STERILIZATION TECHNIQUE

STERILIZATION is a process by which an article, surface or medium is freed from all living micro organism either in the vegetative or spore state
The various agents used in sterilization can be classified as follows
a) physical agents:
1. sunlight
2. drying
3. dry heat : flaming, incineration, hot air
4. moist heat: pasteurization boiling, steam under normal pressure
5. filtration: candles,asbestos pads, membranes
6. radiation
7. ultrasonic and vibrations.
Chemical agents:
1. alcohols: ethyl isopropyl trichlorobutanol
2. aldehydes: formaldehyde, gluteraldehyde
3. dyes
4. halogens
5. phenols
6. surface active agents
7. metallic salts
8. gases
a)heat:
heat is a most reliable method of sterilization and shold be method of choice unless contraindicated. The factor influencing sterilization by heat

are:
1. nature of heat- dry heat or moist heat
2. temperature and time
3. number of micro organism present
4. characteristics such as species, strain, spring capacity
5. type of the material which the organism have to be eradicated
The killing effect of dry heat is due to protein denaturation, oxidative damage and the toxic effects of elevated levels of electrolytes.
The lethal effect of moist effect is due to denaturation and coagulation of protein
Dry Heat:
Flaming : inoculating loop of wire, the tip of the forceps and searing spatulas
Incineration : excellent method of safely destroying materials such as contaminated cloth, animal carcasses and pathological materials, plastics such as PVC

and polythene.
Hot air oven:
Most widely use dmethod of sterilization by dry heat
160c- for one hour- to sterilize glassware, forceps, scissors, scalpels, all glass syringes, swabs, some pharmeceutical products such as liquid

paraffin, dusting powder, fats and grease.