1. Germ Theory

2. Acceptance of germ theory highly significant for medicine
Reformation of both theory and practice
Immunology
Antiseptic/aseptic surgery
Public health
Made medicine more effective

3. Refuting Spontaneous Generation
Bacteriology began in 17th century
No one knew if bacteria had a biological function
Commonly believed the putrefaction (spoilage) generated bacteria

4. Based on older belief in spontaneous generation
Mice
Maggots
Francisco Redi (c.1621 – c.1697)
Proved maggots were not sponanteously generated

5. People still assumed bacteria could spontaneously generate
John Tuberville Needham ( )
Apparently proved this hypothesis
Bacteria appeared in sterilized broth

6. Lazzaro Spallanzani (1729-1799)
Sealed flasks after sterilizing broth
No bacteria

7. 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

8. Louis Pasteur ( )
Disagreed with theory of spontaneous generation
Strongly influenced by his religious beliefs

9. 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)

10. 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

11. 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

12. 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

13. 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

14. 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

15. Also evidence that supported contagion theory
Sometimes attendants did get sick
Outbreaks often followed trade routes

16. Debate divided 19th century medical community
Had huge implications for disease control
Quarantine
Public health policy

17. John Snow ( )
Transmission of cholera
Traced 1854 outbreak to a water pump on Broad St.

18. 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

19. Next step in acceptance of germ theory was to establish that bacteria passed from one victim to another
Casimir-Joseph Davaine ( )
Studied anthrax in cattle
Identified large microbes in blood of infected animals

20. This discovery received little attention
Robert Koch ( )
Intrigued by Davaine’s findings

21. 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

22. 1880: Published on bacteria found in surgical infections
1882: Discovered M. tuberculosis
1883: Dicovered V. cholerae

23. Success based on exceptional technical expertise
Development of solid culture media
.Germ theory commonly accepted by medical community

24. 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

25. 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

26. Decline of the theory of predisposition

27. Immunology 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

28. 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

29. 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

30. 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

31. Stakes were very high for these researchers
General public desperate for solutions
Koch and development of tuberculin another example

32. Other impacts of germ theory
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