Sterilization and Disinfection PDF

STERILIZATION AND DISINFECTION  DEFINITION  Sterilization: The process of freeing an article from microorganisms including their spores.  Disinfection: Reducing the number of pathogenic microorganisms to the point where they no longer cause diseases.  Sepsis: Indicates bacteria...

STERILIZATION AND DISINFECTION  DEFINITION  Sterilization: The process of freeing an article from microorganisms including their spores.  Disinfection: Reducing the number of pathogenic microorganisms to the point where they no longer cause diseases.  Sepsis: Indicates bacterial contamination.  Asepsis: Absence of significant contamination. Bacteriostatic: An agent inhibits growth of bacteria Bactericide: An agent that kills bacteria Antiseptics: These are special types of chemical disinfectants (e.g. ethyl alcohol) which can be safely applied to skin and mucus membranes but are not suitable for systemic administration  Methods of Sterilisation Microbial Control Methods Mechanical Removal Physical Agents Chemical Agents Methods  Physical Agents Heat Radiation Dry Moist Ionizing Non Ionizing Incineration Steam Under X Ray, Cathode, Pressure UV Gamma Dry Oven Sterilization Boiling Water/Hot Water Sterilization Disinfection Pasteurization Disinfection  Chemical Agent Gas Liquids Sterilization Disinfection Animate Inanimate Chemotherapy Antiseptics Sterilization Disinfection  Mechanical Removal Methods Filtration Air Liquids Disinfection Sterilization  Sterilization By Dry Heat  Hot Air Oven Kills by oxidation effects The oven utilizes dry heat to sterilize articles A holding period of 160oC for 2 hr or 170oC for 1 hr is desirable There is a thermostat controlling the temperature. Double walled insulation keeps the heat in and conserves energy, To sterilise metals- glasses- oils and powders  Sterilization By Dry Heat  Flaming: Inoculation loop or Wire, held in a bunsen flame till they are red hot.  Incineration: This is an excellent method of destroying materials such as contaminated cloth, animal carcasses and pathological materials.  Temp below 100oC  Pasteurisation – Process of killing of pathogens in the milk but does not sterilize it. – Milk is heated at 63oC for 30 mins (HOLDER METHOD) – At 72oC for 15-20 Sec. Rapid cooling to 13oC (FLASH PROCESS)  Inspissator – Sterilizes by heating at 80-85oC for half an hour for 3 successive days – Used to sterilize media such as Lowenstein-Jensen & Loefller’s serum STEAM UNDER PRESSURE - AUTOCLAVE  Sterilization is carried out under pressure at 121º for 20 mints at double atmospheric pressure.  134 c for 3-6 mints at 3 atmospheric  Chemical  Alcohols  Ethanol No action on spores 70% in water  Disinfection of clinical thermometer. skin  Aldehydes  Formaldehyde To preserve anatomical specimens  Glutaraldehyde endotracheal tubes anesthetic tubes  Halogens  Iodine skin disinfectant  Chlorine disinfectants in water supplies & swimming pools  Phenols  Sterilisation by filtration  Filtration is mechanical method  sterilization of heat labile fluids e.g. sera, hormones, vitamins, plasma and vitamin C (Seitz filter)  RADIATION  Non- Ionising radiation: Eg: UV rays used to reduce the number of bacteria in operation rooms can be artificially produced by mercury lamp  IONISING RADIATIONS X- rays, gamma rays Cold sterilisation Sterilise plastics Syringes, catheters, grease fabrics metal foils  The levels of disinfection:  High-level Disinfection A procedure that kills all organisms with the exception of large numbers of bacterial sporese.g. hydrogen peroxide  Intermediate-level Disinfection A procedure that kills vegetative bacteria, including acid-fast Mycobacterium tuberculosis, most fungi, and viruses but not bacterial spores e.g. alcohol.  Low-level Disinfection A procedure that kills most vegetative bacteria (but not M tuberculosis) some fungi, and viruses but no spores e.g. quaternary ammonium compounds THANK YOU