中文摘要：

目的检测本院分离的对头孢西丁耐药的肺炎克雷伯菌分子生物学特点。方法以本院临床分离的一株对头孢西丁耐药的肺炎克雷伯菌为研究对象,采用聚合酶链反应（PCR）,分别用特异性引物进行AmpC酶全编码基因及AmpR调节基因的扩增,并且构建pET-22b（＋）-AmpR的表达质粒和表达菌株。结果 PCR分别扩增出约1 140 bp和876 bpDNA片段,经测序证实,1 140 bp的序列与摩根摩根菌染色体上AmpC酶全长编码基因同源性达99.1%,876 bp的序列与摩根摩根菌染色体上AmpR基因同源性达98%。重组质粒pET-22b（＋）-AmpR转化E.coli BL21（DE3）后表达融合蛋白的相对分子量为34 kD,与预期分子量相符。结论对头孢西丁耐药的肺炎克雷伯菌质粒上存在调控因子AmpR,能够表达AmpR蛋白,诱导性耐药机制同样存在于质粒介导的AmpCβ-内酰胺酶中。

英文摘要：

Objective To investigate the molecular biology of one cefoxitin-resistant Klebsiella pneumoniae strain.Methods AmpC and AmpR genes of one cefoxitin-resistant Klebsiella pneumoniae were analyzed by PCR,and then the pET22b（＋）-AmpR expression plasmid and expression strain were constructed.Results A 1 140 bp segment of AmpC and a 876 bp segment of AmpR were cloned.These sequences showed that recombinant AmpC and AmpR genes were highly identical to those of Morganella morganii.Fusion protein about 34 kD was expressed by E.coli BL21（DE3） transfected with recombinant plasmid pET22b（＋）-AmpR.Conclusion There are regulator AmpR genes in plasmid of cefoxitin-resistant Klebsiella pneumoniae isolates.AmpR genes express AmpR fusion protein.Induced resistance mechanism is also found in plasmid-mediated AmpC β-lactamase.