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Koch, Robert

disease anthrax bacillus bacteriology

[kokh] (1843–1910) German bacteriologist: a founder of medical bacteriology.

Koch was one of the 13 children of a mine official; he studied medicine at Göttingen, served in the Franco-Prussian war of 1870 and became a district medical officer in a small town in east Germany. He became interested in anthrax and worked on the disease in a room in his house, using a microscope given to him by his wife. Anthrax is a deadly disease of cattle, which caused huge losses in France at that time. It is highly contagious, can be passed to man, and can infect animals in fields from which cattle have been excluded for years. It was known to be caused by a bacterium. Koch found by 1876 that the anthrax bacilli can form spores (if the temperature is not too low, and if oxygen is present) and that these are resistant to heat and to drying. These spores can re-form the bacillus. Koch was able to isolate the anthrax bacillus from the blood of infected cows and he produced pure cultures, able to cause the disease; for the first time, a laboratory culture was shown to cause disease. (Working competitively on similar lines and in 1882 made an anthrax vaccine which protected against the infection.)

Koch much improved techniques in bacteriology. He used dyes to stain bacteria and so make them more visible under the microscope; he used a solid medium (agar gel) to grow them conveniently and separately on plates, or in the flat glass dishes designed by his assistant J R Petri (1852–1921); and he aided surgery by showing that steam kills bacteria on dressings and instruments more effectively than dry heat. From 1879 he worked in the Health Office in Berlin, where in 1882 he identified the tubercle bacillus. This was difficult work; the bacillus is small and slow-growing, but human tuberculosis (‘TB’) was responsible for one in seven of all European deaths at that time. In 1890 Koch was persuaded to announce a vaccine against it, but the claim was premature and his ‘cure’ survived only as a test method to show whether a patient had experienced tuberculosis.

From the 1880s he travelled widely, much enjoying his position as one of the first of the ‘international experts’. He did major work in Egypt, where he discovered and cultured the cholera vibrio in 1883, and in India on bubonic plague, in Java on malaria, in East Africa on sleeping sickness and in South Africa on rinderpest. Although not as wide-ranging a biological genius as Pasteur, he is the greatest figure in medical bacteriology and many of its leaders after him were his pupils. His Nobel Prize in 1905 was for his work on tuberculosis. His criteria for deciding that an organism causes a disease (Koch’s postulates) remain as critical tests: they require (1) the presence of the organism in every case of the disease examined; (2) the preparation of a pure culture; (3) the re-production of the disease by a pure culture, removed by several generations from the organisms first isolated. Use of these principles of 1890 established modern medical bacteriology.

Kocher, Emil Theodor [next] [back] Knox, Simmie(1935–) - Painter, Chronology, Paints President’s Portrait, Paints Other Famous Subjects

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