简介：Toinvestigatetheprevalenceandgenotypeofextendedspectrumbeta-lactamases(ESBLs)mediatedbyplasmidinGram-negativebacteriafoundinsouthernChina,atotalof1184clinicalisolatesofnon-repetitivestrainsofGram-negativebacteriawerecollectedin2001from5differentcitiesinsouthernChina.TheESBLs-producingisolatesweredistinguishedbymeansofthephenotypeconfimatorytestbasedontheNCCLScriteriaandweresubjectedtoplasmidconjugationandelectroporationexperiments.Thoseclinicalisolatessucceededinplasmidtransfershadundergoneplasmidconjugationandelectro-transformation,plasmidDNAextractionandPstⅠdigestlinger-printinganalysis,aswellasthetmiversalprimerPCRamplificationoftheTEM,SHV,CTX-M,VEB,PERandSFOgenesandtheDNAsequencinginordertodeterminethegenotypesofESBLsandtheirplasmidlocations.ItwasfoundthattheincidenceoftheESBLs-producingstrainsofGram-negativebacteriawas14.6%(173/1184)with67strainsoftransconjugantsand11strainsofelectro-transformants,inwhichCTX-M-14typewas33.3%(26/78);CTX-M-3typewas23.1%(18/78);CTX-M-9typewas14.1%(11/78);CTX-M-5typewas6.4%(5/78);CTX-M-13typewas2.6%(2/78);SHV-5typewas7.7%(6/78);SHV-12typewas5.1%(4/78),SHV-2atypewas2.6%(2/78)andunidentifiedtypewas5.1%(4/78).29.5%ofthewildstrainsalsocarriedbroad-spectrumbeta-lactamasesTEM-1andSHV-1types.TheabovementionedESBLsgeneswerelocatedontransferableplasmidswithvariablesizes(from35to190kb).TheCTX-MtypeESBLswascharacterizedbyhigh-levelofresistancetocefotaxime.ItconcludedthattheCTX-M-typewasthemostprevalentgenotypeinclinicalisolatesofGram-negativebacteriainsouthernChina,andtheSHVtyperanksinthesecondplace.TEM-,VEB-,Toho-andPER-typeswerenotfoundintheseisolates.

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