大肠埃希菌及肺炎克雷伯菌耐药基因分析

目的了解现阶段产超广谱β-内酰胺酶(ESBLs)和头孢菌素酶(AmpC酶)的大肠埃希菌和肺炎克雷伯菌的耐药特性及基因型分布,并作同源性分析。方法纸片扩散法(K-B)检测细菌对抗生素的敏感性;双纸片扩散确诊试验检测ESBLs;三维试验检测AmpC酶;聚合酶链反应(PCR)检测基因型;肠杆菌科基因间重复一致序列(ERIC)PCR作分子生物学分型。结果产酶菌株对亚胺培南、美罗培南、阿米卡星、头孢吡肟耐药性较低,对其他13种抗生素耐药性较高。在PCR扩增试验中,blaCTX-M、blaTEM、blaOXA、blaSHV、blaVEB-1型ESBLs基因及CIT、DHA型AmpC酶基因阳性率分别为75.2%,35.8%,11.0%,4.6%,0.9%,4.6%和4.6%;有46.8%的菌株同时携带多种耐药基因。用ERIC-PCR法将所检测的大肠埃希菌和肺炎克雷伯菌分成42型和22型。结论产ESBLs和AmpC酶大肠埃希菌和肺炎克雷伯菌的耐多药性值得关注;ESBLs及AmpC酶分别以CTX-M型及CIT型和DHA型为主;产酶菌株有散在的克隆流行,应注意监控,防止耐药菌株引起院内感染。

Analysis of antimicrobial resistance genes of Escherichia coli and Klebsiella pneumoniae

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.