Robert Koch

Robert Koch is considered to be one of the founders of the field of bacteriology. He pioneered principles and techniques in studying bacteria and discovered the specific agents that cause tuberculosis, cholera, and anthrax. For this he is also regarded as a founder of public health, aiding legislation and changing prevailing attitudes about hygiene to prevent the spread of various infectious diseases. For his work on tuberculosis,he was awarded the Nobel Prize in 1905.

While in Berlin, Koch became interested in tuberculosis, which he wasconvinced was infectious, and, therefore, caused by a bacterium. Several scientists had made similar claims but none had been verified. Many other scientists persisted in believing that tuberculosis was an inherited disease. In sixmonths, Koch succeeded in isolating a bacillus from tissues of humans and animals infected with tuberculosis. In 1882, he published a paper declaring that this bacillus met his four conditions--that is, it was isolated from diseased animals, it was grown in a pure culture, it was transferred to a healthy animal who then developed the disease, and it was isolated from the animal infected by the cultured organism. When he presented his findings before the Physiological Society in Berlin on March 24, he held the audience spellbound, sological and thorough was his delivery of this important finding. This day has come to be known as the day modern bacteriology was born.

Koch determined guidelines to prove that a disease is caused by a specific organism. These four basic criteria, called Koch’s postulates, are:

1.       A specific microorganism is always associated with a given disease.

2.       The microorganism can be isolated from the diseased animal and grown in pure culture in the laboratory.

3.       The cultured microbe will cause disease when transferred to a healthy animal.

4.       The same type of microorganism can be isolated from the newly infected animal.