抗生素ppt课件（英文精品） molecular mechanisms of microbial pathogenesis and virulence

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1、MolecularMechanismsofMicrobialPathogenesisandVirulenceControllingInfectiousDiseasesThepre-antibioticEra-ImprovingSanitation&hygieneeducationTyphoid(Salmonella),Plague(Yersinapestis)Syphilis(Treponemapallidum)2.TheantibioticEra(1940-70)-Defeatofinfectiousbacteria?3.Post-an

2、tibioticEra-Emergenceandreemergenceofinfectiousdiseases.DeathsduetoTB(3million)&Diarrhea(3-4million)Legionnairesdisease(Legionellapneumoniae)LymeDisease(Borriellaburgdoferi)Gastriculcers&cancer:HelicobacterpyoriCampylobacterjejuni7strainsofE.coliViralagents:SARS,Morbilli,

3、HIV,HuntaWehavelostcontroloverinfectiousdiseases?Why?RoleofAntibiotics:Overuseofantibiotics/antimicrobialshasincreaseddrugresistantmicrobes;nonewantibioticshavebeendiscoveredinthepast20yrSomeexamplesofantimicrobialressistance:Pseudomonasaeruginosadominatehospitalburnunits

4、Emergenceofmultiple(methicillin)resistantstaphylococcusaureus(MRSA);Somestrainsarenowresistanttovancomycin,theonlyeffectiveremainingantibioticDecade2.Improvedstandardofliving:AirconditionersandLegionella3.Removingand/orsubstitutingenvironments:SARS,HIV,Lymedisease4.Agingp

5、opulation,compromisedimmunityMicrobesadapttothestressandpressureplacedonthem1.PhysiologicalAdaptation–Quorumsensing2.GeneticAdaptationVariousstagesofbacteriaeucaryotecellinteractionduringinfectionTrojanHorse:quorumsensingPhysiologyAcquiringnewgenes-GeneticQuorumsensing-ba

6、cterialsignaling:LowmolecularweightcompoundsInhibitmacrophage&TlymphocytefunctioningAbletodeterminecelldensity-switchon/offgenesIncreasedensitytoaneffectiveinfectivitydosewithoutalertinghostofimpendingattack;pathogenesisgenesnotswitchedon.LegionellaincoolingtowersPathogen

7、icmicrobessubvertfunctionsofhostsinmanyways:Hostsignaling,host-parasitesignaling;parasitesignalingAcquiringNewGenes-HorizontalGeneTransfer&GeneticRecombination1.HorizontalGeneTransferMechanisms:TransformationTransductionConjugation2.FateoftheTransferredGeneticMaterial:Inc

8、orporatedintothehostsgenome-themechanismNotincorporatedintothehostsgenome3.ConsequencesfortheHos