Antiseptic

Antiseptics (from Greek ἀντί anti, "against" and σηπτικός sÄ"ptikos, "putrefactive") are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. Antiseptics are generally distinguished from antibiotics by the latter's ability to be transported through the lymphatic system to destroy bacteria within the body, and from disinfectants, which destroy microorganisms found on non-living objects.

Disinfectants do not kill bacterial spores e.g., on surgical instruments; a sterilization process is required for that. Even sterilization may not destroy prions.

Some antiseptics are true germicides, capable of destroying microbes (bacteriocidal), while others are bacteriostatic and only prevent or inhibit their growth.

Antibacterials are antiseptics that have the proven ability to act against bacteria. Microbicides which destroy virus particles are called viricides or antivirals.

Usage in surgery

The widespread introduction of antiseptic surgical methods followed the publishing of the paper Antiseptic Principle of the Practice of Surgery in 1867 by Joseph Lister, inspired by Louis Pasteur's germ theory of putrefaction. In this paper, Lister advocated the use of carbolic acid (phenol) as a method of ensuring that any germs present were killed. Some of this work was anticipated by:

• Ancient Greek physicians Galen (circa 130â€"200) and Hippocrates (circa 400 BC) and Sumerian clay tablets dating from 2150 BC that advocate the use of similar techniques.
• Medieval surgeons Hugo of Lucca, Theoderic of Servia, and his pupil Henri de Mandeville were opponents of Galen's opinion that pus was important to healing, which had led ancient and medieval surgeons to let pus remain in wounds. They advocated draining and cleaning wound lips with wine, dressing the wound after suturing it if necessary, and leaving the dressing on for ten days, soaking it in warm wine all the while, before changing it. Their theories were bitterly opposed by Galenist Guy de Chauliac and others trained in the classical tradition.
• Joseph Smith alluded to the use of alcohol as an antiseptic in February 1833, when he wrote what is now section 89 of the Doctrine and Covenants, popularly known as the "Word of Wisdom". Specifically, verse 7 states: "And, again, strong drinks are not for the belly, but for the washing of your bodies."
• Oliver Wendell Holmes, Sr., who published The Contagiousness of Puerperal Fever in 1843
• Florence Nightingale, who contributed substantially to the report on the Royal Commission on the Health of the Army (1856â€"1857), based on her earlier work
• Ignaz Semmelweis, who published his work The Cause, Concept and Prophylaxis of Childbed Fever in 1861, summarizing experiments and observations since 1847

Functionality

Bacterial growth requires a food supply, moisture, oxygen (if the bacteria are obligate aerobes), and a certain minimum temperature (see bacteriology). These conditions have been studied and dealt with in food preservation and the ancient practice of embalming the dead, which is the earliest known systematic use of antiseptics.

In early inquiries before microbes were understood, much emphasis was given to the prevention of putrefaction, and procedures were carried out to determine the amount of agent that must be added to a given solution to prevent the development of pus and putrefaction; however, due to a lack of a developed understanding of germ theory, this method was inaccurate and, today, an antiseptic is judged by its effect on pure cultures of a defined microbe and/or its vegetative and spore forms. The standardization of antiseptics has been implemented in many instances, and a water solution of phenol of a certain fixed strength is now used as the standard to which other antiseptics are compared.

The fundamental idea of all anti-pathogenic agents is to exploit a difference between parasite and host. For bacteria, that may involve interfering with their cell walls or internal biochemistry which differs from humans'.

Pathogens show a total-dose response: if you expose them to a dilute solution for a long time, this is equivalent to dosing them with a strong solution for less time. This makes the pre-industrial medical notion of poultice clear: weaker antiseptics require longer exposure. This is true for many chemical antibiotics as well as heat and UV exposure.

Some common antiseptics

• Alcohols, most commonly ethanol (60â€"90%), 1-propanol (60â€"70%) and 2-propanol/isopropanol (70â€"80%) or mixtures of these alcohols, are commonly referred to as "surgical alcohol", and are used to disinfect the skin before injections are given, often along with iodine (tincture of iodine) or some cationic surfactants (benzalkonium chloride 0.05â€"0.5%, chlorhexidine 0.2â€"4.0% or octenidine dihydrochloride 0.1â€"2.0%).

• Quaternary ammonium compounds, also known as quats or QACs, include the chemicals benzalkonium chloride, cetyl trimethylammonium bromide, cetylpyridinium chloride, and benzethonium chloride. Benzalkonium chloride is used in some preoperative skin disinfectants (0.05â€"0.5%) and antiseptic towels. The antimicrobial activity of quats is inactivated by anionic surfactants, such as soaps. Related disinfectants include chlorhexidine and octenidine.

• Boric acid is used in suppositories to treat yeast infections of the vagina, in eyewashes, as an antiviral to shorten the duration of cold sore attacks, in creams for burns, and trace amounts in eye contact solutions.

• Brilliant green is a triarylmethane dye still widely used as 1% ethanol solution in Eastern Europe and ex-USSR countries for treatment of small wounds and abscesses. It is efficient against Gram-positive bacteria.

• Chlorhexidine gluconate, a biguanidine derivative, is used in concentrations of 0.5â€"4.0% alone or in lower concentrations in combination with other compounds, such as alcohols as a skin antiseptic and to treat inflammation of the gums (gingivitis). The microbicidal action is somewhat slow, but remanent. It is a cationic surfactant, similar to quats.

• Hydrogen peroxide is used as a 6% (20 Vols) solution to clean and deodorize wounds and ulcers. More commonly, 3% solutions of hydrogen peroxide have been used in household first aid for scrapes, etc. However, the strong oxidization causes scar formation and increases healing time during fetal development.

Hydrogen peroxide vapor at high concentrations (> 50%) in mild vacuum can be used to sterilize surgical instruments with long thin lumens in under an hour without damage to temperature-sensitive electronics.

Hydrogen peroxide and acetic acid make peracetic acid which is more anti-microbial (antiseptic) than peroxide itself.

The above peroxide antimicrobials have the advantage of being cheap and decomposing to biologically harmless water and oxygen (and CO2, acetate, etc.)

• Iodine is usually used in an alcohol solution (called tincture of iodine) or as Lugol's iodine solution as a pre- and postoperative antiseptic. Some people do not recommend disinfecting minor wounds with iodine because of concern that it may induce scar tissue formation and increase healing time. However, concentrations of 1% iodine or less have not been shown to increase healing time and are not otherwise distinguishable from treatment with saline. Novel iodine antiseptics containing povidone-iodine (an iodophor, complex of povidone, a water-soluble polymer, with triiodide anions I₃^âˆ', containing about 10% of active iodine) are far better tolerated, do not negatively affect wound healing, and leave a deposit of active iodine, thereby creating the so-called "remnant", or persistent, effect. The great advantage of iodine antiseptics is their wide scope of antimicrobial activity, killing all principal pathogens and, given enough time, even spores, which are considered to be the most difficult form of microorganisms to be inactivated by disinfectants and antiseptics.

• Mercurochrome is not recognized as safe and effective by the US Food and Drug Administration (FDA) due to concerns about its mercury content. Other obsolete organomercury antiseptics include bis-(phenylmercuric) monohydrogenborate (Famosept).

• Manuka honey is recognized by the FDA as a medical device for use in wounds and burns. Active +15 is equal to a 15% solution of phenol.

• Octenidine dihydrochloride, a cationic surfactant and bis-(dihydropyridinyl)-decane derivative, is used in concentrations of 0.1â€"2.0%. It is similar in its action to the quats, but is of somewhat broader spectrum of activity. Octenidine is currently increasingly used in continental Europe as a QAC and chlorhexidine (with respect to its slow action and concerns about the carcinogenic impurity 4-chloroaniline) substitute in water- or alcohol-based skin, mucosa, and wound antiseptic. In aqueous formulations, it is often potentiated with addition of 2-phenoxyethanol.

• Phenol is germicidal in strong solution, and inhibitory in weaker ones. It is used as a "scrub" for preoperative hand cleansing, and in the form of a powder as an antiseptic baby powder, where it is dusted onto the navel as it heals. Also used in mouthwashes and throat lozenges, it has a painkilling effect, as well as an antiseptic one. Example: TCP. Other phenolic antiseptics include historically important, but today rarely used (sometimes in dental surgery) thymol, today obsolete hexachlorophene, still used triclosan, and sodium 3,5-dibromo-4-hydroxybenzenesulfonate (Dibromol).

• Polyhexanide (polyhexamethylene biguanide, PHMB) is an antimicrobial compound suitable for clinical use in critically colonized or infected acute and chronic wounds. The physicochemical action on the bacterial envelope prevents or impedes the development of resistant bacterial strains.

• Sodium chloride (salt) is used as a general cleanser and as an antiseptic mouthwash. Its weak antiseptic effect is due to hyperosmolality of the solution above 0.9%.

• Sodium hypochlorite was used in the past, diluted, neutralized, and combined with boric acid in Dakin's solution.

• Calcium hypochlorite was used by Semmelweis, as "chlorinated lime", in his revolutionary efforts against childbed fever.

• Sodium bicarbonate (NaHCO₃) has antiseptic and disinfectant properties.

• Balsam of Peru is a mild antiseptic.

Evolved resistance

By continued exposure to antibiotics, bacteria may evolve to the point where they are no longer harmed by these compounds.

In contrast, bacteria can develop a resistance to antiseptics, but the effect is generally less pronounced.

The mechanism by which bacteria evolve may vary in response to different antiseptics. Low concentrations of an antiseptic may encourage growth of a bacterial strain that is resistant to the antiseptic, where a higher concentration of the antiseptic would simply kill the bacteria. In addition, use of an excessively high concentration of an antiseptic may cause tissue damage or slow the process of wound healing. Consequently, antiseptics are most effective when used at the correct concentrationâ€"a high enough concentration to kill harmful bacteria, fungi or viruses, but a low enough concentration to avoid damage to the tissue.

See also

• Henry Jacques Garrigues, introduced antiseptic obstetrics to North America
• Ignaz Semmelweis
• Joseph Lister
• Louis Pasteur

Notes

References

•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Antiseptics". Encyclopædia Britannica (11th ed.). Cambridge University Press. 

External links

•  "Antiseptic". New International Encyclopedia. 1905.