Koch, Heinrich Hermann Robert

Heinrich Hermann Robert Koch's (1843-1910) research helped prove French researcher Louis Pasteur's (1822-1895) theory that germs, or small microorganisms, caused diseases. Koch also worked diligently to find the causes of diseases such as cholera (a severe intestinal disease) and tuberculosis (an infectious disease of the lungs).

Early Life

One of thirteen children born to a mining engineer and his wife, Koch spent his youth in the Harz Mountains in Clausthal, Germany. During Koch's adolescent years, his father insisted he learn the shoemaker's trade. When money became available for an academic career, however, Koch entered the University of Gottingen as a student of medicine and natural science at the age of 19. He graduated in 1866.

After service as a surgeon in the Franco-Prussian War (1870-1871), Koch started a practice as a country doctor in Wollstein, what is now Wolsztyn, Poland. At this time he also began his microscopic studies of bacteria. One of Koch's most important developments was a technique to use gelatin on glass slides to produce a transparent background for examining microorganisms. Koch's techniques are still used in the study of diseases.

Koch Studies Anthrax

One of Koch's early projects was to discover the cause of anthrax, a deadly disease of cattle and sheep. For years, farmers had been confused about outbreaks of anthrax in fields where infected cattle had been removed years earlier. After isolating strains of the anthrax bacillus, Koch showed that, under certain conditions, the bacilli formed spores (a tiny reproductive body) that could remain dormant Inactive) for several years. These spores remained in infected fields and could develop into the disease-causing anthrax bacillus if conditions were right.

By the late nineteenth century, researchers such as Pasteur had put forth the germ theory of disease, but no one had been able to prove that a single identifiable microorganism was responsible for a given disease. Koch's publication of his work with the anthrax bacillus helped prove that Pasteur was right.

Koch and Cholera

In 1883 Koch turned his attention to cholera, a very infectious disease that causes often fatal cases of diarrhea. In intense competition with Pasteur (who had taken a team to Egypt), Koch also took a group of German scientists to Egypt in an attempt to win the race to isolate the causative (responsible) agent. But the epidemic in Egypt ended before Koch's research was completed. He subsequently went to India, where he was able to isolate the comma-shaped bacillus responsible for cholera, Vibrio cholerae, from samples of drinking water, food, and clothing.

The Four Postulates

Koch became famous for his discoveries in the field of bacteriology. In 1885 he was named director of the new Institute of Hygiene in Berlin, Germany. Five years later, Koch published the "Four Postulates" ("four rules") on which modern bacteriological studies have been built. The postulates are:

• The organism must be present in every case of the disease.
• The organism must be cultivated in a pure culture.
• The organism must produce the disease in a susceptible animal upon inoculation.
• The organism must produce the same disease when healthy animals are inoculated.

Tuberculosis Studies Causes Controversy

Koch also contributed to the study of tuberculosis, a disease which attacks the lungs and slowly destroys them. In 1882 he was able to isolate Mycobacterium tuberculosis, the tiny bacillus that causes tuberculosis. It was Koch's search for a cure for tuberculosis, however, that would cause him temporary shame in the eyes of his fellow researchers. He thought he had found the cure, and in 1890, under pressure from the German government, he announced that he had "at last hit upon a substance that has the power of preventing the growth of the tubercle bacillus not only in the test-tube, but in the body of an animal."

Thousands of tubercular patients rushed to Berlin for tuberculin treatment. Those inoculated (injected with the vaccine) eventually died of miliary tuberculosis, considered the worst form of the disease. Koch, who had always conducted his research in secrecy, was forced to reveal the method he used to obtained tuberculin. In his search for a cure, he had cultured tubercle bacilli, heat-killed them, and filtered off the liquid. He had hoped to develop an effective vaccine from this method. But rather than discovering the cure for tuberculosis, Koch actually had discovered the substance that is now used to diagnosis the disease.

Despite the disappointment with his tuberculosis error, Koch received the 1905 Nobel Prize for medicine for his work with tuberculosis. He died in 1910, before he or any of his German colleagues could find a cure for tuberculosis. But his achievement in proving the germ theory of disease was critical to the development of vaccines and cures for many diseases.