Medical
Microbiology
The History
What is Microbiology?
 It
is the study of microbes or
microorganisms

Microbes, or microorganisms are minute
living things that are usually unable to be
viewed with the naked eye.
What is Microbiology
continued
 What

are some examples of microbes?
Bacteria, fungi, protozoa, algae, viruses,
and some are parasites (helminths)
 Some
are pathogenic
 Microbiology
also involves processes that
include immunology, epidemiology,
bacterial physiology
History of Microbiology

First microbes were observed in 1673

Robert Hooke- In 1665 reported that living things
were composed of little boxes or cells


devised the compound microscope and
illumination system
Antoni van Leeuwenhoek- (1673-1723)
He is considered the father of bacteriology
Made simple microscopes and began observing
with them
 Discovered bacteria (he called them
animalcules)

 Leeuwenhoek's
microscope consisted
simply of:
 A) a screw for adjusting the height of the
object being examined
 B) a metal plate serving as the body
 C) a skewer to impale the object and
rotate it
 D) the lens itself, which was spherical
History of Microbiology
 Many
believed in spontaneous generation:

Aristotle synthesized the hypothesis which
stated that some vital force contained in
given to organic matter can create living
organisms from inanimate objects.

In basic terms spontaneous generation
stated that living organisms arise from non
living matter.
History of Microbiology
 Spontaneous
generation was disproved in
1668 by Italian Scientist, Francesco Redi.
History of Microbiology


John Needham- revived the theory of
spontaneous generation in 1745

Needham theorized that if he took chicken broth and
heated it, all living things in it would die.

After heating some broth, he let a flask cool and sit at
a constant temperature. The development of a thick
turbid solution of microorganisms in the flask was
strong proof to Needham of the existence of
spontaneous generation.
Lazzaro Spallanzani (1729-1799)

He demonstrated that microorganisms were
already in the solution, the container, or the air

He took solutions which he knew would "breed"
organisms and boiled them for up to an hour.
The flasks were hermetically sealed to keep out
contaminated air.
History of Microbiology
 Theory

of biogenesis later arose
In 1858 German scientist, Rudolf Virchow
challenged spontaneous generation with his
concept of biogenesis
 Living

organisms arise from pre-existing life
Virchow presented his idea to the scientific
community, but could not back it up with a
convincing experiment
History of Microbiology
 In
1861, a French scientist by the name of
Louis Pasteur demonstrated where
microorganisms came from

Father of Medical Microbiology

Demonstrated the microorganisms exist in
the air and could contaminate sterile
solutions by passing air through cotton filters
 The
air
filter trapped tiny particles floating in the
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History of Microbiology
 Louis
Pasteur performed numerous
experiments to discover why wine and
dairy products became sour

He found that bacteria were to blame

Pasteur called attention to the importance
of microorganisms in everyday life and stirred
scientists to think that if bacteria could make
the wine “sick,” then perhaps they could
cause human illness.
Louis Pasteur’s Swan neck flask
experiment
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Golden Age of Microbiology
1857- 1914

Beginning with Pasteur’s work, discoveries
included the relationship between microbes and
disease, immunity and antimicrobial medicine

Germ theory of disease

Pasteur showed that microbes are responsible for
fermentation

Microbial growth is also responsible for spoilage of
food

Pasteur demonstrated that spoilage bacteria
could be killed with heat (pasteurization)

Developed vaccines for anthrax (1881)and rabies
(1885)
Germ theory disease
 1835:
Agostino Bassi- showed a silkworm
diseases was caused by a fungus
 1865:
Pasteur- believed that another
silkworm disease was caused by a
protozoan
 1840s:
Ignaz Semmelwise- advocated hand
washing to prevent transmission of fever
from one OB patient to another
Germ theory disease

1860s: Joseph Lister- He is the father of antiseptic
surgery.


He used a chemical disinfectant (carbolic acid) to
prevent surgical wound infections after Pasteur’s
work showing microbes are in the air, can spoil
food, and cause animal disease.
1867: Robert Koch- provided proof that
bacterium causes anthrax and provided the
experimental steps, Koch’s postulates, used to
prove that a specific microbe causes a specific
disease.
Koch’s postulates
 Pathogen
must be present in all cases of
disease
 Pathogen must be isolated and grown in
lab in pure culture
 Pathogen from pure cultures must cause
disease when inoculated into healthy,
susceptible lab animal
 Same pathogen must be isolated from the
diseased lab animal
History of Vaccination
A
precursor of smallpox vaccination was
variolation

An early Asian method which introduced
dried scabs of smallpox patients and was later
modified in Europe
 Modification
consisted of injecting infectious
material under the skin

First tested among abandoned children and
prisoners

When it was declared safe, members of the English
royal family were inoculated
Vaccination continued:
 1796:
Edward Jenner is credited with the
development of the smallpox vaccine
 Folk
wisdom suggested that dairy maids
who had contracted cowpox seemed to
be immune to smallpox

Infection with the cowpox virus produced a
much less sever form of disease that
smallpox
Vaccination continued

Jenner conducted an
experiment in which he
used scabs from the
cowpox lesions on the
arm of a dairy maid,
Sarah Nelmes to create
a small pox vaccine

He then used the
material to vaccinate
an 8 year old boy,
James Phipps

After being vaccinated
Phipps appeared to
develop immunity to
the smallpox virus.
Vaccination continued
 Later
Jenner vaccinated his own son and
several other children

He obtained similar results
 Worldwide
elimination of smallpox was
achieved in 1978
 Called
 The
vaccination from vacca for cow
protection is called immunity
Antibiotics

1928: Alexander Fleming
discovered the first antibiotic.

He observed that Penicillium
fungus made an antibiotic,
penicillin, that killed S. aureus.

1940s: Penicillin was tested
clinically and mass produced
and was available towards the
end of World War II
Development of Agar
 Angelina
Hesse developed the use of
Agar to grow microorganisms.



She was the wife of Walter Hesse who
worked in Koch’s laboratory
Advantages of agar- It was not attacked
by most bacteria.
Agar is better than gelatin because of its
higher melting point (96°c) and solidifying
(40–45°c) points.
Petri Dish

Richard Petri (1887)

He developed the Petri dish (plate), a
container used for solid culture media