Pierre-Fid癡le Bretonneau (1778-1862) was a French medical doctor. Bretonneau is one of the pioneers in medicine. He identified typhoid fever and named diphtheria and was one of the first in the medical field to think that disease can be caused by bacteria. He also discovered that the same illness could manifest itself differently in different patients. It was the beginning of scientific medicine: where careful observation is used to find cures for sickness and solutions to problems.