Antibiotics

Question 1

Give examples of inappropriate antibiotic use

Answer 1

Antibiotics not indicated
Redundant spectrum
Duplication
Incorrect dose / regimen
Incorrect duration

Question 2

What 4 factors should be considered when deciding on antibiotic prescription?

Answer 2

Microbial aetiology
Antimicrobial resistance
Patient factors
Antibiotic knowledge

Question 3

Give examples of antibiotic classes

Answer 3

Penicillins
Cephalosporins
Glycopeptides
Aminoglycosides
Macrolides
Quinolones
Metronidazole
Tetracyclines
Nitrofurantoin
Trimethoprim
Clindamycin
Fusidic acid
Chloramphenicol

Question 4

What does TARGET stand for?

Answer 4

Treat
Antibiotics
Responsibly
Guidance
Education
Tools

Question 5

Give examples of beta-lactam antibiotics

Answer 5

Penicillin - G and V
Amoxicillin
Co-amoxiclav
Flucloxacillin
Piperacillin
Cephalexin
Cefuroxime
Meropenem

Question 6

What are the 2 types of penicillin allergy?

Answer 6

Immediate / accelerated - type 1

Delayed

Question 7

Describe a type 1 allergy

Answer 7

0-72h after exposure
IgE mediated, mast-cell mediated
Urticaria, wheeze
Life-threatening

Question 8

Describe a delayed penicillin allergy

Answer 8

> 72 hours after exposure
Worsens with repeated exposure
Doesn’t become immediate type

Question 9

Describe a cephalosporin allergy

Answer 9

Complicated - lots of potential haptens involved
Not a class effect
Penicillin X reactivity occurs more with 1st and 2nd generations

Question 10

Describe amoxicillin pharmacology

Answer 10

Penicillin
Good oral bioavailability
20% protein binding
Half life of 1h
Metabolism: not significant
Excretion: urine

Question 11

What is amoxicillin used for?

Answer 11

S.pyogenes infections (sore throat, skin infections)
Pneumococcal infection (respiratory tract)
Coliform infections (UTI)

Question 12

What is the mechanism of amoxicillin?

Answer 12

Inhibits bacterial cell wall synthesis

Question 13

Describe the pharmacology of clarithromycin

Answer 13

Macrolide
Good oral bioavailability
High protein binding
Half life of 1-6h
Metabolism: hepatic
Excretion: metabolites in bile

Question 14

What is clarithromycin used for?

Answer 14

S.pyogenes infections
Pneumococcal infections
Coliform infections
Cell-wall deficient bacteria e.g. chlamydia

Question 15

What is the mechanism of clarithromycin?

Answer 15

Inhibits protein synthesis in bacterial ribosome (50S subunit)

Question 16

Describe the pharmacology of vancomycin

Answer 16

Glycopeptide
Very low oral bioavailability
50% protein binding
Half life of 4-8h
Metabolism: none
Excreted in urine

Question 17

What is vancomycin used for?

Answer 17

Gram positive bacteria

Resistant strains e.g. MRSA

Question 18

What is the mechanism of vancomycin?

Answer 18

Inhibits bacterial cell wall formation by a different target to beta lactams

Question 19

What are the adverse effects of vancomycin?

Answer 19

Nephrotoxic

Ototoxic

Question 20

Describe the pharmacology of doxycycline

Answer 20

Tetracycline
Good oral bioavailability
Moderate protein binding
Half life of 6-12h
Metabolism: none
Excreted in urine and bile

Question 21

What is doxycycline used for?

Answer 21

Gram positive (streps and staphs)
Some gram negatives (haemophilus)
Cell-wall deficient bacteria e.g. chlamydia
Skin, respiratory tract, genital tract

Question 22

What is the mechanism of doxycycline?

Answer 22

Inhibits protein synthesis in bacterial ribosome (30S subunit)

Question 23

What are the adverse effects of doxycycline?

Answer 23

Dyspepsia

Photosensitivity

Question 24

Describe the pharmacology of nitrofurantoin

Answer 24

Good oral bioavailability
Moderate protein binding
Half life = 1h
Metabolism: none
Excretion: urine

Question 25

What is nitrofurantoin used for?

Answer 25

E.coli
Enterobacteriaecae
Enterococci
Staphs
Some streps
Lower urine infections

Question 26

What is the mechanism of nitrofurantoin?

Answer 26

Complex
Damages bacterial DNA
High resistance threshold