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Robert Koch: One of the founders of microbiology

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Portrait of the family taken in Koch’s birthplace, Clausthal in the Harz region. Source: RKI Portrait of the family taken in Koch’s birthplace, Clausthal in the Harz region. Source: RKI

In the 19th century, diseases like tuberculosis, cholera, diphtheria and wound infections were the most common cause of death worldwide. In Germany alone, hundreds of thousands of people died of them every year. This was the time when the doctor, Robert Koch, discovered that diseases of this kind were caused by tiny organisms – bacteria. He and his colleagues in Berlin managed to identify individual pathogens and infection paths and thus pave the way for therapies and preventive measures.
All this was thanks to new scientific methods, such as solid culture media for cultivating bacteria, microphotography and dyeing techniques, which made it possible not just to trace the pathogens but also to visualise them. In 1891, Koch was appointed director of the newly-founded Royal Prussian Institute for Infectious Diseases, today’s Robert Koch Institute. For his discovery of the tuberculosis bacterium he was awarded the Nobel Prize in Medicine in 1905. Together with Louis Pasteur, Robert Koch is now thought of as the pioneer of microbiology.

The early years and initial scientific achievements

Robert Koch was born to a mining family in Clausthal in the Harz region of Germany on 11 December 1843. He was the third of 13 children. After completing his schooling, he went to university in Göttingen, studying natural sciences for one semester and then changing to medicine. He gained his doctorate in January 1866 and shortly afterwards passed his state examination in Hannover. In 1867, Koch married his childhood friend, Emmy Fraatz. After various positions working as a doctor in the provinces and as a hospital doctor during the Franco-German War, he became a district physician in Wollstein (today’s Wolsztyn in Poland) in 1872.

In his spare time, Robert Koch began researching into anthrax: around Wollstein, the disease regularly claimed the lives of both animals and humans – but the cause was completely unknown. Finally, in 1876, Koch proved that anthrax is triggered by a single pathogen. He discovered the dormant stage of the pathogen, anthrax spores, and thus unravelled the previously unexplained chain of infection and the bacterium’s strong resistance to environmental factors. In doing so, Robert Koch was the first to prove that a micro-organism was the cause of an infectious disease. In 1878, he published a book in which he described the pathogens behind wound infections, Investigations of the Aetiology of Wound Infections (Über die Aetiologie der Wundinfectionskrankheiten). The crucial factor in Koch’s success was the precision with which he developed and applied his scientific methods as well as his logical construction of the chain of evidence – and all this under fairly basic conditions in a poorly equipped laboratory at his home in Wollstein.

Breakthrough in Berlin: the discovery of tuberculosis bacteria

With his wife Emmy and daughter Gertrud, Robert Koch initially moved from Wollstein to Breslau before being appointed to the Kaiserliches Gesundheitsamt (Imperial Health Authority) in Berlin in 1880. Here, he developed the bacteriological methodology that not only drove research into infectious diseases but also the development of tailored countermeasures, such as disinfection procedures.

On 24 March 1882 at the Berlin Institute for Physiology, Koch announced the discovery of the tuberculosis pathogen – with his lecture on the “Aetiology of Tuberculosis” he became world famous overnight. In the course of the 19th century, tuberculosis had become a widespread disease. Roughly a seventh of the population of the German Reich died of the disease, known as the white plague; for a long time, what caused it and how it spread were unclear. Now Koch demonstrated that tuberculosis was triggered by the tubercle bacillus. In order to trace it, special culture media, new culturing conditions and specific dyeing techniques were required. For his discovery of the tuberculosis bacterium Robert Koch was awarded the Nobel Prize in Medicine in 1905.

Tracking down the ‘Asiatic hydra’

Like many scientists at the time, Robert Koch also investigated cholera. In the 19th century, the ‘Asiatic hydra’ had repeatedly broken out in Germany, too, especially in the big city slums. At the end of 1883, Koch and a team of researchers travelled, amongst others, to Calcutta in India to study the disease during an outbreak. There, at the beginning of 1884, he managed to identify the bacterium Vibrio cholerae.

Even though Robert Koch was hailed as the discoverer of the cholera pathogen during his lifetime, he did not deserve all the credit. The Italian anatomist, Filippo Pacini, had already seen and described the pathogen under a microscope back in 1854 – work that found little resonance in Germany at the time and that Koch was unaware of. Thanks to his knowledge on the spread of cholera and the appropriate hygienic methods, Koch helped to contain a serious cholera outbreak in Hamburg in 1892.

New post in Berlin and the tuberculin flop

In 1885, Friedrich-Wilhelms-Universität in Berlin founded the Hygiene Institute under the directorship of the first full Professor of Hygiene, Robert Koch. Here he continued to develop the new scientific discipline of bacteriology. The number of Koch’s staff and students grew; the Hygiene Institute became the hub for doctors interested in bacteriology from all over the world.

Tuberculosis and cholera were to remain important areas of research. Koch searched for ways of specifically containing infectious diseases or preventing them from occurring at all. His dream of discovering a therapeutic agent or even a vaccine against tuberculosis, however, did not come true. The remedy he developed, ‘tuberculin’ – a mixture of components of devitalised tubercle bacteria, which Koch presented at the Tenth International Medical Congress in Berlin in 1890 – later proved to be ineffective. Long-term cures failed, and some patients even died after treatment. Today, tuberculin is still used alongside more recent procedures to diagnose tuberculosis infections.

Nevertheless, Koch’s scientific achievements and the increasing importance of bacteriology at the end of the 19th century were reason enough for the Prussian government to build Robert Koch his own research institute.

The Royal Prussian Institute for Infectious Diseases

The Royal Prussian Institute for Infectious Diseases opened its doors on 1 July 1891 and until 1904, Robert Koch headed the institute. Apart from research, the staff also did contract work for cities and imperial authorities, answered international enquiries and wrote expert reports. ‘Koch’s Institute’ was one of the world’s first biomedical research institutes.

Initially, the institute was located in Berlin-Mitte, next to the Charité, the city’s largest and oldest hospital. The scientific department was set up in a converted residential building known as the ‘Triangle’, due to its shape. The infirmary was housed in individual field huts on the Charité site.

From 1897 to 1900, a new building was constructed for the institute on the Nordufer in Berlin-Wedding. Robert Koch was involved in the planning. On the extensive site there were stables for laboratory animals such as horses, sheep and, at one time, even camels. In the immediate vicinity, the Rudolf Virchow Hospital was opened in 1906; the head of its infection department was also a member of staff at Koch’s Institute. The brick building on the Nordufer is still the headquarters of the Robert Koch Institute to this day.

The late years: Robert Koch on the road

From 1896 onwards, Robert Koch spent several months each year on expeditions to investigate tropical diseases – his second wife Hedwig Freiberg nearly always accompanied him. First of all, he concentrated on animal diseases in southern Africa, such as rinderpest, Texas fever and East Coast fever. Later, he turned to tropical diseases that affect humans, especially malaria and sleeping sickness, to discover how they were transmitted. In 1906 and 1907, a commission led by Koch was sent to East Africa to experiment with ways of treating sleeping sickness. Koch enjoyed some initial success by treating patients with Atoxyl, a drug containing arsenic. But the parasite that caused the infection was only suppressed in the sufferer’s bloodstream for a short time, so, although he was aware of the risks associated with the drug, Koch doubled the dose of Atoxyl. Many patients suffered from pain and colic, some even went blind. Despite this, Koch was still convinced that Atoxyl could be effective. His final research journey was the darkest chapter of his career.

Robert Koch's itineraries. Koch loved travelling and did so frequently - both privately and professionally. Source: RKI Robert Koch's itineraries. Koch loved travelling and did so frequently - both privately and professionally.

At the beginning of April 1910, Robert Koch suffered a massive heart attack in Berlin. He died during a subsequent stay at a sanatorium in Baden-Baden on 27 Mai 1910. The urn containing his ashes was laid to rest in a specially constructed mausoleum at his institute on 4 December 1910.

Robert Koch’s scientific legacy – including 1,500 letters, award certificates, lecture manuscripts and publications, photographs and prepared microscope slides – is preserved at the Robert Koch Institute.

Date: 03.12.2018