1 bacteriology
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The Blind Men and the Elephant
³The sensual eye is just like the palm of the hand. The palm has not the means of covering the whole of the beast.´ (Rumi)
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Introduction to Microbiology
Describe the historical development of
microbiology
Enumerate the development of science withemphasis on person/scientists and their
contributions
Explain the divisions of microbiology
Define terms
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Historical Development
The beginnings«1665, England ± Robert Hooke
Book ³Micrographia´
Compound microscope and its uses
Cell theory: ³All living things are composed
of cells.´ History of cell biology
Jan Swammerdam ± red blood cells
Regnier de Graaf ± Graafian follicles (animalovary)
Marcello Malpighi ± tiny capillaries of ananimal¶s cardiovascular system.
Importance of the microscope as a tool for unlocking the secrets of nature.
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Images: Hooke memorial window, St Helen's Bishopsgate (now destroyed); flea, from Micrographia; t itle page from Micrographia; drawing of cells (the first Biological use of the word) in cork.
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Historical Development: The Beginnings«
My work, which I've done for along time, was not pursued inorder to gain the praise I now
enjoy, but chiefly from acraving after knowledge,
which I notice resides in me
more than in most other men. And therewithal, whenever I
found out anythingremarkable, I have thought it
my duty to put down my
discovery on paper, so that allingenious people might beinformed thereof.
Letter of June 12, 1716 Anton van Leeuwenhoek (1632-1723)
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Historical Development: The Transition Period
S taphylococcus aureus Describes the clustered arrangement
of the cells (staphylo) and the goldencolor of the colonies.
E scherichia coli Honors the discoverer, Theodor Escherich, and describes
the bacterium¶s habitat, the large intestine or colon.
After the first use, scientific names may beabbreviated with the first letter of the genus and the
specific epithet: S taphylococcus aureus and E scherichia coli are found in
the human body. S. aureus is on skin and E. coli , in thelarge intestine.
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Historical Development: The Transition Period
Spontaneous Generation
Aristotle¶s hypothesis:Decaying material could betransformed by the µspontaneous action of nature¶into living animals.
toads, frogs, snakes and mice ± moist/muddy soil or moldygrain
flies and maggots - manure and decaying flesh (rottenmeat)
rats ± sewage and garbage
Jan Baptista van Helmont¶s recipe for mice: Place a dirty shirt or some rags in an open pot or barrel
containing a few grains of wheat or some wheat bran, and in21 days, mice will appear. There will be adult males andfemales present, and they will be capable of mating andreproducing more mice.
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Historical Development: The Transition Period,
Spontaneous Generation Debate
In 1668, Francesco Redi, an Italian physician.
first real experiment to dispute the theory
Conclusion:Only flies can make more flies. In the uncovered jars, flies entered and laid eggs on the meat. Maggots hatched from these eggs and grew into
more adult flies. Adult flies laid eggs on the gauze on the gauze-covered jars. These eggs or the maggots from them dropped through the gauze onto the
meat. In the sealed jars, no flies, maggots, nor eggs could enter, thus none were seen in those jars. Maggots arose only where flies were able to lay eggs.
This experiment disproved the idea of spontaneous generation for larger organisms.
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Historical Development: The Transition Period,
Spontaneous Generation Debate
1745 (1748?): John Needham Put boiled nutrient broth into covered flasks = + Microbial growth
Claimed that there was a ³life force´ present in the molecules of all inorganic matter,including air and the oxygen in it, that could cause spontaneous generation to occur,thus accounting for the presence of bacteria in his soups.
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Historical Development: The Transition Period,
Spontaneous Generation Debate
1765: Lazzaro Spallanzani 1st, boiled soup (1 hour), sealed glass flasks = No microbial growth.
2nd, boiled soup (a few minutes) before sealing the flasks = +Microbial growth.
3rd
, soup boiled (1 hour), flasks sealed with real-corks (air) = +Microbial growth.
Concluded that while 1 hour of boiling would sterilize the soup, only afew minutes of boiling was not enough to kill any bacteria initiallypresent, and the microorganisms in the flasks of spoiled soup hadentered from the air.
Initiated a heated argument over sterilization(boiled broth in closed vs. open containers)as a way of refuting spontaneous generation.
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Historical Development: The Transition Period,
Spontaneous Generation versus Biogenesis
1858 ± Rudolph Virchow: ³Every cell comes from a cell.´
By 1860, Paris Academy of Sciences offered a prize for any experiments that would help resolve the conflictabout spontaneous generation.
The prize was claimed in 1864 by Louis Pasteur :
Observation: From Needham¶s and Spallanzani¶sexperiments, it was known that soup that was exposedto the air spoiled ² bacteria grew in it.
Question: Is there indeed a ³life force´ present in air (or oxygen) that can cause bacteria to develop byspontaneous generation? Is there a means of allowingair to enter a container, thus any life force, if such doesexist, but not the bacteria that are present in that air?
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Historical Development: The Transition Period,
Spontaneous Generation versus Biogenesis
Hypothesis: There is no such life force in air,and a container of sterilized broth will remainsterile, even if exposed to the air, as long asbacteria cannot enter the flask.
Prediction: If there is no life force, broth inswan-neck flasks should remain sterile, even if exposed to air, because any bacteria in the air
will settle on the walls of the initial portion of theneck. Broth in flasks plugged with cotton shouldremain sterile because the cotton is able to filter bacteria out of the air.
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Historical Development: The Transition Period,
Spontaneous Generation versus Biogenesis
Testing: Pasteur boiled broth in various-shaped flasks tosterilize it, then let it cool. As the broth and air in thecontainers cooled, fresh room air was drawn into thecontainers. None of the flasks were sealed ² all wereexposed to the outside air in one way or another.
control group ² Some flasks opened straight up, sonot only air, but any bacteria present in that air, could getinto them.experimental groups ² Pasteur used some flasks withlong, S-shaped necks (swan-neck flasks) and closedothers with cotton plugs. This allowed air to enter these
flasks, but the long, swan neck or the cotton balls filteredout any bacteria present in that air. He subsequentlybroke the long necks off some of the swan-neck flasks.replication ² Pasteur used several flasks in each of hisgroups.
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Historical Development: The Transition Period,
Spontaneous Generation versus Biogenesis
Data: Broth in flasks with necks opening straight upspoiled (as evidenced by a bad odor, cloudiness inpreviously clear broth, and microscopic examination of the broth confirming the presence of bacteria), whilebroth in swan-neck flasks did not, even though fresh air could get it. Broth in flasks with cotton plugs did notspoil, even though air could get through the cotton. If theneck of a swan-neck flask was broken off short, allowingbacteria to enter, then the broth became contaminated.
Conclusion: There is no such life force in air, and
organisms do not arise by spontaneous generation inthis manner. To quote Louis Pasteur, ³Life is a germ, anda germ is Life. Never will the doctrine of spontaneousgeneration recover from the mortal blow of this simpleexperiment.´
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Historical Development: The Transition Period,
Spontaneous Generation versus Biogenesis
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Historical Development - THE GOLDEN AGE OF MICROBIOLOGY:
Fermentation and Pasteurization
1857-1914 Beginning with Pasteur¶s work, discoveries
included the relationship between microbes and
disease, immunity, and antimicrobial drugs
Microbes are responsible for fermentation.
Fermentation is the conversion of sugar to
alcohol to make beer and wine.
Microbial growth is responsible for spoilage of
food.
Bacteria that use alcohol and produce acetic
acid spoil wine by turning it to vinegar (acetic
acid). Spoilage bacteria could be killed by heat that
was not hot enough to evaporate the alcohol in
wine. This application of a high heat for a short
time is called pasteurization.
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The Germ Theory of Disease
Hard for people to believe that diseases were
caused by tiny invisible ³wee animalcules´
Diseases, they thought, were caused by:
demons
witchcraft
bad luck
the wrath of God curses
evil spirits
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Historical Development - THE GOLDEN AGE OF MICROBIOLOGY:
The Germ of Theory of Disease
1835: Agostino Bassi showed asilkworm disease was caused by a
fungus.
1865: Pasteur believed that another
silkworm disease was caused by aprotozoan.
1840s: Ignaz Semmelweis
advocated handwashing to
prevent transmission of puerperal fever from one OB
patient to another.
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Historical Development - THE GOLDEN AGE OF MICROBIOLOGY:
The Germ of Theory of Disease
1860s: Joseph Lister used a chemical disinfectant
(carbolic acid) to prevent surgical wound infections
after looking at Pasteur¶s work showing microbes
are in the air, can spoil food, and cause animaldiseases.
1876: Robert Koch provided proof that a bacterium
causes anthrax and provided the experimentalsteps, Koch¶s postulates, used to prove that a
specific microbe causes a specific disease.
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Exceptions to K och·s Postulates
1. Many healthy people carry pathogens butdo not exhibit symptoms of the disease.These ³carriers´ may transmit the
pathogens to others who then may becomediseased. (hospital-acquired infections,typhoid fever, diphtheria)
2. Some microbes are very difficult or
impossible to grow in vitro in artificial media.(viruses, rickettsias, chlamydias, M . leprae,T . pallidum)
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Exceptions to K och·s Postulates
3. To induce a disease from a pure culture, the
experimental animal must be susceptible to
that pathogen. Many animals (rats) are very
resistant to microbial infections. Manypathogens are species-specific. (V . cholerae
that causes cholera in humans does not
cause hog cholera and vice versa.) Use of human volunteers ± difficult to find; ethical
considerations limit their use
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Exceptions to K och·s Postulates
4. Certain diseases develop only when an opportunisticpathogen invades a weakened host. These secondaryinvaders or opportunists cause disease in a person whois ill or recovering from another disease. (pneumonia andear infections which may follow influenza)
Koch established the Microbial Etiology of 3 importantdiseases of his day:
Cholera (fecal-oral disease)
V ibrio cholerae
2. Tuberculosis (pulmonary infection) Mycobacterium tuberculosis
3. Anthrax (sheep and cattle)
Bacillus anthracis
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Historical Development: V accination
1796: Edward Jenner inoculated a person
with cowpox virus.
The person was then
protected fromsmallpox.
Called vaccination
from vacca for cow The protection is
called immunity
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Historical Development:
The Birth of Modern Chemotherapy Treatment with chemicals is chemotherapy.
Chemotherapeutic agents used to treat infectious
disease can be synthetic drugs or antibiotics.
Antibiotics are chemicals produced by bacteria andfungi that inhibit or kill other microbes.
Quinine from tree bark was long used to treat
malaria.
1910: Paul Ehrlich developed a synthetic arsenicdrug, salvarsan, to treat syphilis.
1930s: Sulfonamides were synthesized.
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Historical Development:
The Birth of Modern Chemotherapy 1928: Alexander
Fleming discovered the
first antibiotic.
He observed thatP enicillium fungus made
an antibiotic, penicillin,
that killed S. aureus.
1940s: Penicillin wastested clinically and
mass produced.
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Historical Development:
Modern Developments in Microbiology
Bacteriology is the study of bacteria.
Mycology is the study of fungi.
Parasitology is the study of protozoa andparasitic worms.
Recent advances in genomics, the study of
an organism¶s genes, have provided new
tools for classifying microorganisms.
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Historical Development:
Modern Developments in Microbiology
Immunology is the study of
immunity. Vaccines and
interferons are being
investigated to prevent and cure
viral diseases.
The use of immunology to
identify some bacteria according
to serotypes (variants within a
species) was proposed byRebecca Lancefield in 1933.
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Historical Development:
Modern Developments in Microbiology
Using microbes
George Beadle and Edward Tatum showed that
genes encode a cell¶s enzymes (1942)
Oswald Avery, Colin MacLeod, and MaclynMcCarty showed that DNA was the hereditary
material (1944).
Francois Jacob and Jacques Monod discovered
the role of mRNA in protein synthesis (1961).
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Selected Novel Prizes in Physiology or Medicine
1901* von Behring Diphtheria antitoxin
1902 Ross Malaria transmission
1905 Koch TB bacterium
1908 Metchnikoff Phagocytes
1945 Fleming, Chain, Florey Penicillin
1952 Waksman Streptomycin
1969D
elbrück, Hershey, Luria Viral replication1987 Tonegawa Antibody genetics
1997 Prusiner Prions
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Historical Development:
Microbes and Human Welfare
Microbial Ecology
Bacteria recycle carbon,nutrients, sulfur, and phosphorusthat can be used by plants andanimals.
Bioremediation
Bacteria degrade organic matter
in sewage.
Bacteria degrade or detoxifypollutants such as oil and
mercury
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Historical Development:
Microbes and Human Welfare
Biological Insecticides
Microbes that are pathogenic to
insects are alternatives to chemical
pesticides to prevent insect damage
to agricultural crops and disease
transmission.
� Bacillus thuringiensis infections are
fatal in many insects but harmless
to other animals including humansand to plants.
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Historical Development:
Microbes and Human Welfare
Modern Biotechnology
and Genetic Engineering
Biotechnology, the use of microbes
to produce foods and chemicals
(centuries old)
Genetic engineering - a new technique
for biotechnology. Bacteria and fungi
can produce a variety of proteins including vaccines and
enzymes.
Missing or defective genes in human cells can be replaced
in gene therapy.
Genetically modified bacteria - used to protect crops from
insects and freezing.
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Historical Development:
Microbes and Human Disease
Bacteria were once classified as plants which gave rise to use of
the term f lora for microbes.
This term has been replaced by microbiota.
Microbes normally present in and on the human body are called
normal microbiota.
Normal microbiota prevent growth of pathogens.
Normal microbiota produce growth factors such as folic acid and
vitamin K.
Resistance is the ability of the body to ward off disease.
Resistance factors include skin, stomach acid, and antimicrobial
chemicals.
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Historical Development:
Microbes and Human Disease
Infectious Diseases
When a pathogen overcomes the host¶s resistance, disease results.
Emerging Infectious Diseases (EID): New diseases and diseases increasing
in incidence
Emerging InfectiousD
iseases West Nile encephalitis
West Nile Virus
First diagnosed in the West Nile region of Uganda in 1937.
Appeared in New York City in 1999.
Bovine Spongiform Encephalopathy
Prion
Also causes Creutzfeldt-Jakob disease (CJD)
New-variant CJD in humans related to cattle fed sheep offal for protein.
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Historical Development:
Microbes and Human Disease
Invasive group A S treptococcus
Rapidly growing bacteria cause extensive tissue
damage.
Increased incidence since 1995
E scherichia coli O157:H7
Toxin-producing strain of E. coli Fist seen in 1982
Leading cause of diarrhea worldwide.
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Historical Development:
Microbes and Human Disease
Ebola hemorrhagic fever
Ebola virus; causes fever, hemorrhaging, and blood clotting
First identified near Ebola River, Congo
Outbreak every few years
H antavirus pulmonary syndrome
H antavirus
Fist identified in 1951 in Korea as cause of hemorrhagic fever
and named for Hantaan River
A new disease involving respiratory symptoms was seen in theU.S. in 1995
The U.S. virus, called H antavirus Sin Nombre virus, probably
came to the U.S. with rats around 1900
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Historical Development:
Microbes and Human Disease
Acquired immunodeficiency syndrome (AIDS)
Human immunodeficiency virus (HIV)
First identified in 1981.
Worldwide epidemic infecting 40 million people;
14,000 new infections everyday.
Sexually transmitted disease affecting males and
females.
In the U.S., HIV/AIDS in people 13-24 years of
age: 44% are female and 63% are African
American.
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Historical Development:
Microbes and Human Disease
Anthrax
Bacillus anthracis
In 1877, Koch proved B. anthracis causes
anthrax.
Veterinarians and agricultural workers are at risk
of cutaneous anthrax.
In 2001, dissemination of B. anthracis via mail
infected 22 people.
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´Microbiology is like sand; it is blown
about by time and is constantly shifting.µ
QUESTIONS?
Identify persons/scientists involved in the
historical development of microbiology and
described their significant contributions.
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ASSIGNMENTDefine the following terms:
Microbiology
Microorganisms
Bacteria
Fungi
Protozoan
Viruses
Pathogen
Opportunistic pathogen
Etiologic agent
Endospore
Pasteurization
Sterilization
Tyndallization
Autoclave
Disinfection
Antisepsis Antiseptic technique
Culture
Resistance
Susceptibility
Pathogenicity
Carrier
Virulence
Infection
Invasiveness
Nosocomial infection
Spoilage
Disease
Microbiota
Infectious diseases
Mode of transmission
Bacteriology
Protozoology
Parasitology
Sensitivity
Virology
Mycology
Immunology Molecular biology
Microbial ecology
Genomics
RecombinantDNAtechnology
Genetic engineering
Bioremediation
Biotechnology
Genetically modified bacteria
Vaccination
Vaccines
Chemotherapy
Immunity
Antimicrobial drugs Antibiotics
Interferons
Antigen
Antibody
Serotype
Toxin
Immunodeficiency
Immunocompromisedimmunosuppression
epidemic
endemic
Pandemic
sporadic
incidence