Progress of an Infection

Progress of an Infection

1. Step 1: Becoming Established

   • Portals of Entry
     • Skin, GI Tract, Respiratory Tract, & Urinary Tract
   • Infectious Dose
     •    the minimum number of microbes necessary to cause an infection to proceed   

2. Step 2: Attaching to the Host

   • Adhesion
     •    fimbriae (pili), surface proteins, adhesive slimes or capsules,  specialized receptors  

3. Step 3: Surviving Host Defenses

   • Phagocytes
     • Slime or Capsule
     • Survival Inside
       • Legionella, Mycobacterium,  and many rickettsias

4. Step 4: Causing Disease

   • Enzymes
   • Toxins
   • Host's Defenses