耐碳青霉烯类阴沟肠杆菌复合群的耐药谱和分子流行病学特征

Drug resistance spectrum and molecular epidemiological characteristics of carbapenem-resistant Enterobacter cloacae

目的分析碳青霉烯类耐药阴沟肠杆菌复合群(CRECL)的耐药谱和分子流行病学特征,指导临床抗感染治疗.方法收集丽水市中心医院2012-2022年分离的非重复CRECL菌株,采用VITEK MS全自动快速微生物质谱检测系统进行菌种鉴定,以微量肉汤稀释法检测最小抑菌浓度值(MIC),利用聚合酶链式反应(PCR)扩增bla_(KPC)、bla_(NDM)、bla_(IMP)、bla_(VIM)、bla_(OXA-48)等碳青霉烯酶基因并测序确认.通过接合实验和复制起始子扩增检测分析耐药基因定位及质粒类型;采用多位点序列分析(MLST)确定各菌株ST型,并结合BV-BRC数据库来源的CRECL构建系统发育树和最小生成树,分析CRECL的分子流行病学特征.结果共收集非重复CRECL菌株22株,分布于14个临床科室,分属于16个ST型;22株菌对美罗培南、头孢他啶、头孢噻肟均100.00%耐药,对左氧氟沙星、氨曲南和多黏菌素的耐药率分别是81.81%、63.63%和31.81%,仅对替加环素100.00%敏感;经测序确认,17株CRECL菌株携带bla_(NDM)基因,占77.27%,且其中15株位于IncX3型质粒,2株位于IncFⅡ型质粒;根据系统发育树和最小生成树分析,CRECL呈散发分布,未发现优势克隆群.结论CRECL呈散发流行,医院分离菌株主要携带bla_(NDM)基因,IncX3型质粒是介导该基因转移的主要原因.

OBJECTIVE To analyze the drug resistance spectrum and molecular epidemiological characteristics of carbapenem-resistant Enterobacter cloacae(CRECL),in order to guide clinical anti-infection treatment.METHODS Non-duplicate CRECL strains isolated from Lishui Central Hospital during 2012 and 2022 were collected and identified by VITEK MS.The minimal inhibitory concentrations(MICs)were detected by broth microdilution method.Carbapenase genes such as bla_(KPC),bla_(NDM),bla_(IMP),bla_(VIM) and bla_(OXA-48) were amplified by polymerase chain reaction(PCR)assay and confirmed by sequencing.The locations of drug resistance genes and plasmid types were analyzed by conjugation experiments and replication initiator amplification assay.The ST types of strains were determined by multilo-cus sequence typing(MLST).The phylogenetic tree and the minimum spanning tree were constructed combined with the sequences of CRECL from BV-BRC database,and to analyze the molecular epidemiological characteristics of CRECL.RESULTS A total of 22 non-duplicate CRECL strains were collected from 14 clinical departments,and classified into 16 STs.Drug resistant rates of all strains to meropenem,ceftazidime and cefotaxime were 100.00%.Rates of drug resistance to levofloxacin,amtronam and polymyxin were 81.81%,63.63%and 31.81%,respectively,and drug sensitive rate to tigacycline was 100.00%.By sequencing,we confirmed that 17 CRECL strains carried bla_(NDM) gene,accounting for 77.27%,15 of which were located in IncX3 plasmid and 2 were located in IncFⅡplas-mid.According to phylogenetic tree and the minimum spanning tree analysis,CRECL strains showed sporadic dis-tribution and no dominant clone group was found.CONCLUSION CRECL is sporadic,and hospital isolated strains mainly carry bla_(NDM) gene.IncX3 plasmid is the main reason for mediating the transfer of this gene.