Bacteria as causative agents of infectious disease

The fact that bacteria can be a potential agent for causing infectious disease came from the study on Anthrax, a serious disease of domestic as well as wild animals, which can be transmissible to humans. From 1850 - 1865 many researchers identified a rod shaped bacteria in enormous amount in the blood stream of infected animals i.e. animals suffering from anthrax. One of them was C. J. Davaine, who showed that the rods are invariably present in diseased animals but undetectable in healthy ones and also the disease can be transmitted to healthy animals by introducing the blood containing the rods shaped elements (bacteria).

Microorganisms as potential threat in surgery

After the invention of anesthesia, surgical treatment became an important part in medical science. Anesthesia gave the doctors the liberty to perform operations of longer duration and complexity. But this increase in time of operation leads to another problem. As time of operation increased the potential of microbes attack on exposed wounds also increased many folds. As a result many people suffered from post operative sepsis and even died. But the actual reason behind sepsis was not understood at first by the doctors. Pasteur by that time already showed the presence of microorganisms in air and developed many ways to prevent organic infusion from getting contaminated by air microbes during his study with “Spontaneous generation theory” (consult earlier posts). Joseph Lister, a young British surgeon was very much impressed by Pasteur’s work & thought that surgical sepsis might be the result of microbial infection of the tissue exposed during operation. He then continued developing many techniques to maintain aseptic condition during operation. Those include sterilization of the surgical instruments, aseptic dressings of the wounds and spraying of antiseptic agents in operation room to minimize air microorganism contamination. These methods gave instant success in reducing surgical sepsis many folds. People were not convinced about his theory but its striking success made every surgeon to follow the aseptic procedures just like canning process was successful in preserving food for long without knowing the reason behind it. This success is also an indirect proof of germ theory of disease.