Module 12: Antibiotics

• antibiotics: chemicals used to selectively target 1 type of organism
• what are the 3 major antibacterial antibiotics?

  1. beta-lactam
  2. flouroquinolones
  3. macrolides
• what does beta-lactam target and how?

  cell wall synthesis

  • inhibits transpeptidation
  • only effective in growing cells
• what does flouroquinolone target and how?

  DNA structure and replication

  • inhibits topoisomerase
  • topoisomerase contributes to supercoiling/DNA structure and DNA synthesis
• what does macrolides target and how?

  protein synthesis

  • inhibit translation at bacterial ribosomes
• how does antibiotic resistance occur?

  selective pressure enhances resistant bacteria
• temporary resistance: microbe growing in biofilm or inaccessible location
• acquired resistance: obtains resistance genes by mutation or horizontal gene transfer
• molecular mechanisms of antibiotic resistance:

  • decreased influx, can't enter cell
  • inactivate antibiotic via antibiotic modifying enzyme
  • changes target
  • target bypass, new protein with same function but not susceptible
  • efflux, pump out of cell