1750-1900 the development of the Germ theory

1750-1900 the development of the Germ theory

1. Germ Theory

   • The idea that there are microbes in the air which cause decay
   • An important breakthrough in scientific understanding
   • Disproved the theory of Spontaneous generation
   • Led Koch to identify the specific microbes that caused some individual diseases
     • This improved understanding of the causes of diseases, scientists hoped they could find ways of treating them
       • But was going to take some time - would need to identify microbe responsible for each separate disease

2. Pasteur

   • When he discovered the technique that created a weakened version of a chicken cholera microbe
     • almost 20 years later, he realised that vaccines for other diseases could be developed
       • But this also depended on microbes for each specific disease being identified
   • Louis Pasteur, was a French Chemist

3. Impact

   • Despite its importance, this breakthrough in scientific knowledge and understanding had limited impact on medicine at the time
     • Because each disease had to be researched individually
   • Progress in the prevention and treatment of disease, was, therefore, slow.

4. The development of Germ Theory

   • 1. In the 1850s Pasteur investigated the problem of liquids turning sour in the brewing and vinegar industries
   • 2. More powerful microscopes had recently become available - which meant Pasteur could observe the growth of unwanted small organisms in the liquids.
   • 3. He discovered heating the liquid killed the bacteria and stopped the liquid going sour
   • 4. 1861- Pasteur published his Germ Theory - showing that there were microbes in the air and that they were causing decay
     • His work disproved the idea of Spontaneous generation
       • No decay happened if matter was placed in a sealed container
         • Showed that the microbes causing decay were not from the matter itself but were in the air around it
   • 5. In 1875, Robert Koch decided to investigate whether bacteria were linked to disease
     • A German doctor who had read Pasteur's work
     • He worked with a team of scientists-funded by the German government
       • He identified specific microbes that caused the disease, anthrax in sheep
     • 6. Koch identified the microbes causing TB in 1882 and those causing cholera in 1883
       • (Tuberculosis)
       • Koch found that chemical dyes could be used to stain specific bacteria so they could be studied more easily under the microscope
   • 6. 1879- Pasteur's team was studying Chicken cholera microbes and injecting chickens with the disease
     • A culture of the bacteria was accidently left on one side- when it was used a couple of weeks later- it had become a weakened version which didn't harm the chickens
       • Pasteur realised that this could be used as a vaccine to create immunity from that disease for chickens.
         • He called this process 'vaccination' - In tribute to the importance of Jenner's work

5. The importance of research teams

   • By the end of the 19th Century, scientific research was usually carried out by a team rather than by an individual.
   • A team was more likely to have funding & be able to afford expensive new technology
     • Such as more powerful microscopes
   • Working in a team made it easier to check each other's work and carry out large-scale testing
   • Different members of a team could offer knowledge of different specialisms
     • e.g. medicine, biology and chemistry