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Methods of Antimicrobial Action:
- Selective Toxicity
- Inhibition of Cell Wall(beta lactam ring interferes with NAG/NAM cell wall)
- Inhibition of Protein synthesis(6 pathways) include:
- 1.Distorts 30S subunit
- 2.Blocks docking site of tRNA
- 3.Blocks peptide chains from forming
- 4.Binds 50S subunit to prevent mRNA from working
- 5.Brings in antisense nucleic acids that block ability to translate amino acids
- 6.Binds to codon and prevents 50S unit from working
- Disruption of cytoplasmic membranes(by targeting ergosterols that pop holes in membrane)
- Inhibition of Metabolic Pathways(sulfa drugs-blocks conversion of PABA in enzymes)
- Inhibition of Nucleic acid synthesis(Uses analogs instead of nucleotides, more efficent in viruses)
- Prevention of virus attachment
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Routes of administration:
- Oral: low concentration, cheap and easy; people forget doses
- Intramuscularly: high concentration in system quickly, but quickly metabolized
- Intravenously: direct line, very severe infection
- Topical
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Mechanisms of Resistance:
- May produce an enzyme that destroys or deactivates drug(b-lactamase)
- May slow or prevent entry of drug into cell
- May alter receptor for drug so it cant bind
- Mayb alter metabolic pathway or abandon that step altogether
- May pump drug out of cell before it can act
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Retarding Resistance:
- Maintain high levels of antibiotic for long period
- Use antimicrobial agents in combination(for superbugs)
- Limit use of antibiotics to necessary cases
- Develop second generation drugs, altering existing drugs
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