Koch’s Postulates

The germ theory of disease is the idea that a microorganism or ‘germ’ causes an infectious disease. It was first proposed in 1546 by Girolamo Fracastoro. 

Along with Louis Pasteur, Heinrich Robert Koch (8143-1910) used the germ theory in isolating the tuberculosis organisms in 1882 and Vibrio cholerae (1883), the bacterium causes cholera.

His 1882 paper to the Berlin Physiological Society is universally considered by microbiologists as a signature moment in medical science and cornerstone of the germ theory of disease.

He published his discovery of the bacteria that cause tuberculosis, describing his findings that the presence of the tubercle bacillus is strongly correlated with occurrence and development of the disease.

He was the first scientist to devise a series of tests used to assess the germ theory of disease. In 1884, Koch outlined his methods as a series of rules – later to be called Koch’s postulates – which he developed during his studies on the etiology of tuberculosis.

Koch's postulates:
*A particular microbe must be found in all cases of the disease and must not be present in healthy animals or humans
*The microorganism must be isolated from a diseased organism and grown in pure culture.
*The same disease must be produced when microbes from the purge culture are inoculated into healthy susceptible laboratory animals.
*The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.

Koch’s Postulates not only helped to prove the germ theory of disease, but also gave a tremendous boost to the development of microbiology by stressing laboratory culture and identification of microbes.
Koch’s Postulates