论文部分内容阅读
目的 :了解革兰阴性菌产CTX M 3型超广谱β内酰胺酶 (ESBLs)的分子传播机制 ,为临床防治提供依据。 方法 :收集革兰阴性菌医院感染无重复株共 378株 ,进行药敏试验和ESBLs产酶株的检测 ;肠杆菌科基因组内重复一致序列 聚合酶链反应 (ERIC PCR)进行克隆株的DNA分型 ;质粒转移实验、质粒谱及耐药质粒酶切指纹分析、等电聚焦电泳、PCR扩增TEM、CTX M基因及其克隆测序进行ESBLs基因分型和质粒定位。结果 :ESBLs的检出率为 16 .9% (6 4 / 378) ,其中CTX M 3型产酶株占 2 0 .3% (13/ 6 4 ) ;CTX M 3基因定位在 6 6kb和 75kb 2种接合性质粒上 ,6 6kb的质粒同时携带TEM 1基因 ;从不同来源的CTX M 3产酶株中可以分离到同种耐药质粒 ,染色体DNA同源性分析显示其为不同的克隆株。结论 :CTX M 3型ESBLs产酶株的传播机制以质粒介导为主 ,并可能存在局部携带CTX M 3基因耐药质粒的爆发
OBJECTIVE: To understand the molecular transmission mechanism of gram-negative bacteria CTX M 3 ESBLs and provide the basis for clinical prevention and treatment. Methods: A total of 378 strains of non-repetitive strains of nosocomial infections were collected from patients with Gram-negative bacteria. Susceptibility tests and ESBLs-producing strains were performed. DNA sequences of cloned strains were determined by repeated sequence-based polymerase chain reaction (ERIC PCR) in the genome of Enterobacteriaceae Type plasmids, plasmid transfer experiments, plasmid spectrum and enzyme digestion fingerprinting, isoelectric focusing electrophoresis, PCR amplification of TEM, CTX M gene and its cloning and sequencing for ESBLs genotyping and plasmid mapping. Results: The detection rate of ESBLs was 16.9% (6 4/378), of which CTX M 3 type strains accounted for 20.3% (13/64). CTX M 3 gene was located at 6 6kb and 75kb Two kinds of junctional plasmids, 6 6 kb plasmids simultaneously carry the TEM 1 gene; from different sources of CTX M 3 enzyme isolates can be isolated from the same drug-resistant plasmids, chromosome DNA homology analysis showed that it was different clonal strains . CONCLUSION: The transmission mechanism of CTX M 3 ESBLs-producing strains is mainly plasmid-mediated, and there may be some local outbreaks of CTX M 3 gene-resistant plasmids