Antibiotics: Penicillins

Question 1

What is the mechanism of action of penicillins?

Answer 1

Inhibition of cell wall synthesis → binds to penicillin binding proteins (PBP) inhibiting transpeptidation of peptidoglycan

Question 2

What is the spectrum of activity of Penicillin V (PO)/ Benzylpenicillin (Penicillin G) (IV)?

Answer 2

• gram positive: streptococcus
• gram negative: no
• anaerobes: oral anaerobes

Question 3

What are the indications of Penicillin V (PO)/ Benzylpenicillin (Penicillin G) (IV)?

Answer 3

• Streptococci infections: skin and soft tissue, endocarditis, pneumonia
• syphilis

Question 4

What is the spectrum of Cloxacillin (PO)/ Coxacillin & Flucloxacillin (IV)?

Answer 4

• gram positive: MSSA, Streptococcus spp
• gram negative: no
• anaerobes: no

Question 5

What are the indications of Cloxacillin (PO)/ Coxacillin & Flucloxacillin (IV)?

Answer 5

• Staphylococcal infections: skin and soft tissue infection bacteraemia, endocarditis

Question 6

what is the spectrum of activity of amoxycillin (PO)/ ampicillin(IV)?

Answer 6

• gram positive: streptococcus sp., enterococcus spp.
• gram negative: some (check susceptibility)
• anaerobes: no

Question 7

what are the indications of amoxycillin (PO)/ ampicillin(IV)?

Answer 7

• pneumonia, ottitis media, bacteraemia

- combination treatment for h. pylori

Question 8

what is the spectrum of activity of amoxicillin- clavunate (augmentin) (PO/IV)?

Answer 8

• gram positive: streptococcus, enterococcus, MSSA
• gram negative: escherichia coli, proteus mirabilis, kiebsella pneumoniae, haemophilus influenzae, moraxella catarrhalis
• anaerobes: yes

Question 9

what is the indications of amoxicillin- clavunate (augmentin) (PO/IV)?

Answer 9

pneumonia, intra-abdominal infection, skin and soft tissue infections (animal bites, diabetic food infections), odontogenic infection, ottitis media, sinusitis

Question 10

what is the spectrum of activity of piperacillin- tazobactam (IV)?

Answer 10

• gram positive: streptococcus, enterococcus, MSSA
• gram negative: escherichia coli, proteus mirabilis, kiebsella pneumoniae, haemophilus influenzae, moraxella catarrhalis
• pseudomonas
• anaerobes: yes

Question 11

what are the indications of piperacillin- tazobactam (IV)?

Answer 11

healthcare associated pneumonia, intra- abdominal infections, skin and soft tissue infection, febrile neutropenia

Question 12

what are the adverse effects of penicillins?

Answer 12

• Hypersensitivity reactions: Anaphylaxis (0.004 - 0.4%), Rash (4 - 8%)
• Hepatic transaminitis (1 - 4%)
• Haematologic neutropenia (1 - 4%)
• Renal interstitial nephritis (<1%)
• Neurologic seizures (rare)