Koch's postulate

Meanings

1. Any of four criteria designed to establish a causative relationship between a microbe and a disease: (i) the microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms; (ii) it must be isolated from a diseased organism and grown in pure culture; (iii) the cultured microorganism should cause disease when introduced into a healthy organism; (iv) the microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.

Etymology

Formulated by Robert Koch and Friedrich Loeffler in 1884.