DISINFECTANTS

 DISINFECTANTS

A disinfectant is a chemical agent, which destroys or inhibits growth of pathogenic microorganisms in the non-sporing or vegetative state.

Disinfectants do not necessarily kill all organisms but reduce them to a level, which does not harm health or the quality of perishable goods.

Disinfectants are applied to inanimate objects and materials such as instruments and surfaces to control and prevent infection.

They may also be used to disinfect skin and other tissues,are called as  

ANTISEPTICS  

An antiseptic is a type of disinfectant, which destroys or inhibits growth of micro-organisms on living tissues without causing injurious effects when applied to surfaces of the body or to exposed tissues.

Some antiseptics are applied to the unbroken skin or mucous membranes, to burns and to open wounds to prevent sepsis by removing or excluding microbes from these areas.

Example :-  Iodine has been modified for use as an antiseptic.

1.   The iodophore, polyvidone-iodine , is effective against bacteria, fungi, viruses, protozoa, cysts and spores and significantly reduces surgical wound infections.

2.   The solution of polyvidone-iodine releases iodine on contact with the skin.

3.   Chlorhexidine  has  a  wide  spectrum of bactericidal and  bacteriostatic  activity and  is effective against both Grampositive and Gram-negative bacteria although it is less effective against some species of Pseudomonas and Proteus and relatively inactive against mycobacteria.

Types of Disinfectants

1.   Air disinfectants

2.   Alcohols

3.   Aldehydes

4.   Oxidizing agents

5.   Peroxy and peroxo acids

6.   Phenolics

7.   Quaternary ammonium compounds

8.   Inorganic compounds

9.   Terpenes

10. Other- non- chemical or herbal agents. 

Air disinfectants

Chemical substance  capable  of disinfecting  microorganism suspended (flooting) in air, use to control aseptic like laboratory.

Alcohols

Ethyl or isopropyl at a concentration of 50-70% are used for some surfaces where a rapid evaporation of the chemical and leaving no residue may be important, such as on laboratory equipment, etc.

Alcohols are low in sporocidal activity and must remain wet on the surface for several minutes to achieve any reasonable disinfection.

Additionally, high-concentration mixtures of 80% ethanol+5%isopropanol are required to effectively inactivate  lipid-enveloped viruses such as HIV, hepatitis B, hepatitis C.

Aldehydes

Glutaraldehyde

Glutaraldehyde is an important dialdehyde that has found usage as a disinfectant and sterilant, in particular for low-temperature disinfection and sterilization of endoscopes and surgical equipment and as a fixative in electron icroscopy.
Glutaraldehyde has a broad spectrum of activity against bacteria and their spores, fungi, and viruses. But  Glutaraldehyde can increase the chance of asthma hence, Ortho-phthalaldehyde is replacing glutaraldehyde.
Formaldehyde is an extremely reactive chemical that interacts with protein DNA and RNA in vitro. 

Oxidizing agents-

1.   Oxidizing Agents by oxidizing the cell membrane the of microorganism,which results in aloss of structure and leads to cell lysis and death. Chlorine and oxygenare strong oxidizers.
2.   Electrolyzed Water or Anolyte
3.   Hydrogen peroxide
4.   Hydrogen peroxide vapour
5.   Ozone
6.   Potassium permanganate

Ozone

Ozone can be used as a chemical disinfectant to kill bacteria and viruses with low ozone concentrations.
Ozone Benefits
1.   Over 50% more efficient at breaking through bacteria membranes compared to chlorine
2.   Eliminates a wide range of bacteria over 3000 times faster than chlorine
3.   Potent disinfectant at low concentrations
4.   Decomposes into oxygen gas leaving no by-products
5.   FDA-approved for direct contact with food
6.   Extends shelf life of most food products
7.   Efficient odor, taste and color remover
8.   Easily and economically produced at point of use
9.   Easily detectable at low concentrations by humans, thereby safe to manage.

Peroxy and peroxo acids- inorganic peroxo acids

Peroxyformic acids 
Peracetic acids 
Peroxypropionic acids 
Monoperoxyglutaric acid 
Monoperoxysuccinic acid 
Peroxybenzoic acid. 

Phenolics

O-phenylphenol less corrosive then phenol.
Chlorhexidine agent used in dettol.
Chlorhexidine is probably the most widely used biocide in antiseptic products, in particular in handwashing and oral products but also as a disinfectant and preservative. 
This is due in particular to its broad-spectrum efficacy, substantivity for the skin, and low irritation. 

Quaternary ammonium compound- 

BenzalKonium chloride are a large group of related compounds
Ammonium at or above 200ppm plus Alcohol solution exhibit efficancy against difficult to kill non-enveloped viruses  such as norovirus,or Polio virus.

Inorganic compound

Chlorine – hypochlorite or hypochlorous acid, chloramines,chlorine dioxide. Iodine
Acids – Sulfurous acids,sulfur dioxide
Bases –Potassium hydroxide  ,Sodium hydroxide

Terpenes 

Thymol Pine oil used as disinfectants.
 DISINFECTANTS NOTES PDF


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