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Infectious Diseases

Author(s): Christine Herrmann, PhD

Koch’s Postulates

Bacteria were discovered in 1675 by Antony van Leeuwenhoek, but it wasn’t until 1876 that a German physician named Robert Koch first demonstrated that specific diseases are associated with particular microorganisms. Koch developed a set of criteria to show that anthrax, a disease of cattle, was caused by a specific bacterium, named Bacillus anthracis, and that tuberculosis was caused by a separate distinct bacterium. 

Koch presented his discovery of Mycobacteium tuberculosis in a lecture in March of 1882. He brought his entire laboratory setup to the lecture hall and demonstrated his procedures for his audience, inviting them to check his findings themselves. His methods were so innovative that his criteria still are useful today in identifying disease-causing agents. 

Difficulties in applying these criteria can arise, however, for agents that are difficult to grow in culture or where a suitable, susceptible experimental host cannot be found. This is an especially difficult situation, and raises ethical concerns, where humans are the only known host. 

Robert Koch was awarded the Nobel Prize in Physiology and Medicine in 1905 for his work in tuberculosis.