Sterilization and Disinfection PDF

Sterilization and disinfection By Eman Mohsen Sterilization and disinfection Sterilization: process of destroying all living microorganisms, and kills all type of life vegetative and spore cells. Disinfection: elimination of microorganisms. and get rid of vegetat...

Sterilization and disinfection By Eman Mohsen Sterilization and disinfection Sterilization: process of destroying all living microorganisms, and kills all type of life vegetative and spore cells. Disinfection: elimination of microorganisms. and get rid of vegetative cells only.  Controlling of bacteria by : # Chemical method # Physical method (disinfection method ) 1. Temperature By using chemical substances. 2. Radiation used for surface , seeds, stems 3. Filtration and leaves. 4. Desiccation 5. Osmosis Chemicals such as : 6. Ultrasonic waves Lysol 3% Dettol 20% Ethanol 70% Savlon 5%  1-Temperature 1.1 Moist heat 2.1 Dry heat A- Autoclaving (steam under A- Oven (hot air ) pressure ) B-Boiling water B- Incineration C-Fraction sterilization D-pasteurization  1.1 Moist heat A- Autoclave (sterilization method) (steam under pressure ) ‫فكرة الجهاز‬ used for : sterilization of media such as ( nutrient agar media) its Conditions : at 121oC, and 1.5 atm , 15-20 min. B-Boiling water(disinfection method ) used for : disinfection of media its Conditions : boiling of media at 100oC for 15 min one time in a day. C-Fraction sterilization (sterilization method) used for : sterilization of media its Conditions : boiling of media at 100oC for 15 min three times in a day Why the Fraction sterilization is consider as sterilization method ? Because in the first time vegetative cell only is killed but in the second and third time be sure that vegetative cell and spore cell are killed  D – pasteurization: Pasteurization :. a process in which foods , drinks , dairy products are treated with mild heat, usually to less than 100 °C , to eliminate pathogens and extend shelf life. This type of treatment preserves the food The process is intended to destroy microorganisms and enzymes that contribute to spoilage or risk of disease, including vegetative bacteria, but not bacterial spores. Since pasteurization is not sterilization method ( is consider as disinfection method ) All germs present are not eliminated, so the pasteurization stage must be followed by a rapid cooling. The conservation of pasteurized products is potentially short because the product has a temporary stabilization. In order to limit the development of microorganisms still present, storage is carried out in positive cold (+4 °C) used for : disinfection of milk and fruit juice its Conditions : * High Temperature for Short Time (H.T.S.T) 71.6 C for 15 sec followed by cooling section * Low Temperature for Long Time (L.T.L.T) 61.6 C for 30 min followed by cooling section. 2.1 Dry heat : A- Oven (hot air ) : (sterilization method) Used for : sterilizing of glass wares, Dry glass wares such as glass tubes, flasks and petri dishes. its condition : are sterilized by dry heat through even that should be available at a temp of about 160oC- 180oC ) for 2 hours. B- Incineration: (sterilization method) Used for : sterilization of Metal tools as needles. Describe Incineration method ? is sterilized by heating a needle in a horizontal position on a bunsen flame until just red hot, then treated by dipping it a alcohol (70%) and then flaming off the alcohol 2- Radiation : It has sterilization , mutation and death effects. Used for : sterilization of plastics as plastic plates , laminar flow (isolation room ) , plastic syringes , gloves. How ? With the use of ultraviolet lamp about half to one hour when the room is unoccupied and spraying the laminar flow with alcohol 70%. 3- Filteration : Used for : sterilization the substance that can not stand the high temperature and sensitive to high temperature as Enzyme , blood, serum and How ? By using bacterial filter paper which consist of very small pore , smaller than the volume of bacteria by putting non sterilized substance over the bacterial filter paper and then pass through filter paper and finally , sterilized substance is obtained. Non sterilized substance Holding clamp sterilized substance