Antibiotics Flashcards
Give examples of inappropriate antibiotic use
Antibiotics not indicated Redundant spectrum Duplication Incorrect dose / regimen Incorrect duration
What 4 factors should be considered when deciding on antibiotic prescription?
Microbial aetiology
Antimicrobial resistance
Patient factors
Antibiotic knowledge
Give examples of antibiotic classes
Penicillins Cephalosporins Glycopeptides Aminoglycosides Macrolides Quinolones Metronidazole Tetracyclines Nitrofurantoin Trimethoprim Clindamycin Fusidic acid Chloramphenicol
What does TARGET stand for?
Treat Antibiotics Responsibly Guidance Education Tools
Give examples of beta-lactam antibiotics
Penicillin - G and V Amoxicillin Co-amoxiclav Flucloxacillin Piperacillin Cephalexin Cefuroxime Meropenem
What are the 2 types of penicillin allergy?
Immediate / accelerated - type 1
Delayed
Describe a type 1 allergy
0-72h after exposure
IgE mediated, mast-cell mediated
Urticaria, wheeze
Life-threatening
Describe a delayed penicillin allergy
> 72 hours after exposure
Worsens with repeated exposure
Doesn’t become immediate type
Describe a cephalosporin allergy
Complicated - lots of potential haptens involved
Not a class effect
Penicillin X reactivity occurs more with 1st and 2nd generations
Describe amoxicillin pharmacology
Penicillin Good oral bioavailability 20% protein binding Half life of 1h Metabolism: not significant Excretion: urine
What is amoxicillin used for?
S.pyogenes infections (sore throat, skin infections) Pneumococcal infection (respiratory tract) Coliform infections (UTI)
What is the mechanism of amoxicillin?
Inhibits bacterial cell wall synthesis
Describe the pharmacology of clarithromycin
Macrolide Good oral bioavailability High protein binding Half life of 1-6h Metabolism: hepatic Excretion: metabolites in bile
What is clarithromycin used for?
S.pyogenes infections
Pneumococcal infections
Coliform infections
Cell-wall deficient bacteria e.g. chlamydia
What is the mechanism of clarithromycin?
Inhibits protein synthesis in bacterial ribosome (50S subunit)
Describe the pharmacology of vancomycin
Glycopeptide Very low oral bioavailability 50% protein binding Half life of 4-8h Metabolism: none Excreted in urine
What is vancomycin used for?
Gram positive bacteria
Resistant strains e.g. MRSA
What is the mechanism of vancomycin?
Inhibits bacterial cell wall formation by a different target to beta lactams
What are the adverse effects of vancomycin?
Nephrotoxic
Ototoxic
Describe the pharmacology of doxycycline
Tetracycline Good oral bioavailability Moderate protein binding Half life of 6-12h Metabolism: none Excreted in urine and bile
What is doxycycline used for?
Gram positive (streps and staphs)
Some gram negatives (haemophilus)
Cell-wall deficient bacteria e.g. chlamydia
Skin, respiratory tract, genital tract
What is the mechanism of doxycycline?
Inhibits protein synthesis in bacterial ribosome (30S subunit)
What are the adverse effects of doxycycline?
Dyspepsia
Photosensitivity
Describe the pharmacology of nitrofurantoin
Good oral bioavailability Moderate protein binding Half life = 1h Metabolism: none Excretion: urine
