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

摘要:

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（EDTA-carbapenem 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 con－centration，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、eCIM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。

Abstract:

Objective：To evaluate the detection ability of modified carbapenem inactivation method（mCIM）/EDTA-carbapenem inac－tivation method（eCIM） 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 carbapen－emase. PCR was used to detect carbapenem resistance genes（blaKPC，blaNDM，blaIMP，blaVIM and blaOXA-48），extended-spectrum β-lactamase genes（SHV，TEM，CTX andOXA-1），AmpC enzyme-encod－ing genes（FOX），and membrane pore proteins ompK35 and ompK36 genes. Results：Among 40 CREs，38 strains carried the carbapen－emase gene，including blaKPC of 35 strains，blaNDM of 7 strains，blaKPC+blaNDM of 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 of 40 CRE strains to common clinical antibiotics，such as the third and the fourth generation of cephalosporins，enzyme inhibitor mix－ture，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.