Sterilisation

Definition

 

Decontamination

- removal of gross organic debris

 

Disinfection

- process of eliminating all microorganisms except bacterial spores

 

Sterilization

- process to eliminate or destroy all forms of microbial life, including bacterial spores

 

Techniques of Sterilisation

 

1. Wet heat

2. Dry heat

3. Chemical

4. Irradiation

 

1.  Wet Heat / Pressurized Steam

 

Autoclaving

- most reliable

- metal instruments

- glass

- some plastics, fabrics & rubbers

 

Technique

- 121°   >103 kPa  ~ 15 minutes

 

Flash

- 134°  205kPa  3 minutes

 

2.  Dry Heat

 

Uses

- glassware

- oils & fats

 

Technique

- fan-driven oven

- 160° C

- minimum 2 hours

 

3.  Chemical

 

indications

- instruments damaged by heat

 

A. Ethylene Oxide

 

Uses

- items unable to withstand heat of >60° C

- instruments with electrical, fibre-optic or electronic components

- heat sensitive plastics

 

Technique

- ethylene oxide must reach all surfaces of article to be effective

- At 60°C in 60% humidity

- minimum time 12 hours

 

B.  Glutaraldehyde

 

Most common used

- thoroughly cleaned instrument immersed in solution

- sterilisation with immersion for 10 hours

- disinfection with immersion for 20 minutes

- precautions with use & thorough rinsing because very irritant

 

4.  Radiation / Sterrad

 

Hydrogen Peroxide made to release free radical by radiowave - 45° C

 

Summary

 

    Temperature Pressure Time    
Wet Heat Complete 121o 103kpa 15 min    
  Flash 134o 205kpa 3 min    
Dry Heat   160o   120 min    
Chemical Ethylene Oxide 60o   12 hours    
  Gluteraldehyde     10 hours