intestinal flora

• Symbiosis:

  • Commensalism (one benefit, one unaffected eg. staphylococcus epidermidis SKIN)
  • Mutualism (both benefit eg. Escherichia coli synthesises vitamin K COLON)
• NORMAL FLORA

  • DEFENCE: prevent pathogenic overgrowth (outcompete for food, release inhibitory compounds, block attachment sites)
  • SYNTHESISE VITAMINS
  • STIMULATE IMMUNE RESPONSE: stimulate production of cross-reactive antibodies
• • 10-100 trillion bacteria/g faeces
  • >1000 different bacteriae colonising the GIT
• • Parasitism (one benefit, one negative eg hookworm - blood loss, iron loss, malabsorption)