Scientific Revolution

Scientific Revolution

The Discovery

Penicillin is a powerful drug used to treat infections caused by bacteria. It was the first antibiotic (a drug produced by microbes) used successfully in the treatment of serious diseases in human beings. Various forms of the drug have become widely available for medical use since the mid-1940's. Penicillins have played a major role in treating pneumonia, rheumatic fever, scarlet fever, and many other diseases. The development of penicillin had a tremendous impact on medicine and encouraged research that lead to the discovery of many other antibiotics.(Johnson, 1991)

The improbable chain of events that led Alexander Fleming to discover penicillin in 1928 is the stuff of which scientific myths are made. Fleming, a young Scottish research scientist with a profitable side practice treating the syphilis infections of prominent London artists, was pursuing his pet theory Ð'-- that his own nasal mucus had antibacterial effects Ð'-- when he left a culture plate smeared with Staphylococcus bacteria on his lab bench while he went on a two-week holiday.(Ho, 2003)

When he returned, he noticed a clear halo surrounding the yellow-green growth of a mold that had accidentally contaminated the plate. Unknown to him, a spore of a rare variant called Penicillium notatum had drifted in from a mycology lab one floor below. Luck would have it that Fleming had decided not to store his culture in a warm incubator, and that London was then hit by a cold spell, giving the mold a chance to grow. Later, as the temperature rose, the Staphylococcus bacteria grew like a lawn, covering the entire plate Ð'-- except for the area surrounding the moldy contaminant. Seeing that halo was Fleming's "Eureka" moment, an instant of great personal insight and deductive reasoning. He correctly deduced that the mold must have released a substance that inhibited the growth of the bacteria.(Ho, 2003)

It was a discovery that would change the course of history. The active ingredient in that mold, which Fleming named penicillin, turned out to be an infection-fighting agent of enormous potency. When it was finally recognized for what it was, the most efficacious life-saving drug in the world, penicillin would alter forever the treatment of bacterial infections. By the middle of the century, Fleming's discovery had spawned a huge pharmaceutical industry, churning out synthetic penicillins that would conquer some of mankind's most ancient scourges, including syphilis, gangrene and tuberculosis. (Ho, 2003)

History

During the late 1930's, a group of British researchers led by Howard Florey and Ernst Chain developed a method of extracting and purifying small amounts of penicillin. Physicians first used penicillin to treat a human being in 1941, when the drug was given to a British police officer suffering from blood poisoning. However, the patient died because the supply of penicillin was inadequate to kill the infectious bacteria. During the next several years, researchers found methods of producing large quantities of the drug. They also discovered ways of obtaining several forms of the drug from broth. Of these forms, penicillin G proved to be the most effective in fighting bacteria. Physicians used penicillin G to cure people of many disorders including pneumonia, rheumatic fever, syphilis, and strep throat.(Johnson, 1991)

However, physicians had a difficult time in using penicillin G. For example, they found that it was not absorbed in the blood well when given orally. Also, penicillin G did not kill certain kinds of bacteria. Other bacteria, particularly staphylococcus aureus, which causes blood poisoning, pneumonia, and many other disorders, became resistant to the penicillin G after a few years.

To overcome the problems with penicillin G, chemist began to make semisynthetic penicillins in the late 1950's. Today, many semisynthetic penicillins are available. Most of them have one or more properties that penicillin G lacks. For example, penicillin V kills the same bacteria as penicillin G but is absorbed into the blood better. Ampicillin and amoxicillin are effective against some kinds of bacteria that are resistant to penicillin G. These two penicillins are widely used in treating infections of the urinary tract and severe throat and ear infections in children. (Johnson, 1991)

There are various forms of penicillins. All of them are obtained from molds of the genus penicillium. Chemists isolate some penicillins naturally by processing by processing penicillium molds in various ways. Other penicillins called semisynthetic penicillins are produced by chemically changing natural penicillin substances. Penicillin G is by far the most widely used semisynthetic penicillin. Commonly used semisynthetic penicillins include ampicillin, amoxicillin and penicillin V. (Johnson, 1991)

Penicillins kill bacteria by preventing the formation of the stiff cell walls bacteria needs to survive. The body cells of human beings and animals do not form stiff cell walls and so are not damaged by penicillins.

Some penicillins are taken by mouth. But others penicillins are destroyed by stomach acids before they reach the bloodstream when given orally. Doctors and physicians usually give such penicillins by injection.

Most people who take penicillins experience no side effects. However, some people suffer allergic reactions. Usually, these reactions involve only minor problems such as fever or rashes. But life-threatening reactions involving shock and breathing difficulties occur in some patients. Patients allergic to one form of penicillin are allergic to all forms of the drug.(Johnson, 1991)

How it is manufactured

Manufacturers grow the mold in huge tanks of broth. They extract the penicillin from the mold and broth, ending up with crystals of pure penicillin. The crystals are then processed into tablets and solutions. In a penicillin factory, workers wear masks and lint-free clothes to keep the antibiotic free from impurities.

Timeline of Penicillin (, 2006)