同时携带blaNDM-1和blaKPC-2基因的一株阴沟肠杆菌检测及临床治疗分析

Detection of a strain of Enterobacter cloacae co-carrying NDM-1 and KPC-2 genes and its drug resistance

目的 探讨一株同时携带NDM-1和KPC-2基因的阴沟肠杆菌的耐药机制及其分子传播机制.方法 菌株分离自2013年3月徐州医科大学附属医院的一例慢性阻塞性肺疾病患者的痰液.采用改良Hodge试验和金属酶初筛试验检测菌株是否产碳青霉烯酶;采用聚合酶链反应（PCR）检测blaMUS-1、blaVIM-1、blaVIM-2、blaIMP、blaKPC-2、blaNDM-1、blaOXA-48和blaGES等碳青霉烯酶基因,并对阳性片段进行基因测序;通过质粒接合、转化实验证实耐药基因是否由质粒介导,采用琼脂稀释法检测菌株对常用抗菌药物的敏感性.结果 阴沟肠杆菌改良Hodge试验和金属酶抑制试验均为阳性,PCR产物测序证实该菌株携带NDM-1和KPC-2基因,其中NDM-1基因携带在54×10^3bp的IncX型质粒上,KPC-2基因携带在42×10^3bp未分型质粒上.药敏试验发现该菌株仅对四环素（2μg/Ml）和替加环素（1μg/Ml）敏感.患者经替加环素联合哌拉西林/他唑巴坦治疗后症状好转.结论 阴沟肠杆菌携带的NDM-1和KPC-2基因可由质粒介导传播,临床上应结合药敏试验治疗该菌引起的感染.

Objective To identify the drug resistance-related genes in a clinically isolated strain of Enterobacter cloacae.Methods A strain of Enterobacter cloacae was isolated from sputum of a patient with chronic obstructive pulmonary disease from the Affiliated Hospital of Xuzhou Medical University in March 2013.Modified Hodge test and metal enzyme inhibition test were performed for drug-resistant phenotype screening.Carbapenemase genes blaMUS-1, blaVIM-1, blaVIM-2, blaIMP, blaKPC-2, blaNDM-1, blaOXA-48 and blaGESwere amplified by polymerase chain reaction （PCR）, and the positive products were sequenced and analyzed.Plasmid conjugation and transformation experiments were used to confirm that the resistance gene mediated by plasmids.Agar dilution method was used for antibiotic susceptibility test.Results Both modified Hodge test and metal enzyme inhibition test were positive in this strain of Enterobacter cloacae.blaNDM-1 gene and blaKPC-2 gene were detected by PCR, and further confirmed by sequencing.blaNDM-1 gene was carried by IncX plasmid with 54×10^3 bp, KPC-2 gene was carried by untyping plasmid with 42×10^3 bp.The strain was only sensitive to tetracycline （MIC=2 μg/mL） and tigecycline （MIC=1 μg/mL）.The symptoms were improved after the patient was treated by tigecycline combined with Piperacillin/Tazobactam.Conclusion blaNDM-1 and blaKPC-2 genes in Enterobacter cloacae can be mediated by plasmids, and appropriate therapy for its infection should be based on the result of antibiotic susceptibility test.