细菌的感染与免疫(II)

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1、Chapter4BacterialinfectionandimmunityNormalfloraandopportunisticinfectionBacterialpathogenicityProcessofinfectionAnti-bacterialimmunityNosocomialinfectionNormalfloraandopportunisticinfectionMicrobesandhumansVeryfewmicrobesarealwayspathogenicManymicrobesarepotentiallypathogen

2、icMostmicrobesareneverpathogenicNormalfloraDefinition–bacteria,fungi,andprotozoathatfrequentlyfoundonorwithinthebodyofhealthypersons.Composition-residentflora,transientfloraFunctionsofnormalflora----Protectiveeffectsofnormalflora----Productionofnutrients-vitaminK----Primingim

3、munesystem-specific(naturalantibodies)----ExclusionofpathogensfromcolonizedsurfacesOpportunisticinfection----Hostdefensescompromised----Dysbacteriosis,superinfection----TranslocationBacterialpathogenicityBacterialVirulenceInvasiveness----surfacestructuresofbacteriaadhesin,cap

4、sule,flagellum,bacterialbiofilm----invasivesubstancesinvasininvasiveenzymes----immuneescapeincompletephagocytosisIgAproteinaseantigenvariationBacterialBacterialtoxinsBacterialVirulence1)ExotoxinsOrigin:---ProducedmainlybyG+---LiberatedfromlivingbacterialcellNature---ProteinCh

5、aracter:---Highlytoxigenicity---Highlyselectivity---Highlyantigenity,canproduceanti-toxin(Neutralize)---DetoxificationtoxoidTypeA-BtoxinPathogenicityisland①为分子量相对较大的染色体DNA片段②存在于强毒株③含编码细菌毒力及毒力相关因子的基因簇④两侧具有同向重复序列和插入元件⑤大多位于tRNA基因位点内或附近⑥G+Cmol%和密码子的使用与宿主菌有明显差异⑦可移动，不稳定2)EndotoxinO

6、rigin:Nature:---ProducedmainlybyG----Liberatedfromcellwallofdeadbacteria---LPS(Lipopolysaccharide)StructureofLPSlipidACorepolysaccharidespecificpolysaccharide---Weaklytoxigenicity---noselectivity---Poorantigenasfreemolecule---Havingnodetoxification,cannotproducetoxoidCharacte

7、r:---Fever---leukocytosisorLeukopenia---Endotoxemiaandshock---Disseminatedintravascularcoagulation(DIC).---ImmunregularEndotoxineffects:NumberofbacterialentryNumberofbacteriaandvirulencepresentinverseproportionPortalentrySimplepathwayMulti-pathwayProcessofinfectionInfectionSo

8、urces---exogenousinfectionpatients;carrier;animal---endogenousinfect