1株多黏菌素和替加环素耐药的肺炎克雷伯菌基因组特征分析

Genomic characteristics analysis of a colistin andtigecycline-resistant Klebsiella pneumoniae

目的本研究对1株分离自2009年的多粘菌素和替加环素耐药菌进行分析,探讨耐药质粒结构及基因遗传环境,为多药耐药菌的防控提供依据。方法对菌株进行多黏菌素和替加环素耐药基因筛查,获得1株mcr和tet(M)阳性菌株(编号为GZ12244)。使用vitek-2进行菌种鉴定,采用微量肉汤稀释法进行药敏试验,运用全基因组测序和生物信息学手段对其分子分型、耐药基因、插入序列、质粒结构、基因遗传背景进行分析。结果菌株GZ12244为肺炎克雷伯菌,对多黏菌素B、替加环素、头孢呋辛、四环素等耐药,并携带mcr-1、tet(M)等多种耐药相关基因,且部分具有抗生素外排和抗生素靶点改变作用的耐药基因存在氨基酸取代突变。mcr-1与tet(M)共存于一个质粒,mcr-1侧翼包括两个插入序列ISApl1,tet(M)基因上下游存在IS15、IS1D、ISEc63等插入序列。结论肺炎克雷伯菌GZ12244为多重耐药菌株,耐药基因存在于质粒中,上下游的移动元件使耐药基因存在潜在传播的可能。

Objective In this study,a strain of colistin and tigecycline-resistant bacteria isolated in 2009 was analyzed,and the structure of drug-resistant plasmid and genetic environment were discussed,so as to provide basis for the prevention and control of multidrug-resistant bacteria.Methods A strain(GZ12244)with positive mcr and tet(M)was obtained by screening colistin and tigecycline resistance genes.Vitek-2 was used for strain identification,and the drug sensitivity test was carried out by broth dilution method.The molecular typing,drug resistance genes,insertion sequences,plasmid structure and genetic background were analyzed by genome-wide sequencing and bioinformatics.Results Strain GZ12244 is Klebsiella pneumoniae,which is resistant to colistin B,tigecycline,cefuroxime and tetracycline,and carries a variety of drug-resistant related genes such as mcr-1 and tet(M),and some of the drug-resistant genes with antibiotic efflux and antibiotic target change have amino acid substitution mutations.Mcr-1 and tet(M)coexist in a plasmid,and mcr-1 flanked by two insertion sequences ISApl1.There are insertion sequences such as IS15,IS1D and ISEc63 in the upstream and downstream of tet(M)gene.Conclusion Klebsiella pneumoniae GZ12244 is a multidrug-resistant strain.The drug-resistant gene exists in plasmid,and the mobile elements in upstream and downstream may spread the drug-resistant gene.