quaternary ammonium compounds
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quaternary ammonium compoundsCompounds in which the four hydrogen atoms of the ammonium radical are replaced by organic radicals. They are used as antiseptics.
quaternary ammonium compoundstypes of chemical disinfecting agent with surfactant and detergent properties, e.g. cetrimide, which is active against Gram-positive bacteria, but which is tissue-toxic and readily inactivated by the presence of organic compounds (see Table 1)
|Phenolic compounds||Widely effective against bacteria and fungi; little action against viruses|
Used as a 2% v/v solution to disinfect soiled but not blood-contaminated items and a 1% v/v solution for non-soiled items
Inactivated by blood and cationic detergents (not inactivated by other organic materials or anionic/non-ionic detergents)
'Coal tar derivative' types are suitable for floor cleaning
'Pine' types are poor disinfectants and unsuitable for clinical use
|Chlorine compounds, e.g. hypochlorites; dichloroisocyanurates (NaDCC)||Effective against microorganisms and viruses, including blood-borne viruses|
Easily inactivated by blood and organic matter, thus items must be washed first, before being disinfected with chlorine-containing products
Used as 0.1% (1000 ppm) solution routinely in the clinic, but as a 1% solution (10 000 ppm) to clean up after blood spillages
Manufactured as concentrates (10% solutions), powders or tablets which are dissolved as necessary for immediate use
• 1 volume of 10% concentrate is diluted with 99 volumes of water to form a solution that contains 0.1% (1000 ppm) available chlorine
• 1 volume of 10% concentrate is diluted with 9 volumes of water to form a solution that contains 1% (10 000 ppm) available chlorine
|Iodine compounds||Alcoholic solutions of iodine are effective disinfectants, but cause skin irritation and staining|
Iodophores (organic complexes containing iodine, e.g. povidone-iodine) are equally effective but less irritant and staining
Iodophores have a wide spectrum of action against bacteria, fungi, viruses and spore forms, and are used for preoperative skin preparation and wound care
|Alcohols||Ethyl and isopropyl alcohol have a wide spectrum of action and a rapid onset of effect; they are not very effective against viruses|
They are prepared as aqueous solutions (70% ethanol in water to 100%; 60-70% isopropyl alcohol in water to 100%)
They are used for the rapid disinfection of clean skin (alcohol hand gels) and hard surfaces (alcohol-impregnated disposable tissues)
They are used in combination with other antimicrobial agents
|Biguanide compounds, e.g. chlorhexidine||Effective against Gram-positive and Gram-negative bacteria, but poor action against viruses|
Their effectiveness is enhanced and more rapid in onset when diluted with alcohol (0.5% chlorhexidine in 70% isopropyl alcohol)
Inactivated by soap and anionic detergent; not recommended for general environmental use
Widely used in skin preparation, as alcohol or cationic detergent-based products
|Triclosan (2,4,4'- thrichlor-2'-hydroxydiphenylether)||Effective against both Gram-positive and Gram-negative bacteria, with little reported toxicity|
Prepared as alcoholic and aqueous solutions
|Quaternary ammonium compounds||A group of disinfecting agents with surfactant properties|
Active against Gram-positive bacteria, but have little action against other microorganisms
5% Cetrimide mixed with 0.5.% chlorhexidine is used as a wound-cleansing agent
|Glutaraldehyde||A widely effective disinfectant, with good antiviral and sporicidal action, but which is irritant to skin (thus immersed items should be rinsed in sterile water). It is no longer routinely used in podiatry|
For disinfection, the item should be immersed in the solution for 20-30 minutes
For sterilization, the item should be immersed in the solution for 3-10 hours
|Hexachlorophene||Effective against Gram-positive bacteria, but little action against other microorganisms|
It has largely been replaced by chlorhexidine or povidone-iodine
1. fourth in a series.
2. made up of four elements or groups.
quaternary ammonium compounds
synthetic cationic detergents commonly used as disinfectants. They act against cell wall lipids in bacteria. An example is benzalkonium chloride. Effective in teat dips for mastitis control. Called also QUATs.
the arrangement of separate polypeptide subunits in the structure of a multimeric protein.