Koch, Robert

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Editors: John Merriman and Jay Winter
Date: 2006
Europe 1789-1914: Encyclopedia of the Age of Industry and Empire
Publisher: Charles Scribner's Sons
Document Type: Biography
Pages: 3
Content Level: (Level 5)
Lexile Measure: 1350L

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About this Person
Born: December 11, 1843 in Clausthal, Germany
Died: May 27, 1910 in Baden-Baden, Germany
Nationality: German
Other Names: Koch, Heinrich Hermann Robert; Koch, Robert Heinrich Hermann
Full Text: 
Page 1262


KOCH, ROBERT (1843–1910), German bacteriologist.

Heinrich Hermann Robert Koch was one of the founding fathers of medical bacteriology, a discipline that established the association of bacteria with disease. He identified a number of bacterial pathogens, devised or improved essential laboratory technologies within the field, reflected on the methodology of establishing bacterial etiologies of infectious diseases, and developed a number of practical applications.


Koch was born 11 December 1843 into the family of a senior mining official in Clausthal, a northern German town. Six of his eight brothers emigrated from Germany, but Koch—who dreamed of emigration himself—stayed and attended the nearby University of Göttingen in 1862. What remained from his youthful dreams was a passion for travel that played an important role in the later stages of his career. Koch initially studied natural sciences, but decided on medicine in 1863 and turned out to be a gifted student. Even though Friedrich Gustav Jacob Henle (1809–1885), who had written an influential treatise on infectious diseases and their causation in 1840, was one of his teachers, it is unlikely that Koch received any inspiration for his future career during his years in Göttingen.

In 1866 he left the university, married Emmy Fraatz, and tried to establish himself as a general practitioner. After several failed attempts to find a position that satisfied his financial needs, Koch finally settled in 1872 as district physician in Pomeranian Wollstein (today Wolstyn, Poland). It seems that he started to work as a bacteriologist in 1873; the chosen object of study was anthrax, a common veterinary disease that was well researched. That this condition could be transmitted by rodshaped structures found in the blood of infected animals was widely assumed. Koch based his experiments on the microbiology of Ferdinand Julius Cohn (1828–1898), a botanist from Breslau (today Wrocław, Poland), and was able to identify these structures as Bacillus anthracis. He established its full life cycle and demonstrated its pathogenicity in animal experiments.

It is not surprising that Koch then turned to Cohn. The latter gave him an enthusiastic welcome and published Koch's paper in a journal that he edited. He also freed him intellectually from the solitude of his countryside practice and brought him into contact with the Breslau pathologist Julius Friedrich Cohnheim (1839–1884) and Carl Weigert (1845–1904), his prosector (one who performs dissections for anatomic demonstration). This opened contacts into the medical world and enabled Koch to complete his education as a medical researcher by learning up-to-date methods of experimental pathology such as the use of the microtome or staining preparations with aniline dyes.

It was on this basis that Koch from 1877 made his own contributions to methodology and technology, most notably the microphotography of bacteria. This improved technology was then tried on the pièce de résistance of pathology of the time, the etiology of septic infections, on which Koch published in 1878. He showed himself to be an ingenious animal experimenter who succeeded in taking the study of human infectious diseases away from the sickbed and into the laboratory. It was also in this context that Koch for the first time made systematic arguments about how to establishPage 1263  |  Top of Article bacterial etiologies. These later became known as Koch's postulates and included the three steps of isolation, cultivation, and inoculation. However, methodology differed widely over the years, and the phrase Koch's postulates was coined by others.

In 1880 Koch took up an academic position. With Cohnheim's help he became head of the imperial health offices bacteriological laboratory and moved to Berlin. The following years were his most productive. He published on laboratory technique in "Zur Untersuchung pathogener Mikroorganismen" ("On the Study of Pathogenic Organisms"), which described his own method of producing mass pure cultures and other important work such as methods for sterilization. In the same period Koch increased the cohesiveness of his group by launching an attack on the French bacteriologist Louis Pasteur (1822–1895).

World fame came in two steps. First, on 24 March 1882 Koch presented the tubercle bacillus Mycobacterium tuberculosis as the pathogen of that condition. Even though Koch was by no means the first to advocate the idea of tuberculosis as an infectious disease, it was his bacillus that firmly established the connection of the various clinical forms of that disease and paved the way to an easy and plausible understanding of its etiology. His identification of the Vibrio cholera as the pathogen of cholera in 1884 was much less satisfying on the scientific side—it did not fulfill the standards of the postulates, and the bacterium as such had been known for decades. However, because part of the research was carried out during an expedition to Egypt and India and because the work itself represented sharp competition with a French group, it raised enormous public interest and shaped Koch's image as a crusader against plagues.


The years after 1885 brought a series of crises to Koch's life and work. After a failed attempt to found and head an imperial institute for bacteriology, Koch was promoted to a professorship at Berlin University in 1885. However, this appointment had been forced on the university by the state administration and was met with stiff resistance from inside the faculty of medicine. Koch had little experience and liking for professorial obligations. Moreover, Koch had problems with his research strategies. While his early successes had largely depended on microbe hunting, it was clear that this could hardly be prolonged. Furthermore, the popular embodiment of diseases as bacteria had raised hopes of specific therapies. These hopes had remained unfulfilled, while—to make things worse—Koch's rival Pasteur had achieved a public triumph with his rabies vaccine in 1885.

Koch attempted to find a way out of this crisis by developing a remedy for tuberculosis, which became known as tuberculin. When tuberculin became available in late 1890, it produced an unprecedented euphoria, even though its composition was kept secret. Public pressure led Koch to publish a description of tuberculin, which turned out to be an extract of tuberculosis pure cultures dissolved in glycerine. It turned out that his secrecy had blocked from view his fantastic commercial plans and the fact that his views on the medicine's therapeutic qualities were highly speculative. Separation from his wife and an affair with the seventeen-year-old student of fine arts Hedwig Freiberg, who later became his second wife, damaged his reputation further, and in early summer 1891 Koch found himself in public disgrace.

Still, Prussian government officials had used the short-lived euphoria following the release of tuberculin to get a parliament decision to found a new institute for research on infectious diseases. In 1891 Koch was appointed director of what today is the Robert-Koch-Institute in Berlin, but he had to accept harsh conditions: he effectively lost the right to hold patents since he had to assign all rights to his future inventions to the Prussian state in advance.

Koch's reputation was restored by the 1892 cholera epidemic that hit Hamburg, where the municipal sanitary administration had produced a disaster. A team of hygienists headed by Koch was sent in by the imperial government to combat the epidemic. On the scientific side the cholera epidemic was a turning point for Koch, who now abandoned the rather simple models of infection that he had employed so far. Epidemiology became important for him; he began to take note of phenomena such as aclinical or subclinical infections, and a few years later put forward the concept of healthy carriers (individuals who carried a disease withoutPage 1264  |  Top of Article showing any symptoms of it themselves), which greatly influenced infectiology and epidemiology.

Beginning in the mid 1890s, Koch focused on tropical infections of humans and animals. Such research enabled him to combine his interest in epidemiology with his lifelong passion for travel and to relaunch his old interest in etiology in research on vector borne tropical diseases. Long periods of absence from Berlin followed, during which the directorship of his institute was effectively left to others. Koch frequently worked for the British colonial office on cattle diseases, and his research on human diseases centered on the two paradigmatic diseases of tropical medicine, malaria and sleeping sickness. In the first case he focused on the developmental cycle of the pathogen, Plasmodium falciparum. In the latter case his work took a more therapeutic direction. This culminated in a large expedition from 1906 to 1907, which occurred after his early retirement in 1904. Because Koch failed to openly reveal the poor efficacy and severe side effects of atoxyl in treating sleeping sickness, this medicine became the basis of a large eradication campaign in the German colonies.

Koch received numerous honors, such as the the Nobel prize in 1905 as well as Prussia's most prestigious medal, awarded the following year. Koch died on 27 May 1910 during a stay at the south German spa of Baden-Baden.


Primary Sources

Essays of Robert Koch. Translated by K. Codell Carter. New York, 1987.

Gesammelte Werke von Robert Koch. 2 vols. Edited by Julius Schwalbe. Leipzig, Germany, 1912.

Secondary Sources

Brock, Thomas D. Robert Koch: A Life in Medicine and Bacteriology. Madison, Wis., 1988.

Gradmann, Christoph. Krankheit im Labor: Robert Koch und die medizinische Bakteriologie. Göttingen, Germany, 2005.


Source Citation

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Gale Document Number: GALE|CX3446900442