不同感染途径CREC分子分型特点及耐药分析

Molecular typing and drug resistance analysis of carbapenem-resistant Escherichia coli in different infections

目的探讨我院不同感染途径耐碳青霉烯大肠埃希菌(carbapenem-resistant Escherichia coli,CREC)分子分型特点以及耐药情况,为临床预防和治疗提供依据。方法收集我院2017年9月-2018年12月间不同感染途径获得的CREC共14株;菌株鉴定及药敏采用VITEK2-Compact全自动细菌鉴定/药敏系统,联合纸片扩散法(KB法)、E-Test方法进行药敏试验;用PCR技术分别对碳青霉烯类耐药基因(blaKPC、blaNDM、blaIMP、blaVIM和blaOXA-48)、超广谱β-内酰胺酶基因(blaSHV、blaTEM、blaCTX和blaOXA-1、AmpC酶耐药基因(blaFOX、blaMOX和blaDHA)、膜孔蛋白基因(ompk35和ompk36)进行检测,同时进行质粒接合试验,掌握我院CREC耐药基因分布及流行情况;采用PFGE对14株不同感染途径CREC进行同源性分析,分析我院CREC分子流行特点。结果临床资料:14株CREC主要来自重症医学科,占57.14%(8/14);痰标本检出5株,尿标本检出4株,血液标本检出2株,灌洗液、脑脊液、导管尖端各检出1株。耐药基因检出情况:14株CREC有12株携带blaNDM-5、1株携带blaKPC-2和1株携带blaNDM-1;我院CREC通常携带blaNDM-5以及ESBLs耐药基因,并伴有ompk36基因的缺失。接合试验结果:仅1株CREC接合试验成功。PFGE分型结果:14株CREC分为4个PFGE分型,其中PT03为优势型别,包含11株菌。菌株耐药情况:CREC耐药情况十分严重,对单环β-内酰胺类、头孢类、左氧氟沙星、碳青霉烯类药物均表现耐药;而对氨基糖苷类以及磺胺类药物也达到92.86%的耐药率;对替加环素和多黏菌素均表现为敏感。结论我院CREC主要来自呼吸道标本,且存在克隆的流行,其优势型别的菌株多携带blaNDM-5以及ESBLs耐药基因,并伴有Ompk36基因的缺失,且表现对多种抗生素呈高度耐药,提示我们应加大对CREC的管控,需密切监测并采取控制措施,阻断CREC在院内的传播和暴发。

Objective To investigate molecular typing and drug resistance analysis of carbapenem-resistant Escherichia coli(CREC)in our hospital in order to provide evidence for clinical prevention and treatment.Methods From September 2017 to December 2018,14 CREC strains obtained from different routes of infections in our hospital were collected.The strain identification and drug sensitivity were tested by VITEK 2-compact automatic bacterial identification/drug sensitivity system,combined with the disk diffusion method(K-B method)and the E-test method.Carbapenem resistance gene(blaKPC,blaNDM,blaIMP,blaVIM,and blaOXA-48)extended spectrumβ-lactamase gene(blaSHV,blaTEM,blaCTX,blaOXA-1),AmpC enzyme gene(blaFOX,blaMOX and blaDHA),and membrane pore protein gene(ompk35 and ompk36)were detected by PCR.At the same time,they were tested by plasmid conjugation experiments,in order to understand the distribution and prevalence of drug-resistant genes of CREC in our hospital.The homology analysis of 14 different infection pathways of CREC was carried out by PFGE,and the epidemiological characteristics of CREC in our hospital were analyzed.Results Clinical data:14 CREC were mainly from the intensive care unit,accounting for 57.14%(8/14).5 of 14 strain were detected in sputum,4 in urine,2 in blood,1 in lavage fluid,cerebrospinal fluid,and catheter tip respectively.Detection of drug resistance genes:12 strains of 14 CREC carry blaNDM-5,1 strain carries blaKPC-2,and 1 strain carries blaNDM-1.The CREC resistance mechanism in our hospital is that these CREC usually carried blaNDM-5 and ESBLs resistance gene,accompanied by ompk36 gene deletion.The results of conjugation experiment:only one CREC was successful.The results of PFGE typing showed that 14 CREC were divided into 4 PFGE types,among which PT03 was the dominant type,including 11 strains.Drug resistance:CREC resistance was very serious.All strains were resistant to monocyclicβ-lactams,cephalosporins,levofloxacin,and carbapenems.The resistance rate of the strains to aminoglycosides and sulfonamides reached 92.86%.These strains were sensitive to both tigecycline and polymyxin.Conclusion The CREC in our hospital was mainly from respiratory specimens,and there was a clonal epidemic.The dominant strains carried blaNDM-5 and ESBLs resistance genes,accompanied by the deletion of ompk36 gene,and they were highly resistant to various antibiotics.It is suggested that we should increase the control of CREC,close monitoring and control measures should be taken to block the spread and outbreak of CREC in the hospital.