Macrolides

• What do macrolides end in?

  -thromycin
• Give 3 examples of macrolide antibiotics.

  Erythromycin

  Clarithromycin

  Azithromycin
• How do macrolides work (brief)?

  Bind to 50S ribosomal subunit -> inhibit protein synthesis by blocking the polypeptide exit tunnel -> prevents peptide chain prolongation -> production of short peptides
• How do bacteria become resistant to macrolides?

  Methylates the 50S ribosomal subunit -> resistance to macrolides

  Mediated by erm gene (found in plasmids) which is easily transferred horizontally via conjugation
• What is the mechanism of resistance in S.aureus?

  Inducible resistance, involving ermC gene

  ermC enzyme methylates part of ribosome (drug target) -> macrolides can no longer bind to the target