Penicillin

Question 1

MoA

Answer 1

Interferes with bacterial cell wall synthesis
Not useful in CNS infections except meningitis
Broad spectrum
Bactericidal

Question 2

Narrow spectrum

Answer 2

Beta-lactamase sensitive
- Benzylpenicillin
- Phenoxymethylpenicillin

Question 3

Benzylpenicillin

Answer 3

Uses - meningitis
PARENTERAL use only
- not gastric acid stable

Question 4

Phenoxymethylpenicillin

Answer 4

Uses - RTIs in children (strep throat, tonisilitis)
Oral use
- gastric acid stable

Question 5

Broad spectrum

Answer 5

Do not give blindly for sore throats - causes maculopapular rash in glandular fever.
Causes antibiotic-associated colitis
Inactivated by beta-lactamases
- Ampicillin
- Amoxicillin

Question 6

Ampicillin

Answer 6

High resistance
Use - UTIs, otitis media, acute COPD exacerbations
How to take - before food

Question 7

Amoxicillin

Answer 7

Co-amoxiclav = amoxicillin and clavulanic acid
Active against beta-lactamase producing strains
SE = cholestatic jaundice (do not exceed 14 days)

Question 8

Penicillinase-resistant

Answer 8

Flucloxacillin

Question 9

Flucloxacillin

Answer 9

Use = penicillin resistant staphylococcal infections (except MRSA) e.g. skin infections, impetigo, cellulitis
SE = cholestatic jaundice and hepatitis
- Can occur up to 2 months after
- Increasing age and > 14 days treatment increases risk
How to take = before food

Question 10

Antipseudomonal (extended spectrum)

Answer 10

Piperacillin (with tazobactam)
Ticarcillin (with clavulanic acid)
Used for serious infections
- Septicaemia, complicated UTI, HAP
- Active against pseudomonas aeguinosa

Question 11

Temocillin

Answer 11

Reserved for beta-lactamase producing strains of gram negative bacteria.

Question 12

Side effects

Answer 12

Hypersensitivity (1-10%)
Anaphylaxis (<0.05%)
Maculopapular rash (ampicillin + amoxicillin)
Abx associated colitis
CNS toxicity - rare but serious, occurs at high doses or renal impairment

Question 13

Penicillin allergy

Answer 13

Rashes or anaphylaxis
Atopic allergies = higher risk of anaphylactic reactions

Question 14

True allergy

Answer 14

Immediate rash
Anaphylaxis
Hives
DO NOT USE ANY BETA-LACTAM ANTIBIOTIC
- Cephalosporins
- Carbapenems
- Monobactam

Question 15

May not be allergic

Answer 15

• Minor rash; small, not itchy and non-confluent
• Rash after 72 hrs
  DO NOT WITHOLD PENCILLIN FOR SERIOUS INFECTIONS

Question 16

Route

Answer 16

Do not give penicillins as intrathecal injections
- Encelopathy (cerebral irritation and can be fatal)