Antibiotics: Penicillins, penicillinase-resistant

Question 1

Indications of Penicillins, penicillinase-resistant (e.g. flucloxacillin)?

Answer 1

Staphylococcal infection, usually as part of combination therapy, including:​
- Skin and soft tissue infections (e.g. cellulitis​)

• Osteomyelitis and septic arthritis​
• Other infections, including endocarditis

Question 2

Example of Penicillins, penicillinase-resistant?

Answer 2

flucloxacillin

Question 3

Spectrum of activity of Penicillins, penicillinase-resistant (e.g. flucloxacillin)?

Answer 3

Narrow spectrum

Works against Gram-positive staphylococci.

Question 4

MOA of Penicillins, penicillinase-resistant (e.g. flucloxacillin)?

Answer 4

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.

An acyl side chain PROTECTS the beta-lactam ring from beta-lactamases (bacteria can make β-lactamases, which break the β-lactam ring -resistance).
→ effective against beta-lactamase-producing staphylococci​

Question 5

Adverse effects of Penicillins, penicillinase-resistant (e.g. flucloxacillin)?

Answer 5

GI upset
Penicillin allergy -skin rash

Anaphylactic reaction
- hypotension
- bronchospasm
- orofacial/pharyngeal/laryngeal oedema

Liver toxicity
- cholestasis
- hepatitis

Question 6

Warnings of Penicillins, penicillinase-resistant (e.g. flucloxacillin)?

Answer 6

Reduce dose in renal failure

Contraindication:
- hx of penicillin allergy
- prior flucloxacillin-related hepatoxicity

Use with caution in hepatic impairment.

Question 7

Interactions of Penicillins, penicillinase-resistant (e.g. flucloxacillin)?

Answer 7

All penicillins reduce renal excretion of methotrexate, hence increasing risk of toxicity.

Question 8

Monitoring of Penicillins, penicillinase-resistant (e.g. flucloxacillin)?

Answer 8

Check infection resolves by:
- symptoms/signs improved (e.g. pyrexia, erythema of cellulitis)
- blood markers e.g. falling CRP and WCC

Question 9

Pt education of Penicillins, penicillinase-resistant (e.g. flucloxacillin)?

Answer 9

Aims to get rid of infection and improve symptoms.

Check for penicillin allergy.

Seek medical advice if they develop a rash.

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.