产NDM-1金属β-内酰胺酶阴沟肠杆菌耐药传递机制及药物敏感性分析

Resistance transmission mechanisms and antimicrobial susceptibility of NDM-1 metal β-lactamase-producing Enterobacter cloacae

目的研究碳青霉烯耐药阴沟肠杆菌的耐药机制和耐药传递,分析其药物敏感性。方法收集大连医科大学附属第一医院2015年8月-2016年8月碳青霉烯耐药阴沟肠杆菌9株,利用改良Hodge试验对碳青霉烯耐药阴沟肠杆菌进行表型确证,EDTA纸片增效试验检测金属酶。PCR方法检测碳青霉烯酶基因,超广谱β-内酰胺酶(ESBLs)基因,AmpC beta-内酰胺酶(AmpC酶)基因,质粒介导的喹诺酮类耐药基因以及氨基糖苷类耐药基因。通过质粒接合实验分析碳青霉烯耐药性在种属间的传递。结果改良Hodge试验阳性2株,EDTA纸片增效试验阳性9株,均携带NDM-1基因,ESBLs基因TEM、CTX-M、SHV阳性菌株数分别为8株、3株、4株。喹诺酮类耐药基因qnrA、qnrB、qnrS、aac(6’)-Ib-cr阳性菌株数分别为5株、2株、1株、7株。质粒接合实验表明NDM-1基因可通过质粒在不同种属间传递。对左氧氟沙星、环丙沙星、妥布霉素、四环素的敏感率较低,均为11.1%。对阿米卡星、庆大霉素、多黏菌素B、替加环素及磷霉素的敏感率较高,分别为88.9%、66.7%、88.9%、100%、100%。结论碳青霉烯耐药阴沟肠杆菌为NDM-1型,耐药性可通过质粒进行传递,需引起重视,应根据药敏结果合理应用抗菌药物,同时加强院感的防控。

OBJECTIVE To study the drug resistance mechanisms and resistance transmission of carbapenem-resistant Enterobacter cloacae so as to analyze the drug susceptibility.METHODS Totally 9 strains of carbapenem-resistant E.cloacae were collected from the First Affiliated Hospital of Dalian Medical University from Aug 2015 to Aug 2016,the phenotypes of the carbapenem-resistant E.cloacae were verified by using modified Hodge test,metalloenzymes were detected by means of EDTA paper synergy test,and the carbapenemase genes,extended spectrumβ-lactamases(ESBLs)genes,AmpC beta-lactamase(AmpC)gene,plasmid-mediated quinolones resistance genes and aminoglycosides resistance genes were detected by PCR.The transfer of carbapenem resistance between species was analyzed by plasmid conjugation experiments.RESULTS Totally 2 isolates were positive by modified Hodge test,9 isolates were positive by EDTA synergy test.All of the isolates carried with the NDM-1 gene.There were 8 isolates positive for ESBLs gene TEM,3 isolates positive for CTX-M and 4 positive for SHV.There were 5 isolates positive for quinolone resistance gene qnrA,2 isolates positive for qnrB,1 isolate positive for qnrS and 7 isolates positive for aac(6’)-Ib-cr.The plasmid conjugation experiment indicated that the NDM-1 gene can be transferred to different species by plasmids.The drug susceptibility rates to levofloxacin,ciprofloxacin,tobramycin and tetracycline were 11.1%;the drug susceptibility rates to amikacin,gentamicin,polymyxin B,tigecycline and fosfomycin were 88.9%,66.7%,88.9%,100%and 100%,respectively.CONCLUSION The carbapenem-resistant E.cloacae belongs to NDM-1 type,the drug resistance can be transmitted through the plasmid,which should be attached great importance to.It is necessary to reasonably use antibiotics based on the result of drug susceptibility testing and strengthen the prevention and control of nosocomial infection.