Definition of Koch's postulates
Koch's postulates: In 1890 the German physician and bacteriologist Robert Koch set out his celebrated criteria for judging whether a given bacteria is the cause of a given disease. Koch's criteria brought some much-needed scientific clarity to what was then a very confused field.
Koch's postulates are as follows:
However, Koch's postulates have their limitations and so may not always be the last word. They may not hold if:
A harmless bacteria may cause disease if:
Despite such limitations, Koch's postulates are still a useful benchmark in judging whether there is a cause-and-effect relationship between a bacteria (or any other type of microorganism) and a clinical disease.
Last Editorial Review: 9/20/2012
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