Antimicrobial agent that inactivates or destroys microbes
"Sanitizers" redirects here. For the software, see
AddressSanitizer.
This article is about antimicrobial agents. For the Macintosh anti-virus software, see
Disinfectant (software).
A disinfectant is a
chemical substance or compound used to inactivate or destroy
microorganisms on inert surfaces.[1] Disinfection does not necessarily kill all microorganisms, especially resistant
bacterial spores; it is less effective than
sterilization, which is an extreme physical or chemical process that kills all types of life.[1] Disinfectants are generally distinguished from other antimicrobial agents such as
antibiotics, which destroy microorganisms within the body, and
antiseptics, which destroy microorganisms on living
tissue. Disinfectants are also different from
biocides—the latter are intended to destroy all forms of life, not just microorganisms.
Disinfectants work by destroying the cell wall of microbes or interfering with their metabolism. It is also a form of decontamination, and can be defined as the process whereby physical or chemical methods are used to reduce the amount of pathogenic microorganisms on a surface.[2][3]
Disinfectants can also be used to destroy microorganisms on the skin and mucous membrane, as in the medical dictionary historically the word simply meant that it destroys microbes.[4][5][6][7][8]
Sanitizers are substances that simultaneously clean and disinfect.[9] Disinfectants kill more germs than sanitizers.[10] Disinfectants are frequently used in hospitals, dental surgeries, kitchens, and bathrooms to kill infectious organisms. Sanitizers are mild compared to disinfectants and are used majorly to clean things that are in human contact whereas disinfectants are concentrated and are used to clean surfaces like floors and building premises.[citation needed][11]
In
wastewater treatment, a disinfection step with
chlorine,
ultra-violet (UV) radiation or
ozonation can be included as tertiary treatment to remove
pathogens from wastewater, for example if it is to be discharged to a river or the sea where there body contact immersion recreations is practiced (Europe) or reused to irrigate golf courses (US). An alternative term used in the
sanitation sector for disinfection of waste streams,
sewage sludge or
fecal sludge is sanitisationorsanitization.[citation needed]
Sterilant means a chemical agent which is used to sterilize critical medical devices or medical instruments. A sterilant kills all micro-organisms with the result that the sterility assurance level of a microbial survivor is less than 10^-6. Sterilant gases are not within this scope.[citation needed]
High level disinfectant means a disinfectant that kills all
microbial pathogens, except large numbers of bacterial endospores when used as recommended by its manufacturer.
Instrument grade
Instrument grade disinfectant means:
a disinfectant which is used to reprocess reusable therapeutic devices; and
when associated with the words “low”, “intermediate” or “high” means “low”, “intermediate” or “high” level disinfectant respectively.
Hospital grade
Hospital grade disinfectant means a disinfectant that is suitable for general purpose disinfection of building and fitting surfaces, and purposes not involving instruments or surfaces likely to come into contact with broken skin:[citation needed]
in premises used for:
the investigation or treatment of a disease, ailment or injury; or
procedures that are carried out involving the penetration of the
human skin; or,
in connection with:
the business of beauty therapy or hairdressing; or
the practice of podiatry;
but does not include :
Instrument grade disinfectants; or
sterilant; or
an antibacterial clothes preparation; or
a sanitary fluid; or
a sanitary powder; or
a sanitiser.
Household/commercial grade
Household/commercial grade disinfectant means a disinfectant that is suitable for general purpose disinfection of building or fitting surfaces, and for other purposes, in premises or involving procedures other than those specified for a hospital-grade disinfectant, but is not:[citation needed]
an antibacterial clothes preparation; or
a sanitary fluid; or
a sanitary powder; or
a sanitiser
Measurements of effectiveness
One way to compare disinfectants is to compare how well they do against a known disinfectant and rate them accordingly. Phenol is the standard, and the corresponding rating system is called the "
Phenol coefficient". The disinfectant to be tested is compared with phenol on a standard microbe (usually Salmonella typhi or Staphylococcus aureus). Disinfectants that are more effective than phenol have a coefficient > 1. Those that are less effective have a coefficient < 1.[citation needed]
The standard European approach for disinfectant validation consists of a basic suspension test, a quantitative suspension test (with low and high levels of organic material added to act as ‘interfering substances’) and a two part simulated-use surface test.[14]
A less specific measurement of effectiveness is the
United States Environmental Protection Agency (EPA) classification into either high, intermediate or low levels of disinfection. "High-level disinfection kills all organisms, except high levels of bacterial spores" and is done with a chemical germicide marketed as a sterilant by the U.S.
Food and Drug Administration (FDA). "Intermediate-level disinfection kills mycobacteria, most viruses, and bacteria with a chemical germicide registered as a 'tuberculocide' by the Environmental Protection Agency. Low-level disinfection kills some viruses and bacteria with a chemical germicide registered as a hospital disinfectant by the EPA."[15]
An alternative assessment is to measure the Minimum inhibitory concentrations (MICs) of disinfectants against selected (and representative) microbial species, such as through the use of microbroth dilution testing.[16] However, those methods are obtained at standard inoculum levels without considering the inoculum effect. More informative methods are nowadays in demand to determine the minimum disinfectant dose as a function of the density of the target microbial species.[17]
Properties
A perfect disinfectant would also offer complete and full microbiological
sterilisation, without harming humans and useful form of life, be inexpensive, and noncorrosive. However, most disinfectants are also, by nature, potentially harmful (even
toxic) to humans or animals. Most modern household disinfectants contain
denatonium, an exceptionally bitter substance added to discourage ingestion, as a safety measure. Those that are used indoors should never be mixed with other cleaning products as
chemical reactions can occur.[18] The choice of disinfectant to be used depends on the particular situation. Some disinfectants have a wide spectrum (kill many different types of microorganisms), while others kill a smaller range of disease-causing organisms but are preferred for other properties (they may be non-corrosive, non-toxic, or inexpensive).[19]
There are arguments for creating or maintaining conditions that are not conducive to bacterial survival and multiplication, rather than attempting to kill them with chemicals. Bacteria can increase in number very quickly, which enables them to
evolve rapidly. Should some bacteria survive a chemical attack, they give rise to new generations composed completely of bacteria that have resistance to the particular chemical used. Under a sustained chemical attack, the surviving bacteria in successive generations are increasingly resistant to the chemical used, and ultimately the chemical is rendered ineffective. For this reason, some question the wisdom of impregnating cloths,
cutting boards and worktops in the home with
bactericidal chemicals.[citation needed]
Air disinfectants are typically chemical substances capable of disinfecting microorganisms suspended in the air. Disinfectants are generally assumed to be limited to use on surfaces, but that is not the case. In 1928, a study found that airborne microorganisms could be killed using mists of dilute bleach.[20] An air disinfectant must be dispersed either as an
aerosol or
vapour at a sufficient concentration in the air to cause the number of viable infectious microorganisms to be significantly reduced.
Although glycols are effective air disinfectants in controlled laboratory environments, it is more difficult to use them effectively in real-world environments because the disinfection of air is sensitive to continuous action. Continuous action in real-world environments with outside air exchanges at door, HVAC, and window interfaces, and in the presence of materials that absorb and remove glycols from the air, poses engineering challenges that are not critical for surface disinfection. The engineering challenge associated with creating a sufficient concentration of the glycol vapours in the air have not to date been sufficiently addressed.[24][25]
Alcohol and alcohol plus
Quaternary ammonium cation based compounds comprise a class of proven surface sanitizers and disinfectants approved by the
EPA and the
Centers for Disease Control for use as a hospital grade disinfectant.[26] Alcohols are most effective when combined with
distilled water to facilitate diffusion through the cell membrane; 100% alcohol typically denatures only external membrane proteins.[27] A mixture of 70% ethanol or
isopropanol diluted in water is effective against a wide spectrum of bacteria, though higher concentrations are often needed to disinfect wet surfaces.[28] Additionally, high-concentration mixtures (such as 80% ethanol + 5% isopropanol) are required to effectively inactivate lipid-enveloped viruses (such as
HIV,
hepatitis B, and
hepatitis C).[27][28][29][30]
The efficacy of alcohol is enhanced when in solution with the wetting agent
dodecanoic acid (coconut soap). The synergistic effect of 29.4% ethanol with dodecanoic acid is effective against a broad spectrum of bacteria, fungi, and viruses. Further testing is being performed against
Clostridium difficile (C.Diff) spores with higher concentrations of ethanol and dodecanoic acid, which proved effective with a contact time of ten minutes.[31]
Some bacteria have developed resistance to glutaraldehyde, and it has been found that glutaraldehyde can cause asthma and other health hazards, hence
ortho-phthalaldehyde is replacing glutaraldehyde.[citation needed]
Oxidizing agents
Oxidizing agents act by oxidizing the cell membrane of microorganisms, which results in a loss of structure and leads to cell
lysis and death. A large number of disinfectants operate in this way.
Chlorine and
oxygen are strong oxidizers, so their compounds figure heavily here.
Electrolyzed water or "Anolyte" is an oxidizing, acidic hypochlorite solution made by
electrolysis of
sodium chloride into
sodium hypochlorite and hypochlorous acid. Anolyte has an oxidation-reduction potential of +600 to +1200 mV and a typical pH range of 3.5––8.5, but the most potent solution is produced at a controlled pH 5.0–6.3 where the predominant oxychlorine species is
hypochlorous acid.
Hydrogen peroxide is used in
hospitals to disinfect surfaces and it is used in solution alone or in combination with other chemicals as a high level disinfectant. Hydrogen peroxide is sometimes mixed with
colloidal silver. It is often preferred because it causes far fewer
allergic reactions than alternative disinfectants. Also used in the
food packaging industry to disinfect foil containers. A 3% solution is also used as an antiseptic.
Hydrogen peroxide vapor is used as a
medical sterilant and as room disinfectant. Hydrogen peroxide has the advantage that it decomposes to form oxygen and water thus leaving no long term residues, but hydrogen peroxide as with most other strong oxidants is hazardous, and solutions are a primary irritant. The vapor is hazardous to the respiratory system and eyes and consequently the
OSHA permissible exposure limit is 1 ppm (29 CFR 1910.1000 Table Z-1) calculated as an eight-hour time weighted average and the
NIOSH immediately dangerous to life and health limit is 75 ppm.[32] Therefore, engineering controls, personal protective equipment, gas monitoring etc. should be employed where high concentrations of hydrogen peroxide are used in the workplace. Vaporized hydrogen peroxide is one of the chemicals approved for decontamination of anthrax spores from contaminated buildings, such as occurred during the
2001 anthrax attacks in the U.S. It has also been shown to be effective in removing exotic animal viruses, such as avian influenza and
Newcastle disease from equipment and surfaces.
The antimicrobial action of hydrogen peroxide can be enhanced by
surfactants and organic acids. The resulting chemistry is known as
Accelerated hydrogen peroxide. A 2% solution, stabilized for extended use, achieves high-level disinfection in 5 minutes, and is suitable for disinfecting medical equipment made from hard plastic, such as in
endoscopes.[33] The evidence available suggests that products based on Accelerated Hydrogen Peroxide, apart from being good germicides, are safer for humans and benign to the environment.[34]
Ozone is a gas used for disinfecting water, laundry, foods, air, and surfaces. It is chemically aggressive and destroys many organic compounds, resulting in rapid decolorization and deodorization in addition to disinfection. Ozone decomposes relatively quickly. However, due to this characteristic of ozone, tap water chlorination cannot be entirely replaced by ozonation, as the ozone would decompose already in the water piping. Instead, it is used to remove the bulk of oxidizable matter from the water, which would produce small amounts of
organochlorides if treated with chlorine only. Regardless, ozone has a very wide range of applications from municipal to industrial water treatment due to its powerful reactivity.
Potassium permanganate (KMnO4) is a purplish-black crystalline powder that colours everything it touches, through a strong oxidising action. This includes staining "stainless" steel, which somewhat limits its use and makes it necessary to use plastic or glass containers. It is used to disinfect
aquariums and is used in some community swimming pools as a foot disinfectant before entering the pool. Typically, a large shallow basin of KMnO4 / water solution is kept near the pool ladder. Participants are required to step in the basin and then go into the pool. Additionally, it is widely used to disinfect community water ponds and wells in tropical countries, as well as to disinfect the mouth before pulling out teeth. It can be applied to wounds in dilute solution.
Phenolics are active ingredients in some household disinfectants. They are also found in some mouthwashes and in disinfectant soap and handwashes. Phenols are toxic to cats[35] and newborn humans[36]
Phenol is probably the oldest known disinfectant as it was first used by
Lister, when it was called carbolic acid. It is rather corrosive to the skin and sometimes toxic to sensitive people. Impure preparations of phenol were originally made from
coal tar, and these contained low concentrations of other
aromatic hydrocarbons including
benzene, which is an
IARCGroup 1carcinogen.
o-Phenylphenol is often used instead of
phenol, since it is somewhat less corrosive.
Hexachlorophene is a phenolic that was once used as a germicidal additive to some household products but was banned due to suspected harmful effects.
Thymol, derived from the herb thyme, is the active ingredient in some "broad spectrum" disinfectants that often bear ecological claims. It is used as a stabilizer in pharmaceutic preparations. It has been used for its antiseptic, antibacterial, and antifungal actions, and was formerly used as a vermifuge.[37]
Although not a phenol,
2,4-dichlorobenzyl alcohol has similar effects as phenols, but it cannot inactivate viruses.
Quaternary ammonium compounds
Quaternary ammonium compounds ("quats"), such as
benzalkonium chloride, are a large group of related compounds. Some concentrated formulations have been shown to be effective low-level disinfectants. Quaternary ammonia at or above 200ppm plus alcohol solutions exhibit efficacy against difficult to kill non-enveloped viruses such as
norovirus,
rotavirus, or
polio virus.[26] Newer synergous, low-alcohol formulations are highly effective broad-spectrum disinfectants with quick contact times (3–5 minutes) against bacteria, enveloped viruses, pathogenic fungi, and
mycobacteria. Quats are biocides that also kill algae and are used as an additive in large-scale industrial water systems to minimize undesired biological growth.[citation needed]
Inorganic compounds
Chlorine
This group comprises aqueous solution of
chlorine,
hypochlorite, or
hypochlorous acid. Occasionally, chlorine-releasing compounds and their salts are included in this group. Frequently, a concentration of < 1 ppm of available chlorine is sufficient to kill bacteria and viruses, spores and mycobacteria requiring higher concentrations.
Chlorine has been used for applications, such as the deactivation of pathogens in drinking water, swimming pool water and wastewater, for the disinfection of household areas and for textile bleaching[38]
The
biguanidepolymerpolyaminopropyl biguanide is specifically bactericidal at very low concentrations (10 mg/L). It has a unique method of action: The polymer strands are incorporated into the bacterial cell wall, which disrupts the membrane and reduces its permeability, which has a lethal effect to bacteria. It is also known to bind to bacterial DNA, alter its transcription, and cause lethal DNA damage.[40] It has very low toxicity to higher organisms such as human cells, which have more complex and protective membranes.
Common
sodium bicarbonate (NaHCO3) has antifungal properties,[41] and some antiviral and antibacterial properties,[42] though those are too weak to be effective at a home environment.[43]
Non-chemical
Ultraviolet germicidal irradiation is the use of high-intensity shortwave
ultraviolet light for disinfecting smooth surfaces such as dental tools, but not porous materials that are opaque to the light such as wood or foam. Ultraviolet light is also used for municipal
water treatment. Ultraviolet light fixtures are often present in
microbiology labs, and are activated only when there are no occupants in a room (e.g., at night).
Heat treatment can be used for disinfection and sterilization.[44]
The phrase "sunlight is the best disinfectant" was
popularized in 1913 by
United States Supreme Court Justice
Louis Brandeis and later advocates of
government transparency. While sunlight's ultraviolet rays can act as a disinfectant, the Earth's
ozone layer blocks the rays' most effective wavelengths. Ultraviolet light-emitting machines, such as those used to disinfect some hospital rooms, make for better disinfectants than sunlight.[45]
Since the mid-1990s
cold plasma has been shown to be an efficient sterilization/disinfection agent.[46][47] Cold plasma is an ionized gas that remains at room temperature. It generates reactive oxygen and reactive nitrogen species that interact with bacterial wall and membrane and cause oxidation of the lipids and proteins and can also lyse the cells. Cold plasma can inactivate bacteria, viruses, and fungi.
Electrostatic Disinfection
There has been a rise in the use of electrostatic disinfectants in recent years.[48] Electrostatic disinfection is a process achieved by use of electrostatic sprayers notable examples of which include the
Vycel -Vycel 4 or the
Techtronics Ryobi. Electrostatic Sprayers are a new technology for disinfecting surfaces. Unlike conventional spraying bottles or devices
electrostatic sprayers apply a positive ionic charge to liquid disinfectants as they pass through the nozzle of the device. The positively charged disinfectant distributed through the nozzle of an electrostatic sprayer is attracted to negatively charged surfaces, which allows for efficient coating of disinfectant solutions on to hard nonporous surfaces.[49] There are a number of specific disinfectants designed for use with electrostatic sprayers and these are often dissolved in solution or diluted with water. Notable disinfectant sprays that are designed for use with electrostatic sprayers include Citrox Disinfectant Solution and Vital Oxide Disinfectant Solution.[citation needed]
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^For a review of the toxicity of triethylene glycol, see: United States Environmental Protection Agency (September 2005). "Reregistration eligibility decision for triethylene glycol". EPA 739-R-05-002. {{
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