Chapter 3 Disinfection and
Sterilization
消毒与灭菌
disinfection消毒

The reduction or elimination of
pathogenic microorganisms in or on
materials, so they are no longer a
health hazard.
sterilization灭菌

The process of destroying all microbial
forms. A sterile object is one free of all
microbial forms, including bacterial
spores.
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.
Bacteriostasis抑菌
Asepsis 无菌
Bacteriostasis抑菌 Inhibits the growth of
microorganisms.
 Asepsis 无菌No living microorganisms
exists.

Controlling Microorganisms By
Physical Agents物理消毒灭菌法





High Temperature热力灭菌法
Radiation辐射杀菌法
Filtration滤过除菌法
supersonic wave超声波杀菌法
Desiccation干燥与Low Temperature低温
抑菌法
热力灭菌法

干热灭菌法— 焚烧：废弃物、尸体
灼烧：接种环、试管口
干烤：玻璃器皿
红外线：医疗器械

湿热灭菌法— 巴氏消毒法：61.0-62.8
℃30min或71.7
℃15-30s,主要用于牛乳消毒。
煮沸法
流动蒸汽消毒法
间歇蒸汽消毒法
高压蒸汽灭菌法

Dry heat干热：protein oxidation
 Hot
air sterilization干烤
 Incineration焚化
 red heat赤热
 flaming烧灼

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
鲜奶巴氏杀菌
63℃/30分钟
 72℃/15秒
 89℃/1秒
 90℃/0．5秒
 100℃/0．01秒

 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 min
Last remaining germinated endospores are killed
Radiation辐射杀菌法

Ultraviolet Radiation紫外线
波长200-300nm的紫外线具有杀菌作用。
其主要作用于DNA，使一条DNA链上相邻的两个胸腺嘧 啶共价结合
形成二聚体，导致细菌变异和死亡。
very poor penetrating power
damage the eyes, cause burns, and cause mutation in cells of the skin


Ionizing Radiation电离辐射
高速电子、X射线、γ射线
microwave微波
波长1mm~1m
Ultraviolet Radiation

microbicidal activity of
ultraviolet (UV) light
depends on:
Mechanism: thymine-thymine dimers胸
腺嘧啶二聚体
 length
of exposure
 wavelength of UV: 260
nm - 270 nm

photoreactivation光复
活作用
strong visible light
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
滤过除菌法 Filtration

赛氏滤器 sterilize
solutions that may be
damaged or denatured by
high temperatures or
chemical agents

玻璃滤器

薄膜滤器
超声波杀菌法
是一种机械的作用因素，每秒超过2万次
振动的声波即为超声波。常用的超声波
发生器能产生20-100千赫的声波。可使
细菌细胞壁裂解而死亡。
干燥 低温 抑菌法

干燥法Desiccation has a static effect on
microorganisms by inhibiting the action of
microbial enzymes
 低温法Low Temperature： inhibits
microbial growth by slowing down microbial
metabolism低温可使细菌的新陈代谢减慢，
常用作保存细菌菌种。冷冻真空干燥法是
目前保存菌种的最好方法。
第二节 化学消毒灭菌法

消毒剂的种类：酚类、醇类、重金属盐类、氧
化剂、表面活性剂、烷化剂。

消毒剂的应用：病人排泄物与分泌物、皮肤、
粘膜、饮水、厕所、空气、手。
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
Factors Influencing Antimicrobial
Activity影响消毒灭菌效果的因素






The concentration and kind of a chemical agent used;消
毒剂的性质、浓度
The intensity and nature of a physical agent used;
The length of exposure to the agent;作用时间
The temperature at which the agent is used;温度
The number of microorganisms present;数量
The species or strain of microorganism;微生物的种类
常用的化学消毒剂
类别
酚类
作用机制
常用种类
蛋白变性，细胞膜损伤 洗必泰
醇类
卤素
重金属盐
醛类
表面活性剂
去除脂类，蛋白变性
乙醇
氯气、碘酊 、碘伏
蛋白变性
红汞、硫柳汞、硝酸银
蛋白变性
福尔马林、戊二醛
蛋白变性
蛋白变性，细胞膜损伤 新洁而灭
酸碱类
破坏细胞膜、细胞壁， 十一烯酸
蛋白变性
干扰氧化、抑制繁殖
龙胆紫
染料
Different categories of such
chemical agents

Phenol and phenol derivatives酚衍生物
 chlorhexidine洗必泰
 alter
membrane permeability and denature proteins
 ineffective against endospores
Alcohols

 denature
membranes
 70% solutions of ethyl or isopropyl alcohol乙醇或
异丙醇
 ineffective against endospores and non-enveloped
viruses

Chlorine 氯
reacts with water to form hypochlorite次氯酸盐 ions,
which in turn denature microbial enzymes

Iodine碘 and iodophores碘伏
 denatures
microbial proteins
 effective against some endospores
Heavy metals
重金属盐
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

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
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.
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
Definitions:
Sterilization – the process of destroying all forms of
microbial life on an object or in a material.
Disinfection – the process of destroying vegetative
pathogens but not necessary endospores.
Antisepsis – chemical disinfection of skin, mucous
membranes or other living tissues
Method for killing all microbes is
called ____________。
a.disinfection
 b.sterilization
 c.antisepsis
 d.asepsis
 e.inhibiting the growth of bacteria

Each of the following statements concerning
the killing of bacteria is correct EXCEPT:
____________。




a.A 70% solution of ethanol kills more effectively
than absolute (100%) ethanol
b.An autoclave uses steam under pressure to
reach the killing temperature of 121℃
c.The pasteurization of milk kills pathogens but
allows many organisms and spores to survive
d.Iodine kills by causing the formation of thymine
dimers in bacterial DNA
Which one of the following methods
is most effective for killing bacterial
spore____________。
a.boiling
 b.free flowing steam
 c.fractional sterilization
 d.autoclaving
 e.ultraviolet light
