简介：Klebsiellapneumoniae(K.pneumoniae)isoneofthemaingram-negativebacilliinclini-calpractice.NosocomialinfectionscausedbyK.pneumoniaeproducingextended-spectrumβ-lactama-ses(ESBLs)areverydifficulttotreat.ThispaperinvestigatedtheresistantcharacteristicsofK.pneu-moniaeproducingESBLsandtheiraminoglycoside-modifyingenzymegeneexpressionsincludingN-acetyhransferasesandO-adenyhransfemses.BacteriaidentificationandESBLsconfirmatorytestswereperformedbyPhoenix~(TM)-100system.Andminimuminhibitoryconcentrations(MICs)ofgentamicin,amikacin,kanamycin,tobramycin,netilmicinandneomycinin53K.pneumoniaeisolateswerede-tectedbyagardilution.Inaddition,sixaminoglycoside-modifyingenzymegeneswereamplifiedbypolymerasechainreaction(PCR)andverifiedbyDNAsequencer.Itwasfoundthatimipenemandmeropenemagainst120K.pneumoniaeisolatesproducedpowerfulantimicrobialactivities.Theresis-tantratesofgentamicinandamikacinwere55.0%and46.7%,respectively.Exceptneomycin,MIC_(50)andMIC_(90)ofgentamicin,amikacin,kanamycin,tobramycinandnetilmicinin53K.pneumoni-aewereall>128μg/ml,andtheresistantrateswere83.0%,52.3%,75.5%,81.1%and69.8%,respectively.However,neomycinwasonly39.6%.Inaddition,fivemodifyingenzymegenes,includingaac(3)-Ⅰ,aac(3)-Ⅱ,aac(6')-Ⅰb,ant(3″)-Ⅰ,ant(2″)-Ⅰgenes,werefoundin53isoahesexceptaac(6')-Ⅱ,andtheirpositiverateswere11.3%,67.9%,47.2%,1.9%and39.6%,respectively.Itwasalsoconfirmedbynucleotidesequenceanalysisthattheaboveresistantgenessharednearly100%identitieswithGenBankpublishedgenes.TheresultsobtainedinthepresentstudyindicatedthatK.pneumoniaeproducingESBLsstrainsarerapidlyspreadinginourhospital,andtheirresistancetoaminoglycosidesmaybeassociatedwithaminoglycoside-modifyingenz-ymegeneexpressions.

简介：Itisknownthataminoglycosideantibioticscandamagethevestibularandauditorysensoryepithelia,andtheloopdiureticscanenhancetheototoxiceffectofaminoglycosides.Previousstudiesonthesynergisticeffectofthesetwotypesofdrugshaveusedmice,guineapigsandcats,butnotrats.Theaimofthisstudywastodeterminethissynergisticeffectsinratcochleae.Ratsreceivedintravenousinjectionsofdifferentdosesoffurosemideand/orintramuscularinjectionsofkanamycinsulfate.Auditorybrainstemresponse(ABR),scanningelectronmicroscopy(SEM)andimmunocytochemistrywereusedtodeterminetheeffectsofdrugadministration.Inthegroupreceivingcombinedadministrationoffurosemideandkanamycin,theABRthresholdshowedsignificantelevation3daysafterdrugadministration,greaterthansingledrugadministration.Thehaircellsshowedvariousdegreesofinjuryfromtheapicalturntothebasalturnofthecochleaandfromtheouterhaircellstotheinnerhaircells.Neuronfibersofthehaircellsshowedsignificantloss7daysafterthedrugadministration,butthenumberofspiralgangliadidnotdecreaseandsupportingcellsshowednosignsofinjury.Ourstudysuggestthatcombinedadministrationoffurosemideandkanamycinhasansynergisticototoxiceffect,andcanresultinhaircelllossandhearinglossinrats.