Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

NadiaA

History of Microbiology
LO:




How microorganisms were identified
The debate about how life arises (spontaneous generation vs biogenesis)
The importance of Koch’s postulates

Observations
1665- Robert Hooke





Used microscope to observe cells
Coined the term cells
First person to see microbes e
...
mould
He marked the beginning of cell theory- all living things are made of cells

1673- 1723- Anton van Leeuwenhoek







Father of biology
Improved the resolution of microscopes
He did his studies and described what he saw as ‘animacules’ from rain, faeces and tooth
scrapings
Animalcules- live bacteria and protozoa
Was ridiculed by scientists such as Hooke but persevered
Finally, his findings were found to be true

Aristotle- spontaneous generation



The hypothesis that living organisms arise from non-living matter and a ‘vital force’ forms
life
e
...
maggots on meat arose spontaneously

1668- Francesco Redi





Conducted experiment to test spontaneous generation hypothesis
Experiment 1
...

The jar sealed had no maggots on it; the jar that was not sealed had maggots on it
...

Thus there is not spontaneous generation
...
Thus there is spontaneous generation
...
To ensure that this time oxygen got in, he left another 3 jars with a fine mesh
over it, with decaying meat
...

He found that the 3 jars with mesh had no maggots, and the 3 open jars had maggots

1

NadiaA
Thus, the flies were needed to get maggots to form; it was not oxygen that was the cause of
maggots to appear
...

1745- John Needham






Heated nutrient broth and put it into a sealed flask
...
Nutrient broth was placed into
flask, heated then sealed
...
g
...
e
...
g
...

For example before Pasteur’s findings, people believed that people breathing in bad air can
cause malaria
...

Post Pasteur’s findings (above), people realised that microbes can cause disease- this is the
germ theory; This was a difficult concept to grasp for people as they couldn’t believe what
they couldn’t see (as they can’t see microbes)
There were soon studies to prove the germ theory

1840s- Ignaz Semmelweis





Physicians who didn’t wash their hands routinely transmitted infections between patients
He advocated hand washing to prevent transmission of germs
His findings were not recognised until after he died
He did of a bacterial infection, sepsis after being beaten up by asylum guards

1850s- John Snow







Came up with view that contaminated water caused cholera
He traced an outbreak of cholera in Soho down to a single pump that was local to people
in the area
The people who didn’t contract cholera had a water supply from the brewing of alcohol
He stopped this outbreak of cholera by removing the pump’s handle
This caused the birth of epidemiology – tracking diseases, where they came from, where
are they going to go
There was a lady who moved from Soho to Hampstead who took the water from the
pump with her and she died of cholera too- this confirmed that contaminated water
from the pump caused cholera in that area

1860s- Jospeph Lister


Applied Pasteur’s work showing that microbes in the air can spoil food and cause disease
3

NadiaA








He used a disinfectant- carbolic acid, a phenol
Used it to sterilise surgical instruments
Used it to clean wounds
Thus prevented surgical wound infections
This was quickly adopted by surgeons
This made surgeries safer and reduced post-surgery infections
Thus he proved that microbes cause surgical wound infections

1876- Koch











Devised a series of experiments to prove microbes cause disease- Koch’s Postulates
His series of experiments proved that a specific microbe causes a specific disease
Made connection that anthrax is caused by a bacterium
He used observation and staining to identify what was causing the disease- the pathogen
He isolated the pathogen and grew it in a culture, he then inserted into a healthy lab mouse
These mice became diseased or died
He took the mice and repeated the identification process to see whether what pathogen he
got was the one that he put into the mice and it was;
Thus the organism you put in is the organism you get out
We can prove Koch’s postulates for diseases when we have an appropriate animal model
Gold standard- this is the standard test used to identify an emerging infection e
...
HIV, Ebola
which were not in humans but got into humans later on

Syphilis got into humans, we don’t see that now, the parasite has become less pathogenic, we have
become immune to it, things become more to an equilibrium
The birth of chemotherapy








Paul Ehrlich coined the term chemotherapy
Chemotherapy- any chemical used to treat any disease
Worked in the dye industry
He believed that infectious diseases could be treated by synthetic chemicals
He speculated about a ‘magic bullet’ that could destroy a pathogen without harming the
host- selective toxicity
In the dye industry, he noticed some cells take up certain dyes some don’t in relation to
other cells== so he thought this idea can be used for killing parasites—chemotheraphy!
so he reasoned that dyes can be differentiated between parasite and host

1905- Thomas and Breinl




Demonstrated that atoxl protected mice form trypanosomes, by giving it to mice infected
with trypanosomes
Mouse survived
However, this drug doesn’t work on humans!

4

NadiaA




They produced derivatives to be able to produce one that kills the pathogen without
affecting the host and came up with ‘compound 606’ marketed as Salvarsan
...

The derivative from Atoxyl- you can see the chemical structure is similar

((Golden age ends in 1914))
After this companies started developing new drugs
1930s- Sulphonamides



e
...
Prontosil was manufactured by the company, Bayer
although using sulphonamides can be fatal

1928- Penicillin






Fleming accidently discovered the antibacterial activity of penicillin
He found that a penicillinium fungus made an antibiotic that killed staphlpcus aureus
It caused a ‘zone of inhibition’
Bad asepsis made him discover penicillin
((Accredited with identifying penicillin- although he only observed it))

1940s- Florey, Chain and Heatley


purified and demonstrated the effectiveness and use of penicillin and this started the
‘Antibiotic revolution’

1940s- Waksman



Coined the term antibiotic
Identified streptomycin/neomycin from soil microbes

1948- Brotzu



Identified cephalosporin from sewer bugs
Very profitable antibacterial agent

5



---