Transcript Germ Theory and Principles of Infection

Germ Theory
and Principles of Infection
By
Rabia Chaudhry
Louis Pasteur, French microbiologist and the 'father' of
“Germ theory of disease.”
Background of Theorists
Louis Pasteur (1822-1895),
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French professor of microbiology.
Studied how yeasts (fungi) ferment in wine and beer
Proved that heat destroys bacteria and fungi
First to propose the Germ theory of disease in 1958.
Pasteur proves that germs cause disease.
Micro organism enter the body in number of ways.
Specific diseases are caused by specific micro- organism.
Natural immunity is an inherited resistance to infection.
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Therapeutic measures suggested by the Germ Theory included asepsis, antisepsis and disinfection techniques (to prevent contamination by
microbes).
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He theorized that a specific bacterial organism were capable of causing an infectious disease.
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This theory seems simple but it is one of the most critically beneficial in medical field.
(Jeffery, 2006)
Robert Kock (1843-1910)
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German general practitioner
Grew bacteria in culture medium
Showed which bacteria caused particular diseases
Classified most bacteria by 1900
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He stained germs to help him to see them better.
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Among others, he identified the germs which cause tuberculosis and cholera.
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More scientific basis “Robert Koch postulates”.
(Thomas, 1996)
Germ Theory of Disease
Louis Pasteur discovered that germs cause
disease. He believed that they caused things like
food and drink to go bad, and brought sickness to
animals and men.
Research on Theory
Pasteurization
Louis was studying wine and why wine went
bad. He found that the wine remained good
if it is air sealed.
In addition, he found that heat kills the
germs. In turn, milk is heated today to
destroy germs. We call it ‘pasteurised
milk’. Pasteurization prevents milk from
going sour by killing the germs and we
sealing it from the air.
(Ernst, 1995)
Linking Germs to Disease/Infection
• Louis proposed “If wine and beer
are changed by germs, then the
same can and must happen
sometimes in humans and
animals.”
• French Silk Industry
• Asked Pasteur to investigate
why their silkworms kept
dying.
• He discovered that a certain
germs were responsible for it.
(Ernst, 1995)
Theory applied to Nursing
In 1873 Louis Pasteur’s little daughters died
from typhoid. He mourned his daughter but also
decided to study the disease which attacked
animals and men.
He began to work in hospitals
which were dreadful places in
1800s, full of germs. He used
disinfectants to kill germs and
kept everything clean. After
that, number of deaths reduced
dramatically in the hospital.
(Jeffery, 2006)
Theory applied to Nursing
(Vaccinations)
Germ = Germination
Louis was able to show that germs caused disease in
sheep. He noticed that once an animal had a disease they
never caught it again. He decided it must have been that
the dead germs in blood saved the animals from new, living
germs. So if he put some harmless germs into the animals
blood it would never be attached by live germs. Today we
call this vaccination. This was a wonderful discovery!
Pasteur also produced a vaccines for chicken cholera and
anthrax, and then a vaccine for humans against rabies.
(Jeffery, 2006)
Further Research with Theory
Louis/Koch’s
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Koch’s demonstrated the Germ Theory of
Disease
Koch’s Postulates:
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The same pathogen must be present in every case of
the disease.
Pathogen must be isolated from the diseased host
and grown in pure culture.
The pathogen from the pure culture must cause the
disease when inoculated into a healthy susceptible
laboratory animal.
Pathogen must be isolated from the inoculated animal
and shown to be the original organism.
(Tortora, 2004)
Koch’s Postulates
Tortora, 2004
Theory applied in Nursing
Practice
• According to the CDC, hand-washing is the single most important
means of preventing infection
• Pasteur brought the use of aseptic techniques which is wildly used all
over the world
• Handling contaminated materials carefully
• Paying special attention to cleanliness of respirators/humidifiers
• Single-use dressings/tubes
• Prescribe antibiotics only when necessary
• Using personal protective equipment [PPE]
• Isolation (Contact, Droplet, Airborne)
• Environmental cleaning
• Risk management/assessment
(McEwen, 2007)
Conclusion
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Acceptance of germ theory is highly
significant for medicine.
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Reformation of this theory helped
practicing medicine more efficiently
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Immunology
Antiseptic/aseptic surgery
Public health
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Medicine became more effective once the cause of disease had been found, scientists
could work on preventions and cures.
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It influenced public health , e.g. encouraging the 1875 Public Health Act.
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Emphasis on breaking chain of infection
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Germ phobia & changes in hygienic practices were implemented.
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Recent events: the swine flu to fight this virus most important thing is to do frequent
handwashing.
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Discovery of healthy carriers
Typhoid fever
References
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Ernst, H. C.,Pasteur, L., On the extension of germ theory to the etiology of certain disease.
http://biotech.law.lsu.edu/cphl/history/articles/pasteur.htm#paperIII, 1995.
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Jeffrey, C. P., (2006). Alcamo's Fundamentals of Microbiology: Body Systems. Microbiology then and
now. (pp19-22). Jones and Bartlett Publishers.
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McEwen, M., (2007). Theoretical Basis for Nursing. (2nd Ed.), Philosophy, Science, and Nursing.
(pp.3-23). Lippincott Williams & Wilkins
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Pasteur, Louis. (2001).Scientific Papers. Vol. XXXVIII, Part 7. The Harvard Classics. New York:
P.F. Collier & Son, 1909–14; Bartleby.com. www.bartleby.com/38/7/.
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Thomas, D. B., (1996). Robert Koch: a life in medicine and bacteriology Sequence-based
identification of microbial pathogens a reconsideration of Koch's postulates
by Clin Microbiol Rev. Jan;9(1):18-33.
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Tortora, F., (2004). Microbiology: An Introduction, (8th Ed.), Infectious Diseases and Epidemiology:
Concepts; Koch's Postulates. Pearson Education, Inc, San Francisco.