Sterilization & Disinfection PDF

Sterilization & Disinfection Dr. Hanan Samir Prof of Microbiology & Immunology Cleaning, Disinfection, Sterilization 1- Cleaning (a- manual) Manual Cleaning  1- Cleaning (b- mechanical) Washer Ultrasonic cleaner  Sterilization & Disinfection...

Sterilization & Disinfection Dr. Hanan Samir Prof of Microbiology & Immunology Cleaning, Disinfection, Sterilization 1- Cleaning (a- manual) Manual Cleaning  1- Cleaning (b- mechanical) Washer Ultrasonic cleaner  Sterilization & Disinfection Physical Chemical LLD ILD Heat Radiation Filtration HLD Sterilant Dry Moist  Sterilization & Disinfection Physical Heat Dry  Dry heat This method kills bacteria by oxidation and charring penetrates slowly So, much higher temperature and longer exposure are required to sterilize the article Types: 1- Red heat 2- Hot air oven 3- Incineration  Dry heat “Hot air oven” Uses: Sterilization of glassware, powders, oil A temperature of 160°C for 1 hour  Dry heat “Hot air oven” Precautions of use: 1. The glassware should be perfectly dry before placing in the oven 2. Overloading of the oven should be avoided 3. The oven should not be opened until it cools down otherwise the glass will crack  Moist heat - kills bacteria by coagulation or denaturation of cell protein - Lower temperature and shorter exposure are required to sterilize the article by moist heat.  Moist heat ˂100⁰C At 100⁰C ˃100⁰C Moist heat At 100⁰C Boiling  Moist heat at 100⁰C Boiling p32 - It is a high level disinfection procedure - Boiling in a water bath for 10 minutes - Some spores resist boiling for many hours - Uses: disinfection of baby milk bottles  Moist heat ˂100⁰C It has minimal applications e.g. pasteurization  Moist heat ˃100⁰C Autoclave Principle: When the pressure increases above atmospheric, the boiling point also increases. 2P = 121˚C for 20 minutes 3P = 134˚C for 3 minutes Packaging Packaging  Autoclave Uses: Sterilization of - surgical instruments, surgical dressing - bed linen, gowns - cotton, gauze - Any item not destroyed by heat  Autoclave Precautions of use: - Do not overload the autoclave - Make sure that there is no air left inside before closing the steam tap - Start timing from the moment the manometer reads appropriate atmospheric pressure depending on type of sterilizer used. - Do not open the lid before the pressure goes down to atmospheric pressure, otherwise articles will be blown up and accidents can happen  Autoclave Steam sterilization monitoring (sterilization assurance indicators): 1. Mechanical methods: print out shows cycle time, temperature and pressure 2. Chemical methods: change its colour according to time and temperature  External chemical indicators: exposure of the package to temperature  External chemical indicators: exposure of the package to temperature  Internal chemical indicators: indicates penetration of steam inside the package  Autoclave 3. Biological methods (Spore indicator): Bacillus stearothermophilus is the standard spore-bearer killed at 121°C  Autoclave 1. Principle 2. uses 3. Precautions 4. Monitoring  B) Radiation Ultra-violet Ionizing rays radiation 1- Ultra-violet rays p27 From mercury vapour lamps Used to reduce the number of bacteria in air in operation rooms 2- Ionizing radiation p32 Gamma rays from cobalt 60 have a high penetrating power and no residual radioactivity They are used to sterilize disposable plastic syringe, catheters, gloves  C) Filteration used for fluids sterilization which are destroyed by any type of heat e.g. serum, plasma and hormones e.g. Millipore filter Made of synthetic membranes  Disinfection Physical Chemical Disinfectants Heat Radiation - Moist at 100⁰C UV rays - Moist ˂100⁰C  Sterilization Physical Chemical Sterilants Heat Radiation Filtration - Moist ˃ 100⁰C Ionizing Millipore filter - Dry heat radiation  Chemical Methods Disinfectant Sterilant Liquid Liquid Gas Antiseptic Disinfectant LLD ILD HLD Disinfectants act by destruction of proteins, lipids or nucleic acids in the bacteria Disinfectant: Used to disinfect inanimate objects only as it is a potent toxic substance. E.g. phenolic and chlorine compounds. Antiseptic: Suitable for superficial application to living tissues e.g. wounds as it is a less toxic substance. Disinfectant & Antiseptic: as alcohol Antiseptics (Tissue): Alcohols: in concentration of 60-90% in water (water is essential for its transfer across cell wall of the bacteria). Iodine: e.g. Betadine. Chlorhexdine gluconate 2% 1- Alcohols 2- Iodine 3- Chlorhexdine gluconate 2% HLD: 2% Glutraldehyde e.g cidex Chemical Sterilants  Chemical Sterilants Used at low temperature for heat sensitive items e.g. plastic, rubber