The Discovery of Antibiotics

For most of human history, a simple cut or a common infection could be a death sentence. Wounds turned poisonous, ordinary illnesses spread through the body unchecked, and doctors, however skilled, had almost no way to stop the tiny living things that caused such sickness. All of this changed in the twentieth century with the arrival of a new kind of medicine, the antibiotic, which for the first time gave people a reliable weapon against bacterial disease. Few discoveries have done more to lengthen human life or to ease human suffering.

Antibiotics are medicines that fight bacteria, the microscopic single-celled organisms that cause a great many infections. An antibiotic works either by killing the bacteria outright or by preventing them from growing and multiplying, giving the body's own defences the chance to finish the job. It is important to understand what antibiotics can and cannot do. They act only against bacteria, and they have no effect at all on viruses, which are quite different and far smaller. This is why an antibiotic will do nothing for an ordinary cold or for influenza, both of which are caused by viruses rather than by bacteria.

The discovery of the first antibiotic was, famously, something of an accident. In 1928 a Scottish scientist named Alexander Fleming returned from holiday to find that one of his laboratory dishes, in which he had been growing bacteria, had become contaminated by a stray mould. To his surprise, he noticed that the bacteria had been killed in a clear ring all around the patch of mould. The mould, it turned out, was producing a substance that destroyed the bacteria, and that substance was given the name penicillin. It was the first of the antibiotics, and its discovery opened an entirely new chapter in medicine.

Turning Fleming's observation into a usable drug proved far from easy, and it was more than a decade before other scientists found ways to produce penicillin in the large quantities that treatment required. When at last it became widely available, its effects seemed almost miraculous. Infections that had once killed swiftly could now be cured in days, and operations that had been deadly dangerous became far safer. Over the following years many other antibiotics were discovered, each effective against different kinds of bacteria, and together they transformed the practice of medicine.

In recent decades, however, a serious problem has emerged. Bacteria are living things, and they can change over time. When antibiotics are used too often, or are not used properly, most of the bacteria are killed but a few, which happen to be able to withstand the drug, survive. These survivors then multiply, passing their resistance on to the next generation, until a strain of bacteria arises against which the antibiotic no longer works. This growing danger is known as antibiotic resistance, and it threatens to return us to a time when common infections could once again prove deadly.

Because of this threat, doctors and health authorities now urge that antibiotics be used far more carefully than they once were. Patients are asked not to demand antibiotics for illnesses, such as colds, that the drugs cannot cure, and, when antibiotics are prescribed, to finish the full course even after they begin to feel better, so that no hardy bacteria are left alive to multiply. Meanwhile scientists work to develop new antibiotics to replace those that are losing their power. The story of these medicines is thus a reminder that even the greatest of discoveries must be used with wisdom if its benefits are to last.