CHEMICAL DISINFECTANTS
The chemical substances known as disinfectants are used to kill pathogenic organism.
Mechanism of Chemical Disinfectants
A chemical disinfectant acts by coagulating the bacterial protein or by changing the composition of protein so that is no longer exist in the same form
Commonly Used Disinfectants
- Phenol
- Lysol
- Formalin
- Dettol
- Alcohol
The Choice of Disinfectant Based on
- The strength of the solution
- Type of bacteria to be killed
- Type of articles
- Length of exposure
- The articles should be fully immersed in the lotions
Chemical Agent, Mechanism and Uses
- Alcohols (ethanol, isopropanol)
Mechanism: denaturation of bacterial proteins
Uses: skin antiseptics, surface decontamination of incubators and cabinet interiors, disinfection of clinical thermometers
- Aldehyde (formaldehyde and glutaraldehyde)
Mechanism: inactivation of bacterial proteins
Uses: preservation of biological specimens, destroying anthrax spores in wool, fumigation.
Cold sterilant and fixative, surface decontamination, disinfection of hospital instruments, equipment, glasswares
- Biguanides (chlorhexidine)
Mechanism: damage plasma membranes
Uses: skin and mucous membrane disinfection
- Dyes (aniline dyes, malachite green, acridine dyes, acriflavine, proflavine)
Mechanism: react with acid group in cell
Impair DNA and destroy reproductive capacity
Uses: selective agents in culture media, e.g. LJ media
Skin antiseptic
- Beta propiolactone
Mechanism: damage DNA, RNA and cause alkylation
Uses: fumigation, sterilization of biological products
- Halogens (chlorine and iodine)
Mechanism: oxidizing agent and protein denaturation
Uses: surface decontamination, emergency spills clean-up, disinfectant
- Metallic salts (silver, mercury)
Mechanism: combine with sulfhydryl groups, coagulate proteins and inactivate enzymes
Uses: antiseptic to prevent against gonorrheal infections in infants
- Phenolic compounds (phenol, cresol)
Mechanism: damage to cell membranes, inactivation of proteins, oxidases and dehydrogenases
Uses: disinfectant in hospitals
- Perioxides (hydrogen peroxide)
Mechanism: oxidizing agent
Uses: disinfectant
- Quaternary ammonium compounds (zephiran, triclosan)
Mechanism: surface active agents (cationic detergent)
Uses: surface decontaminant and disinfecting equipment
- Surfactants (soaps and detergent, sodium lauryl sulphate, benzalkonium chloride, cetrimide)
Mechanism: disruption of cell membrane
Uses: detergents and wetting agents
Advantages
- This method is used to sterilize instruments which are damaged by heat and metallic objects prone to corrosion
- It is an easy method
Disadvantages
- A disinfectant cannot destroy the spores
- Disinfectants are injurious to skin and the articles
General Instruction
- The disinfectant chosen should destroy the pathogens
- It should be used in correct strength
- The article should be fully submerged it
- The article should be kept in the disinfectant for sufficient time
- The disinfectant should not be injurious to the skin and the article
- The disinfectant should be cheap
- Before dipping the article into the disinfectant clean it properly to free it from organic material
