Robert Koch (1843-1910)
The German doctor Robert Koch is considered the founder of modern bacteriology. His discoveries made a significant contribution to the development of the first ‘magic bullets’ - chemicals developed to attack specific bacteria - and Koch was awarded a Nobel Prize in 1905.
Koch developed a new experimental method to test whether a particular micro-organism is the cause of a disease. Building on Pasteur's work on germ theory, Koch used experiments to prove that the bacterium Bacillus anthracis was the cause of anthrax - the bacterium could be observed in the tissue of anthrax victims. He extracted this bacterium from a sheep which had died of anthrax, grew it and injected a mouse with it. The mouse developed the disease as well. Koch repeated this process over 20 generations of mice, before he announced in 1876 that he had proved this bacterium caused anthrax.
Koch continued to improve his methods and techniques. By solidifying liquids such as broth with gelatine and agar, for instance, he created a solid medium for growing bacteria which was easier to handle than the liquids used by Pasteur. Koch's assistant Julius Richard Petri (1852-1921) developed the Petri dish, which made the observation of bacteria even easier.
Koch and his team also developed ways of staining bacteria to improve the bacteria’s visibility under the microscope, and were able to identify the bacterial causes of tuberculosis (1882) and cholera (1883). Adopting Koch's method, other researchers were able to identify the bacteria that caused diseases such as typhus (1880), tetanus (1884) and the plague (1894).
Related Themes and Topics
T D Brock, Robert Koch: A Life in Medicine and Bacteriology (Washington, DC: ASM Press, 1999)
C Gradmann, 'Robert Koch and the pressures of scientific research: tuberculosis and tuberculin', Medical History, 45/1 (2001), pp 1-32
R Koch, 'On bacteriological research', in German Essays on Science in the Twentieth Century, (The German library, vol. 82), translated by D Theisen, (New York: Continuum, 1996)
A tiny single-celled living organism too small to be seen by the naked eye. Micro-organisms that cause disease are called bacteria.
Micro-organisms which can cause disease but have an important role in global ecology.
A disease found in humans and other animals. It can be transmitted to humans through contact with animal hide or excrement. In humans it attacks the lungs (causing pneumonia) or the skin (producing skin ulcers). It can be fatal, but is treatable by penicillin.
A shallow dish used in science to grow micro-organisms. A Petri dish is circular, transparent and has a lid.
A severe and often fatal infectious disease. It is transmitted mainly by body lice. Its symptoms are high fever, stupor, intense headache, and a dark red rash.
An acute infectious disease, affecting the nervous system. Infection generally occurs through contamination of a wound. Symptoms include a locked jaw, arching of the back or neck and the inability to urinate.
An acute contagious fever with high levels of mortality. Both the 'Black Death' that swept Europe in the 1340s and the Great Plague of London in 1665 are believed to have been bubonic plague.