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Germ Theory. Acceptance of germ theory highly significant for medicine Reformation of both theory and practice Immunology Antiseptic/aseptic surgery Public health Made medicine more effective. Refuting Spontaneous Generation. Bacteriology began in 17 th century

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Acceptance of germ theory highly significant for medicine
  • Reformation of both theory and practice
    • Immunology
    • Antiseptic/aseptic surgery
    • Public health
  • Made medicine more effective
refuting spontaneous generation
Refuting Spontaneous Generation
  • Bacteriology began in 17th century
  • No one knew if bacteria had a biological function
  • Commonly believed the putrefaction (spoilage) generated bacteria
Based on older belief in spontaneous generation
    • Mice
    • Maggots
  • Francisco Redi (c.1621 – c.1697)
    • Proved maggots were not sponanteously generated
People still assumed bacteria could spontaneously generate
  • John Tuberville Needham (1731-1781)
    • Apparently proved this hypothesis
    • Bacteria appeared in sterilized broth
Lazzaro Spallanzani (1729-1799)
  • Sealed flasks after sterilizing broth
  • No bacteria
Claimed to have disproved spontaneous generation
  • Critics claimed all it proved was that spontaneous generation could not occur without air
  • Debate not resolved until the 19th century
Louis Pasteur (1822-1895)
  • Disagreed with theory of spontaneous generation
  • Strongly influenced by his religious beliefs
Those who opposed Darwin’s theory also opposed spontaneous generation
  • Appeared to threaten human morality
  • Pasteur’s work in the wine industry caused him to believe that bacteria caused fermentation (not vice versa)
Pasteur was opposed by Felix Pouchet (1800-1872)
  • Demonstrated that even carefully sterilized infusions would spoil if exposed to oxygen
  • Declined to enter into a public contest with Pasteur
In fact, Pouchet might have won
  • No one knew about heat resistant (spore forming) bacteria
  • In later years, Pasteur was forced to admit that these organisms could threaten sterilizing techniques
Today, scientists believe that life did arise spontaneously on early Earth
  • So, was Pasteur correct or not?
  • By 1890s, spontaneous generation rejected as an explanation for putrefaction
accepting contagion theory
Accepting Contagion Theory
  • Prior to 19th century, contagion theory not accepted
  • Some observed facts seemed to fly in face of contagion
  • Diseases could break out in widely separated areas of the country
People who attended the sick didn’t always succumb to the disease
  • Miasma (bad air) a common experience in crowded urban environments where disease broke out
Also evidence that supported contagion theory
  • Sometimes attendants did get sick
  • Outbreaks often followed trade routes
Debate divided 19th century medical community
  • Had huge implications for disease control
    • Quarantine
    • Public health policy
John Snow (1813-1858)
  • Transmission of cholera
  • Traced 1854 outbreak to a water pump on Broad St.
Cholera transmissible in water
  • William Budd announced similar conclusion days later
  • Did not know what spread the illness
  • Budd speculated that it was a fungus
Next step in acceptance of germ theory was to establish that bacteria passed from one victim to another
  • Casimir-Joseph Davaine (1812-1882)
  • Studied anthrax in cattle
  • Identified large microbes in blood of infected animals
This discovery received little attention
  • Robert Koch (1843-1910)
  • Intrigued by Davaine’s findings
Discovered that anthrax bacteria formed spores
  • Able to relate this finding to the epidemiological facts surrounding outbreaks
  • Published findings in 1876; one year before Pasteur
1880: Published on bacteria found in surgical infections
  • 1882: Discovered M. tuberculosis
  • 1883: Dicovered V. cholerae
Success based on exceptional technical expertise
  • Development of solid culture media
  • .Germ theory commonly accepted by medical community
1880-1900 golden age of bacteriology
  • New bacterial diseases identified at rate of 1/yr
    • Gonococcus
    • Syphilis
    • Child bed fever
  • Fuelled hopes that diseases such as cancer also caused by germs
impact of germ theory
Impact of Germ Theory
  • Dramatic consequences for public health
  • Emphasis on breaking chain of infection
    • Discovery of healthy carriers
    • Typhoid fever
    • Story of typhoid Mary
  • Germ phobia & changes in hygienic practices
  • Based on the fact that living entities have immune systems
  • Can artificially produce immunity
    • Artificial passive immunity
    • Artificial active immunity
  • Smallpox & artificial active immunity already discussed
immunology after vaccination
Immunology After Vaccination
  • Several other vaccines were produced in the late 19th century
  • Produced by manipulating organisms so that they lose virulence, but retain capacity to produce antibodies
    • Attenuated vaccines
    • Killed vaccines
Pasteur played significant role
  • Accidental attenuation of chicken cholera organism
  • Discovered it rendered chickens immune to the virulent organism
  • Used this model to develop anthrax vaccine
Also developed rabies vaccine
  • Pasteur criticized by some of his contemporaries and present day historians
    • Used unproven vaccine on Joseph Meister
    • Appropriated techniques developed by other researchers
    • Was not completely honest about how he produced anthrax & rabies vaccine
Stakes were very high for these researchers
  • General public desperate for solutions
  • Koch and development of tuberculin another example
Impact of vaccines
    • Mortality due to contagious diseases fell dramatically
    • Mortality shifted to chronic diseases
  • Other impacts of germ theory
    • Search for specific remedies
    • Abandonment of general therapies
    • Reduced mortality after introduction of aseptic techniques