Louis Pasteur, a French chemist, is often called the father of modern microbiology. Through the development of vaccines for cholera, anthrax, rabies, staphylococcus, and streptococcus, he discovered much about the nature of infection and laid the groundwork for the microbial theory of disease. Pasteur also contributed greatly to the field of infectious epidemiology by demonstrating how pathogens spread through animal and human populations.

[Page 791]Pasteur examined the role of microorganisms in the transformation of organic matter, which at the time was greatly misunderstood. Instructed by Napoleon to investigate diseases infecting wines, he determined that fermentation results from the action of a specific microorganism. To enable fermentation, the right microorganism must be introduced, and microorganisms that could alter the process must be kept out. With Claude Bernard, ...