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3. Disinfection and Sterilization

3. Disinfection and Sterilization

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3. Disinfection and Sterilization

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  1. 3. Disinfection and Sterilization

  2. Basic terms • sterilization灭菌 • disinfection消毒 • Antisepsis 防腐 • Bacteriostasis抑菌 • Asepsis 无菌

  3. sterilization灭菌 • The process of destroying all microbial forms. A sterile object is one free of all microbial forms, including bacterial spores.

  4. disinfection消毒 • The reduction or elimination of pathogenic microorganisms in or on materials, so they are no longer a health hazard.

  5. Antisepsis 防腐 • Use of chemical agents on skin or other living tissue to inhibit or eliminate microbes; no sporicidal (杀芽胞的 )action is implied.

  6. Bacteriostasis抑菌 • Inhibits the growth of microorganisms.

  7. Asepsis 无菌 • No living microorganisms exists.

  8. Controlling Microorganisms By Physical Agents • High Temperature • Radiation 辐射 • Filtration 过滤 • Low Temperature • Desiccation干燥

  9. High Temperature static action cidal action

  10. Dry heat干热:protein oxidation • Hot air sterilization干烤 • Incineration焚化 • red heat赤热 • flaming烧灼

  11. Moist heat湿热:denature proteins and melt lipids; more effective • Autoclaving: 121℃,103.4kPa,20min cidal for both vegetative organisms and endospores • Boiling water煮沸灭菌 • Pasteurization巴氏消毒法: to kill particular spoilage organisms or pathogens • flash method瞬间法: 71.6°C, 15s • holding method持续法: 62.9°C, 30 min

  12. fractional sterilization间歇蒸气灭菌法: 1) Steam heating to 100 °C for 30 min——常压/流动蒸气消毒法 Vegetative cells are destroyed but endospores survive 2) Incubate at 30 °C -37 °C overnight Most bacterial endospores germinate 3) Second heat treatment, 100 °C, 30 min Germinated endospores are killed. 4) Second incubation at 30°C-37 °C overnight Remaining endospores germinate 5) Third heat treatment, 100 °C, 60 minLast remaining germinated endospores are killed

  13. Radiation • Ultraviolet Radiation紫外线辐射 • Ionizing Radiation 电离辐射

  14. Ultraviolet Radiation • microbicidal activity of ultraviolet (UV) light depends on: • length of exposure • wavelength of UV: 260 nm - 270 nm

  15. Mechanism: thymine-thymine dimmers胸腺嘧啶二聚体

  16. photoreactivation光复活作用 strong visible light

  17. very poor penetrating power • damage the eyes, cause burns, and cause mutation in cells of the skin

  18. Ionizing Radiation 电离辐射 • X-rays and gamma rays • more energy and penetrating power than UV • used to sterilize pharmaceuticals and disposable medical supplies such as syringes, surgical gloves, catheters导尿管, and sutures缝合线 • used to retard spoilage in seafoods, meats, poultry, and fruits

  19. Filtration 过滤 • sterilizesolutions that may be damaged or denatured by high temperatures or chemical agents

  20. Low Temperature • inhibits microbial growth by slowing down microbial metabolism

  21. Desiccation干燥 • has a static effect on microorganisms byinhibiting the action of microbial enzymes

  22. Using Disinfectants and Antiseptics to Control Microorganisms

  23. Antimicrobial modes of action for disinfectants and antiseptics • damage the lipids and/or proteins of the semipermeable cytoplasmic membrane of microorganisms resulting in leakage of cellular materials needed to sustain life • denature microbial enzymes and other proteins by disrupting the hydrogen and disulfide bonds

  24. Different categories of such chemical agents • Phenol and phenol derivatives • alter membrane permeability and denature proteins • chlorhexidine洗必泰 • ineffective against endospores

  25. Soaps and detergents • Anionic (negatively charged) detergents: mechanically remove microorganisms and other materials but are not very microbicidal. • Cationic (positively charged) detergents: alter membrane permeability and denature proteins; ineffective against endospores, M. tuberculosis结核分枝杆菌, and P. species假单胞菌.

  26. Alcohols • denature membranes • 70% solutions of ethyl or isopropyl alcohol乙醇或异丙醇 • ineffective against endospores and non-enveloped viruses

  27. Acids and alkalies alter membrane permeability and denature proteins and other molecules • Salts of organic acids: food preservatives • Undecylenic acid十一烯酸: dermatophyte皮肤真菌 infections

  28. Heavy metals denature proteins • Mercury compounds (mercurochrome红汞, merthiolate硫柳汞) : bacteriostatic, ineffective against endospores • Silver nitrate 硝酸银(1%) : put in the eyes of newborns to prevent gonococcal ophthalmia淋菌性眼炎

  29. Chlorine reacts with water to form hypochlorite次氯酸盐ions, which in turn denature microbial enzymes

  30. Iodine and iodophores • denatures microbial proteins • effective against some endospores

  31. Aldehydes醛 denature microbial proteins • Formalin 福尔马林(37% aqueous solution of formaldehyde gas) • glutaraldehyde戊二醛: kill vegetative bacteria in 10-30 minutes and endospores in about 4 hours

  32. Factors Influencing Antimicrobial Activity • The concentration and kind of a chemical agent used; • The intensity and nature of a physical agent used; • The length of exposure to the agent; • The temperature at which the agent is used; • The number of microorganisms present; • The species or strain of microorganism; • The nature of the material bearing the microorganism; • The presence of organic or other interfering substances.

  33. 常用的化学消毒剂

  34. 1.杀灭芽胞最常用和最有效的方法是:____________。1.杀灭芽胞最常用和最有效的方法是:____________。 a.紫外线照射 b.煮沸5min c.巴氏消毒法 d.流通蒸气灭菌法 e.高压蒸气灭菌法 2.灭菌方法错误的是____________。 a.手术室空气-紫外线 b.排泄物-漂白粉 c.饮水-氯气 d.含血清培养基-高压蒸气灭菌 e.温度计-75%酒精 3.下述不可能杀灭细菌芽胞的方法是: ____________。 a.煮沸法 b.巴氏消毒法 c.间歇灭菌法 d.干热灭菌法 e.高压蒸气灭菌法

  35. 4.关于紫外线,说法错误的是____________。(第03章)4.关于紫外线,说法错误的是____________。(第03章) a.其杀菌作用与波长有关 b.可损坏细菌的DNA构型 c.260-270nm杀菌作用最强 d.其穿透力弱,故对人体无损害 e.紫外线适用空气和物体表面的消毒 5. ____________常用于空气或物体表面的消毒。(第03章) a.高压蒸气灭菌法 b.紫外线照射法 c.滤过除菌法 d.巴氏消毒法 e.干烤法 6. ____________常用于基础培养基灭菌。(第03章) a.高压蒸气灭菌法 b.紫外线照射法 c.滤过除菌法 d.巴氏消毒法 e.干烤法

  36. 7.常用于手术器械的灭菌____________。 a.高压蒸气灭菌法 b.紫外线照射法 c.滤过除菌法 d.巴氏消毒法 e.干烤法 8.常用于血清的除菌____________。 a.高压蒸气灭菌法 b. 滤过除菌法 c. 紫外线照射法 d.巴氏消毒法e.干烤法 9.将牛奶加热62℃30分钟的目的是____________。 a.使牛奶中的蛋白质变性,易于吸收 b.杀灭牛奶中的所有微生物 c.杀死牛奶中的病原菌 d.使牛奶不含活菌 e.防止或抑制微生物在牛奶中生长和繁殖 10.乙醇消毒剂常用的浓度是: ____________。 a.100% b.95% c.75%d.50%e.30%