医学微生物学(第八)第二细菌的生理剖析.ppt

重点与难点 Bacteria Multiplication Binary fission (二分裂) The Growth Curve 2.菌落（colony）-单个细菌分裂繁殖成一堆肉眼可见的细菌集团。 第五节 抑制或杀灭微生物 Prevention of microoganisms 消毒Disinfection The process that reduces the number of pathogenic microorganisms. Bacterial spores and other relatively resistant organisms may remain viable. 灭菌(Sterilization) A treatment that destroys all microbial life, including vegetative form and endospores 抑菌 (Bacteriostasis) To inhibit the growth of bacteria 防腐(Antisepsis) A chemical agent safely used in or on living tissue to destroy microorganisms 无菌(Asepsis) A condition in which living microorganisms are absent 无菌或无菌操作技术(Aseptic techniques) Measures taken to ensure that living microorganisms are absent METHODS Physical methods of disinfection and sterilization Chemical methods of disinfection and sterilization Biotic controlling of pathogenic micobial infection 1. Physical controls on microoganisms Including: Heat Cold Drying Radiation Filtration Osmotic strength Dry heat(干热) Hot air sterilization Flaming Incineration Hot air sterilization Conditions 160-170℃, 1-2hrs Significance applications glassware, metal objects(operating knife、scissor、forceps) Moist heat(湿热) Moist heat Boiling water Autoclaving Pasteurization Pasteurization Definition: a process in which fluids are heated at temperatures below boiling point to kill pathogenic microorganisms in the vegetative state without altering the fluid’s palatability. Conditions: 62℃, 30 minute or 71.7℃, 15second Significance: kills vegetative pathogens Applications: milk, beer Boiling 100℃ at 1 atmospheric pressure. 5min killing most non-sporing bacteria. For 1-2h will kill a few sporing microoganisms. 2% sodium carbonate can enhance the efficiency ,105℃(the boiling point). Steam sterillization(with common pressure) It applies water vapor to disinfect 100℃ for 15～30min, not useful for spore. Fractional sterilization