ANTISEPTICS

Antiseptics are compounds that act to counteract sepsis, which is an illness caused by a bacterial infection of the blood. Antiseptics are able to counteract sepsis by preventing the growth of pathogenic (disease causing) microorganisms. An antiseptic may kill a microorganism, but it does not necessarily have to. The treated microbes may only be weakened. The weaker, slower growing microbes may then be more susceptible to the defense mechanisms of the host.

The terms antiseptic and disinfectant are used almost interchangeably nowadays. Yet they do have different meanings. An antiseptic is a chemical or technique that is used on people. A disinfectant is a chemical that is applied to an inanimate object or surface to get rid of microorganisms. An antiseptic generally does not have the same potency as a disinfectant. Otherwise, the chemical would harm the tissues it is in contact with. For this reason, an antiseptic should not be used to treat inanimate objects. Likewise, the generally more toxic disinfectant should not be used to treat skin or areas such as the mucous membranes of the nose.

While more is known of the molecular basis of antiseptic actions, the use of antimicrobial compounds is ancient. For example, the black eye make-up known as kohl, which was used by the ancient Arabs and Egyptians, is a mixture of copper and antimony. These compounds are antiseptic. Indeed, the modern cure for trachoma (blindness caused by infection of the eyes by the bacterium Chlamydia trachomatis) is remarkably similar in composition to kohl.

There are a number of antiseptics and antiseptic procedures.

In a health care setting, powerful antiseptics are used to ensure that the skin is essentially sterile prior to an operation. Examples of such antiseptics include chlorhexidine and iodophors (iodine-containing compounds). Alcohol is an antiseptic, which is routinely used to swab the skin prior to an injection. Alcohol acts to coagulate the protein in bacteria. The irreversible change in the protein is lethal to the bacteria. In the example of the injection, alcohol swabbing of the injection site will kill the bacteria on the skin, so that living bacteria are not carried into the body upon insertion of the needle. Dilution of alcohol, so that a solution is 30% alcohol by volume, makes this antiseptic even more potent, as it allows the alcohol to permeate into the bacteria. Pure alcohol rapidly coagulates surface proteins, producing a coagulated crust around the bacteria.

Another antiseptic is carbolic acid. This is also known as phenol. The coal tar-based product was discovered in 1834. Originally phenol was poured down sewers to kill microorganisms. Over time, its use expanded. In 1863, the British surgeon Joseph Lister began using a spray of phenol to disinfect open wounds during surgery. Prior to his innovation, such surgery was only performed when all other avenues of treatment had failed, since the risk of death from infection was extremely high.

Still another antiseptic compound is pine oil. It is added to household disinfectants more because of its pleasant smell than its aseptic power nowadays. In fact, it inclusion actually weakens the bacteria-killing power of the household disinfectant.

Lister's method was supplanted by the adoption of extreme cleanliness in the operating room, such as the use of sterile masks, gloves and gowns, in order to keep the surgical area free of microorganisms. This approach is known as antiseptic surgery. As strange as it may seem now, surgeons in Lister's era often did not change or clean their operating garb between operations. A surgeon would often commence an operation wearing a gown covered with the blood and germs of many previous operations. Prior to the introduction of antisepsis in the operating room, the rate of death following surgery was almost 60%. After the introduction of antisepsis, the recorded death rate in England dropped to four per cent.

Hand washing has also become standard practice in the hospital and the home.

Another antiseptic technique is sterilization. The use of steam at higher than atmospheric pressure is an effective means of killing many types of bacteria, including those that form spores.

In the home, antiseptics are often evident as lotions or solutions that are applied to a cut or scrape to prevent infection. For these uses, it is necessary to clean the affected area of skin first to dislodge any dirt or other material that could reduce the effectiveness of the antiseptic. Antiseptics, particularly those used in the home, are designed for a short-term use to temporarily rid the skin of microbes. The skin, being in primary contact with the environment, will quickly become recolonized with microorganisms. Long-term use of antiseptics encourages the development of populations of microorganisms that are resistant to the antiseptic. Additionally, the skin can become irritated by the long exposure to the harsh chemical. Some people can even develop allergies to the antiseptic.

Another hazard of antiseptics that has only become apparent since the 1990s is the contamination of the environment. Antiseptic solutions that are disposed of in sinks and toilets can make their way to rivers and lakes. Contamination of the aquifer (the surface or underground reserve of water from which drinking water is obtained) has become a real possibility.