Koch’s Postulates

 Robert Koch stated that a specific disease is caused by a particular organism. He isolated anthrax from a diseased host and conducted experiments on it. He then formulated certain postulates that were based on the following four rules:

 The microorganism must be identified only in the diseased individual and not in the healthy individual.

 The microorganism should be isolated from the diseased individual and cultured.

 The cultured microorganism should cause disease when introduced to a healthy individual.

 The microbe should be isolated again from the experimental host and should be identical to the original organism.