细菌对抗生素耐药的演变（英文ppt）humans nature the causes and consequences

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1、EvolutionofResistancetoAntibioticsinBacteriaPresentedbyJanaBoozerKatelinErwinAshleyGregorySaraThompsonHUMANS&NATURE:Whatisantibioticresistance?Antibioticresistanceoccurswhenanantibiotichaslostitsabilitytoeffectivelycontrolorkillbacterialgrowth;inotherwords,thebacteriaare"r

2、esistant"andcontinuetomultiplyinthepresenceoftherapeuticlevelsofanantibiotic.Whydobacteriabecomeresistanttoantibiotics?Whenantibioticsareusedtokillthebacterialmicroorganisms,afewmicroorganismsareabletostillsurvive,becausemicrobesarealwaysmutating,eventuallyleadingtoamutati

3、onprotectingitselfagainsttheantibioticAntibioticsthatareusedcorrectlyoverwhelmtheharmfulbacteriaOveruseofantibioticsorunnecessaryusecreatesaselectiveenvironmentResistantbacteriahasbetterfitnessinthiscontextResistantstrainssurviveandmultiply.Afterreproducing,theresistantbac

4、teriamovetoanotherhost.Howhumanshavecreatedtheupsurgeofbacterialdiseases:InternationaltravelInadequatesanitation“antibioticparadox”Howdobacteriabecomeresistant?Bacteriacangainresistanceovertimethrough:AcquiredresistanceVerticalgenetransferHorizontalgenetransferAcquiredResi

5、stanceMechanismsaredevelopedbybacteriainordertoacquireresistanceEithermodificationofexistinggeneticmaterialoracquisitionofnewgeneticmaterialfromanothersource.Developmentofresistancethroughspontaneousmutationiscalledprimaryresistance.ErrorsinDNAsynthesisduringreplicationOcc

6、asionalfailuresintheDNArepairsystemsVerticalGeneTransferResistantgenesaredevelopedGenesdirectlytransferredtoprogenyduringDNAreplicationThisisdirectlyrelatedtoDarwin’stheoryofevolution.HorizontalGeneTransfer(HGT)“lateralgenetransfer”Geneticmaterialiscontainedinsmallpacketso

7、fDNA.Packetscanbetransferredbetweenindividualbacteriaofthesamespeciesordifferentspecies.3MechanismsofHGTTransductionTransformationPenicillin-resistantgonorrheaConjugationIn1968,12,500peopleinGuatemaladiedofShigelladiarrheaepidemic.SpreadofResistantBacteriaRapidgrowthofbact

8、eriaSmallsizeSimpleinternalstructureMultiplyrapidlyNewgenerationinaslittleas20minutesStra