Introduction to Bacteriology Flashcards
What is spontaneous generation?
Before Germ Theory, this was the widespread belief that microorganisms spawned inside dirt and food to then cause disease.
When and how did Louis Pasteur develop Germ Theory?
1862: He boiled meat broth in a flask, heated the neck of the flask in a flame and bent it into the shape of an ‘s’. Air could enter the flask, but microorganisms could not - they got stuck in the neck. When Pasteur tilted the flask so that the broth reached the lowest point in the neck, where any airbourne particles would have settled, the broth rapidly became cloudy with life.
What did Pasteur’s Flask Experiment prove?
This experiment proved that Spontaneous Generation did not occur and that microorganisms are everywhere, even in the air.
What was the case of Semmelweiss and how did it contribute evidence toward Germ Theory?
1841: Semmelweiss ran a maternity ward made of two birthing wards. Deaths from septicaemia among mothers in the birthing ward run by doctors were much higher than in the birthing ward run by mid-wives.
Controversially, Semmelweiss suggested that the doctors were spreading an invisible pathogen. Death rates in the doctor’s ward dropped drastically when doctors began to frequently wash their hands in disinfectant.
What is Germ Theory?
The theory that microorganisms are the cause of some or all diseases.
(fun fact) When were anaesthetics introduced and what medical development did they allow?
Anaesthetics were introduced in the 1840s and led to the development of complex surgery.
What achievement is credited to Joseph Lister?
This surgeon massively reduced surgical sepsis after reasoning that microbial contamination of surgical instruments was leading to sepsis.
When and how did Robert Koch prove the connection between microbes and disease?
In 1876 he noted that Anthrax Bacillus was always present in diseased animals. He injected the bacteria into healthy animals, who soon died. Germ theory is formally proven!
Outline Koch’s Postulates (1884).
- The bacterium must be present in every case of the disease.
- The bacterium must be isolated from the diseased host & grown in pure culture.
- The specific disease must be reproduced when a pure culture of the bacterium is inoculated into a healthy susceptible host.
- The bacterium must be recoverable from the experimentally infected host.
What are the 4 limitations of Koch’s Postulates?
- A normally harmless bacterium that is part of the normal flora can become a pathogen in certain situations :-
- normal flora gain access to deep tissues by trauma, surgery.
- normal flora acquire extra virulence factors making them pathogenic, eg certain strains of E. coli.
- in immunocompromised patients the normal flora can cause disease - Not all of those infected or colonised by a pathogenic bacterium will develop disease (sub-clinical infection is more common than clinically obvious infection)
- Some bacteria are not culturable in vitro (e.g. Mycobacterium leprae, Treponema pallidum)
- There is an assumption in postulate 4, namely that the other host must have a genetic make-up that causes it to react to the organism in the same way as the original host.
By which two methods was drinking water protected from waterbourne diseases?
Filtration and chlorination!
What is Edward Jenner remembered for discovery and how did he discover this?
Immunisation! He noticed that milkmaids were immune to smallpox infection, and that exposure to cowpox was the defining difference between milkmaids and others. In 1803 smallpox vaccination was common in England.
What is considered the most important medical contribution of the 20st century?
The eradication of smallpox in 1977.
What did Paul Ehrlich develop in 1910?
The first antibiotic for Syphilis, developed through selective toxicity through specific binding of arsenic-based dye to the syphillis bacterium.
