Objective To elucidate the influence of quinolone resistance gene, mediated by plasmids, on the characteristics and mechanism of drug resistance in Kscherichia coliCE. Coli) producing extended spectrum |3-lactamase(ESBLs). Methods The susceptibility of 59 strains of K. Coli to 11 kinds of antibiotics was detected by disc diffusion(K-B method). Drug resistance genes, including qnrA, qnrB,qnrS,qnrC, aac(6 )- I b and qepA were identified by polymerase chain reaction(PCR) and confirmed by sequencing and BLAST analysis. Results Among the 59 strains of E. Coli, 5. L%(3/59) were positive with qnrB gene, 37. 3% (22/59) with aac(6 )- I b. The qnrB genes were confirmed to be qnrB4 , aac(6 )- I b gene were confirmed to be aac(6 )- I b-cr type for 1 strain and aac(6 )- I b-suzhou type for 3 strains, by sequncing. Conclusion The mechanisms of this multi-drug resistance in E. Coli were related to the production of ESBLs and the exist of qnrB4 , aac(6 )- I b and aac(6 )- I b -cr type genes. This study was the first report that aac(6 )- I b-suzhou type gene could be detected in E. Coli.%目的 了解质粒介导的喹诺酮耐药基因在产超广谱β-内酰胺酶(ELBLs)大肠埃希菌的耐药特点及耐药机制.方法 用纸片扩散法检测59株产ESBLs的大肠埃希菌对11种抗生素的敏感性,采用聚合酶链反应(PCR)检测qnrA、qnrB和qnrS、qnrC、aac(6′)-Ⅰb及qepA基因,并对扩增阳性基因qnrB、aac(6′)-Ⅰb测序后进行BLAST比对分析.结果 59株产超广谱β-内酰胺酶的大肠埃希菌共检出qnrB 3株(5.1%)、aac(6′)-Ⅰb 22株(37.3%),qnrB经测序证实为qnrB4,aac(6′)-Ⅰb经测序证实为aac(6′)-Ⅰb-cr 型1株(1.7%)和aac(6′)-Ⅰb-suzhou型3株(5.1%).结论 大肠埃希菌多重耐药机制与产超广谱β-内酰胺酶及携带qnrB4、aac(6′)-Ⅰb和aac(6′)-Ⅰb-cr 基因有关;本研究是国内首次从大肠埃希菌中检出aac(6′)-Ⅰb-suzhou型基因.
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