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From antisepsis to asepsis

Around 1500 words

Published: 14 October 2018

Antisepsis is the practice of using antiseptics to eliminate the microorganisms that cause infections. It is the forerunner to asepsis, the system of infection control we use today.

Most people are familiar with antiseptics as chemicals that are applied to the skin to prevent microorganisms such as bacteria and viruses from entering the body and causing infections such as such as sepsis, septicaemia (blood poisoning) and gangrene (dead tissue). Some antiseptics are germicides that kill microorganisms on contact, others are bacteriostatic and only prevent or inhibit their growth. Disinfectants are used to destroy microorganisms on non-living objects.

Antisepsis is the practice of using antiseptics to eliminate the microorganisms that cause disease. The term was developed by the British surgeon Joseph Lister. His antisepsis system used antiseptics in the air, on wound dressings and in the operating theatre to prevent germs from entering open wounds.

The difference between antisepsis and asepsis

An antisepsis system destroys the microorganisms—germs—on the surgeon’s hands and instruments and in the immediate surroundings, using antiseptic washes and sprays as barriers to new infection.

In asepsis a sterile environment, free from germs, is created using a combination of hygienic and antiseptic measures such as high temperatures, antiseptics and soap and water.

The rapid acceptance of Lister’s antisepsis system by surgeons in the 19th century paved the way for the routine safe surgery that we take for granted. But in order for this to happen, the medical establishment had to accept the scientific and empirical basis of Lister’s research.

Understanding infection

In the 19th century, even when an operation or treatment had been successful, the patient often died from infection. Infections in hospital wards, particularly after surgery, were so common that the phenomenon was known as hospitalism or ward fever. Inexplicably, an infection might sweep through an entire ward, killing the most vulnerable. No wonder surgery was a last resort for most patients.

The use of general anaesthetic in the mid-19th century meant that surgeons could attempt longer, more complicated operations. Unfortunately, this also increased the body’s exposure to infections, and hospital mortality rates soared.  

Surgeon James Y. Simpson, the discoverer of chloroform, claimed that ‘a man laid on the operating table in one or our surgical hospitals is exposed to more chance of death than was the English soldier on the field of Waterloo’.

A view of a hospital ward

As early as 1847, the Hungarian doctor Ignaz Semmelweis  had realised that infection rates were far worse in maternity wards attended by doctors, who handled a variety of patients and dead bodies, than in wards where midwives only delivered the babies. Semmelweis introduced antiseptic hand-washing in his wards and found the infection rates were greatly reduced.

The infections were being transferred from patient to patient by unwitting surgeons and physicians, who used the same unwashed apron and operating table for all operations and rarely washed their own hands or instruments between procedures. But no one knew how infections spread or what caused them, which was one of the reasons why Semmelweis’s findings were not widely adopted. Tragically Semmelweis himself died from blood poisoning caused by a cut on his finger.

The germ theory of disease

The French scientist Louis Pasteur speculated that the spread of microorganisms (called germs) in the body could explain infectious disease. This was known as the germ theory of disease. Although he never tested the theory, Pasteur suggested that a disease might be controlled by exposing the wound to germ-killing chemicals—antiseptics.

Different bacteria seen through a microscope Wellcome Collection, CC-BY
Different bacteria seen through a microscope.

Joseph Lister was inspired by Louis Pasteur’s research and, when he published his own findings, he acknowledged Pasteur’s work as the inspiration for antisepsis:

It occurred to me that decomposition in the injured part might be avoided without excluding the air, by applying as a dressing some material capable of destroying the life of the floating particles. Upon this principle I based a practice Antiseptic Principle of the Practice of Surgery.

But Pasteur’s germ theory was not widely accepted, and without the belief that germs were real and dangerous, many surgeons found the antiseptic system unnecessarily complicated and excessive.

Some surgeons thought that Lister was proposing carbolic acid as a treatment for infection rather than as one possible barrier against it. They objected that carbolic acid was poisonous: in strong solutions it irritated and burned the wound and surrounding skin, and an overdose could cause excessive vomiting.

Lister produced statistical data to demonstrate the effectiveness of the antisepsis system in his wards at Glasgow Infirmary, but his data was limited and failed to convince many of his critics. Most surgeons preferred to wait until there was stronger evidence that antisepsis worked before committing themselves.

The importance of hospital sanitation

Some of Lister’s critics argued that good hygiene and cleanliness were all that was needed to control infection, and that Lister’s meticulous antisepsis system was simply improving sanitation.

Earlier in the century, when Florence Nightingale went to care for injured soldiers from the Crimean War, she saw for herself the effect of poor sanitation in hospital wards. She used statistical evidence based on the data she gathered from the Crimean War to demonstrate the importance of cleanliness and good sanitary practice for controlling infection. She collaborated with the epidemiologist William Farr in the preparation of hospital statistics for her book Notes on Hospitals (1859).

Florence Nightigale's statistical chart showing causes of mortality in the army of the East, 1858. Wellcome Collection, CC-BY
Florence Nightigale's statistical chart showing causes of mortality in the army of the East, 1858.

Such compelling statistical evidence convinced many hospitals that improved sanitation, and not antisepsis, was the way to reduce infection-related diseases in hospitals.

Lister didn’t agree. His sanitary procedure in the operating room simply consisted of removing his coat, rolling up his sleeves and pinning a clean (but not sterilised) towel over his waistcoat and trousers. Such was his faith in antisepsis that cleanliness seemed irrelevant to him. In an address to the British Medical Association he declared:

‘My patients have the dirtiest wounds and sores in the world’ but, he explained, ‘aesthetically they are dirty, though surgically they are clean’.

Both the sanitarians and the Listerians had yet to be convinced of the benefits of each other’s method.

From antisepsis to asepsis

In 1877 the German scientist Robert Koch provided convincing evidence that germs were the cause of infectious diseases such as anthrax and typhoid. His laboratory work on bacterial infection also showed that dry heat and steam sterilisation were as effective as chemical agents such as carbolic acid in controlling and preventing the growth of bacteria. Learning from Koch’s research, German surgeons began to adopt an aseptic rather than antiseptic approach to infection control.

An aseptic procedure is done under sterile conditions, where all germs are excluded. Not only is all equipment sterilised, but every effort is made to exclude germs from entering the environment on the person or clothing of medical staff.

Lister also accepted Koch’s findings and reduced his reliance on antiseptics in order ‘to ensure… aseptic purity without contact of any antiseptic material within the wound’. By 1887 he had given up the use of carbolic spray in the operating theatre—to the relief of medical staff and patients who had breathed in the noxious fumes.

Gustave Neuber is credited with being the first surgeon to use a sterilized surgical gown, and in 1883, he reported a decrease in surgical site infections with the use of both cap and gown. In 1894 an American nurse, Caroline Hampton, was the first person to use sterilised medical gloves devised for her by surgeon William Halsted.

Surgeons at work in a hospital operation Wellcome Collection, CC-BY

Modern infection control: antibiotics and superbugs

In modern hospitals asepsis rather than antisepsis is the norm, with sterile gloves, masks and gowns in the operating theatre and antiseptics and antibiotics used to control post-operative infection.

The discovery of antibiotics in the 1940s made a dramatic difference to the control of bacterial infection in the body. But doctors and hospitals became complacent about standards of hygiene, just as Lister had been when he saw the life-saving results of antisepsis.

Cleanliness and the prevention of infection became less important when infectious diseases could be effectively managed with antibiotics. But overuse of antibiotics has led to an increase in antibiotic-resistant strains of ‘superbugs’ in hospitals.  A reminder that the risk of infection has not gone away, and good hygiene and asepsis remain as important as ever.

Suggestions for further research

More about infection control in hospitals

More about germ theory

Historical texts