J. Antimicrob. Chemother.-2009-Liu-895-900

JournalofAntimicrobialChemotherapy(2009)63,895–900

doi:10.1093/jac/dkp068

AdvanceAccesspublication18March2009

NovelCTX-Mb-lactamasegenotypedistributionandspreadintomultiplespeciesofEnterobacteriaceaeinChangsha,SouthernChinaWen’enLiu1*,LameiChen1,HonglingLi1,HuiliDuan1,YunliZhang1,XianghuiLiang1,XianLi1,

MingxiangZou1,LiXu2andPeterM.Hawkey2,3

1ClinicalLaboratory,2XiangyaHospital,CentralSouthUniversity,87XiangyaRoad,Changsha,Hunan410008,P.R.China;HealthProtectionAgencyWestMidlandsPublicHealthLaboratory,HeartofEnglandNHSFoundationTrust,BirminghamB95SS,UK;3SchoolofImmunityandInfection,UniversityofBirmingham,

Edgbaston,BirminghamB152TT,UK

Received3November2008;returned16December2008;revised14February2009;accepted15February2009

Objectives:TheaimofthisstudywastoundertakeasurveyoftheoccurrenceofCTX-MandSHV

extended-spectrumb-lactamase(ESBL)genotypesinEnterobacteriaceaefromHunanProvince,China.

Methods:Clinicalisolates(425)fromthreemajorhospitalsinChangsha,HunanProvince,werecol-

lectedbetweenOctober2004andJuly2005,andtheirantimicrobialsusceptibilitiesofthegenotypeof

blaCTX-MandblaSHVweredetermined.Randomampli edpolymorphicDNAwasusedtocharacterize

theclonalityofalloftheisolates.

Results:TheoverallrateofESBL-positiveisolateswas33.4%(142/425).ThedominantESBLswere

CTX-Mtypes,andwerefoundin109/142(76.8%)isolatescomprisingsevendifferentgenera/species,

namelyEscherichiacoli,Klebsiellapneumoniae,Enterobactercloacae,Enterobacteraerogenes,

Citrobacterfreundii,ProteusvulgarisandProvidenciastuartii.ThemostcommonblaCTX-M

genotypeswereblaCTX-M-14(47.7%),blaCTX-M-3(29.4%)andblaCTX-M-15(17.4%).Anovelgenederived

fromblaCTX-M-15,blaCTX-M-82(Ala-40!Pro),wasidenti ed.

Conclusions:ThedominantESBLgenotypeinHunanProvincewasblaCTX-M.Thehighprevalence

(17.4%)ofblaCTX-M-15hasnotpreviouslybeenreportedfromChina.Ourresultsidentifythatanepi-

demicofblaCTX-MinChangsha,HunanProvince,hasevolvedwiththeappearanceandspreadof

blaCTX-M-15againstthedominantgenotypesblaCTX-M-14andblaCTX-M-3.Theworldwidedominanceof

blaCTX-M-15couldbepoisedtospreadtoChina,displacingthecurrentprevailinggenotypes.

Keywords:ESBLs,blaCTX-M,HunanProvince

IntroductiondemonstratedthatCTX-MESBLswerethedominantESBLin

thatcity.Thiswasthe rstdescriptionofthegenotypesCTX-M-typeextended-spectrumb-lactamases(ESBLs)haveCTX-M-13and-14.CTX-M-14hastranspiredtobethedomi-becomeoneofthemostprevalenttypesofESBLsglobally.1–3nantgenotypeinbothChinaandothercountriesinsouth-eastInChina,ESBL-producingEnterobacteriaceaeareaseriousAsiaforwhichdataareavailable,aswellasbeingpresentinproblemwithamuchhigherincidenceofcarriageinEuropeandNorthAmerica.1,5,10–14CTX-M-typeESBLsaretheEscherichiacoliandKlebsiellapneumoniaethaninmostothermostcommongenotypeinthesevenprovincesand/orcitiesinregionsoftheworld.4–6EarlyreportssuggestedthatSHVgeno-Chinaforwhichdataareavailable.ThedominantgenotypeistypeESBLswerethedominanttypepresentinChina.7StudiesCTX-M-14,CTX-M-9and-3beinglesscommon,whilstinthe1990s,whilstdemonstratinghighratesofESBLpro-bladuction,includedlittledataongenotypesotherthanthoseCTX-M-15isabsentintheseareasexceptintherecentreport

byYuetal.12whichdescribes4outof399blareportedbyChanawongetal.8andWangetal.9ThestudyofCTX-M-positive

strainsthatcarriedblaChanawongetal.8of15isolatesfromGuangzhouin1997 rstCTX-M-15.5,12,13Therefore,weexpected

thatthegenotypedistributionofblaCTX-MinHunanProvince,

.....................................................................................................................................................................................................................................................................................................................................................................................................................................

*Correspondingauthor.Tel/Fax:þ86-731-4327437;E-mail:liuwenen@http://wendang.chazidian.com

.....................................................................................................................................................................................................................................................................................................................................................................................................................................

895

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Liuetal.

thecentreofSouthernChinaandapreviouslyunstudiedareawithSubsequently,speci cprimersamplifyingthewholeopenreadingapopulationof70million,wouldshowapatternthatmightbeframe(ORF)ofblaCTX-M( 1300bp)onlyfromgroups1and9differentfromthosepreviouslyreportedduetoitsrelativesepar-wereusedtofurtherscreentheblaCTX-M-positiveisolates.16ationfromtheareasalreadystudied.WeundertookaprospectiveBacterialDNAwaspreparedbysuspendingoneortwofreshcolo-surveyin2004–05ofEnterobacteriaceaeinChangsha,thelargestniesin50mLofsteriledistilledwaterandheatingat958CforcityinHunanProvince,todeterminetheincidenceandmolecular5min.ThePCRampli cationwasperformedat958Cfor5min,fol-epidemiologyofESBL-producingEnterobacteriaceae.lowedby29cyclesof948Cfor30s,568Cfor30sand728Cfor

60s,witha nalextensionat728Cfor10min.Ampli cationofthe

ORFofblaSHV( 900bp)wasperformedonall142ESBL-positive

isolatesusingapreviouslydescribedmethod.16

Materialsandmethods

ClinicalisolatesGenotypingblaCTX-M-positiveisolatesbydenaturingAtotalof425non-duplicateclinicallysigni cantisolatesofHPLC(dHPLC)

Enterobacteriaceaefromhospitalpatientswerecollectedconsecu-

tivelyfromthreeuniversity-af liatedhospitals(eachwith1500–ThepreviouslydescribedmethodofXuetal.17,18wasusedto2000beds,whichreceivepatientsfromthesurroundingprovince)amplifyblaCTX-Mofgroups1and9,whichgeneratesproductsizeslocatedinChangshaCity,HunanProvince,China,duringtheperiodof255and293bp,respectively.Brie y,PCRproductsofeithercon-October2004toJuly2005.ThenumberofisolatesofeachspeciestrolsortheclinicalisolatesweremixedwithanidenticalqualityofisshowninTable1.referenceDNAandheatedat958Cfor5min,followedbygradual

coolingto258Ctoformthehomo-andheteroduplexDNAmol-

ecules;theduplexedPCRproductswerethenanalysedonadHPLC

Antimicrobialsusceptibilitytestingandcon rmationsystem(WAVE4500DNAfragmentanalysissystem,TransgenomicofESBLsInc.,Omaha,NE,USA).Thechromatographicsignaturesof

unknownblaCTX-M-typewerecomparedwiththereferencepeaks.

AllisolatesweretestedusingtheVitek2system(bioMe´rieux,

France).ESBLproductionwasdetectedbothbyVitek2andaphe-

notypiccon rmatorytest(clavulanicacidcombinationdisc)asrec-Randomampli edpolymorphicDNA(RAPD)typingommendedbytheCLSI.15ofbacterialisolates

TheMICsoftheantibioticsamikacin,aztreonam,cefotaxime,TheRAPDanalysiswasperformedusingtheEnc1Rprimer.16ceftazidime,ceftriaxoneandmeropenemweredeterminedusingReactionswererununderthefollowingconditions:2minat948C;agardilutionforallisolatesidenti edasESBLproducers.1535cyclesof1minat958C,1minat258Cand4minat728C;andThecontrolstrainsusedforthisstudywereE.coli(ATCC nally8minat728C.ThePCRproductswereelectrophoresizedon25922),K.pneumoniae(ATCC700603)andPseudomonasa1%agarosegel.Isolatesofthesamespeciesweretypedtogetheraeruginosa(ATCC27853).inasinglebatchtoensurereproducibilitywithrepresentativesof

eachtyperunonasinglegeltode nethestabilityoftheband

PCRampli cationofblapatterns.Bandingpatternswerecomparedvisuallyusingstandard

CTX-MandblaSHVcriteriaforstrainidenti cation.19

IsolateswereinitiallyscreenedforthepresenceofblaCTX-Mby

multiplexPCR,whichisdesignedtoyieldPCRproductsizesof

693bp(blaNucleotidesequence

CTX-M-1group),684bp(blaCTX-M-2group),695bp

(blaCTX-M-8group)and683bp(blaCTX-M-9group),respectively.16ThesequencesofblaCTX-MandblaSHVORFweredeterminedusing

anABI3100GeneticAnalyzer(AppliedBiosystems,CA,USA).

Table1.PrevalenceofblaNucleotideandaminoacidsequencealignmentswereanalysedby

CTX-Mproductionandgenotypeamong

ESBL-positiveisolatesofEnterobacteriaceaefromthreehospitalsinusingtheBLASTandsequenceanalysisserver(http://bio.lunderg.Changsha,HunanProvincegu.se/).Sequencesreportedinthisstudywere ledintheGenBank

databasewiththefollowingaccessionnumbers:DQ256091

(blaCTX-M-82fromE.coli),DQ302097(blaCTX-M-15from

blaCTX-MK.pneumoniae),DQ302096(blaCTX-M-15fromEnterobactercloacae),

genotypeDQ335219(blaCTX-M-15fromE.coli),DQ299902(blaCTX-M-3from

E.coli),DQ303119(blaCTX-M-3fromK.pneumoniae),DQ303118

SpeciesTotalisolatesESBL-positive315149(blaCTX-M-3fromE.cloacae),DQ328958(blaCTX-M-3from

Citrobacterfreundii),DQ328957(blaCTX-M-3fromEnterobacter

E.coli1605066351aerogenes),DQ304479(blaCTX-M-14fromE.coli),DQ304478K.pneumoniae11047812131(blaCTX-M-14fromK.pneumoniae),DQ328959(blaCTX-M-14fromE.cloacae983110233E.cloacae)andDQ323547(blaCTX-M-14fromProvidenciastuartii).

C.freundii1775000

E.aerogenes2433000

P.stuartii210010Results

P.vulgaris1430000

Total425a142b3220525MICsandphenotypiccon rmatorytestsforESBLs

TheMICsof veantibioticsfor25exemplarstrainsareshown

a

bNinety-sevenisolateswerefromICUs.inTable2.Phenotypiccon rmatorytestsrevealedthat33.4%ofForty-twoisolateswerefromICUs.isolatesofEnterobacteriaceae(142/425)wereESBL-producing

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NovelCTX-Mb-lactamaseinChangsha,SouthernChina

Table2.Characteristicsof25blaCTX-M-producingisolatesselectedtorepresentallRAPDtypesandthoseforwhichtheORFwasfullysequenced

MIC(mg/L)

Species/isolateSpecimenAMKCTXCAZCROMEMblaCTX-MRAPDtypeaE.coli

E13secretion1161320.015CTX-M-14ET1E20woundsecretion1642640.015CTX-M-14ET1E21woundsecretion16641640.008CTX-M-14ET2E23urine412841280.015CTX-M-3ET3E26sputum212841280.015CTX-M-3ET2E32urine112842560.03CTX-M-14ET4E7woundsecretion2512645120.015CTX-M-82ET1E48blood4512322560.015CTX-M-15ET4E49endotrachealsecretions1644160.015CTX-M-14ET5E50sputum4256322560.015CTX-M-15ET4E51sputum.102412881280.03CTX-M-14ET4E52sputum2642160.015CTX-M-14ET1K.pneumoniae

K13sputum64648320.015CTX-M-14KT1K16sputum.1024256325120.015CTX-M-15KT2K17sputum.10246432320.015CTX-M-14KT3K22sputum.10242561282560.03CTX-M-15KT4K30sputum1281281281280.03CTX-M-3KT5K41sputum.10242562562560.03CTX-M-15KT4E.cloacae

C4sputum.1024256642560.03CTX-M-15CT3C8sputum.10241281281280.03CTX-M-3CT4C24urine.1024256165120.03CTX-M-14CT1C30sputum112841280.03CTX-M-3CT2

C.freundii

Q42wound.1024644640.03CTX-M-3NDE.aerogenes

Q2sputum13221280.015CTX-M-3NDP.stuartii

Q10earswab.1024642320.03CTX-M-14NDAMK,aamikacin;CAZ,ceftazidime;CTX,cefotaxime;CRO,ceftriaxone;MEM,meropenem;ND,notdone,insuf cientnumberofstrains.RAPDtypesaredesignatedasfollows.The rstletter‘E’,‘K’and‘C’representsstrainsofE.coli,K.pneumoniaeandE.cloacae,respectively.Thesecondletter‘T’plusdifferentArabicnumbersrepresentsdifferentRAPDtypesineachgroupofisolates.

strainsconsistingofsevenspecies:E.coli(31.3%,50/160),genewaspresentin109isolates.TheseisolateswereE.coliK.pneumoniae(42.7%,47/110),E.cloacae(31.6%,31/98),(48),K.pneumoniae(34),E.cloacae(18),C.freundii(5),

C.freundii(41.2%,7/17),E.aerogenes(12.5%,3/24),ProteusE.aerogenes(3)andP.stuartii(1).Thespecieswiththehighestvulgaris(21.4%,3/14)andP.stuartii(50%,1/2)(Table1).carriageratesofblaCTX-MwereE.coli(96%,48/50)andE.coli,K.pneumoniaeandE.cloacaewerethemostcommonK.pneumoniae(72%,34/47)(Table1).TofurthercharacterizeESBL-producingspeciesinChangsha,HunanProvince,amongthe109blaCTX-M-positiveisolates,thefull-lengthORFswhichK.pneumoniaeshowedthehighestESBLs’occurrence(1300bp)ofblaCTX-Mwereampli edusinggroup1-andrate.Amongatotalof425isolates,43.3%oftheisolatesfrom9-speci cprimers.AblaCTX-Mgenebelongingtogroup1wasintensivecareunit(ICU)patients(42/97)and30.5%fromdetectedin52isolates,including12E.coli,20K.pneumoniae,non-ICUpatients(100/328)wereESBL-positive.12E.cloacae,5C.freundiiand3E.aerogenes.Theremaining

57isolatesharbouredablaCTX-Mgroup9gene:36E.coli,14

GenotypingofblaK.pneumoniae,6E.cloacaeand1P.stuartii(Table1).These

CTX-MgenesbyPCRanddHPLCresultsshowedthatall109blaCTX-M-positiveisolatescarrieda

MultiplexPCRdesignedtodetectblaCTX-Mfromallgroupswasgroup1orgroup9blaCTX-MgeneinChangsha,Hunanperformedon142ESBL-producingisolates,andablaCTX-MProvince,China.

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Liuetal.

ThesubsequentdHPLCgenotypingofthe52group1isolatesStraintypingbyRAPDanalysis

showedthat32and20hadblaCTX-M-3andblaCTX-M-15pro les,

respectively.OneoftheisolateswithablaCTX-M-16pro leRAPDwasperformedonCTX-M-positiveisolatesofE.coliwhenselectedforfullsequencingrevealedanovelvariantandK.pneumoniae.Atotalof vedifferentRAPDpatterns,blaCTX-M-82.Speci cchromatographicsignatureswerealsodesignatedET1–5,wereidenti edinthe48E.colistrainswithobtainedforthe57group9isolates(52blaCTX-M-14andasinglebandvariationbetweenthem.AnexampleofRAPD5blaCTX-M-9).ThedistributionofblaCTX-Mamongthe109iso-typingresultsforE.coliisshowninFigure1.RAPDanalysislatesissummarizedinTable1.distinguished vetypes,designatedKT1–KT5,amongthe34

K.pneumoniaestrains(datanotshown).Inaddition,fourRAPD

subtypes(CT1–CT4)wereidenti edforE.cloacae.

Interestingly,someE.coli(4outof48)isolatesexhibitedthe

121313344sameRAPDpatterns,butcarrieddifferentblaCTX-Mgenotypes

RAPD patternTTTTTT2

TTTT51

TT

EEEEEEEEEEEE(datanotshown).Furthermore,twoE.colistrainsfromdifferent

Clone IdM202122232425262732333435

bphospitalsshowedidenticalRAPDpatterns,indicatingsome

3000clonalspread.TheseresultssuggestthattheblaCTX-Mtrans-

missionamongclinicalisolatesisproli c.

2000

1500

1200DNAsequencingofblaCTX-MandblaSHV

1037Twenty- veisolatesofthevariousspeciesfromthethreehospi-

talsthatrepresentedeachofthedifferentRAPDpro lesencoun-

500tered(Table2)wereselectedforDNAsequencing.Twenty- veofthe109blaCTX-MgenotypedusingdHPLCwereveri edby

DNAsequencing(Table2).OneblaCTX-M-15-genotypedE.coli

Figure1.RAPDpatternsforrepresentativeclonesoftheblaCTX-M-isolateproducedblaCTX-M-82,http://wendang.chazidian.comne1,100bpDNAladder;lanes2–13,isolateonenucleotideG!Cposition.Thisisanon-synonymousnumbersaredisplayedabovelanes.mutationleadingtoanaminoacidchange,Ala-40!

Pro.Table3.Characteristicsof19blaSHV-positiveESBLisolates

MIC(mg/L)

Species/isolateSpecimenAMKCTXCAZCROMEMblaSHVblaCTX-MK.pneumoniae

K20sputum.1024128642560.03SHV-28CTX-M-15K22sputum.10242561282560.03SHV-28CTX-M-15K23sputum.10242561282560.03SHV-28CTX-M-15K28CSF.102451212810240.03SHV-28CTX-M-15K39sputum.1024256325120.03SHV-28CTX-M-15K29sputum.10245121285120.03SHV-28CTX-M-15K31sputum.10245121282560.03SHV-28CTX-M-15K32throatswab10246416320.015SHV-11NDK3sputum10246441280.015SHV-28ND

K4sputum.10243281280.03SHV-28CTX-M-14K8sputum5121632160.015SHV-5NDK26sputum.1024643240.015SHV-12ND

K27sputum.10241632320.015SHV-12CTX-M-14E.cloacae

C5sputum256512645120.03SHV-12NDC7sputum256512645120.03SHV-12ND

C8sputum.1024128641280.03SHV-12CTX-M-3C9pus464321280.03SHV-12CTX-M-3C17sputum116128160.015SHV-12ND

C.freundii

Q11sputum4644640.03SHV-11CTX-M-3AMK,amikacin;CAZ,ceftazidime;CTX,cefotaxime;CRO,ceftriaxone;MEM,meropenem;ND,notdetected.

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NovelCTX-Mb-lactamaseinChangsha,SouthernChina

AlthoughthedHPLCtypingmethodthatdetectsthesequenceofresistancetob-lactamsinEnterobacteriaceaeinallregionsvariationswithinthe200–300bpfragmentsofblaCTX-Mana-ofChinaandamajorthreattopublichealth,includingthelysedenablesthedifferentiationofthemajorityofcommoncommunity.

CTX-Mgenotypes,theAla-40!PromutationisbeyondtheThediversityofblaCTX-MgenotypesexhibitsaregionalregionthatisselectedfordHPLCanalysis,thuswewereunablepatterninChina.OnestudyshowedthatblaCTX-M-14isthemosttodistinguishblaCTX-M-82fromblaCTX-M-15inourdHPLCcommongenotypefrom15isolateswithESBLsinGuangzhou,analysissincetheyhaveidenticalsequencesinthefollowedbyblaCTX-M-9.8OtherreportsfromlargersamplepoolsPCRfragmentsselectedfordHPLCanalysis(datanotshown).insixprovincesand/orcitiessuggestthatblaCTX-M-14,ThegenotypespredictedbydHPLCforthreerepresentativeiso-blaCTX-M-3,blaCTX-M-24(closelyrelatedtoblaCTX-M-14)andlatesofC.freundii,E.aerogenesandP.stuartiiwerealsoveri-blaCTX-M-22arethemostcommongenotypes.12,13,20The edbyDNAsequencing(Table2).Nineteenofthe142genotypeblaCTX-M-15wasonlyfoundasaveryraregenotypeESBL-positiveisolateswerefoundtocarryblaSHVgenesbybyYuetal.12(4/399isolates)andinHongKong(3/42PCR[K.pneumoniae(13),E.cloacae(5)andC.freundii(1)],E.coliisolates).12,30WefoundthatblaCTX-M-14(47.7%)isthebutnoE.coliisolateswerepositive.WefurtherdeterminedthemostcommongenotypeinHunanProvince,butsurprisingly,genotypesofthese19blaSHV-positiveisolatesbyDNAsequen-blaCTX-M-15isthethirdmostprevalentgenotypeofCTX-Mwithcing,andfoundfourgenotypesofblaSHV(Table3).asubstantialincidenceof17.4%.WedetectedblaCTX-M-15with

almostequalfrequencyinE.coliandK.pneumoniae,apattern

re ectedinotherpartsoftheworld(Table2).31Thisstudyalso

Discussionidenti edanewblaCTX-M-15variant,blaCTX-M-82,withasingle

nucleotidemutationresultingintheaminoacidsequencechange

Thisstudy,incommonwithothers,foundahighincidenceAla-40!Pro.GenotypeblaCTX-M-15isdistinguishedfrom(33.4%)ofESBLs,predominatelyoftheCTX-M-type,carriedblaCTX-M-3bythesubstitutionofAsp-240!Gly,whichconfersbyisolatesofEnterobacteriaceaeinalargepreviouslyunstudiedasigni cantincreaseinactivityagainstceftazidime.32TheMICareaofCentralChina.TheearlierAsia-Paci cregionalsurveil-datashowedthatblaCTX-M-82iscapableofef cienthydrolysisoflancedata(1998–2002)fromBeijingandGuangzhoudemon-ceftazidime(Table2),mostlikelyduetotheretentionofstratedthattheincidenceofESBL-producingisolateswasAsp-240!Gly.

13%to35%inE.coliand30%inK.pneumoniae.4,6OnecharacteristicofCTX-M-typeESBLsisthatthehostESBL-producingEnterobacteriaceaearecommoninthesmallplasmids

numberofstudiesofChinesehospital-derivedisolates.4,8,9,2032arevariably‘mobile’amongdifferentgenerabyconju-gation.MostCTX-MESBLsarefoundpredominantlyinTheprevalenceinanationalsurveyofcommunityisolatesinvol-E.coli,Klebsiellaspp.andE.cloacae,andoccasionallyinotherving1615isolatesfromsevenmajorcitiesthroughoutChinageneraofEnterobacteriaceae.31Here,wereportthe rstdetec-alsorevealedasubstantialincidenceofESBLs.21OurcurrenttionofblaCTX-M-14inP.stuartii,agenusofopportunisticallystudyalsofoundaveryhighincidenceofESBLproductioninpathogenicbacteria,representingyetfurtherdisseminationofE.coli,supportingtheimportanceofcommunityisolatesincon-CTX-MESBLs.

tributingtothehighratesofESBLinChina,asituationsimilarInsummary,theblaCTX-MgenotypewasfoundtobethetothatexistingintheUKandothercountries.3However,thedominantESBL,with17.4%carryingCTX-M-15,agenotypedistributionofdifferentgenotypesofESBLsinChinaispoorlypreviouslyreportedtobeveryrareinChina.CTX-M-15hasunderstood.EarlyreportsofgenotypesofESBLgenesfromspreadfromtheIndiansubcontinenttoEurope,theMiddleEastChinaweresporadicandinvolvedSHV-2,aswasbeingreportedandNorthAmerica.31Our ndingssuggestthatCTX-M-15mayfromtherestofAsia.22Subsequently,SHV-5andSHV-12werebesettoemergeasamajorgenotypeinChina,theworld’smostthemostfrequentlyreportedESBLgenotypesfromAsiainthepopulouscountry.

1990s.5ThiswasparticularlytrueofTaiwanwhenSHV-5was

reportedin1997followedbythe–25emergenceofasingleaminoacidvariant,SHV-12,in1998.23SHV-5achievedworldwide

distributionearlyinthe1990spriortotheemergenceofCTX-MFunding

ESBLs,beingparticularlycommoninKlebsiellaspp.andyetThisworkwassupportedbygrantB2004-025(W.L.)fromtherareinE.coli.24–26Our ndingthatnoE.coliisolatescarriedHealthBureauofHunanProvinceandtheStartResearchFundblaSHVisconsistentwiththesehistorical ndingsandacontem-forReturnedOverseasResearchersGrant(W.L.)fromXiangYaporarysurveyofWesternChina,inwhichonly8outof325Hospital,CentralSouthUniversity.

E.colicarriedblaSHV.27The rstrecognitionoftheimportance

ofCTX-MESBLscamewiththe rstdescriptionofCTX-M-13

and-14inGuangzhouinisolatescollectedin1997–98.8

Similarly,13outof58E.coliisolatesand41outof81Transparencydeclarations

K.pneumoniaeisolatesfromShanghaiHuashauHospitalpro-

ducedCTX-MESBLs.28Thepre-eminenceofCTX-MESBLsNonetodeclare.

wasreportedbyMundayetal.13andcon rmedinamorerecent

comprehensivestudy.12Regionalvariationscanbeexpectedas

alimitedsurveyinthecoastalcityofShantou,GuandongReferences

Province,29showedthatSHV-typeESBLswerethemostcommon.Ourcurrentstudy,togetherwiththeseprevious1.CantonR,NovaisA,ValverdeAetal.Prevalenceandspreadof

extended-spectrumb-lactamase-producingEnterobacteriaceaein

reports,showsthatCTX-MESBLshavebecomethemaincauseEurope.ClinMicrobiolInfect2008;14Suppl1:144–53.

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