Hygiene & Antisepsis

Hygiene and antisepsis cut the routes that germs take from one person to the next: hands, instruments, dressings and water. Washing with soap, keeping water apart from sewage, chemicals that kill germs on wounds and heat that sterilises tools made childbirth and surgery far safer in the second half of the nineteenth century.

What it is

Germs pass between people along routes nobody sees: a hand that touched a sick patient and then a wound, a knife wiped on an apron, water drawn downstream of a latrine. Hygiene and antisepsis are the habits and tools that cut these routes. Soap and water remove germs. Heat and certain chemicals kill them. Asepsis, in the surgeon’s sense, keeps them away from a wound from the start.

The plate shows three stages of this idea: the washbasin set at the door of a Vienna maternity ward in 1847, the carbolic acid spray Joseph Lister used in the 1870s, and the steam autoclave that, from the 1880s, sterilised instruments and dressings by heat instead of chemicals.

How it works

Bacteria are single cells a few thousandths of a millimetre long; viruses are far smaller and multiply only inside living cells. Both ride on skin, droplets, dust, food, water or tools, and faeces carry them in vast numbers. An infection needs a source, a carrier and a way in, such as the mouth or a break in the skin. Washing hands between one patient and the next takes away the carrier, and the germ goes no further.

Rubbing with the fingers interlaced reaches the skin between them, one of the places most often missed.

Soap works mostly by carrying microbes away. One end of each soap molecule holds on to water and the other to grease, so it lifts the oily film of the skin, with the microbes caught in it, into the rinse. It also breaks open viruses wrapped in a fatty envelope, such as the flu virus.

Heat kills by unfolding a microbe’s proteins for good, the way it sets egg white. A rolling boil kills ordinary bacteria, viruses and parasites. Some bacteria, among them the agents of tetanus and botulism, can shut down into spores whose tough coats survive boiling. Steam under pressure in an autoclave, held at 121 °C or more for long enough and reaching every surface of the load, kills these too: that is sterilisation in the strict sense.

Antiseptics are chemicals used on living tissue; disinfectants are used on objects. Alcohol unfolds proteins, which is why hand rubs contain at least 60% of it. Chlorine compounds, like the chlorinated lime used in Vienna or household bleach, oxidise whatever part of the cell they touch. Lister’s carbolic acid killed germs but also damaged patients’ tissue and surgeons’ hands, and was dropped. Dirt and blood shield germs from all these chemicals, so cleaning comes first.

How to build

These are everyday habits recommended by public-health bodies, not medical procedures.

Wash your hands properly. Wet them with clean running or poured water and lather with soap. Rub palm to palm, each palm over the back of the other hand with fingers interlaced, palm to palm again with fingers interlaced, the backs of the fingers, each thumb turned inside the other palm, and the fingertips into the palm. The WHO sequence takes 40 to 60 seconds; the CDC asks for at least 20 seconds of scrubbing. Rinse and dry on a clean towel or in the air.

Know when to wash. After the toilet or a nappy change, before cooking and eating, before and after tending a sick person or a wound, and after touching animals or rubbish.

Keep water and waste apart. Dig latrines downhill of any well or spring and at least 30 m from it, further in gravel or fissured rock, with the bottom of the pit at least 1.5 m above the highest water table of the rainy season. These distances are a starting point: ask the local health or water service to check the ground and the way the groundwater flows.

Count the twenty minutes from the moment the water boils hard, and add nothing after that.

Boil tools and cloths. Wash scissors, tweezers and cloths with soap first, since heat penetrates dried blood and grease badly. Cover them with water in a lidded pot, bring it to a full boil and count 20 minutes from then without adding anything. Let it cool, lift the items out with tongs boiled at the same time and put them straight into a boiled container with a lid. They will do for removing a splinter or cutting a dressing. Boiling disinfects but does not sterilise: needles and anything that enters the body must come sterile and sealed from a pharmacy or clinic.

Clean a small cut. Wash your hands, then rinse the cut under clean tap water or cooled boiled water until no dirt remains, and wash the skin around it with soap. Pat it dry and cover it with a sterile dressing or plaster from a pharmacy.

Safety. Do not make antiseptics or disinfectants at home, and never mix cleaning products: bleach with acids or ammonia releases toxic gas. Nothing here is to be swallowed or injected. Boiling water and steam scald, so keep children away from the pot. Call emergency services for bleeding that will not stop or a very deep cut. Get medical care quickly for a gaping or long cut, a burn, any bite from an animal or a person, or a wound with soil in it, and if a wound becomes red, swollen or more painful, oozes pus or comes with fever. A tetanus injection may be needed.

History and evolution

At the Vienna maternity hospital, the clinic where medical students trained lost about one mother in ten to childbed fever, the midwives’ clinic about one in thirty. In March 1847 Jakob Kolletschka, a colleague of the young doctor Ignaz Semmelweis, died of a cut received during an autopsy, with the same signs as the women. Semmelweis concluded that students carried “cadaveric particles” from the autopsy room to the labour ward. From May 1847, the date this plate takes as its start, he had them wash in chlorinated lime solution, and in 1848 deaths in his clinic fell to 1.27%. Many colleagues rejected his explanation.

In 1854 John Snow tied a London cholera outbreak to one street pump. At the Scutari army hospital, where Florence Nightingale nursed, deaths among admitted soldiers reached 42% in February 1855, then fell once the sewers were repaired and the wards aired.

Pasteur’s swan-neck flask: dust caught in the bend never reached the broth, which stayed clear.

In the early 1860s Louis Pasteur showed that boiled broth in a flask with a long bent neck stayed clear, while broth open to falling dust spoiled: living germs caused decay. In Glasgow, Joseph Lister reasoned that germs also made wounds fester. In August 1865 he dressed a boy’s open leg fracture with carbolic acid, and it healed cleanly; he published the method in 1867. Among his amputations, deaths fell from 16 in 35 to 6 in 40, numbers he admitted were small.

Charles Chamberland, Pasteur’s assistant, designed a steam steriliser in 1879, and in 1886 Ernst von Bergmann in Berlin switched to steam-sterilised dressings. Surgeons now kept germs out of the wound with sterilised instruments, gowns and, from the 1890s, rubber gloves. The WHO’s 2009 hand hygiene guidelines name five moments when a carer must clean their hands.