CHEMICAL AGENT
There are several chemical agent used for disinfection. Disinfectant is a chemical substance that destroyed microorganism in an inanimate object. The chemical agent that kill germs or inhibit it growth is called germicide. While the chemical agent that kill the growth of bacterial is called bactericide.
A chemical that is used to kill or inhibit the growth of microorganism in human body without the chemical poses any effect to the body tissue is called antiseptic.
While chemical agent used to prevent organism to growth in a culture media but does not kill the organism is called bacteriostatic
They way which these chemical substance works are change by many different factor. Some chemical are very powerful in the present of organic material while some are less powerful in the present of these material. Chemical substance work as sterilizing agent by the way which they kill organism i.e;
- Destruction of the organism cell membrane
- Interference with enzyme of the organism called poison
- Coagulate their protein
- Oxidation process
There are varieties of chemical substance used for disinfectant, but few once will be our major focus, such are those one that are very essential in the laboratory;
Glycerol: with 50% concentration of glycerol, it killed several micro organisms. Sometime this substance is used as a preservative of some virus organisms; this chemical has no effective action which may kill the virus.
Aldehyde: this substance is in two forms, which are formaldehyde supply in 40% concentration called formalin, and glutaraldehyde. Generally formalin gass cause so much discomfort, but they are used for disinfecting complete used up protective cabinet. Glutaraldehyde cause less discomfort compare to formalin gases. The substance is advisable to use where there is less organic material because they have low penetrating power; the compound is generally also used for preserving tissue for autopsy.
Chloroform: these is use for keeping the sterility of serum in case the serum is require for clinical chemistry test, the substance is incubated in water bath at temperature of 56ºC for a short time, the chloroform will evaporate. The effective of this substance depend on it concentration for at least it should have concentration of 0.25% before it could be used.
Phenol and Cresol: These substances are powerful antiseptic agent. They are used on object for incineration, such as discarded culture plate, pipettes, syringe, needle, and some other medical non reused material. The concentration of this chemical used is 5%, at this concentration it is very effective. But in such case that the concentration is more than 5% will yield a stronger solution, this solution need to be diluted to lessen it power, because when the stronger solution react with the micro organism it will form cluster and this cluster are coagulated into a shield that act as a barrier to the micro organism and confer a resistance to the middle cluster of the organism.
Alcohol (Ethanol): this substance is less effective in it absolute alcoholic form because at this concentration it has low penetrating power, but the power can be boosted by diluting it with distilled water for approximately 70% will be effective for sterilization of skin either during injection or Verne puncture e.g when taken patient blood for analysis.
Chlorine: this chemical are mostly in microbiology laboratories, virology department mostly used it as their disinfectant of choice. They poses a poor penetrating power when in contact with organic matter, and can lost their potential when combine with thiosuphate, sulphide, and ion salt. In such case it is very important to protect them from this inhibitory substance.
Quaternary Ammonium Compound: These substances are mainly used for skin disinfection such as infected skin with Pseudomona aeruginosa, Mycobacterium turberculosis and bacteria spore. The compound is a cationic detergent. The species of this detergent is mostly used in the hospital is called (cetrimide) cetyltrimethyl-ammonium bromide.
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