introduction to medical microbiology

1. ‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬
Introduction to Microbiology (1)
Dr. Abdelhakam Hassan Aldigeal
Assistant Professor of Medical Microbiology
Aldigeal007@gmail.com

2. Scope of Microbiology
Microbiology
 study of organisms too small to be seen by the naked eye.
• Microbes or Microorganisms
 commonly referred to as “germs” or “bugs”
 include bacteria, viruses, fungi, algae, protozoa and
helminths.
 Prions (“infectious proteins”) are recent addition.

3. Why study Microbiology
• Microbes are related to all life.
– In all environments
– Many beneficial aspects
– Related to life processes (food, nutrient cycling)
– Only a minority are pathogenic.
– Most of our problems are caused by microbes

4. Old times…
• Humans knew how to deal with germs before even knowing
about their existence
• Storing food in cooler temperatures
• Salting, drying, smoking
• Cremation of dead burying

5. Discovery of Microorganisms
Antony van Leeuwenhoek
(1632-1723), the father of
microbiology
– microscopist
Dutchman
– first to observe and
describe
microorganisms
accurately

6. Hook’s microscope

7. Jenner and vaccination
•Vaccination comes from Latin
word “vacca” meaning cow.
• Jenner laid the foundation for
Pasteur’s later work with
other vaccinations.
is credited with first vaccine – in
epidemics of smallpox during the
late 1700’s he observed that milk
maids didn’t get the disease.

8. Flemming and Penicillium
• Alexander Fleming - Scottish physician and bacteriologist -
1928
• Observed mold growing on a bacteria culture, there was a ring
of clearing around the mold where the bacteria didn’t grow, the
mold was later found to be a Penicillium species and the
naturally secreted chemical was called penicillin, an antibiotic

9. Where do microorganism originate
from?
•Spontaneous generation??
Few days of
being
exposed to air.

10. The Conflict over Spontaneous Generation
• spontaneous generation
– living organisms can develop from nonliving or
decomposing matter
– publically a common sense vision with social and cultural
roots (almost 2000 years ago)
– Examples:
• flies from rotten meat and animal carcasses
– Scientific methodology was not established
– What was the proof?

11. Jan Baptista Van Helmont
(1577-1644)
• A Flemish noble man, alchemist
and physician
• believed in spontaneous generation

12. Jan Baptista Van Helmont
The Origin of life
(17th Centuray)
Adult mice
1579-1644

13. Spontaneous Generation

14. Could spontaneous
generation be true
for microorganisms?

15. Francesco Redi
(1626-1697)
•First blow to spontaneous generation
•Laying eggs is required for maggots and flies to come to
existence
•Supporters of SG:
• Life is necessary in order to bring about life in certain cases!

16. Francesco Redi
(1626-1697)

17. John Needham
(1713-1781)
• Conclusion: Organic matter had vital force that confers
properties of life to non-living matter
• BUT: he had left the flasks unsealed after bioling

18. Lazzaro Spallanzani
(1729-1799)
•Air carries germs to broth and boiling kills the existing ones
•Supporters of SG:
•Compounds essential for generation of life were destroyed by
heating!!
•sealing prevents air that is necessary for spontaneous generation
Microorganisms
Killed
Time
Microorganisms
Killed
Time

19. Louis Pasteur
(1822-1895)
• Pasteur – French scientist that dealt the
death blow to the spontaneous
generation theory.
• He proved that fermentation was
caused by a microbe – yeast
• He developed vaccines for rabies and
anthrax.
• He began the revolution in science that
led to the Golden Age of Microbiology
(from 1857-1914)

20.  Pasteur’s Swan neck
flasks could supply air but
could also trap ambient germs
from entering broth

21. 21

22. Pasteur Refutes the Spontaneous
Generation
He was very lucky – no endopores present, or it would have failed
(resistant to boiling)

23. Pasteur Refutes the Spontaneous Generation
ambient germs are necessary for promoting growth principle of
sterility and aseptic work is important

24. Other evidence…
• Joseph Lister (1827-1912)
– provided indirect evidence
– used diluted carbolic acid (phenol)
to wash surgical devices and wash wounds
– developed the principles of aseptic
surgery
– his patients had fewer postoperative
infections
– Disease frequency dropped in his hospital