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Chapter 7 Disinfection and sterilization

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Chapter 7   Disinfection and sterilization Powered By Docstoc
					Teaching plan of bilingual teaching

            双语教学教案




          Gannan Medical College
      Department of pathogenic Biology
Teacher                        Date                      Lecture type     Theory Course      Class hour
                                                                                                           1 hours
(教师)                          (日期)                       (授课类型)             (理论课)            (学时)

 Grade                        Speciality     Clinical medical    Subject             Medical Microbiology
(年级)                            专业             (临床医学)           (课程)                   医学微生物学

   chapters and sections
                              Chapter 7 Disinfection and sterilization
       (授课章节)

                              1. Master the condition of physical methods of disinfection.
   Objective and request      2. Master the mechanism of the antiseptic effect of chemical agents.
    教学目的和要求                   3. Master the following concepts :
                                 disinfection; sterilization; asepsis; antisepsis

                              1. The condition of physical methods of disinfection
  Emphasis and difficulty
                              2. Types of Hospital infection he mechanism of the antiseptic effect of chemical
    授课重点、难点
                                 agents.


Reference teaching material   1.周正任主编.《医学微生物学》第 6 版
        参考教材                  2.Medical microbiology(21 edition, Jawetz, Melnick, and Adelberg)


       Teaching aid
                              Powerpoint
       媒体与教具

                                           Teach contents(教学内容)


                               Chapter 7       Disinfection and sterilization

   Concepts:
     1. disinfection: To kill pathogenic microorganisms (vegetative form)
     2. sterilization: To kill all microorganisms, including .pathogenic & non-pathogenic , vegetative &spore.
     3. asepsis: a state of sterility (no living bacteria) ,
     4. antisepsis: To inhibit the growth and reproduction of bacteria in vitro.
     5. bacteriostasis: prevention of growth of bacteria, but without killing them.

                                           Section I. Physical methods

   I. heat lethal
       make bacterial protein denature. bacterial DNA degrade, injury cell membrane .
    1. dry heat:
      (1) flame
      (2) burn


                                                         1
   (3) hot air oven: 160-170°C, 2-3hrs
   (4) infrared
       vegetative form: 80-100°C ,1hr
       spore: 160°C , 2hrs
2. moist heat :
 1)advantages over dry heat:
   (1) Bacteria absorb H2O , proteinis easy to solidify and denature .
   (2) Strong penetration
   (3) lalent heat gas –liquid .
 2) Methods:
   (1) pasteurization
   (2) Boiling
   (3) Steaming and intermittent sterilization:    Arnold 3times.
                                 2
   (4) Autoclaving: 1.05 kg/ cm , 121.3℃ 15-30′-spore

II.radiation
 1. ultraviolet light: 200-300nm
                     interfere DNA replication ,form dimmer of Thymine .
                     strongest spectrum 260nm, DNA absort specfurm,
                     weak penetration : definite time and intensity
                     stimulate skin, eyes,.
                     Application: air . operation room
 2. ionizing radiation: eg ,x-ray, r-ray.

III. filtration

IV. Other:

                                    Section II Chemical disinfection

Disinfectant:
 Antiseptic:
  1. chemical agents and mechanism
   1) heavy –metal salts
        (1) bind to –SH and destroy it, inhibit activity of enzymes.
        (2) Protein denature. Merbromin .thimerosal 0.1%disinfectant
   2) Oxidizer
        H2 O 2; KMnO 4 ;CHCOOH
        Halogen(iodine, chlorinated lime)
      (1) SH: S-S- enzyme
      (2) destroy amino group, indol group.
     (3) denature protein
  3) surfactant
     combine with phospholipid


                                                      2
      increast membrane permeability
      bromogeramine(
      domiphen
    4)aldehyde
        farmaldehyde、
        enzyme deactivity
    5)alcohol 70% alcohal protein denature。
    6)phenolprotein denature, destroy cell membrane。
2. Application
      Skin: 2.5% iodine tincture; 70% alcohol
      mucosa : 2% mercurochrome; 0.1% bromogeramine
      drinking water: bleaching powder
      patients excreta : 5% phenol; 2%lyson
      air: formalin spray
3. Affecting factors
    (1) concentration and time
    (2) properties and quantity
    (3) temperature and PH
    (4) antagonist: organs protein, excreta




    question         1.   What is the mechanism of UV light’s killing bacteria?
    思考题              2.   What factors influence the effectiveness of antimicrobial agents?




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