Prescott's Microbiology 8th Edition by Joanne Willey, Linda Sherwood, Christopher J. Woolverton, Lansing Prescott, John Harley, Donald Klein

Exercise 2

Describe Koch's postulates. What is a pure culture? Why are pure cultures important to Koch's postulates?

Step 1 of 3

Koch’s postulates are set of rules to show that a specific microorganism is causing a particular disease.

• The first postulate is that all patients that have a specific disease must also carry the specific microorganism. All healthy patients should not have this microbe.

• The second postulate states that one must be able to isolate the microbe and obtain a pure culture of it.

• The third postulate requires that healthy individuals be inoculated with the isolate microorganism and they must get the same disease.

• The fourth postulate states that the microbe must be re-isolated from the experimentally inoculated diseased individual.

This microbe should be the same as the one that was used to infect the health individual in the first place.