Antibiotics and Resistance Flashcards
What are the different generic modes of action of antibiotics?
- Inhibition of cell wall synthesis
- Inhibition of protein synthesis
- Bacterial enzyme inhibition
- Alteration of cell membranes
All these modes of action cause either:
- death of bacterium => bactericidal
- inhibition of bacterial growth => bacteriostatic
What are the different routes of administration?
=> Oral
- Used in minor infections and is cheap
- Requires good absorption
=> IM
- Painful
- Contraindicated in bleeding disorders
=> IV
- Used in severe cases
- Achieves high concentrations quickly
=> Rectal
What are the possible reasons why an antibiotic course may fail?
- Incorrect diagnosis
- Wrong drug chosen
- Drug not reaching infection site
- Incorrect dose, duration or route of administration
- Resistance
- Superinfection
- Course stated too late
- Antibiotic inactivated by another drug
- Antibiotic metabolised too quickly
What are the reasons for antibiotic resistance?
- No active site for antibiotic molecule
- Cell wall impermeable
- Antibiotic destroyed or modified
- Alternative biochemical pathway
What are the different types of antibiotics?
- B lactams
- Aminoglycosides
- Macrolides
- Glycopeptides
- Tetracyclines
- Quinalones
What is the MOA of B lactams?
- Prevent cross-linking in cell wall
- Active against streptococci, pneumococci, meningococci and trepnems
- Most strains of Staph Aureus are resistant
What are the different types of B lactams?
- Penecillins
- Cephalosporins
- Carbepenems
What are the different types of Penecillins?
- Basic Penecillins
- Anti Staphylococcal Penecillins
- Broader spectrum Penecillins
- Anti-Pseudomonal Penecillins
- B lactamase inhibitors
What is the MOA and adverse side effects of Aminoglycosides?
- Binds to 30S subunit in bacteria causing protein synthesis inhibition
- Nephrotoxic and Ototoxic
=> Gentamycin, Streptomycin, Amikacin
What is the MOA and adverse effects of Macrolides?
- Binds to 50s subunit, causing protein synthesis inhbition
- Used for patients allergic to Penecillin
- Can cause nausea and a prolonged QT interval
=> Erythromycin, Clarythromycin, Azithromycin
What is the MOA and adverse effects of Glycopeptides?
- Inhibits cell wall synthesis
- Nephrotoxic, ototoxic and red man syndrome
=> Vancomycin and Teicoplanin
What is the MOA and adverse effects of Tetracyclines?
- Binds to 30s, causing protein synthesis inhibition
- May causes photosensitivity, discolouration of teeth, black hairy tongue
=> Tetracycline, Doxycycline
