneys?

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

Answer 20

3 - methotrexate

• increases risk of toxicity

Question 21

In severe infections how are broad spectrum antibiotics typically administered?

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

Answer 21

2 - IV

• standard amoxicillin dose = 1g/8h
• standard flucloxacillin dose = 1-2g/6h

Question 22

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 22

4 - all of the above

Question 23

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 23

3 - 48h

Question 24

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 24

3 - microbiology results