Understanding Antibiotic Classes and Mechanisms

Nov 17, 2024

Antibiotics: Classifications, Targets, and Mechanisms

Introduction

  • Video speaker: Dr. Mike
  • Objective: Memorize antibiotic classes, their target spectra (gram-negative or gram-positive bacteria), examples, and mechanisms of action.
  • Mnemonic: "The Queen's Guidance Counselor said antibiotics can protect many, if not most, royal members."
    • T: Tetracycline
    • Q: Quinolone and fluoroquinolone
    • G: Glycopeptides
    • C: Cephalosporins
    • S: Sulfonamides
    • A: Aminoglycosides
    • C: Carbapenem
    • P: Penicillin
    • M: Macrolides, Monobactam
    • R: Rifampin
    • ME: Metronidazole

Antibiotic Classes and Their Targets

Gram-Positive and Gram-Negative Bacteria

  • Cell Wall: Differences in cell wall thickness determine Gram stain classification.
    • Gram-positive: Thick cell wall, absorbs purple dye.
    • Gram-negative: Thin cell wall, does not absorb dye, appears pink.

Spectrum of Activity

  • Tetracycline: Both gram-positive and gram-negative
  • Quinolone/Fluoroquinolone: Both
  • Glycopeptides: Gram-positive only
  • Cephalosporins: Both
  • Sulfonamides: Both
  • Aminoglycosides: Gram-negative only
  • Carbapenem: Both
  • Penicillin: Both
  • Macrolides: Gram-positive only
  • Monobactam: Gram-negative only
  • Rifampin: Both
  • Metronidazole: Both

Examples of Antibiotics

  • Tetracycline: Doxycycline
  • Quinolone/Fluoroquinolone: Nalidixic acid, Ciprofloxacin
  • Glycopeptide: Vancomycin
  • Cephalosporin: Cefotaxime
  • Sulfonamides: Sulfamethoxazole
  • Aminoglycosides: Gentamicin, Streptomycin
  • Carbapenem: Meropenem
  • Penicillin: Amoxicillin
  • Macrolides: Erythromycin
  • Monobactam: Aztreonam
  • Rifampin: Rifampicin
  • Metronidazole: Metronidazole

Mechanisms of Action

Cell Wall Synthesis Inhibitors

  • Glycopeptides, Cephalosporins, Carbapenems, Penicillins, Monobactams: Inhibit cell wall synthesis causing bacterial cell to burst.

Protein Synthesis Inhibitors

  • Tetracycline, Aminoglycosides: Inhibit 30S ribosomal subunit, stopping translation.
  • Macrolides: Inhibit 50S ribosomal subunit, stopping translation.

DNA Synthesis Inhibitors

  • Quinolones/Fluoroquinolones: Inhibit bacterial topoisomerases II and IV, blocking DNA synthesis.

Folic Acid Synthesis Inhibitors

  • Sulfonamides: Inhibit bacterial folic acid synthesis, vital for survival.

Transcription Inhibitors

  • Rifampin: Inhibits RNA polymerase, blocking DNA transcription.

DNA Damage

  • Metronidazole: Causes oxidative damage to DNA, hindering replication and function.

Conclusion

  • Mnemonic as a study aid for memorizing antibiotic classes, targets, examples, and actions.
  • Encouragement to explore more videos and content.

Full transcript