醫(yī)學(xué)微生物學(xué)資料：Disinfection and sterilization

1、Disinfection and sterilizationRevised in 2014-09Questions that I dont expect you to answerWhat are industrial definition of sterilization and disinfection ?How to evaluate efficacy and safety of disinfection technology?How to implement quality control of disinfection?Clinical application of disinfec

2、tion (when and how?)AgentReservoirExit pointReleaseMeans of spreadTransmissionEntry siteInf. doseSusceptible hostIncubation periodContainment,equipment& practices(vaccination)PersonalprotectiveequipmentVaccinationSurveillanceChain of infection and interventionArtificial classification of bacteria St

3、erilizationTry to eradicate all microbes including spores, (but never be sure ) DisinfectionInactivate vegetative germs but not sporesSterilization & DisinfectionStandard of ICHSterilization is a process through which the quantity of bacteria is decreased from 10000000 cell / ml to not more than 1 c

4、ell/10000000 ml, that means, 10-7 /ml or lessDisinfection is a process through which the quantity of bacteria is decreased from 10000 cell/ ml to not more than 1 cell/ ml, that means, 10-4 / ml* Being sterile but may have dead cells including LPS! So, Disinfection and Sterilization are different qua

5、ntitatively!Sterilization & DisinfectionVery low temperature ( 50C to 95C ) will kill bacteria because of a. Dehydration of cytoplasm leading to increased concentration of electrolytes b. Inactivation of some enzymes by removal of SH group c. Damage of cell membraneSterilization & DisinfectionKineti

6、cs of bacteria activationThe target of disinfection protein cell membrane and virus envelop DNA cell wall othersSTERILIZATION METHODSPhysical Agents HEATDRY : Heat AirHUMID : Pressure steamPOUPINEL STOVESTERILIZERIONIC RADIATIONg RAY ELECTRONSChemicalAgents GASES ETHILENE OXYDEFORMALDEHYDEPLASMA GAS

7、 OF HYDROGEN PEROXYDELQUIDS : GLUTARALDEHYDE, PERACETIC ACIDAntimicrobial agentsPhysical methodsI. Heat 1. Pasteurization (principles) 2. Dry heat 3. Moist heat a. Autoclave b. Steam c. WaterDry Heat160 170C for 2 -4 hoursDry heatAutoclaving: most popular instrument for sterilizationSteam Sterilizat

8、ionAutoclavesSteam under pressure (moist heat)Usually 121C for 30-60 minutesDependent on agent and materialSteam SterilizationSmall Portable AutoclavesSteam SterilizationLarge Autoclaves (cage racks)Steam PenetrationSteam must be in contact with the material being sterilized to be effective.Alkaline

9、 Hydrolysis Caustic DigestersUsed for animal carcassesCombines an alkaline solution and heat to reduce tissue into sterile aqueous solutionLarge volume reduction in waste腐蝕消化爐Effluent DecontaminationChemical systemsGood for smaller volumes May be detrimental to environmentAdjust pH for release to sa

10、nitary sewerContinuous Effluent DecontaminationGood for smaller volumes Doesnt handle solids Continuous Effluent DecontaminationMoves pressurized effluent through length of piping Measures temp at beginning and end of piping loop Length of piping and flow rate determine time waste is held at that te

11、mpDisinfection and sterilizationPhysical methodsII. Radiation 1. UV light ( 250 270nm ) 2. and X ray radiation 3. Microwaves IrradiationGamma irradiation (e.g. Cobalt 60) for heat-sensitive materialsspecially designed containment equipment is required and only used by industryUVpoor penetration and

12、should not be used to decontaminate waste of hospital and other polluted surfaceQuality controlQC of finish productProcedure controlLow cost and easy to operateEasy to identify the technical errorSampling may cover the same lot of product Reliability and qc assurance Re-call performanceHigh cost Cha

13、llenge to UV application as an example of quality control 1. Effective wavelength2. Radiation dosage3. Radiation range4. Control of radiation safety Conclusion: UV radiation is not recommended in hospitalExample of methodology choice based on QC approachUV radiation is used in water treatment and fo

14、od industryThe method is safe without residual effects or chemicalsEasy to operate and dose need special training of staffHoweverDisinfection and sterilizationPhysical methodsFiltration Requirements for pore sizeSterilizing agent 130 LFFORMALDEHYDE: a multidisciplinary substance It is an organic mol

15、ecule existing in a natural form, and originates in methanol oxidation.Normal element in the human metabolism, excreted through urinal ways. It appears in multitude of substances: rain water, fruits, vegetables, coffee, beer, cosmetics, personal care products, glues, construction materials, newspape

16、rs, etc.It is used for industrial purposes and in Health Care Centres: Pathology Departments, morgues, Radiology, etc. BIOCHEMISTRY FUNDAMENT OF ITS LETALITYIt gets the inactivation of the cellules by means of proteins clots and nucleics acid methylation Low Temperature Water Steam (60- 78 C)+ Forma

17、ldehyde (only 2% ) H2COCYCLE PROFILE FOR 60C AND 78C600 C Cycle: 3,5 hours780 C Cycle: 2 hours130 LFChemical disinfectants類別作用機(jī)制常用種類酚類蛋白變性，細(xì)胞膜損傷洗必泰醇類去除脂類，蛋白變性乙醇鹵素蛋白變性氯氣、碘酊 、碘伏重金屬鹽蛋白變性紅汞、硫柳汞、硝酸銀醛類蛋白變性福爾馬林、戊二醛表面活性劑蛋白變性，細(xì)胞膜損傷新潔而滅酸堿類染料破壞細(xì)胞膜、細(xì)胞壁，蛋白變性干擾氧化、抑制繁殖十一烯酸龍膽紫Inactivation of chemical disinfectant b

18、y organic materialsFactors influencing the sterilizing effect of AEOW Organics Temperature Concentration of sodium chloride pH Hardness of water Saving environment Efficacy assessment of disinfectant cell wall structure cell wall components cell membrane structureStructure-based principle disinfecta

19、ntG+G-Myco-bacteria sporefungiEnvelop-VNon-envelop-Vphenol+ethanol+formaldehyde+glutaraldehyde+hypochloride+iodine+Hibitan+Heavy +H2O2+消毒劑 種類革蘭陽性菌革蘭陰性菌分枝 桿菌芽胞真菌包膜病毒無包膜病毒酚類+醇類+甲醛+戊二醛+氧化乙烯+次氯酸鹽類+氯胺類+碘+洗必泰+重金屬類+過氧化氫+季胺類+Safety assessment of disinfectant general toxicity local toxicity speed of effect a

20、nti-organic activity anti-detergent activity environment toxicity pricedisinfectantG-toxicityL-toxicityspeedProtein inactivationDetergent-inactivationpriceEnvironment pollutionphenol+mid+low+ethanol+fastmidformaldehyde+slow+low+gludaldehyde+slow+high+hypochloride+fast+lowiodine+fast+high+hibitan+mid+high+Heavy metals+slow+high+H2O2+fast+mid消毒劑 種類全身毒性局部毒性作用速度蛋白滅活表面活性劑滅活價格環(huán)境污染酚類+中+低+醇類+快中甲醛+慢+低+戊二醛+慢+高+氧化乙烯+慢+高+次氯酸鹽類+快+低氯胺類+快+低碘+快+高+洗必泰+中+高+重金屬類+慢+高+過氧化氫+快+中季胺類+中+中Clean and d