Koch, Robert (1843–1910)

Robert Koch is considered one of the founders of modern bacteriology and a key contributor to the etiology of diseases, along with Louis Pasteur. He isolated several disease-causing bacteria, including those for anthrax (1877), tuberculosis (1882), and cholera (1883), and developed Koch's postulates criteria for ascertaining the microbial causes of a specific disease.

Robert Koch was born in Clausthal, Germany, in 1843, one of 13 children. He received a medical degree from the University of Go¨ttingen in 1866. Following this, Koch served as a physician in several German towns, was a field surgeon during the 1870 to 1872 Franco-Prussian war, and then became a medical officer in Wollstein, Germany. It was during this latter part of his career that Koch did most of his research, in a laboratory he developed in Wollstein.

Koch's first major scientific breakthrough occurred when he isolated anthrax bacillus and proved that it caused disease. He did this by injecting healthy mice with spores of Bacillus anthracis that had been obtained from the spleens of animals infected with anthrax. Mice injected with these spores later developed anthrax, while mice injected with spores from healthy animals did not. This was the first time that a specific microorganism was causally related to a specific disease.

Following this discovery, Koch developed a set of criteria to prove that a disease is caused by a specific microorganism. These four criteria are commonly referred to as Koch's postulates. Koch argues that for a microorganism to cause a specific disease, each of the four of Koch's postulates had to be fulfilled. While these criteria are not literally believed today, their development contributed significantly to the establishment of the germ theory of disease.

In 1882, Koch isolated the tuberculosis bacillus and then inoculated uninfected animals with it. This induced tuberculosis in the animals and thus established the etiologic role of the bacterium in the causation of disease. He later did further work on tuberculosis by investigating the possible protective effect of injecting a person with dead tuberculin bacilli and then subsequently injecting them with live tuberculosis bacilli and suggesting that he may have discovered a cure for the disease. Although it was not successful as a cure, findings from this work have been important in the development of the tuberculin test currently used today to detect tuberculosis infection in individuals.

Finally, Koch traveled to Egypt and India where he identified the cholera bacillus and determined that its mode of transmission was waterborne. Following this discovery, he did some work investigating vectorborne diseases such as malaria.

Koch not only did work isolating bacteria but also developed many microbiology techniques. These included methods of staining bacteria and investigation using the microscope. Furthermore, Koch introduced the solid culture medium for the cultivation of bacteria. In this way, Koch was an important contributor to the methodology of bacteriology.

Koch received the Nobel Prize in Physiology or Medicine in 1905 for his discoveries in tuberculosis. Koch was married twice during his lifetime and had one child, a daughter. He died in 1910 in BadenBaden, Germany.