Robert Koch was a German Scientist. He used Pasteur’s findings of the late 1860’s to begin his own study into the cause of disease.
Koch had the advantage of being a Doctor, so he could apply medical knowledge to his experimentation. By 1875 he had successfully identified the microbe that caused Anthrax. A link was now made between germs and diseases, which allowed for Jenner’s earlier work to now be more fully understood and used. (Pasteur found the vaccine for Anthrax in 1881).
Koch used this new knowledge to begin a study of the causes of blood poisoning, or septicemia. He knew that a Microbe must be responsible for causing the spread of the disease, but at first couldn’t see the microbe, even with the aid of the most powerful microscopes. Industrialisation however led to the development of dyes that could be used to stain microbes. Koch created a liquid that contained just one germ, and dyed it. Through testing on mice he could show that this specific microbe, or germ, was responsible for the spread of the disease. (Koch photographed the spread of the dye, the start of the disease and it’s spread to prove his theory).
Koch later developed a solid culture to grow germs on. This meant that germ theory could be done much more reliably than with liquid cultures such as those by pasteur.
Koch’s work led him to discover the germs that caused tuberculosis and cholera.