Koch's postulates are four criteria designed to establish a causal relationship between a microbe and a disease. The postulates were formulated by Robert Koch and Friedrich Loeffler in 1884, based on earlier concepts described by Jakob Henle, and the statements were refined and published by Koch in 1890. Koch applied the postulates to describe the etiology of cholera and tuberculosis, both of which are now ascribed to bacteria. The postulates have been controversially generalized to other diseases. More modern concepts in microbial pathogenesis cannot be examined using Koch's postulates, including viruses and asymptomatic carriers. They have largely been supplanted by other criteria such as the Bradford Hill criteria for infectious disease causality in modern public health and the Molecular Koch's postulates for microbial pathogenesis.
Robert Hermann Koch (11 December 1843 – 27 May 1910) was a German physician who developed Koch's postulates.
A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells.
A cluster of Escherichia coli bacteria magnified 10,000 times
Mahavira postulated the existence of microscopic creatures in the 6th century BC
Antonie van Leeuwenhoek was the first to study microscopic organisms.
Lazzaro Spallanzani showed that boiling a broth stopped it from decaying.
