The Nature of Infection

Antimicrobial targets

Cytoplasmic membrane

  • Energy generation in bacteria - positive charge
  • Target of lots of common antimicrobial agents e.g. ethanol

Cell wall

  • Gram-positive bacteria: thick layer of peptidoglycan in cell wall retains primary Gram stain (purple)
  • Gram-negative bacteria: thinner peptidoglycan layer, allows crystal violet to wash out and are stained by counterstain (pink)

Lipopolysaccharide (LPS)

  • Key component of endotoxin (part of outer membrane of cell wall in Gram-negative bacteria)
  • Structural role
  • Antigen and bacterial toxin
  • Antibiotic uptake, inflammation

Factors for baterial growth

  • Food
  • Temperature
  • pH
  • Osmotic protection
  • Oxygen
notion image

Multicellularity

  • Colony development and differentiation
  • Biofilms: colonies of bacteria that adhere together and adhere to environmental surfaces
    • Bacteria inside a biofilm are much more resistant to antimicrobial agents