ANTIBIOTIC MECHANISMS OF ACTION

Cell Wall inhibition
1. Bacterial Walls
  1. Beta-lactams (natural)
    1. Penacillin
    2. Cephalosporins
    3. Break down PG
  2. Methicillin and Cephalothin (Semi-synthetic)
    1. More stable in stomach acid
    2. More readily absorbed
    3. Less susceptible to deactivation by bacterial enzymes
  3. Vancomycin and cycloserine
    1. Blocks formation of peptide bridges in many G+
  4. Bacitracin
    1. Blocks transport of NAM + NAG
  5. Isoniazid and ethambutol (Antimycobacterials)
    1. Blocks formation of mycolic acid layer
      1. Excessively long treatment time (6 months)
2. Fungal walls
  1. Echinocandins
    1. Block enzyme for glucan synthesis
Protein Synthesis Inhibition
1. Prokaryotic Ribosome
  1. Aminoglycosides
    1. Streptomycin + Gentomycin
    2. Attacks 30S subunit
  2. Tetracycline
    1. Blocks tRNA docking site on ribosome
  3. Chloramphenicol
    1. Blocks enzymatic site on 50S ribosome; prevents translation
  4. Lincosamides, streptogramins, macrocodes (erythromycin)
    1. Stops translocation
  5. Mupirocin
    1. Binds tRNA carrying isoleucine
    2. Used for skin infections (i.e. MRSA)
  6. Mitochondrial Hazard
2. Antisense nucleic acids
  1. RNA or ss DNA bind to pathogen nucleic acid
    1. halts translation
  2. Fomiversen
    1. 1st approved
    2. Inactivates cytomegalovirus
      1. treats eye infections
Cell membrane Disruption
1. Gramicidin
  1. Forms channel in membrane
2. Polyenes
  1. antifungals
  2. Nystatin, amphotericin B
  3. Attaches to ergosterol
    1. sterol for fungal cells
3. Azoles (fluconazole) & allylamines
  1. Antifungals
  2. blocks synthesis of ergosterol
4. Polymixin
  1. G- (like pseudomonads)
  2. toxic to kidneys
  3. Topical use only
5. Pyrazinamide
  1. Transport across M. tuberculosis membrane
6. Praziquantel & ivermectin
  1. antiheminthic
    1. antiworm
  2. Permeability of cell membrane
Metabolic pathway inhibition
1. Sulfonamides
  1. analog of para-aminobenzoic acid (PABA)
    1. Humans use folic acid
  2. Synthesis of nucleotides
2. Trimethoprim
  1. Nucleic acid synthesis
3. Amantadine & Rimantadine
  1. Antivirals
  2. Neutralize acid of phagolysosome
    1. Blocks uncoating
  3. Amantadine used for influenza A only
4. Protease inhibitors
  1. Blocks protease activity
    1. involved in assembly
  2. HIV
Nucleic Acid Synthesis
1. Nucleotide analogs
  1. Distort shape of DNA and RNA
  2. Blocks replication, transcription or translation
  3. Viral infections
2. Rifampin
  1. Binds prok RNA polymerase preferentially
    1. Blocks RNA synthesis
  2. Used against slow growers
3. Quinolones and Fluoroquinolones
  1. inhibits DNA gyrase
    1. Humans have topoisomerase
  2. prokaryotic specific
4. Clofazimine
  1. Binds DNA of M. leprae
  2. Prevents transcription & replication
  3. Tuberculosis too
5. Reverse transcriptase inhibitors
  1. HIV
  2. RNA to dsDNA; incorporates into genome... Reverse transcriptase inhibitors stop it

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ANTIBIOTIC MECHANISMS OF ACTION

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	Created by Connor Clark over 7 years ago