Abstract: ObjectiveTo understand the current resistance and genotype of extended-spectrum beta-lactamase(ESBLs)and AmpC-producing Escherichia coli and Klebsiella pneumoniae and to perform homology analysis.MethodsAntibiotic susceptibility test was performed by Kirby-Bauer method.ESBLs-producing isolates were confirmed by double disk diffusion confirming test.AmpCβ-lactamases were detected by the three-dimensional test.PCR was performed to understand the genotype of ESBLs and AmpCβ-lactamases.DNA fingerprints of isolates were constructed by enterobacterial repetitive intergenic consensus PCR(ERIC-PCR).ResultsEnzyme-producing strains were more sensitive to Imipenem, Meropenem,Amikacin and Cefepime but resistant to 13 other antimicrobials.75.2%,35.8%,11.0%,4.6%,0.9%,4.6% and 4.6% of the isolates was found carried blaCTX-M,bla TEM,blaOXA,blaSHV,blaV EB-1,CIT and DHA gene,respectively,by PCR.In addition,46.8% of all strains carried more than oneβ-lactamase gene.The genotype of E.coli and K.pneu was divided into 42 and 22 clusters by ERIC-PCR.ConclusionAttention should be paid to multidrug resistance of enzyme-producing E.coli and K.pneu.BlaCTX-M and CIT,DHA were the predominant genotypes in ESBLs-producing and AmpC-producing strains.The prevalence of multidrug resistance clone in the clinic reminded us to control nosocomial infection effectively.