L19 - Antimicrobials Flashcards
5 main methods of anti - microbial action
Inhibit cell wall synthesis Inhibit protein synthesis Inhibit folate synthesis Inhibit DNA/ RNA synthesis Inhibit cell membranes synthesis
Cell wall synthesis inhibitors
Bactericidal
Beta lactams
- penicillin - amoxicillin and flucloxacillin
Glycopeptide
- Vancomycin
Carbopenams
- meropenem
DNA/ RNA synthesis inhibitors
Can be bactericidal or bacteriostatic
Flouroquinolones
Rifamycins
Folate synthesis inhibitors
Trimethoprim
Sulfonamides
Protein synthesis inhibitors
Bacteriostatic
Tetracyclines - doxycycline
Macrolides - clarythromycin or erythromycin
Aminoglycosides - gentamycin (also bactericidal)
Mechanisms of antibiotic resistance
Efflux
Bypass
Target modification
Inactivating enzymes
Reasons for drug monitoring
Narrow therapeutic window Maximum effective dose Risk of toxicity - gentamicin - ototoxic - vancomycin
Time dependent killing of bacteria
Time where antibiotic concentration is over the minimum inhibitory concentration
- long half life is beneficial
- spend longer time at the binding site
- e.g. Beta lactams
Why are antibiotics used
Short term management of bacterial infections
Prophylaxis - e.g. before high risk procedures
Co-amoxiclav
Made of:
Clavulanic acid
- inhibits beta lactamases
- amoxicillin will work better
Amoxicillin
- cell wall synthesis inhibitor
What factors govern antibiotic choice
Likely source of infection High risk patients Trends e.g. resistance Special groups e.g. hepatically or regally impaired Allergies Interactions with other drugs
Anti microbial stewardship
- prevent overuse resistance and side effects
- start broad then narrow to more appropriate antibiotics
- policies
I five
Identify Isolate Investigate Inform Intimate treatment
Identification factors
A - abroad B - blood born virus C - colonised D - diarrhoea E - expectorating (cough) F - funny looking rash
Aciclovir use
Anti viral used in herpes simplex virus
Dose dependent on first presentation or relapse or immunocompromised
