Substance that counteracts or prevents infection.
These can either be non-specific (disinfectant), or specific (immunotherapy).
Ideal Microbial Agent
1. Most potent
2. Most selective
3. Least toxic
4. Most cost-effective
What the drug does to your body (or target).
What your body does to the drug.
Killing the bacterial cells.
These are important for critical infections (bacteria in bloodstream or CNS).
A substance (or concentration) that inhibits bacterial growth for 24 hours.
These may be okay for soft tissue infections in patients with a functional immune system.
Ideal Concentration of an Antibiotic
You want to be > 4 times the MIC at the site of infection.
Concentration Dependent Killing
Requires a high dose for effective killing. A large dose is administered at once to bring the concentration to higher than the MIC (ideally 4x higher or more).
Examples include aminoglycosides and FQ.
Time Dependent Killing
Certain drugs work best by maintaining a concentration above the MIC for a period of time.
Examples are beta-lactams.
Mechanisms of Antibacterial Agents
1. Inhibit cell wall
2. Inhibit protein synthesis
3. Disrupt DNA and NA synthesis
Target Sites of Action in Bacteria
1. Cell wall
2. Plasma membrane
An enzyme secreted by resistant bacteria that cleaves the antibiotic molecules before they have a chance to bind to transpeptidase.
The bacterial enzyme that is responsible for cross-linking peptidoglycan.
Also known as penicillin binding protein (PBP).
Come in many generations and target G+ bacteria. The further the generation, the increased potency against G- bacteria, but the slightly less potency against G+.
Mechanisms of Antibacterial Resistance
1. Enzyme inactivation
2. Decreased permeability
3. Efflux pump
4. Alteration of target site or enzyme modification
5. Overproduction of target
6. Bypass inhibited process