CHAPTER 9CHAPTER 9
sterilization & sterilization & disinfectiondisinfection
biocidebiocide
A chemical agent that inactivates A chemical agent that inactivates microorganismsmicroorganisms
Usually broad-spectrumUsually broad-spectrum
bacteriostaticbacteriostatic
A biocide is able to inhibit bacterial A biocide is able to inhibit bacterial multiplicationmultiplication
Multiplication resumes upon removal Multiplication resumes upon removal of the agentof the agent
bactericidalbactericidal
A biocide is able to kill B.A biocide is able to kill B.
The “killed” organism can no longer The “killed” organism can no longer reproduce, even after being removed reproduce, even after being removed from contact with the agentfrom contact with the agent
Sterilization:Sterilization:
Completely destroys or removes all Completely destroys or removes all
microbial life, including spores. microbial life, including spores.
by physical or chemical processby physical or chemical process
disinfectantsdisinfectants
Products or biocides used to kill Products or biocides used to kill microorganisms on inanimate objects microorganisms on inanimate objects or surfaces.or surfaces.
antisepticantiseptic
A biocide or product that destroys or A biocide or product that destroys or inhibits the growth of M. in or on living inhibits the growth of M. in or on living tissuetissue
asepticaseptic
Absence of pathogenic microbesAbsence of pathogenic microbes
DisinfectionDisinfection killing, or removal of killing, or removal of
microorganisms that may cause microorganisms that may cause disease.disease.
Methods for control of Methods for control of microorganismsmicroorganisms
Physical methodsPhysical methods HeatHeat Hot-air sterilizerHot-air sterilizer
Autoclaving Autoclaving
RadiationRadiation FiltrationFiltration UltrasoundUltrasound DrynessDryness Low temperatureLow temperature
Chemical agentsChemical agents
Section 1Section 1
physical physical sterilization and sterilization and disinfectiondisinfection
Physical agentsPhysical agents
heat heat radiationradiation filtration ---- Remove organismsfiltration ---- Remove organisms Ultrasonic and sonic vibrationsUltrasonic and sonic vibrations Freezing Freezing
Impart energyImpart energy
heatheat
denature or coagulate proteins denature or coagulate proteins
damage membranedamage membrane
enzymatic cleavage of DNAenzymatic cleavage of DNA
moist heat sterilizes at a lower temperature moist heat sterilizes at a lower temperature
than dry heatthan dry heat
Two waysTwo ways
1.1. Dry heat Dry heat
2.2. Moist heatMoist heat
IncinerationIncineration
Direct flamesDirect flames
Hot-air sterilizerHot-air sterilizer
160-170160-170C for 2 hours----sporesC for 2 hours----spores
Glass petri dishes and pipettesGlass petri dishes and pipettes
InfraredInfrared
microwavemicrowave
Dry heatDry heat
For glassware and materials For glassware and materials impervious to steamimpervious to steam
Kill of all organisms, including the Kill of all organisms, including the spore formersspore formers
Moist heatMoist heat
Autoclaving:Autoclaving: pressure: 15 1b/inpressure: 15 1b/in2 2
temperature: 121temperature: 121 held: 15-20 minutes held: 15-20 minutes autoclaves or pressure cookersautoclaves or pressure cookers kill both vegetative organisms and endkill both vegetative organisms and end
osporesospores
pasteurizationpasteurization
Two methods:Two methods: 62 for 30 minutes℃62 for 30 minutes℃ 72 for 15 seconds℃72 for 15 seconds℃
to kill particular spoilage organisms or to kill particular spoilage organisms or pathogenspathogens
Primarily for milkPrimarily for milk
fractional sterilizationfractional sterilization间歇蒸气灭菌法 间歇蒸气灭菌法 ::
1) Steam heating to 100 1) Steam heating to 100 °°C for 30 min(C for 30 min( 常压常压 // 流动蒸气流动蒸气消毒法消毒法 ) ) Vegetative cells are destroyed but endospores survVegetative cells are destroyed but endospores survive ive
2) Incubate at 30 2) Incubate at 30 °°C -37 C -37 °°C overnight C overnight Most bacterial endospores germinate Most bacterial endospores germinate
3) Second heat treatment, 100 3) Second heat treatment, 100 °°C, 30 min: GC, 30 min: Germinated endospores are killed. erminated endospores are killed.
4) Second incubation at 304) Second incubation at 30°°C-37 C-37 °°C overnigC overnight: Remaining endospores germinate ht: Remaining endospores germinate
5) Third heat treatment, 100 5) Third heat treatment, 100 °°C, 60 min: LasC, 60 min: Last remaining germinated endospores are killt remaining germinated endospores are killeded
fractional sterilization:fractional sterilization:
radiationradiation
Two types of radiationTwo types of radiation
ultraviolet lightultraviolet light
Ionizing RadiationIonizing Radiation
UV lightUV light
at 250-260 nmat 250-260 nm
absorbed by purine and pyrimidin bases oabsorbed by purine and pyrimidin bases of DNAf DNA
form thymine dimersform thymine dimers
inhibit DNA replicationinhibit DNA replication
very poor penetrating power very poor penetrating power To sterilize the air and any exposed To sterilize the air and any exposed
surfacessurfaces damage the cornea and skin :damage damage the cornea and skin :damage
the eyes, cause burns, and cause the eyes, cause burns, and cause mutation in cells of the skin mutation in cells of the skin
UV lightUV light
filtrationfiltration
for certain solutions for certain solutions that that may be damaged or may be damaged or denatured by high denatured by high temperatures or chemical temperatures or chemical agentsagents
has a pore size of 0.22 μmhas a pore size of 0.22 μm physically trap particles physically trap particles
larger than the pore size larger than the pore size and retain smaller particles and retain smaller particles
Section 2Section 2
chemical chemical sterilization and sterilization and disinfectiondisinfection
Alcohols Alcohols 醇醇 Aldehydes Aldehydes 醛醛 Halogens Halogens 卤素卤素 Heavy metals Heavy metals 重金属重金属 Phenolics Phenolics 酚酚 Detergents Detergents 去污剂 去污剂
Chemical agentsChemical agents
常用的化学消毒剂常用的化学消毒剂类别类别 作用机制作用机制 常用种类常用种类酚类酚类 蛋白变性,细胞膜损伤蛋白变性,细胞膜损伤 洗必泰洗必泰醇类醇类 去除脂类,蛋白变性去除脂类,蛋白变性 乙醇乙醇卤素卤素 蛋白变性蛋白变性 氯气、碘酊 、碘伏氯气、碘酊 、碘伏
重金属盐重金属盐 蛋白变性蛋白变性 红汞、硫柳汞、硝酸银红汞、硫柳汞、硝酸银
醛类醛类 蛋白变性蛋白变性 福尔马林、戊二醛福尔马林、戊二醛
表面活性剂表面活性剂 蛋白变性,细胞膜损伤蛋白变性,细胞膜损伤 新洁而灭新洁而灭酸碱类酸碱类
染料染料
破坏细胞膜、细胞壁,破坏细胞膜、细胞壁,蛋白变性蛋白变性干扰氧化、抑制繁殖干扰氧化、抑制繁殖
十一烯酸十一烯酸
龙胆紫龙胆紫
Nature, concentration and acting Nature, concentration and acting time of the disinfectanttime of the disinfectant
Type and amount of the microbeType and amount of the microbe TemperatureTemperature pHpH Organic matterOrganic matter
Factors affecting the results
Chemical agentsChemical agents
1.1. disruption of the lipid-containing cell disruption of the lipid-containing cell membranemembrane
2.2. modification of proteinsmodification of proteins
3.3. modification of DNA modification of DNA
disruption of the cell membranedisruption of the cell membrane
AlcoholsAlcohols to clean the skinto clean the skin disorganizing the lipid structure in disorganizing the lipid structure in
membranesmembranes denature proteinsdenature proteins far more effective at 70% than at 100% far more effective at 70% than at 100%
DetergentDetergent
SurfactantsSurfactants Disrupt the membraneDisrupt the membrane Widely used for skin antisepsisWidely used for skin antisepsis
phenolsphenols
The first disinfectant used in the The first disinfectant used in the operating roomoperating room
Too causticToo caustic Damage membranes and denature Damage membranes and denature
proteinsproteins
modification of proteinsmodification of proteins
ChlorineChlorine
to purify the water supplyto purify the water supply
to treat swimming poolsto treat swimming pools
an oxidizing agentsan oxidizing agents
iodineiodine
the most effective skin antisepticthe most effective skin antiseptic
tincturetincture: to prepare the skin prior to : to prepare the skin prior to
blood culture blood culture
irritate to the skinirritate to the skin
iodophorsiodophors: to prepare the skin prior to : to prepare the skin prior to
surgerysurgery
less irritatingless irritating
Heavy metalsHeavy metals
mercury and silvermercury and silver: :
have the greatest antibacterial have the greatest antibacterial
activityactivity
bind to sulfhydryl---- block bind to sulfhydryl---- block
emzymatic activityemzymatic activity
Ethylene oxideEthylene oxide
for heat-sensitive materialsfor heat-sensitive materials
alkylate both proteins and nucleic alkylate both proteins and nucleic
acids acids