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Penicillin

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Penicillin

  • See Also
  1. Penicillin Allergy
  2. Natural Penicillin
  3. Aminopenicillin
  • Background
  1. Penicillin first discovered by Alexander Fleming in 1928
    1. Observed inhibited growth of Staphylococcus on an agar plate
    2. Agar was contaminated with growth of Penicillium mold
  2. Penicillin was first introduced to pharmaceutical market in 1946
  • Types
  • Penicillin Categories
  1. Natural Penicillins (covers Streptococci and Anaerobes)
    1. Original Natural Penicillins
      1. Penicillin V or Phenoxymethylpenicillin (oral)
      2. Penicillin G or Benzylpenicillin (IV)
    2. Semisynthetic Penicillins derived from Penicillin G for long duration after IM Injection
      1. Procaine Penicillin G
      2. Benzathine Penicillin G
  2. Penicillinase-Resistant Semisynthetic Penicillin (covers streptococci and MSSA)
    1. Cloxacillin
    2. Dicloxacillin
    3. Methicillin
    4. Nafcillin
    5. Oxacillin
  3. Aminopenicillins (covers streptococci and Gram Negative Bacteria)
    1. Amoxicillin (oral) or Ampicillin (IV)
    2. Augmentin (oral) or Unasyn (IV)
  4. Extended Spectrum Penicillin (covers streptococci, Gram Negatives and Pseudomonas)
    1. Piperacillin Tazobactam (Zosyn)
    2. Piperacillin
    3. Carbenicillin
    4. Ticarcillin
  • Mechanism
  1. Penicillin inhibits cell wall synthesis
  2. All Penicillins contain a beta lactam ring central to their functionality
    1. Beta lactam ring is also found in Cephalosporins and carbopenems
    2. In addition, all Penicillins also have a thiazoldine ring and a side chain
  3. Beta lactam ring binds Penicillin binding Protein, which interferes with peptidoglycan synthesis
    1. Inhibition of peptidoglycan synthesis blocks cross-linking of the Bacterial cell wall components
  4. Extended spectrum agents include additional side chains to combat resistance
    1. Bulky side chains decrease Penicillinase resistance
  • Mechanism
  • Penicillin Resistance Mechanisms
  1. Bacterial Production of Beta lactamase
    1. Staphylococcus aureus
    2. Staphylococcus epidermidis
    3. Neisseria gonorrhoeae
    4. Moraxella catarrhalis
  2. Bacterial Alteration in Penicillin-binding Proteins
    1. Streptococcus Pneumoniae (Pneumococcus)
  • Adverse Effects
  1. Anaphylaxis and other Hypersensitivity Reactions
  2. Nephritis
  3. Hyperkalemia
  4. Neutropenia
  5. Seizures
    1. Beta Lactam ring is similar to GABA and may inhibit GABA activity