Sterilisation and Disinfection Methods

STERILIZATION AND DISINFECTION

• Microorganisms are ubiquitous. Since they cause contamination, infection and decay, it becomes necessary to remove or destroy them from materials or from areas.

 

DEFINITIONS

• Sterilization – Process by which an article, surface or medium is freed of all living microorganisms either in the vegetative or spore state.

• Disinfection – Destruction or removal of all pathogenic organisms.

• Antisepsis – Prevention of infection, usually by inhibiting the growth of bacteria in wounds or tissues.

• Antiseptics – Chemical disinfectants which can be safely applied to skin or mucous membrane and are used to prevent infection by inhibiting growth of bacteria.

• Bactericidal agent- An agent which can kill bacteria.

• Bacteriostatic agent– An agent which only prevents multiplication of bacteria.

 

CLASSIFICATION OF STERILIZATION/DISINFECTION METHOD

PHYSICAL AGENTS OF STERILIZATION/DISINFECTION METHOD                                            

• Sunlight                                                   
• Drying                                             
• Dry heat – flaming, incineration, hot air                                                                       
• Moist heat – pasteurization, boiling,                                      
• Steam under normal pressure,                                      
• Steam under pressure.                                                   
• Filtration – candles, asbestos pads, membranes.                               
• Radiation
• Ultrasonic and sonic vibrations.

 

CHEMICAL AGENTS OF STERILIZATION/DISINFECTION METHOD

•       Alcohols – Ethyl, isopropyl, trichlorobutanol

•       Aldehydes – Formaldehyde, glutaraldehyde

•       Dyes

•       Halogens

•       Phenols

•       Surface active agents

•       Metallic salts

•       Gases – ethylene oxide, formaldehyde