Transcript Alexander Fleming

By: M.Bilal
Class: 8-T
Who is Alexander Fleming?
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Sir Alexander Fleming was a Scottish biologist,
pharmacologist and botanist.
His best-known discoveries are the enzyme
lysozyme in 1923 and the world's first
antibiotic substance benzylpenicillin from the
mould Penicillium notatum in 1928, for which
he shared the Nobel Prize in Physiology or
Medicine in 1945 with Howard Florey and
Ernst Boris Chain.
He wrote many articles on bacteriology,
immunology, and chemotherapy.
Early Life and Education.
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Alexander Fleming was born on August 6,
1881 at his parents’ farm located near the
small town of Darvel, in Scotland, UK.
Alexander attended the Polytechnic School,
where he studied business and commerce.
He started in a class appropriate to his age, but
his teachers soon realized he needed more
challenging work.
He was moved into a class with boys two years
older than him and finished school aged 16.
Medical school and work.
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In 1903, aged 22, Alexander enrolled at London’s St Mary’s
Hospital Medical School, graduating with distinction three
years later as Bachelor of Medicine, Bachelor of Surgery.
Alexander was persuaded by Almroth Wright to become a
researcher in his bacteriology group at St Mary’s Hospital
Medical School. While carrying out this research Fleming
graduated, in 1908, with a degree in bacteriology and the
Gold Medal for top student.
St Mary’s Hospital Medical School then promoted him to
the role of bacteriology lecturer.
Fleming became particularly fascinated by the fact that,
although many people suffered bacterial infections from
time to time, the majority of people’s natural defenses
prevented infections from taking hold.
The greatest contributions to science.
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In 1914 World War 1 broke out and Fleming, aged 33, joined the
army, becoming a captain in the Royal Army Medical Corps,
working in field hospitals in France.
There, in a series of brilliant experiments, he established that
antiseptic agents used to treat wounds and prevent infection were
actually killing more soldiers than the infections were!
The antiseptics, such as carbolic acid, boric acid and hydrogen
peroxide, were failing to kill bacteria deep in wounds; worse, they
were in fact lowering the soldier’s natural resistance to infection
because they were killing white blood cells.
Fleming demonstrated that antiseptic agents were only useful in
treating superficial wounds, but were harmful when applied to
deep wounds.
Almroth Wright believed that a saline solution – salt water –
should be used to clean deep wounds, because this did not
interfere with the body’s own defenses and in fact attracted white
cells. Fleming proved this result in the field.
Discovery of Lysozyme
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In 1919 Fleming returned to research at St Mary’s Hospital Medical School
in London. His wartime experience had firmly established his view that
antibacterial agents should only be used if they worked with the body’s
natural defenses rather than against them; in particular, they must not
harm white blood cells.
His first discovery of such an agent came in 1922, when he was 41 years
old.
Fleming had taken secretions from inside the nose of a patient suffering
from a head cold. He cultured the secretions to grow any bacteria that
happened to be present. In the secretions, he discovered a new bacterium
he called Micrococcus lysodeikticus, now called M lutes.
. A few days later, Fleming was examining these bacteria. He himself was
now suffering from a head cold, and a drop of mucus fell from his nose on
to the bacteria. The bacteria in the area the drop had fallen were almost
instantly destroyed. Always on the lookout for natural bacteria killers, this
observation excited Fleming enormously
He tested the effect of other fluids from the body, such as blood serum,
saliva, and tears, on these bacteria and found that bacteria would not grow
where a drop of one of these fluids had been placed.
Discovery of Lysozyme Part 2
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Fleming discovered the common factor in the fluids was an enzyme.
He named his newly discovered enzyme lysozyme. The effect of lysozyme was to
destroy certain types of microbe, rendering them harmless to people. The presence
of lysozyme in our bodies prevents some potentially pathogenic microbes from
causing us harm. It gives us natural immunity to a number of diseases.
However, lysozyme’s usefulness as a medicine is rather limited, because it has little
or no effect on many other microbes that infect humans.
It did, however, mean that Fleming had discovered a natural antibiotic which did
not kill white blood cells. If only he could find a more powerful antibiotic, then
medicine could be transformed.
Today, lysozyme is used as a food and wine preservative. It is naturally present in
especially large concentrations in egg-whites, offering protection against infection
to chicks.
It is also used in medicines, particularly in Asia, where it is used in treatments for
head colds, athlete’s foot and throat infections.
Lymozome enzyme
•Lysozyme
is
shown here in
blue. It is an
enzyme, meaning
it is a type of
protein. It
destroys bacteria
by breaking
down their cell
walls, shown in
pink.
Discovery of penicillin
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On Monday, September 3, he returned to his laboratory and saw a pile of Petri dishes
he had left on his bench. The dishes contained colonies of Staphylococcus bacteria.
While he was away, one of his assistants had left a window open and the dishes had
become contaminated by different microbes.
Fleming looked through the dishes and found something remarkable had taken place
in one of them.
A fungus was growing and the bacterial colonies around it had been killed. Farther
from the fungus, the bacteria looked normal. Excited by his observation, he showed
the dish to an assistant, who remarked on how similar this seemed to Fleming’s
famous discovery of lysozyme.
Hoping he had discovered a better natural antibiotic than lysozyme, Fleming now
devoted himself to growing more of the fungus. He identified that it belonged to the
Penicillium genus and that it produced a bacteria-killing liquid. On March 7, 1929 he
formally named the antibiotic – it would be known as penicillin.
Fleming published his results, showing that penicillin killed a variety of bacteria
which were then the scourge of humanity, including those responsible for scarlet
fever, pneumonia, meningitis and diphtheria. Furthermore, penicillin was non-toxic
and it did not attack white blood cells.
The awards he received
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Fleming was always fulsome in his praise for
Florey, Chain, and their team, and he downplayed
his own role in penicillin’s story. Despite his
modesty, he became a worldwide hero. Millions of
people owed their lives to the antibiotic he had
discovered.
In 1945 he toured America, where chemical
companies offered him a personal gift of $100,000
as a mark of respect and gratitude for his work.
Typically of Fleming, he did not accept the gift for
himself: he donated it to the research laboratories
at St Mary’s Hospital Medical School.
Sir Alexander Fleming
Alexander
Fleming died
aged 73 of a
heart attack in
London on
March 11, 1955.
His ashes were
placed in St
Paul’s Cathedral.