7. Antibiotics And Resistance Flashcards
What are the classifications of antimicrobials?
Antibacterial, antifungal, antiviral &
antiprotozoal agents
What are the classifications of antibacterial agents?
– Bactericidal or bacteriostatic – Spectrum – ‘broad’ v. ‘narrow’ – Target site (mechanism of action) – Chemical structure (antibacterial class)
How do you choose an antibiotic?
- Is it active against target organism?
- Does it reach the site of infection?
- Is it available in the right formulation (IV vs oral)?
- What is the half life (decides dosing frequency)?
- Does it interact with other drugs?
- Is there toxicity issues?
- Does it require therapeutic drug monitoring?
What are the 4 ways to test antibiotic activity?
Disc sensitivity testing
Disc testing
MIC broth microdilution
MIC - E test
Describe Disc sensitivity testing
D
Describe disc testing
F
Describe MIC broth microdilution
I
Describe MIC - E test
Nn
How are antibiotic activity calculated
M
Which 4 structures of the bacteria are targeted by antibacterials?
Cell wall synthesis
Cell membrane function
Protein synthesis
Nucleic acid synthesis
What are the 3 types of resistance?
Intrinsic
Acquired
Adaptive
What does intrinsic resistance mean?
– No target or access for the drug – Usually permanent
What does acquired resistance mean?
– acquires new genetic material or mutates – Usually permanent
What does adaptive resistance mean?
– The organism responds to a stress (e.g. subinhibitory level of antibiotic)
What are the 3 mechanisms of resistance?
• Enzymatic modification or destruction of
antibiotics • Enzymatic alteration of antibiotic targets • Mutations of bacterial target sites
