Robert Kok was the person who greatly contributed towards an understanding of the germ theory proposed by pasture. cow was a German doctor who was familiar with anthrax, a deadly disease that causes skin ulcers. anthrax periodically ravaged cattle and sheep and could affect humans as well. anthrax was responsible for huge financial losses to farmers in the 1800s. caulk examine the blood of animals infected with anthrax and notice that anthrax has two stages. The bacillus stage which is a rod shaped, as shown here, in with the green arrow and sport stage Which is shown here with wet arrows.
And the spore stage was shown to be a resting stage goc injected the spores into healthy mice, and the spores produced anthrax in the mice, which means that the sports were responsible for the transmission of the disease. To prove that this bacillus is the causative agent of anthrax, Robert cop to the blood from disease sheep and cattle and injected it into healthy buys. He then noticed that the mice had the same symptoms as the cattle and when he performed autopsies, he found out similar signs of pathology in the mice. From the blood of these mice, he isolated a few rooms Ship bacterial cells that we call as vasculitis, as shown here in dark blue. After growing the bacteria in culture and allowing several hours for the bacteria to multiply, he noticed that the bacteria formed tangled threads and then formed these spores. These spores were highly resistant to extreme conditions of temperature.
He took these spores and injected them into healthy mice. And again, the signs and symptoms of anthrax appeared in the mice. When he autopsied these animals, he found the blood contained anthrax bassline, now the cycle was complete. The anthrax basler is relatively large And easily identified with a microscope. Therefore, it was easy for caulk to identify the bacteria. However, because most bacteria are small and hard to differentiate between one bacterium and the other, Robert Kok had a hard time in studying other diseases.
He solved the problem by using samples of sputum, blood or purse and isolating the bacteria by actually mirroring the sample onto a solid surface such as the gelatin as shown here, or a potato. Similar to what is shown here. What he obtained were bacterial cells that multiplied forming small masses that we, he called us colonies as shown here by this white spot and this spot. He hypothesize that each colony was a progeny of a single cell. a diversity of such colonies is shown here in these three samples. The shape of the colonies can be round as shown in samples one and two, are irregular as shown in sample three.
The appearance of the colonies can be shiny as shown in sample one, our dough as in sample two and three. Determining the colony morphology using several criteria, including the shape and appearance is an important tool in the description and identification of a particular microorganism. The petri dish is a small shallow dish with a lid made out of plastic or glass that is used to culture cells. The dish is named after its inventor Julia Petri, who was an assistant to Robert Kok? How would you prove that a particular organism? was the cause of a particular disease in an animal?
How could you be sure that you found the right microorganism and did not associate the disease with one of the millions of microorganisms that occur in an animal? This problem challenge scientists for decades, eventually, Cox Koch's postulates became the accepted scientific method for identifying the agent that caused the disease. The following diagram summarizes Cox postulates through an experiment with anthrax that he performed it allows us to learn how scientists still identify which micro organisms cause which disease. When anthrax is isolated from a disease animal, the bacteria can be identified under the microscope or cultured in the lab. That's what is shown in one two a and to be. The cultured bacteria can then be re inoculated into a healthy mouse as shown in three, and after the mouse produces the disease in the healthy animal, as shown in for the bacteria can be re isolated and re cultured.
Again as shown here we isolated and re cultured in five a and five B Club presented three rules for experimental proof of the pathogenicity of microorganism in 1883. A fourth rule was added by EF Smith in 1905. Briefly, these rules are as follows. The microorganism should be present in the sick animal and not in the healthy animal. Or in other words, the suspected organism must be constantly associated with the disease. To the microorganism can be isolated from the sick animal and be grown as pure culture.
It is very important to isolate the microorganism that is present in the tissues or other samples of the diseased animal. It is also crucial to be able to obtain a pure culture of the microorganism devoid of any contamination with other microorganisms. Not causing disease free, the isolated pathogen must cause the disease when inoculated into a healthy lab animal. When a healthy animal is inoculated with the pathogen from pure culture, that animal must develop signs and symptoms of the original disease. For the pathogen must be re isolated from the new lab animal and shown to be identical to the originally inoculated pathogen. The same pathogen that is present in the original animal must be re isolated from the infected lab animal under experimental conditions.
These rules proving that a certain disease is caused by a certain microorganism are referred to as Koch's postulates. Clock also worked with other bacteria in In 82, he isolated the bacteria that causes tuberculosis, which is also shaped as a rock that's being called the tuberculosis bacillus. In 1883. He interrupted his work with TV and started studying cholera in Egypt and India, in both countries caught, isolated a coma shaped bacteria. He therefore confirmed Jon Snow's suspicion that water is key to its transmission. In 1891, he became the director of the Berlin Institute for infectious diseases.
In 1905, Robert Kok received the Nobel Prize in Physiology or Medicine. Although the work with bacterial diseases was advancing, the cause of diseases such as measles, mumps, yellow fever and smallpox was still our In 1892, a Russian scientist named Dmitri ivano ski used a filter that was actually developed by the pasture group to filter what he thought was the bacteria that caused the tobacco mosaic disease. The disease causes mottled and stunted tobacco leaves. To his surprise when he applied the filtrate it that is the liquid that passed through the filter to healthy plants, the leaves became mottled and stunted. He assumed that the bacterial cells somehow slipped through the filter. Seven years later, not knowing even though skis work, a Dutch investigator named Martinez wager rink, did similar experiments with the tobacco mosaic disease and suggested that the pathogen that causes the disease is a contagious living liquid that acted like a poison.
Or the other name for poison is virus. And that word is derived from the Latin. In 1898, Sergey Brin Winogradsky discovered the first filterable virus affecting animals with the hoof and mouth disease. Finally, in 1901, Walter Reed and American army physician concluded that the pathogen responsible for yellow fever in humans is also a filterable agent.