koch's postulates

• 1. The suspected micro-organism (causative agent) must be present in all diseased organisms and absent from all healthy organisms
• 2. The micro-organism must be isolated from a diseased organism and grown in pure culture
• 3. The cultured micro-organism is inoculated into a healthy host which must cause the same disease (host should develop the same symptoms)
• 4. The micro-organism (causative agent) must be re-isolated from second host, cultured and identified as the same micro-organism that was originally isolated and cultured