【摘要】 目的探讨产志贺毒素大肠埃希菌产超广谱β-内酰胺酶(extended spectrum β-lactamases,ESBLs)类型及耐药机制。方法采用纸片琼脂扩散法筛选36株产志贺毒素大肠埃希菌产ESBLs菌株,接合传递实验、质粒谱分析、PCR检测耐药基因和DNA序列分析产ESBLs菌株的表型和基因型。结果双纸片扩散法证明有2株产志贺毒素大肠埃希菌产ESBLs,美国株E.coli 5nonO157:H7和中国株E.coli 27 O157:H7对头孢他啶等第三、第四代头孢菌素和氨基糖苷类抗生素耐药,并能通过5.8kb的质粒传递给受体菌。PCR检测含有blaTEM基因。DNA同源分析表明861bp的blaTEMDNA片段与blaTEM-IDNA片段同源。结论产志贺毒素大肠埃希菌美国株和中国株产生相同类型的ESBLs,表现出对第三、第四代β-内酰胺酶类抗生素耐药。更多还原

【Abstract】 Objective To investigate the genotype and antimicrobial mechanism of extended spectrum beta-lactamases among Shiga toxin-producing E.coli(STEC).Methods Antibiotic susceptibility was tested by the disk diffusion to screen out the strains that produced the ESBLs;conjugative transfer test,plasmid profile,PCR and DNA sequencing were used to detect the phenotype or genotype of STEC.Results Of 36 samples,there two isolates producing ESBL,E.coli 5 non O157:H7 from American and E.coli 27 O157:H7 from China,and they both were resistant to aminoglycosides and the third generation cephalosporins such as ceftazidime.Double disk test showed that they produced ESBL and the resistant phenotype were transferred to the recipient by a conjugative plasmid of 5.8kb.TEM β-lactamases-encoding gene was identified by PCR and the 861bp fragment of blaTEM DNA had a high homology with that of blaTEM-1.Conclusions STEC isolates from America and China carry the same genotype ESBLs,which may be the major resistance mechanism against the third and fourth generation cephalosporins.更多还原