The fight against infectious diseases officially started in 1683, when Anton Van Leeuwenhoek created a microscope and managed for the first time to observe micro-organisms becoming thus, the “Father of microscopy”. This discovery was crucial to understanding the concepts of infection and infection prevention.
In 1862 Louis Pasteur, a French chemist and microbiologist published findings on how some diseases are caused by germs. Robert Koch though, shortly after Pasteur, was the first to link a specific bacterium to a specific disease. He developed new microscopic techniques for identifying bacteria and clarified that they exist as distinct species, each producing specific clinical symptoms. His new techniques included the development of solid culture media. He started with observing fungi growing on potato slides. He was placing liquid cultures in gelatin, cooled the solution and produced a clear and homogeneous culture medium where bacteria could multiply, forming visible colonies. He then experimented with agar, a substance extracted from seaweed with higher melting point, and used shallow, covered dishes into which media could be poured, cooled to solidity, and be protected from contamination. All these developments led to Koch’s famous “plate technique” with which bacterial colonies could be grown, studied and being subjected to experiments.
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• Cunha BA. Historical aspects of infectious diseases, Infectious disease clinics, part II, 2004: 18(2)