阴沟肠杆菌产超广谱β-内酰胺酶与AmpC酶基因及其流行病学研究

目的分析医院2008-2010年临床分离阴沟肠杆菌产ESBLs和AmpC酶及其对抗菌药物的耐药性,并了解其耐药基因的传播机制。方法采用改良三维试验筛选AmpC酶,双纸片扩散法检测ESBLs,聚合酶链反应(PCR)检测ESBLs和AmpC酶的基因,采用微量肉汤稀释法分析细菌耐药性,质粒接合试验分析耐药基因的传播特点。结果同时产ESBLs和AmpC酶菌株对三、四代头孢菌素及含酶抑制剂药物的耐药率均>50.0%;45株改良三维试验阳性,14株ESBLs确证试验阳性,ESBLs和AmpC酶的基因阳性者分别为25、38株,分别以TEM-1型、MIR-3型为主,其次为CTX-M-3、DHA-1型,SHV-11型广谱β-内酰胺酶2株,未检测到CIT、MOX、FOX、ACC型AmpC酶的基因,5株接合试验成功。结论阴沟肠杆菌主要携带TEM-1型广谱β-内酰胺酶、CTX-M-3型ESBLs和MIR-3型AmpC酶,耐药现状严重,应采取积极有效的措施预防多药耐药菌株的播散与暴发流行。

Research on ESBLs and AmpC beta-lactamase genes in Enterobacter cloacae and their epidemiology

OBJECTIVE To investigate the distribution and drug resistance of AmpC beta-lactamases and ESBLs-producing Enterobacter cloacae from 2008 to 2010.METHODS The modified three dimensional test was used to detect AmpC beta-lactamases.ESBLs were detected by using disk diffusion phenotypic confirmatory test.And the polymerase chain reaction(PCR) was adopted to test the genotype of AmpC beta-lactamases and ESBLs.Broth dilution method was employed to analyze the bacterial resistance,and bonding plasmid test was carried out to analyze the spread of resistant genes.RESULTS The drug resistant rates of ESBLs and AmpC-producing isolates to the third,fourth generation of cephalosporins,or the antibiotics containing enzyme inhibitor were higher than 50.0%;there were 45 AmpC-producing strains by the method of modified three-dimensional experiment and 14 ESBLs-producing were identified via confirmatory test;there were 25 ESBLs-positive strains and 38 AmpC-positive strains,TEM-1 as well as MIR-3 was the main genotype,followed by CTX-M-3 and DHA-1,there were 2 SHV-11 ESBLs-producing isolates,no strains that produced AmpC genotypes of CIT,MOX,FOX and ACC were detected,five isolates were successed in conjugation experiments.CONCLUSION Drug resistance of E.cloacae which mainly carries TEM-1 ESBLs and MIR-3 AmpC beta-lactamase is severe.It is necessary to take effective measures to prevent the dissemination and prevalence of multidrug-resistant isolates.