医学微生物课件.ppt_人人文库网

来自 : www.renrendoc.com/p-854720...h 发布时间：2021-03-25

Chapter11bacterialinfection,,Infection感染,TheprocessofinterplaybetweenM.andhost.M.HostdefensesDifferentresultsafterinfection,,,Pathogen:Amicroorganismcapableofcausingdisease.Nonpathogen:Amicroorganismthatdoesnotcausedisease.Opportunisticpathogen条件致病菌:somenon-pathogensmaycausediseasesundersomespecialconditions.,,Section1normalmicrobialfloraandopportunisticB.,1.Normalflora正常菌群,ThevariousB.andF.thatarepermanentresidentsofcertainbodysitesvaryinnumberandkindfromonesitetoanotherthelocationsareusuallyskin,oropharynx,colon,andvagina(mucousmembranes),肠道的正常菌群,健康青年粪便涂片,健康壮年粪便涂片,健康中年粪便涂片,鼻咽腔葡萄球菌、甲，丙型链球菌肺炎球菌、奈氏菌、类杆菌等,外耳道葡萄球菌、类白喉杆菌绿脓杆菌、非致病性分枝杆菌,表皮葡萄球菌口腔甲，丙型链球菌类白喉杆菌、肺炎球菌奈氏菌、乳杆菌、梭杆菌螺旋体、放线菌、白念珠菌,肠道大肠杆菌、产气杆菌、变形杆菌绿脓杆菌、葡萄球菌、厌氧性细菌真菌、乳杆菌，双歧杆菌等,阴道大肠杆菌、乳杆菌白念珠菌、类白喉杆菌非致病性分枝等,皮肤葡萄球菌、绿脓杆菌、白念珠菌丙酸杆菌、类白喉杆菌、非致病性分枝杆菌,人体内正常菌群的分布,眼结膜白色葡萄球菌、干燥杆菌,尿道白色葡萄球菌、类白喉杆菌、非致病性分枝杆菌,,RoleofnormalflorakeephealthCausedisease,2.beneficialeffectsofthenormalflora,PrimingofimmunesystemplayanimportantroleinthedevelopmentofimmunologiccompetenceInducecross-reactionwithpathogenicorganisms,,exclusionaryeffect生物拮抗---colonizationresistanceProductionofessentialnutrients----produceseveralBvitaminsandvitaminK,3.opportunisticB.条件致病菌,Manyspeciesamongthenormalfloraareopportunists.Memberofthenormalfloramaythemselvesproducediseaseundercertaincircumstances.,threeconditionscorrelatedwithopportunisticinfection,ImmunesystemcompromiseDysbacteriosis菌群失调Changeofinhabitingplaces,dysbacteriosis,Whentheresidentfloraisdisturbed,somelittlesignificantM.maycolonize,proliferateandproducediseases.Mainlyresultfromlongtermandlargedosesantibioticstaken,nosocomialinfections医院获得性感染,definitionAnyinfectionacquiredwhileinhospital,sources,HospitalpersonnelEnvironmentMedicaldevices医疗用具Bloodandbloodproducts,Section2bacterialpathogenesis,,Pathogen病原菌:havethecapacitytoinitiatediseasesPathogenicity致病性:thecapacityofB.toinitiatediseases,致病性,,毒力,侵入数量,侵入途径,,侵袭力,毒素,,荚膜、微荚膜,黏附素,侵袭性物质,,内毒素,外毒素,表面结构,鞭毛,生物被膜,,,侵袭性酶,侵袭素,,virulence毒力:AquantitativemeasureofpathogenicityLD50:thenumberneededtokillhalfthehostsID50:thenumberneededtocauseinfectionInhalfthehosts,Bacterialvirulencefactors,Invasiveness侵袭力Toxins毒素Quantity数量Pathwayofbacterialentrance途径,invasiveness,定居、生长繁殖、扩散,A.Adherencefactors粘附因子,SurfacemoleculesofB.pililipoteichoicacidproteinF,B.Invasionofhostcellsandtissues,Capsule:preventthephagocytefromadheringtotheB.EnzymesBacterialbiofilms生物膜Integrin整合素,enzymes,tissue-degradingenzymesIgA1proteases,Bacterialbiofilms,Anaggregate凝聚物ofinteractiveB.attachedtoasolidsurfaceortoeachotherandencased包装inanexopolysaccharide表多糖matrixDistinctfromplanktonic浮游生物orfree-livingbacterialgrowth,,AsinglespeciesofB.maybeinvolved,ormorethanonespeciesmaycoaggregateGenesmaybeactivatedthatinfluencemetabolicpathwaysandtheproductionofvirulencefactorsB.deepwithinthematrixtendtohavedecreasedmetabolism,,SomeoftheB.withinthebiofilmshowmarkedresistancetoantimicrobialsInteractionsofM.occurwithinthebiofilm(community)Drug-resistancecanspreadfastAreimportantinhumaninfectionsthatarepersistentanddifficulttotreat,toxins,TwogroupsexotoxinendotoxinP73table4-4,1.exotoxin,producedbyG+andG-B.ExcretedbylivingcellPolypeptidestoxicityishighUsuallybindtospecificreceptorsoncellhaveanA-BsubunitstructureA:toxicactivityB:bindtheexotoxintospecificreceptors,exotoxin,Relativelyunstable(heating)Highlyantigenic:antitoxins----preventiontoxoids----usedinprotectivevaccinesDividedintodifferenttypes,2.endotoxin,componentofthecellwallpresentonlyinG-B.LPSRelativelystabletoxicityislowNospecificreceptorsfoundoncellsallproducethesamegeneralizedeffectsweaklyantigenic,TheactivitiesofLPS,FeverLeukopenia白细胞减少andhypoglycemia低血糖HypotensionandshockComplementcascadeDisseminatedintravascularcoagulation,Thebiologiceffectsofendotoxin,Fever:thereleasebymacrophagesofendogenouspyrogenHypotension,shock,impaired受损的perfusion灌注ofessentialorgans:vasodilation血管舒张,increasevascularpermeability,decreaseperipheralresistance,内毒素的生物学作用：①发热反应：IL-1内毒素致热原IL-6TNF-α下丘脑体温调节中枢体温升高,,,,,,,,,,,3.DIC:activationofthecoagulationsystem4.Inflammationandtissuedamage:activatetheC.cascade5.ActivationofmacrophagesandBlymphocytes,,,致病性,,毒力,侵入数量,侵入途径,,侵袭力,毒素,,荚膜、微荚膜,黏附素,侵袭性物质,,内毒素,外毒素,表面结构,鞭毛,生物被膜,,,侵袭性酶,侵袭素,,Section3theinitiationandcourseofinfection,Sourcesofinfection,exogenousinfectionEndogenousinfection,A.Exogenousinfection,PatientsCarriersanimals,patients,Maytransmitthepathogensfromtheincubationperiod潜伏期torecoverystageofthedisease,MayharborthepathogensforonlyabriefperiodorforlongperiodsMaybetheimportantsourcesofinfection,carries,animals,ExistprimarilyinanimalsandincidentallyinfecthumansProduceinfectionofhumansthatisinadvertent不慎的,amistakeinthenormallifecycleoftheorganism,Pathwayofbacterialentrance,Horizontaltransmission水平传播人-人动物-人消化道、呼吸道、接触、节肢动物Verticaltransmission垂直传播亲代---子代胎盘、产道,Pathwayofbacterialentrance,mucousmembrane粘膜skinsexualcontact多途径,Endogenousinfection,B.causingdiseasescomefromhostwheretheyresideMostofendogenousinfectionsareopportunisticpathogeninfections,Typesofbacterialinfection,InapparentinfectionApparentinfection,M.Hostdefensesinducevarioustypes,,A.Inapparentinfection,SubclinicalM.Hostdefenses,overpower,,B.Apparentinfection,ThehostshaveevidentclinicsymptomsM.Hostdefenses,,overpower,在显性感染中，又分,Chronicinfection慢性感染,Localinfection局部感染,Systemicinfection全身感染,Acuteinfection急性感染,,,IfB.spreadtowholebody,Bacteriemia菌血症:B.circulatebutnotmultiplyinthebloodToxemia毒血症:B.multiplyatinvadinglocationanddonotenterbloodstream,buttheexotoxinsenterbloodandcausecorrespondingtoxicsymptoms,,Endotoxemia内毒素血症:G-B.releasealotofamountendotoxinreleasedfrombacterialcellrupture细胞破裂Septicemia败血症:B.circulateandmultiplyintheblood,producetoxicproductsandcausehighswinging猛烈的typeoffeverandothertoxicsymptomsPyemia脓毒血症:pyogenicB.producesepticemiawithmultipleabscessesininternalorgans,毒素入血细菌入血中毒症状毒血症+--菌血症-+-败血症+++脓毒血症+++新的化脓灶,,,C.carrier,Afterinapparentorapparentinfectionthepathogensarenoteliminatedintime,theB.stillsurviveandmultiplyinhostatlowspeedB.spreadintotheenvironmentImportantsourcesofinfection,,chroniccarrierstate:theorganismscontinuetogrowwithorwithoutproducingsymptoms----importantsourceofinfection,publichealthhazardTyphoid伤寒Marry,,TyphoidMarry,,Section4hostdefenceagainstbacterialinfection,HostdefencesystemInnateimmunityAcquiredimmunity,,physicalbarriersInnatereticuloendothelialsystemphagocytosisantibody-mediatedAcquiredcell-mediated,,,细菌感染免疫的分类,Stagesofbacterialpathogenesis,Transmission,entryEvasionofprimaryhostdefensesAdherenceColonizationDiseasesymptomsHostresponsesProgressionorresolution,Typicalstagesofaninfectiousdisease,IncubationperiodProdromeperiodSpecific-illnessperiodRecoveryperiod,Afterrecoveryperiod,chroniccarrierslatentinfection:thesameformrecurdifferentsignsandsymptoms,,Didtheorganismisolatedfromthepatientactuallycausethedisease,Koch’spostulates,1.Theorganismmustinsolatedfromeverypatientwiththedisease.2.Theorganismmustbeisolatedfreefromallotherorganismsandgrowninpurecultureinvitro.3.Thepureorganismmustcausethediseaseinahealthy,susceptibleanimals.4.Theorganismmustberecoveredfromtheinoculatedanimals.,Postulates3.and4.areimportantindefiniteproofoftheroleofagentinhumandisease.However,thisdependsontheabilitytodevelopanimalmodelsthatresemblethehumandisease.Inmanycasessuchmodelsdonotexist.,Reviewquestions,Whatarethemaindifferencesbetweenexotoxinandendotoxin?Pyemia, 展开阅读全文