Antibiotics: Penicillins, broad-spectrum

Question 1

Indications of Penicillins, broad-spectrum (e.g. amoxicillin, co-amoxiclav)?

Answer 1

Treat susceptible infections, including:​
- Uncomplicated community-acquired pneumonia​
- Otitis media​
- Sinusitis​
- UTI

H. Pylori (triple therapy)

Co-amoxiclav is a common choice for severe, resistant and HOSPITAL-ACQUIRED INFECTION, including:​
- Respiratory tract infection​
- Genitourinary infection​
- Abdominal infection​
- Cellulitis​
- Bone and joint infections​

Question 2

Spectrum of activity of Penicillins, broad-spectrum (e.g. amoxicillin, co-amoxiclav)?

Answer 2

Broad spectrum

Works against Gram-positive and Gram-negative cocci and bacilli (rods).

Question 3

MOA of Penicillins, broad-spectrum (e.g. amoxicillin, co-amoxiclav)?

Answer 3

Inhibit the enzymes responsible for cross-linking peptidoglycans in bacterial cell walls.
→ This weakens cell walls and prevents them from maintaining an osmotic gradient.
→ Uncontrolled entry of water into bacteria causes:
- cell swelling
- lysis
- death

Contains beta-lactam ring
→responsible for bactericidal activity.

These drugs are synthesised by addition of an amino group to the beta-lactam ring side chain.
→ this broadens the activity against aerobic Gram-negative bacteria.

Question 4

Adverse effects of Penicillins, broad-spectrum (e.g. amoxicillin, co-amoxiclav)?

Answer 4

GI upset:​
- Nausea​
- Diarrhoea

Antibiotic-associated collitis (C.diff)

Penicillin allergy -skin rash

Anaphylactic reaction

Acute liver injury (jaundice or hepatitis)

Question 5

Warnings of of Penicillins, broad-spectrum (e.g. amoxicillin, co-amoxiclav)?

Answer 5

Reduce dose in severe renal impairment.

Contraindication:
- hx of penicillin allergy

Use with caution in people at risk of C.difficile infection (pts in hospital or elderly pts or hx of penicillin associated liver injury)

Question 6

Interactions of Penicillins, broad-spectrum (e.g. amoxicillin, co-amoxiclav)?

Answer 6

Can enhance anticoagulant effect of warfarin by killing normal gut flora that synthesise vitamin K.

Question 7

Monitoring of Penicillins, broad-spectrum (e.g. amoxicillin, co-amoxiclav)?

Answer 7

Check infection resolves by:
- symptoms/signs improved (e.g. pyrexia, lung crackles, dysuria)
- blood markers e.g. falling CRP and WCC

Question 8

Pt education of Penicillins, broad-spectrum (e.g. amoxicillin, co-amoxiclav)?

Answer 8

Aims to get rid of infection and improve symptoms.

Check for penicillin allergy.

Seek medical advice if they develop a rash or unexpected symptoms.

If allergy develops during treatment, give pt written and verbal advice NOT to take this abx class in future and make sure that the type of reaction (including its nature) is clearly documented in pt’s medical records.

Question 9

Examples of broad-spectrum abx?

Answer 9

Amoxicillin
Co-amoxiclav