mCIM、eCIM对碳青霉烯酶检测能力评估及CRE耐药特点分析

Modified carbapenem inactivation method/EDTA-carbapenem inactivation method test to evaluate detection ability of carbapenemase and analyzing drug-resistance characteristics of carbapenem-resistant Enterobacteriaceae

目的:评估碳青霉烯酶失活试验(modified carbapenem inactivation method,mCIM)、EDTA碳青霉烯酶失活试验(EDTAcarbapenem inactivation method,eCIM)及改良Hodge试验对肠杆菌科细菌不同基因型碳青霉烯酶的检测能力,分析碳青霉烯类耐药的肠杆菌科细菌(carbapenem-resistant Enterobacteriaceae,CRE)对临床常用药物最低抑菌浓度(minimum inhibitory concentration,MIC),便于临床合理选择用药。方法:收集华北理工大学附属医院2018年6月至12月临床标本中分离的CRE菌株40株,经VITEK 2 Compact全自动细菌鉴定/药敏系统进行鉴定及药敏试验,E-test法检测亚胺培南、美罗培南、替加环素、阿米卡星、左氧氟沙星、复方新诺明对CRE的MIC,微量肉汤稀释法检测多粘菌素的MIC。用mCIM、eCIM和改良Hodge试验检测CRE菌株产碳青霉烯酶的情况,用聚合酶链式反应(polymerase chain reaction,PCR)检测碳青霉烯类耐药基因(blaKPC、blaNDM、blaIMP、blaVIM、blaOXA-48)、超广谱β-内酰胺酶基因(SHV、TEM、CTX、OXA-1)、AmpC酶编码基因(FOX)及膜孔蛋白ompK35、ompK36基因。结果:40株CRE中38株确定携带碳青霉烯酶基因,其中携带blaKPC35株,包括同时携带blaNDM7株,blaKPC+blaNDM4株。改良Hodge试验和mCIM、e CIM试验对KPC型碳青霉烯酶的阳性率均为100%(38/38);mCIM、eCIM试验对NDM型碳青霉烯酶的阳性率为100%(3/3),改良Hodge试验对NDM型碳青霉烯酶的阳性率为0。耐药性分析:40株CRE菌株对临床常用抗菌药物如三代、四代头孢菌素,酶抑制剂复合制剂,氨曲南,亚胺培南及美罗培南的耐药率均为100%,对左氧氟沙星、阿米卡星、复方新诺明的耐药率分别为90.0%、60.0%和42.5%,尚未发现对替加环素及多黏菌素耐药的菌株。结论:mCIM、eCIM试验和改良Hodge试验对KPC型碳青霉烯酶的敏感度高,mCIM、eCIM试验对NDM型的敏感性高于改良Hodge试验;不同基因型的CRE菌株耐药情况不同,建议针对不同耐药表型的CRE感染,合理选择抗菌药物。

Objective:To evaluate the detection ability of modified carbapenem inactivation method(mCIM)/EDTA-carbapenem inactivation method(e CIM)test and modified Hodge test for carbapenemase of different genotypes in Enterobacteriaceae,and to analyze the minimum inhibitory concentration(MIC)of carbapenem-resistant Enterobacteriaceae(CRE)on common clinical medicines,so as to aid the clinician to choose reasonable medicines.Methods:Forty CRE strains isolated from clinical specimens in our hospital from June 2018 to December 2018 were collected.VITEK 2 Compact automatic bacterial identification/drug sensitivity system was used to conduct the identification and drug sensitivity;E-test method was used to detect the imipenem,meropenem,tegacycline,amikacin,levofloxacin and compound sulfamethoxazole on MICs of CRE;broth microdilution method was used to detect the MIC of polymyxin.The mCIM/eCIM test and modified Hodge test were used to detect the situation of CRE to produce carbapenemase.PCR was used to detect carbapenem resistance genes(blaKPC,blaNDM,blaIMP,blaVIMand blaOXA-48),extended-spectrumβ-lactamase genes(SHV,TEM,CTX andOXA-1),AmpC enzyme-encoding genes(FOX),and membrane pore proteins ompK35 and ompK36 genes.Results:Among 40 CREs,38 strains carried the carbapenemase gene,including blaKPCof 35 strains,blaNDMof 7 strains,blaKPC+blaNDMof 4 strains.Positive rates of the modified Hodge test,mCIM/eCIM test to KPC carbapenemase were 100%(38/38).Positive rates of mCIM/eCIM test to NDM carbapenemase were 100%(3/3).Positive rates of the modified Hodge test to NDM carbapenemase were 0.Drug resistance analysis:drug-resistance rates of40 CRE strains to common clinical antibiotics,such as the third and the fourth generation of cephalosporins,enzyme inhibitor mixture,aztreonam,imipenem and meropenem,were all 100%;those to levofloxacin,amikacin and compound neotamin were 90.0%,60.0%and 42.5%,respectively.It is not found that strains were resistant to tigecycline and polymyxin.Conclusion:Both mCIM/eCIM test and modified Hodge test have high sensitivity to KPC carbapenemase,but mCIM/eCIM test is more sensitive than modified Hodge test to NDM carbapenemase,suggesting to select suitable antibiotics for CRE to different drug resistance phenotypes.