Chapter7

BacterialInfectionandimmunityBasictermsBacterialinfection（細(xì)菌的感染）Pathogen（病原菌）Nonpathogen（非病原菌）Opportunisticpathogen（機(jī)會致病菌）BacterialInfection細(xì)菌的感染Theprocessofbacteriainvadinginthebody,growinginthetissues,producingtoxinsandcausingdiseasesiscalledbacterialinfection.Opportunisticpathogen（機(jī)會致病菌）Conditionedpathogen（條件致病菌）Somebacteriaarecapableofcausingdiseasesonlyundercertainconditions.Theseorganismscancausediseaseonlyifoneormoreoftheusualdefencemechanismshumanshaveevolvedtorestrictmicroorganismsfromtheirusuallysterileinternalorgansandtissuearebreachedbyaccident,byintent(e.g.surgery),orbyanunderlyingmetabolicoraninfectiousdisorder(e.g.AIDS).OutlineNormalfloraandopportunisticpathogenBacterialpathogenesisThehostimmunedefencesystemTheinitiationandcourseofinfectionHospitalinfectionSection1

NormalfloraandopportunisticpathogenLocationsSurfacetissuesofskinOralcavityRespiratorytractGastrointestinaltractGenitourinarytractNormalfloraonintestinalmucosa腸道的正常菌群PrimeoflifeSenium★BeneficialeffectsofthenormalfloraBiologicalantagonism（生物拮抗）Productionofessentialnutrients（營養(yǎng)作用）Primingofimmunesystem（免疫作用）Anti-aging（抗衰老作用）Anti-tumor（抗腫瘤作用）Biologicalantagonism(生物拮抗)Biologicalbarriers（生物屏障）Receptorcompetition（受體競爭）Harmfulmetabolites（有害代謝產(chǎn)物）Nutrientcompetition（營養(yǎng)競爭）Conditionedpathogen（條件致病菌）Somebacteriaarecapableofcausingdiseasesonlyundercertainconditions.Thesebacteriaarecalledopportunistic(conditioned)pathogensandthiskindofinfectioniscalledopportunisticinfection（機(jī)會性感染）.★

Opportunisticpathogen（機(jī)會致病菌）Dysbacteriosis（菌群失調(diào)）Iffloradisequilibriumoccurs,forexample,whentheresidentfloraisdisturbed,somelittlesignificantmicroorganismsmaycolonize,proliferate,andproducedisease,whichiscalleddysbacteriosis.Dysbacteriosismainlyresultedfromlongtermandlargedoseantibioticstaken.Superinfection（重疊感染）Afrequentcomplicationofdrugtherapyformicrobialinfection.Itmayresultfromopportunisticcolonizationfollowingimmunosuppressionbytheprimarypathogenandcanbeinfluencedbythetimeintervalbetweeninfections,microbialphysiology,orhostresistance.DysbacteriosisandsuperinfectionProbiotics（益生菌）Probiotics（益生菌）&Prebiotics（益生元）Section2BacterialPathogenesisBasictermBacterialPathogenicity

BacterialvirulenceNumberofinvadingorganismsPortalofentryExotoxinPili(Fimbrial)CapsuleVirulentEnzymeAdhesinsFlagellaIronbindingproteinVirulencesurfaceproteinBacterialvirulencefactors（細(xì)菌毒力因子）Bacterialvirulence（細(xì)菌的毒力）Virulence（毒力）Invasiveness（侵襲力）Toxin（毒素）Adherence&permanentplanting（黏附與定植）Multiplication&diffusion（增殖與擴(kuò)散）Anti-defensefunctionofhost（免疫逃逸）Endotoxin（內(nèi)毒素）Exotoxin（外毒素）1.Adhesin（粘附素）Protiensonbacterialsurfaceassociatedwithadhesion.Adhesinsbindtoadhesinreceptorsonhostcells.Classification:Pili(fimbriae)adhesin(菌毛黏附素)Non-fimbriaeadhesin(非菌毛黏附素)AdhesionAdhesinEpitheliumReceptorBacteriumCapsule(莢膜)ofstreptococcuspneumoniaeMicrocapsule（微莢膜）

Slimelayer（黏液層）ProtectthecellwallagainstattackbydrugsInhibitingestionandkillingbyphagocytesPlayaroleintheadherenceofhumantissueAntigenicity2.Capsule（莢膜）3.Invasivesubstances（侵襲性物質(zhì)）

Invasin（侵襲素）Encodedbyinvasivegenes（侵襲基因）MediateinvadingadjacentepithelialcellsInvasiveenzyme（侵襲性酶）Somebacteriamaygenerateinvasiveenzymes,whichcandamagebodytissuesandpromotetheinvasionanddiffusionofthebacteria.4.Bacterialbiofilm（細(xì)菌生物被膜）★Definition：Themembraneousbacterialcommunitycomposedofbacteriaandtheextracellularpolymerssecretedbybacteriaaftertheyadheretothesurfaceoflivingornonlivingmaterials.BacterialbiofilmFunctionsFacilitatesbacterialadhesionBafflesthepenetrationofantibioticandtherejectionofimmunesystemProfitssignalcommunicationamongbacteria.BacterialbiofilmBiofilmintheendoscope（內(nèi)窺鏡）Staphylococcusepidermidis（表皮葡萄球菌）biofilminthesurfaceofvenouscatheter（靜脈導(dǎo)管）ExotoxinsEndotoxinsExcretedbylivingcells;highconcentrationsinliquidmedium.IntegralpartofthecellwallofG-bacteria.Releasedonbacterialdeathandinpartduringgrowth.Maynotneedtobereleasedtohavebiologicactivity.ProducedbybothG+andG-bacteria.FoundonlyinG-bacteria.PolypeptidesLPS(lipidAportionprobablyresponsiblefortoxicity.)Relativelyunstable;toxicityoftendestroyedrapidlybyheatingattemperaturesabove60℃.Relativelystable;withstandheatingattemperaturesabove60℃forhourswithoutlossoftoxicity.ExotoxinsEndotoxinsHighlyantigenic;stimulateformationofhigh-titerantitoxin(抗毒素).Antitoxinneutralizestoxin.Weaklyimmunogenic;antibodiesareantitoxicandprotective.Relationshipbetweenantibodytitersandprotectionfromdiseaseislessclearthanwithexotoxins.Convertedtoantigenic,nontoxictoxoids(類毒素)byformalin,acid,heat,etc.Toxoidsareusedtoimmunize.Notconvertedtotoxoids.Highlytoxic;fataltoanimalsinmicrogramquantitiesorless.Moderatelytoxic;fatalforanimalsintenstohundredsofmicrograms.ExotoxinsEndotoxinsUsuallybindtospecificreceptorsoncells.Specificreceptorsnotfoundoncells.Usuallydonotproducefeverinthehost.Selectivetoxicityandspecificclinicalsyndromes.Neurotoxins(神經(jīng)毒素)Cytotoxins(細(xì)胞毒素)Enterotoxins(腸毒素)UsuallyproducefeverinthehostbyreleaseofIL-1andothermediators.Frequentlycontrolledbyextrachromosomalgenes(e.g.plasmids).Synthesisdirectedbychromosomalgenes.區(qū)別要點(diǎn)外毒素內(nèi)毒素來源革蘭陽性菌與部分革蘭陰性菌革蘭陰性菌編碼基因質(zhì)粒、前噬菌體或染色體基因染色體基因存在部分從活菌分泌出，少數(shù)菌崩解后釋出細(xì)胞壁組分，菌裂解后釋出化學(xué)成分蛋白質(zhì)脂多糖穩(wěn)定性60～80℃，30分鐘破壞160℃，2～4小時(shí)破壞毒性作用強(qiáng)，對組織器官有選擇性毒害效應(yīng)，引起特殊的臨床表現(xiàn)較弱，各菌的毒性效應(yīng)大致相同，引起發(fā)熱、白細(xì)胞增多、微循環(huán)障礙、休克、DIC等抗原性強(qiáng)，刺激機(jī)體產(chǎn)生抗毒素；甲醛液處理脫毒形成類毒素弱，刺激機(jī)體產(chǎn)生的中和抗體作用弱；甲醛液不能脫毒形成類毒素SpecificpolysaccharideLPSProcedureCytotoxins（細(xì)胞毒素）Diphtheriatoxin（白喉毒素）inhibitsproteinsynthesisinmammaliancellsandcausesnecrosisofcellsDiphtheriamembraneonthroatNeurotoxin（神經(jīng)毒素）Tetanustoxin（破傷風(fēng)毒素）Enterotoxin（腸毒素）

CholeraenterotoxinBiologicalrolesofendotoxinFever（發(fā)熱）Leukopeniaandleukocytosis（白細(xì)胞反應(yīng)）Endotoxemiaandshock（內(nèi)毒素血癥與休克）EndotoxinActivatesmacrophagesActivatescomplementActivatesHagemanfactorIL-1,TNF,NitricoxideFeverandhypotensionC3a,C5aHypotensionEdemaCoagulationcascadeDICSection4theinitiationandprocessofinfectionSourcesofinfectionPathwayofbacterialentranceTypesofbacterialinfectionExogenousinfection（外源性感染）PatientsCarriers（帶菌者）AnimalsEndogenousinfection（內(nèi)源性感染）OpportunisticpathogensSourcesofinfectionPathwayofpathogenentrance

RespiratoryGastrointestinalGenitalSkinandmucosaAnimalbitesBloodSexualtransmissionTypesofbacterialinfectionInapparentinfection（隱性感染）Apparentinfection（顯性感染）Carrierstate（帶菌狀態(tài)）Inapparentinfection（隱性感染）Subclinicalinfection（亞臨床型感染）Aninfectionthathasnoobservablesymptoms.Itoccurswhenthehostimmunityispotentorthepathogenicityofthepathogenisweak.Thetipoftheiceberg

Apparentinfection（顯性感染）AcuteinfectionChronicinfectionLocalinfectionGeneralizedinfection★Toxemia(毒血癥)Endotoxemia(內(nèi)毒素血癥)Bacteremia(菌血癥)Septicemia(敗血癥)Pyemia(膿毒血癥)Toxemia（毒血癥）Bacteriamutiplyatinvadinglocationanddonotenterbloodstream,buttheexotoxins（外毒素）enterbloodandcausecorrespondingtoxicsymptoms.Endotoxemia（內(nèi)毒素血癥）Gram-negativebacteriamultiplyatlocationorinbloodstream,releasealotofamountendotoxin（內(nèi)毒素）

releasedfrombacterialcellrupture.Bacteremia（菌血癥）Afterenteringblood,bacteriacirculatebutnotmultiplyintheblood.Septicemia（敗血癥）Bacteriacirculateandmultiplyintheblood,inwhichbacteriaproducetoxicproductsandcausehighswingingtypeoffeverandothertoxicsymptoms.Pyemia（膿毒血癥）Pyogenic（化膿性）bacteriaproducesepticemiawithmultipleabscess（膿腫）ininternalorganssuchasspleen,liverandkidneys.★

Carrierstate（帶菌狀態(tài)）Afterinapparentinfectionorapparentinfection,sometimesthepathogensarenoteliminatedintime,sothebacteriawillsurviveandmultiplyinhostatlowspeed,andbacteriaspreadintotheenvironment.Carrier（帶菌者）isimportantsourceofinfection.HospitalinfectionDefinitionBasiccharacteristicsClassificationMicrobialecologicalcharacteristicsEpidemiologicalcharacteristicsRiskfactorsofNosocomialInfectionHospitalInfection（醫(yī)院感染）Nosocomialinfection（醫(yī)院內(nèi)感染）Hospitalacquiredinfect