Koch, Heinrich Herman Robert
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Koch, Heinrich Herman Robert(kok)
German bacteriologist, 1843–1910.
Koch's bacillusMycobacterium tuberculosis.
A local inflammatory reaction resulting from injection of tuberculin into the skin of a person who has been previously exposed to the tubercle bacillus. The test represents the clinical application of a type IV (delayed-type) hypersensitivity reaction. In contemporary skin tests for tuberculosis, Koch's, or “old, ” tuberculin has been replaced by tuberculin purified protein derivative. See: tuberculosis
The criterion used in proving an organism is the cause of a disease or lesion: the microorganism in question is regularly found in the lesions of the disease; pure cultures can be obtained from it. When inoculated into susceptible animals, pure cultures can reproduce the disease or pathological condition; and the organism can be obtained again in pure culture from the inoculated animal.