Disinfectant agents
Def:
Is the process of destruction or removal of microorganisms and reducing them
to the level not harmful to health .
If the object is inanimate (lifeless) ,such as working area ,dishes ,benches ,
etc. The chemical agent is know as disinfectants.
However if the object is animate (living) such as human body tissue ,the
chemical is know as antiseptic .
Types:
High level disinfection.
Intermediate level disinfection .
Low level disinfection .
High level disinfection
High level disinfection destroy vegetative bacteria ,mycobacteria ,fungi and
enveloped (lipid) and non enveloped (non lipid) viruses but not necessarily
bacterial spores .
It must be capable of sterilization when contact time is extended.
Intermediate level disinfection:
Intermediate level disinfection kill vegetative bacteria ,most viruses and most
fungi but not resistance bacteria spores .
Low level disinfection : kill most vegetative bacteria and
some fungi , don’t kill mycobacteria or bacteria spores .
Used to clean environmental surfaces .
An ideal disinfectant should have following properties :
Broad spectrum.
Economical.
Non toxic.
Easy to use .
Fast acting.
Soluble.
Odorless.
not affected by the physical factor
Surface compatibility.
Stable on storage .
Classification of disinfectants:
Acid and alkalis.
Dyes.
Halogens.
Quaternary ammonium compounds.
Heavy metals
Detergents and soups
Phenol and its derivatives.
Heat .
Alcohols.
Radiation .
Aldehydes.
Filtration.
1-Acid and alkalis: strong acids and alkali kill the bacteria but weak organic acids inhibit
their growth.
2-Halogens :chlorine ,fluorine, bromine and iodine in the free state as well as their compouds
strongly act as germicidal.
3-Heavy metals : the most widely used heavy metals are those of mercury , silver.
-it act as antimicrobial by combining with influence with the cellular protein.
-high concentration of salts and heavy metals like mercury , cooper and silver coagulate cytoplasm
protein , resulting in damage or cell death .
4- phenol and its derivatives : is the cheap product obtain by the distillation of the cool
tar .
-phenol 1% has bactericidal action .
- many derivatives of phenol are more effective and less costly .
5- Alcohols : it have fairly rapid bactericidal action against vegetative bacteria when polluted to
concentration of 60% to 70% v/v with water .
-ethanol 60%to 70% v/v and isopropanol 50%to 60% v/v are used as skin disinfectants while
methanol vapor has been used as fungicide .
-The higher alcohols (propyl , butyl, amyl etc. ) are more germicidal than ethyl alcohol .
-alcohols are used as preservatives in some vaccines .
6- Aldehyde : formaldehyde is the main aldehyde used for disinfection.
-formaldehyde in solution is useful for sterilization of certain instruments .
7- Quaternary ammonium compound : are widely used for the control of microorganism
on floor , walls , nursing home and other public places .
-they are also used as skin antiseptics and as sanitization agent in dray ,egg and fishing industries .
8- Dyes : a number of dyes have been used to inhibit the bacterial growth .
-basic dyes are more effective bactericide than acidic dyes.
-acridine and triphenylmethane dyes are commonly used as antimicrobial agents.
9- Detergents and soaps : they are widely used as surface active agents ,
wetting agents and emulsifiers .
-they are classified into four main groups such as anionic , cationic , non-ionic and
amphoteric .
Mode of action of disinfectants :
Alteration of membrane permeability .
Damage to protein .
Rupture of cell membrane.
Damage to nucleic acid .
Interfere with metabolic pathway .
Factor affecting disinfection :
Concentration of disinfected.
Formulation of disinfectant.
Temperature.
Chemical structure of disinfectant
Time of contact .
Types and number of microorganism
PH of environment .
present.
Surface tension.
.
Presented by :
Rasha elsayed.
Asmaa Mohammed.
 AYA Mohammed elsayed.
Ahmed Esmat.
Mohammed elwaey
Ebrahim zamzam.
Mohammed elashery.
 Ahmed Khaled
Ahmed Salama.