Download S01 Scope And History Of Microbiology

07/02/2017
Scope and History of
Microbiology
Jacquelyn G. Black, Microbiology, 8th
Edition
Chapter 1 – Page 1
Mahmoud Alkawareek, PhD
Introduction
• Microbiology
is the
study
of
microbes
(microorganisms), they are so small (in the scale of
microns) that need microscope to study them.
• Microorganisms present almost everywhere; in air,
water (oceans, springs, drinking water), soil, animal
& human body (GIT, respiratory tract and skin), in the
deep hot interior of earth (temp reaching 110 °C),
Antarctic…
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Why Study Microbiology? –
Importance of Microorganisms
• Important disease mediators
• Production of antibiotics and vaccines
• Genetic engineering: production of interferon,
growth hormone, insulin…
• Food industry: to make pickles, yogurt…
• Fermentation: used to make dough and
alcohol
• Nitrogen fixation for plants
Mahmoud Alkawareek, PhD
Why Study Microbiology? –
Importance of Microorganisms
• Can be the first element of a food chain: some
capture energy & store it in molecules that
other organisms use as food source
• Certain m.o. live in digestive system of grazing
animals & serve in digestive process
• Some m.o. decompose dead organism or
waste material
• Research: ecology, biochemistry, genetics…
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Scope of Microbiology –
Types of Microorganisms
• Bacteria
- Prokaryotes
- Majority are single celled with spherical , rod, spiral shapes, few are
filamentous.
- Most of them absorb nutrient from environment, some make their
nutrient by photosynthesis or other route.
- Widely distributed in environment & decaying matter
- Some cause diseases (pathogenic bacteria)
• Algae
- Many of them are single celled microscopic organism
- Some are large complex multicellular
- They capture energy from light & are a source of food for other
organisms
Mahmoud Alkawareek, PhD
Scope of Microbiology –
Types of Microorganisms
• Fungi
- Yeasts are unicellular, but molds may be unicellular or multicellular
such as mushrooms
- All fungi absorb ready made nutrients
- Fungi are distributed in water, soil & decomposing dead organisms,
- Some cause diseases, others produce antibiotics
• Viruses
- Acellular entities composed of nucleic acids (DNA or RNA) and
proteins
- Very small size; not seen by light microscope
- When viruses are extracellular they are non-viable, but once they
enter a living cell they start to replicate
- Many viruses can invade human cells & cause disease
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Scope of Microbiology –
Types of Microorganisms
• Viroids
- Very small acellular infectious agents
- Composed of nucleic acid without protein coating
- They cause plant diseases
• Prions
- Protein without any nucleic acid
- Cause mad cow
Encephalopathy - BSE)
disease
(Bovine
Spongiform
- in humans: Creutzfeldt-Jakob Disease (CJD)
Mahmoud Alkawareek, PhD
Scope of Microbiology –
Types of Microorganisms
• Protozoa
- Single celled microscopic m.o.; although few amoeba can be seen by
naked eye
- With at least one nucleus & numerous intracellular structures
- They gain food by engulfing or ingesting other m.o.
- They are found in soil, water & animals
• Helminths (worms)
- They are bigger organisms but have microscopic stage in their life cycle
• Arthropods (insects)
- Studied in microbiology because they can transmit microbes & cause
diseases (i.e. biological vectors)
- e.g. Tsetse fly is a vector of Trypanosoma which causes sleeping
sickness
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Scope of Microbiology –
Fields of Microbiology
Mahmoud Alkawareek, PhD
Scope of Microbiology –
Fields of Microbiology
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Scope of Microbiology –
Fields of Microbiology
Mahmoud Alkawareek, PhD
History of Microbiology
• Robert Hooke (1664)
- Built a compound microscope and used it to observe thin slices of
cork
- He coined the term cell to describe the orderly arrangement of small
boxes that he saw
because they reminded him of the cells (small, bare rooms) of monks
• Anton van Leeuwenhoek (1684)
- The first to make and use lenses to observe living microorganisms
- The lenses Leeuwenhoek made were of excellent quality; some gave
magnifications up to 300X
- Everywhere he looked he found what he called ‘‘animalcules.’’
• Schleiden and Schwann
- Formulated the cell theory
It states that cells are the fundamental units of life and carry out all the basic
functions of living things
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History of Microbiology –
The Germ Theory of Disease
• The Hypothesis of Spontaneous Generation
- It sets that the combination of water , fire , air and soil can
create or convert a non living thing to a living organism
e.g. rodents arose from mist grains, beetles from dust, worms & frogs
from mud, maggots from rotting meat!
• Francesco Redi:
- Meat & open/closed jar.
- He discovered that maggots only appeared on the
uncovered meat (when flies laid eggs in the meat.)
• Lazaro Spallanzani
- Boil broth, close it  no spoilage (no microbial growth)
- But critics: loss of O2 inhibited growth of organisms
Mahmoud Alkawareek, PhD
History of Microbiology
• Louis Pasteur (1822)
- Ended the debate about ‘spontaneous generation’ with his
famous swan-neck flask experiment
-
This experiment allowed air to contact the broth
-
Microbes present in the dust were not able to navigate the tortuous
bends in the neck of the flask
- He developed the technique of pasteurization so as to kill
unwanted organisms (heating wine to 56 °C in the absence of
oxygen for 30 min)
- He contributed in the wine and silk industry
- Developed vaccine for rabies
- Made of dried spinal cord from rabbits infected with rabies
- Administered to a 9-year-old boy who had been severely bitten by a
rabid, then the boy survived
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History of Microbiology
Mahmoud Alkawareek, PhD
History of Microbiology
• Robert Koch
- Found ways to grow bacteria in pure culture
First he used gelatin but it melts as some microbes liquefy it, then he
took the suggestion of Angelina Hesse to add agar to his
bacteriological media
- Identified the bacteria that causes anthrax in both dividing
and dormant (spore) form
- He identified the bacterium that causes tuberculosis
- He developed tuberculin as a vaccine for tuberculosis
Although tuberculin failed as a vaccine, it is still used in a skin test to
diagnose tuberculosis
- He coined a theory that associates a certain microorganism
with a certain disease (Koch’s Postulates )
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History of Microbiology
• Koch’s Postulates
1.
The causative microbe should be
found in all organisms suffering
from the disease, but not in healthy
ones
2.
The microbe must be isolated from
a diseased organism and grown in
pure culture
The cultured microbe should cause
the same disease when inoculated
into a healthy organism
The microbe should be re-isolated
from the newly infected organism
and shown to be the same as the
original causative microbe
3.
4.
Mahmoud Alkawareek, PhD
History of Microbiology
• The Germ Theory of Disease
- Findings of the previous scientists paved the way for
recognizing the germ theory of disease
- It states that microorganisms (germs) can invade other
organisms and cause disease
• Virology
- Emerged after bacteriology due to size of viruses
- Scientists used porcelain filter to remove bacteria
from water but the filtrate remained infectious due to
very small pathogenic agents which were then
recognized to be viruses
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History of Microbiology –
Aseptic Technique
• Ignaz Semmelweis
- He found a connection between staff hygiene (cleanliness)
and the incidence of puerperal (childbed) fever
- He proposed the practice of hand washing with
chlorinated lime (calcium hypochlorite) solutions to reduce
the postpartum mortality rate
- But some doctors were offended by his suggestions!!
• Joseph Lister
- Initiated the use of dilute carbolic acid (phenol) on
bandages & instruments to reduce the incidence of postoperative infections
- Considered as the father of aseptic surgery
Mahmoud Alkawareek, PhD
History of Microbiology –
Immunology
• The Ancient Chinese
- Noticed that a person scarred by smallpox would not again
get the disease
- Took dried scabs from people recovering from the disease
and ground them into a powder that they sniffed. This
technique is known as ‘Variolation’
- ‘Variolated’ people acquired a mild case of smallpox but
were protected against subsequent infection
- Variolation was later practiced in Europe but by soaking a
thread in the fluid of a smallpox vesicle (blister) and then
introducing it through a small incision in the arm
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History of Microbiology –
Immunology
• Edward Jenner
– Observed that milkmaids who got cowpox didn't get smallpox
(because the antigen of cowpox is similar to smallpox)
– Inoculated an 8-year-old child with fluid from a cowpox blister, then he
inoculated the same child with smallpox and noticed that the child
remained healthy
– The word vaccinia (vacca, the Latin name for ‘‘cow’’) gave rise both to
the name of the virus that causes cowpox and to the word vaccine
• Elie Metchnikoff
– Older scientists believed that immunity is due to non-cellular
substances in the blood
– Metchnikoff discovered that certain cells in the body would ingest
microbes. He named those cells phagocytes 'cell eating'
– He developed several vaccines, some were successful while others
failed
Mahmoud Alkawareek, PhD
History of Microbiology –
Chemotherapy
• Paul Ehrlich
– Discovered that certain dyes stained microorganisms but not animal
cells which set the ground for the concept of ‘selective toxicity’
– This led him to search for the ‘magic bullet’, a chemical that would
destroy specific bacteria without damaging surrounding tissues
– He used Salvarsan to treat syphilis
– He coined the term ‘chemotherapy’
• Alexander Fleming
– Observed that a colony of Penicillium mold contaminating a culture of
Staphylococcus had prevented the growth of bacteria, this observation
lead to the discovery of penicillin
• While the work on penicillin was going on, sulfa drugs were also
being developed from sulfonamide-containing dyes (i.e. prontosil)
• Many antibiotics were then produced from soil bacteria e.g.
streptomycin, chloramphenicol and chlorotetracycline
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Modern History of Microbiology –
Examples
• Genetic engineering
– Scientists have converted bacteria and other
microorganisms to factories that produce drugs,
hormones, vaccines & other biologically important
compounds
• Bacteriophage therapy
– Bacteriophages are viruses that attack & kill specific
bacteria
– Developed back in the 1920s especially in Eastern Europe
and the Soviet Union
– Today, there is a trend to re-examine such an approach
especially with the progressive emergence of antibiotic
resistance.
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