1 Bacteriology

8/6/2019 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)



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



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.



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.





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)





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.



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.



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.





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.





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.




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?





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.





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.





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.´







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.



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




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.




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.



K och·s Postulates



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)




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




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



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



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.




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.




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.





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.







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).



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




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





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.





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.




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.





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.





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.





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





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.





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.



´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.



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

Documents

1 Bacteriology