洛菲不动杆菌株多药耐药NDM-1基因的鉴定

摘要

目的 检测并鉴定洛菲不动杆菌多药耐药菌株中新德里金属β内酰胺酶新德里金属β-内酰胺酶(new delhi metallo-β-lactamase,NDM)-1基因表达.方法 抗菌药物最小抑菌浓度(minimal inhibitory,MIC)筛选多药耐药菌株,PCR方法鉴定候选菌株中金属β-内酰胺酶基因,经PCR测序、亚胺培南和亚胺培南+ EDTA复合纸片的双纸片协同法鉴定金属β内酰胺酶表型,并采取接合实验和全基因组测序来确定NDM-1.结果 自458株金属β-内酰胺酶阳性菌株中分离出一株洛菲不动杆菌,并检出NDM-1基因,此菌株并不合并存在VIM和IMP金属β-内酰胺酶基因阳性表达.该菌株对所有的β-内酰胺类抗生素均不敏感,而对阿米卡星、多粘菌素、替加环素敏感.全基因组测序确定其位于一个48.9 kb的质粒上,目标带纯化后克隆、扩增的目标序列与文献报道的NDM-1基因同源性为100%.结论 NDM-1是一种针对碳青霉烯类抗生素耐药的新机制,临床工作者应关注其对洛菲不动杆菌多药耐药的影响.%Objective To detect and identify multidrug resistance gene of new delhi metallo - beta - lactamase (NDM) 1 in a Acinetobacter lwoffii isolate. Methods Tigecycline MICs were used to screen the multidrug isolate while PCR were used to detect the expression of metallo - β - lactamases among the isolates. Species identification and phenotype analysis were carried out by PCR sequencing, Imipenem and EDTA double disc synergy test, respectively. Genetic location of NDM - 1 was determined by Conjugation experiments and whole genome sequencing. Results One strain of A. lwoffii with positive expression of NDM - 1 was isolated from 458 carbapenem - non - susceptible cases, which without VIM and IMP genes positive expression concomitantly. This strain with expression of NDM - 1 gene resist to all β - lactam antibiotics while retaining the susceptibility to amikacin, colistin and tigecycline. Sequencing showed 100% identities with previously reported genes, and whole genome sequencing conformed NDM - 1 gene located on a 48. 9 kb plasmid. Conclusions NDM - 1, as a naive mechanism, involved in resistance to carbopenems. The clinical physicians should pay more attention on impact of multidrug resistance of Acinetobacter lwoffii due to the expression of NDM - 1.