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1、GameplanLectureAntibioticsAntibioticresistanceGenetransferTransformationTransductionConjugationExtracreditassignmentLabLabExamPre-labTransformation-1928:Flemingdiscoveredpenicillin,producedbyPenicilliumDiscoveryofAntimicrobialDrugsFigure1.5Wheretoantimicrobialscomefrom?Broadspectrum-

2、affectabroadrangeofgram-positiveandgram-negativebacteriaNarrowspectrum-affectsanarrowrangeofbacteriaSpectrumofactivityThisbacteriumislysingbecauseanantibioticdisrupteditscellwall.Whydoesn’ttheantibioticlysehumancells?PitStopTheActionofAntimicrobialDrugsFigure20.2Casestudyinnarrowspec

3、trumantibiotics:Penicillin-Naturalpenicillins-SemisyntheticpenicillinsFigure20.7PenicillinretentionAcasestudyinbroadspectrum:TetracyclineFigure20.11ResistancetoAntibioticsFigure20.20EnzymaticdestructionofdrugPreventionofpenetrationofdrugAlterationofdrug'stargetsiteRapidejectionofthed

4、rugFigure20.8Apeekatantibioticresistance…penicillinaseFigure20.21Antibioticresistanceandsuperinfections-Avarietyofmutationscanleadtoantibioticresistance-Misuseofantibioticsselectsforresistancemutants.Misuseincludes:UsingoutdatedorweakenedantibioticsUsingantibioticsforthecommoncoldand

5、otherinappropriateconditionsUsingantibioticsinanimalfeedFailingcompletetheprescribedregimenUsingsomeoneelse'sleftoverprescription-ResistancegenesareoftenonplasmidsortransposonsthatcanbetransferredbetweenbacteriaMechanismsofresistanceThefutureofantibioticresistance…NDM-1-NDM-1-NewDelh

6、imetallo-beta-lactamasegeneconfersresistancetoallantibioticsexceptcolistin(affectsmembranes)andtigecycline(proteinsynthesisinhibitor~tetracylcine)-OriginallyidentifiedinDecember2009inKlebsiellapneumoniaefrompatientinNewDelhi,India-CurrentlyfoundinK.pneumonia,E.coli,andEnterobacteriac

7、eaeinIndia,Pakistan,theUnitedKingdom,theUnitedStates,Canada,andJapanHowwasNDM-1tranfered?VerticalgenetransferHorizontalgenetransferAlltransfermethodsrelyonrecombinationFigure8.22Horizontalgenetransfer:TransformationDemoHorizontalgenetransfer:Transformation1920s-GriffithexperimentHori

8、zontalgenetr