A Dutch cloth merchant, named Antonie van Leeuwenhoek, was the one who started the study on bacteria in the human body. What started as a hobby where, in addition to making microorganisms, the plate was removed from the mouth, moistened with rainwater and observed for a time what happened, it became an impressive result.As the merchant himself said, once set in motion one of his experiments, "the human body contains a large number of animals that move extravagantly. There are so many, that the number exceeds the inhabitants of a kingdom. "
Van Leeuwenhoek was known as the "father of microbiology" who, in addition, stood out for being the first to execute observations and discoveries with microscopes whose manufacture he himself perfected.