Koch and Anthrax

After the discovery that anthrax can be transmitted from infected to healthy animal through inoculation of blood serum, Robert Koch started thinking about cultivating the causative agent of anthrax. To achieve this goal he performed a simple experiment. He took the spleen out from an infected animal and chopped it into fine particles & then dropped the particles in drops of sterile serum. He looked at it hour after hour and observed the tiny rods of bacterium forming long filaments. In between these filaments he also observed ovoid, refractive bodies somewhat different from the original bacteria (rod shaped). He mentioned that these are spores germinated from the original bacteria due to adverse environmental conditions. He was the first to isolate spores of bacteria. He eventually introduced the spores into fresh serum & again observed the formation of rods, filaments & spores. Likewise eight successive transfers of spores into fresh serum has been carried out and after that the spores were introduced in a healthy animal which rendered the animal ill. Finally the rod shaped organisms could again be isolated in culture.

Robert Koch

The proof of bacteria causing anthrax (etiology) was provided by a German country doctor Robert Koch in 1876. He was nowhere near a scientist and had no laboratory. He worked in his home with very primitive instruments and few small animals. He showed that mice cane be infected with by transferring materials (serum) from diseased animals and this he had done up-to a series of 20 mice by successive inoculation. Strikingly in every transfer the same symptoms were observed. He then performed an experiment to observe the bacterium or rather the causative agent as whether it was due to a bacterium was not clear till then.