During world war II, the battle against disease-causing
micoorganisms saw an innovation that has saved more sick and injured people than
any single invention in history: Penicillin, also known as the magic bullet.
From ancient times, doctors and patients have dreamed
of a drug that would make people well after getting an infection. In the 1920s,
Alexander Fleming serendipitously discovered that the mold penicillium produced
a “juice” that would kill other organisms: the anti-life discovery. Fleming
published his work, but was never able to purify Penicillin nor produce it in
mass quantities and his work was left behind. But after a decade, everything changed…..
and history was made.
An accidental discovery: more
than a contaminated plate
"When I woke
up just after dawn on September 28, 1928, I certainly didn't plan to
revolutionize all medicine by discovering the world's first antibiotic, or
bacteria killer, but I suppose that was exactly what I did" Fleming said.
By 1927, Fleming
had been investigating the properties of staphylococci.
He was already well-known from his earlier work, and had developed a reputation
as a brilliant researcher, but his laboratory was often untidy. On September
1928, Fleming returned to his lab having spent August on holiday with his
family. Before leaving, he had stacked all his cultures of staphylococci on a
bench in a corner of his lab. Once Fleming got into his lab, he picked up his
plates and noticed that one culture was contaminated with a fungus, and that
the colonies of staphylococci immediately surrounding the fungus had been
destroyed, whereas other staphylococci colonies farther away were normal,
“That’s funny”, he said. Fleming showed the contaminated culture to
his former assistant Merlin Price, who reminded him, "That's how you
discovered Lysozyme."
Fleming grew the mould in a pure culture and found that it produced a substance
that killed a number of disease-causing bacteria. He identified the mould as
being from the Penicillium genus,
and, after some months of calling it "mould
juice", named the substance it released Penicillin on March 7, 1929.
Beauty on the making
Fleming had neither the lab
resources nor the chemistry background to take the next giant steps of
isolating the active ingredient of the penicillium mold juice, purifying it and
how to use it.
In
1938, they decided to study some natural antibacterial compounds, Chain (his
interest piqued by Fleming’s 1929 article), suggested penicillin and Florey
went along with him. That was the very beginning.
Not long after Chain, Florey recruited Norman Heatley, an
English recently graduated PhD in biochemistry from Cambridge University. He
was assigned to come up with a method to produce and extract enough penicillin for
Chain to study. And how clever this man was!! Heatley's initial contribution (the
first in a remarkable series) was the "cylinder plate," or
"penicillinder," to determine how powerful this unknown substance
was. The assay plates contained short lengths of glass tubing embedded into
bacteria-laden agar, and each tube was filled with a different penicillin
solution. The diameter of the growth-free
circle of agar around each tube was measured from a glass scale illuminated
from underneath. The assay gave rise to the ‘Oxford Unit’ of Penicillin. But
this incredibly smart assay created by Heatley had another important
capability: it indicated the critical time when a culture should be harvested
at the peak of antibacterial activity. Furthermore, this man discovered that the
Penicillium growing time could be reduced by reusing the fungus and producing
up to twelve crops of the penicillin fluid underneath a single fungal mat.
Chain, along with chemist Edward
Penley Abraham on the other hand, worked out a successful technique for
purifying and concentrating penicillin. The keys seemed to lie in controlling
the pH of the “juice,” reducing the sample’s temperature and evaporating the
product over and over (essentially freeze-drying it). In
the first step of penicillin’s purification set up by Chain, the cooled and
slightly acidified culture was mixed with ether, which took up the penicillin
and left impurities behind. But penicillin was amazingly unstable, and it was
this instability, which had defeated earlier scientists including Fleming,
precluded conventional separation techniques.
During a meeting in March 1940,
Heatley, by nature modest and quiet, listened as Chain and Florey hotly debated
why penicillin vanished. Then, half-apologetically, he put forward what he
later called a ‘laughably simple’ idea, although heretofore it had crossed no
one’s mind. If penicillin could be extracted from a neutral buffer of water
into ether, why shouldn’t it be possible to transfer it out of the ether into
water made alkaline by passing the mould broth back and forth between acid and
alkaline to purify it, like extracting an egg yoke by slipping it between two
broken shells? Heatley nailed it and this “back-extraction” method worked
brilliantly. The resulting watery solutions of
penicillin were freeze-dried into a stable brown powder that was remarkably
powerful in a dilution of one to a million. Yet-as the Oxford team later
learned-the powder contained only 1% pure penicillin. Nevertheless, this method
produced enough penicillin in 7 weeks for Florey to test the effects of the
antibiotic in animals.
Soon after, Chain ran down to a
laboratory that maintained test animals and requested that two mice be injected
with a sample of the extracted penicillin. Though the injection represented a
far higher dosage than that administered in Fleming’s similar experiment, the
mice survived apparently unharmed; the more-concentrated penicillin had passed
its first toxicity test. Florey then directed that the antibacterial properties
of penicillin in mice be tested—the crucial step that Fleming had not
taken.
On May 25, 1940, in an experiment monitored by Heatley,
eight mice were infected with Streptococcus. An hour later, four of them were
given penicillin. Heately wrote in his lab notebook: "After supper with some friends, I returned to the lab
and met the professor to give a final dose of penicillin to two of the
mice. The controls were looking very sick, but the treated animals
seemed very well. I stayed at the lab until 3:45 a.m. by which time all four
control animals were dead. It really looks as if P. [penicillin] may be of
practical importance”.
In the morning, he was able to tell Florey that the four
treated with penicillin were still alive. Brilliant science!
On August 24, 1940, Florey and
Chain reported their findings in theLancet: the article
electrified research groups around the world that were seeking cures for
bacterial disease. It was at that point that Florey realized that
he had enough promising information to test the drug on people. But the problem
remained: how to produce enough pure penicillin to treat people?
Going big thanks to Norman Heately
In
spite of efforts to increase the yield from the mold cultures, it would take 2,000
liters of mold culture fluid to obtain enough pure penicillin to treat a single
case of sepsis in a person. Again, Heatley solved
the problem. He was a supreme improviser, known for using his skills to cobble
together functional efficient laboratory set-ups from whatever he could lay his
hands on. First, he automated his back-extraction process with available
equipment. This apparatus consisted of milk churns and soft drink bottles
connected with yards of glass and rubber tubing, and included a warning bell to
signal when a bottle was full or empty. It stood six feet (1.8 m) tall upon a
stand made from an old bookcase discarded by the Bodleian Library. Six columns
of extracted penicillin from uniform droplets of acidified culture flowed in a
counter current direction to the top of a column where it was collected while
the spent watery liquid was discharged below.
But Heatley needed to grow more mold juice to keep pace with
his extraction machine that processed 12 liters of medium an hour. Because it
was wartime, there were great scarcities of everything. With the outbreak of
war, resources were limited, and thus the mould had to be grown in whatever
they could lay their hands on such as pie dishes, trays, biscuit tins, gasoline
cans, sterilized bottles and even old-fashioned bed pans borrowed from the Radcliffe
Infirmary, can you imagine that?!
However, he found that amog of all 'fancy' objects, the best one for culturing the mold was the old fashioned enamel bedpan with a side arm through which the culture could be inoculated and harvested!!! Inspired by the bedpan, Heatley designed a square-sided ceramic vessel that could be quickly and inexpensively made by a slipcast process (a technique for the mass-production of pottery and ceramics)
Each utensil held a liter of medium and could be stacked horizontally in the
incubator, vertically in the autoclave, and in neat rows lining the walls of the
Dunn School operating theater. Heatley fetched the first 174 (of 500) bespoke
bedpans from a nearby pottery, in a "bull-nosed Morris two-seater….
groaning under the weight," and incubated them with the mold on Christmas
Day 1940.
Six penicillin girls” hired by Florey were in charge of handling the
culture pots. Within a month, the now famous "bedpans" produced
enough penicillin to justify the beginning of Florey's clinical trials.
When Chain urged that a patent
be sought on penicillin, as was usual in German research institutes, Florey
refused to enter into such a commercial agreement on a discovery he presumed
would benefit all mankind—a decision that long rankled Chain.
Penicillin is tested for the
first time in a person
In early January 1941 Florey
was ready to test penicillin on humans. The first English patient to whom the
drug was administered was a young woman whose cancer was beyond treatment and
who had agreed to test penicillin’s toxicity. She showed an alarming
reaction—trembling and sharply rising fever. However, Abraham was able to show
that impurities in the drug, not the drug itself, had caused the adverse
reaction. In February a policeman became the first patient with an infection to
be treated with penicillin. He nicked his face working in his rose garden. The scratch,
infected with streptococci and staphylococci, spread to his eyes and scalp.
Although Alexander was treated with doses of sulfa drugs, the infection
worsened and resulted in smoldering abscesses in the eye, lungs and shoulder.
Florey and Chain heard about the horrible case at high table one evening and,
immediately, asked the Radcliffe physicians if they could try their ”purified”
penicillin. No one
knew the dosages and the length of treatment required to eliminate various
bacterial infections; these parameters were being worked out by just such
trials—primitive by today’s standards. After five days of injections , the policeman began to
recover, but the penicillin supply had almost run out, and even retrieving
penicillin from the man’s own urine (a commonly used procedure in the early
clinical trials) failed to save him and died. Florey vowed that from then on he
would always have enough penicillin to complete a treatment.
Using Heatley’s homemade contraptions, six patients treated
during spring of 1941 at Oxford’s Radcliffe Infirmary used a total of 2 million
units of the drug, with only one fatality (the policeman). Remarkably, the
Oxford team's entire research effort to this point took just 18 months and was
based on a mere 4 million units of Heatley's handmade penicillin, an amount
that today represents a daily dose for a single person.
Florey planned an even larger trial, but the problem once
again was to obtain enough penicillin. To increase penicillin supplies, Florey approached various British
pharmaceutical firms, but only ICI considered itself in a position to accept
the challenge (though many later joined the effort). In July 1941, with the help of the Rockefeller
Foundation, Florey and Heatley carried the secret to the United States to
persuade scientists and companies to undertake the production work that had
been so crippled by shortages in the United Kingdom. The entry of the United
States into the war in December 1941 altered the course of history in regard to
penicillin, and by the end of 1943 its production was the second-highest
priority of the U.S. War Department. New climates and traditions of research
then clearly emerged — for instance, the British Medical Research Council
believed that patenting medicines was unethical. They rejected Chain's urgent
requests that the work be protected — a refusal that bore more than a hint of
anti-Semitism. American companies patented their production techniques, and
Chain's prophecy that he would have to pay royalties to use his own invention
proved correct, although whether the Oxford scientists could have patented
their preliminary work remains debatable.
Some chemists were confident that
they would soon be able to synthesize penicillin from a few organic chemicals.
This attitude resulted in a major effort conducted on both sides of the
Atlantic to understand the structure of the penicillin molecule as the
prerequisite for its eventual synthesis. A structure was proposed by Chain and
Abraham and later confirmed by new instrumental techniques for analyzing the
structure of organic molecules, including X-ray crystallography, which was
practiced by Dorothy Hodgkin, a near neighbor of the Oxford
chemists. Unfortunately, Hodgkin’s work on the molecule culminated too late in
the war to be used in devising a synthesis for penicillin. Even after 1957,
when such a synthesis was created, fermentation continued to underlie the
commercial production of penicillin and related antibiotics. But the structural
knowledge gained in the war years proved invaluable in developing
penicillin-like antibiotics after the war that could be administered more conveniently,
were more effective, and had fewer side effects….. and the rest, as they say,
is history.
With World War II over and the
Nobel Prizes distributed to Fleming, Florey, and Chain for their work on
penicillin. Heatley, the genius was left behind. In 1990 he
was awarded an honorary Doctorate of Medicine from Oxford. What makes the honor
particularly remarkable is that Heatley is the only person to receive that
award in the university's 800- year history.
Have you ever taken penicillin? Next time you or your kids
do, remember of all the effort and bedpans behind.
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