HISTORY OF MICROBIOLOGY

Koch’s Postulates
Koch then went on to isolate Mycobacterium tuberculosis, the causative agent of tuberculosis. In the publication of his results, he put forth the series of steps necessary to prove the cause of any infectious disease. These are now known as Koch’s Postulates and are held to be one of his most important contributions to the study of microbiology.
Koch's Postulates are as follows:

1. The suspected causative agent of a disease must be found in every case, and absent in healthy individuals.
   
2. The agent must then be isolated and grown outside the host (i.e. cultivated in a laboratory environment).
   
3. When a healthy, susceptible host is inoculated with the agent, the host must develop the same disease.
   
4. That same agent must then be reisolated from the experimental host.
   Go to the link below for reading about the history of microbiology and more...
   http://www.theguardians.com/Microbiology/gm_mbi02.htm