MICROBIOLOGY PPT LECTURE NOTES | Karya Tulis Ilmiah

3. Disinfection and Sterilization

Basic terms

灭菌
 disinfection 消毒
 Antisepsis 防腐
 Bacteriostasis 抑菌
 Asepsis 无菌
 sterilization

sterilization 灭菌


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

disinfection 消毒


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

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


Inhibits the growth of microorganisms.

Asepsis 无菌



No living microorganisms exists.

Controlling Microorganisms By
Physical Agents
High Temperature
 Radiation 辐射
 Filtration 过滤
 Low Temperature
 Desiccation 干燥


High Temperature

static action

cidal action



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



Moist heat 湿热： denature proteins
and melt lipids; more effective
 Autoclaving: 121℃,103.4kPa, 20min
cidal for both vegetative organisms and
endospores

water 煮沸灭菌
 Pasteurization 巴氏消毒法 : to kill
 Boiling

particular spoilage organisms or
pathogens
 flash method 瞬间法 : 71.6°C, 15s
 holding method 持续法 : 62.9°C, 30 min

 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
Ultraviolet Radiation 紫外线辐射
 Ionizing Radiation 电离辐射


Ultraviolet Radiation


microbicidal activity of ultraviolet (UV) light
depends on:
 length

of exposure
 wavelength of UV: 260 nm - 270 nm



Mechanism: thymine-thymine dimmers 胸腺

嘧啶二聚体



photoreactivation 光复活作用

strong visible light

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

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

Filtration 过滤


sterilize solutions that
may be damaged or
denatured by high
temperatures or chemical
agents

Low Temperature


inhibits microbial growth by slowing down
microbial metabolism

Desiccation 干燥


has a static effect on microorganisms by
inhibiting the action of microbial enzymes

Using Disinfectants and Antiseptics
to Control Microorganisms

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



Different categories of such
chemical agents


Phenol and phenol derivatives
 alter

membrane permeability and denature proteins
 chlorhexidine 洗必泰
 ineffective against endospores



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 .



Alcohols
 denature

membranes
 70% solutions of ethyl or isopropyl alcohol 乙醇
或异丙醇
 ineffective against endospores and non-enveloped
viruses



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



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



Chlorine

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



Iodine and iodophores
 denatures

microbial proteins
 effective against some endospores



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

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.

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

酸碱类

破坏细胞膜、细胞壁， 十一烯酸
蛋白变性

醇类
卤素
重金属盐
醛类
表面活性剂
染料

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
干扰氧化、抑制繁殖

龙胆紫

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

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

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 ％