摘要
目的评价改良碳青霉烯类失活法(modified carbapenem inactivation method,m CIM)和EDTA碳青霉烯类失活法(EDTAcarbapenem inactivation method,e CIM)对肠杆菌科细菌碳青霉烯酶表型的筛选能力。方法分别收集碳青霉烯类耐药和敏感肠杆菌科细菌102株和53株,采用m CIM和e CIM进行碳青霉烯酶表型筛选试验,PCR法检测blaKPC-2、blaNDM-1、blaIMP-4、blaVIM-1和blaOXA-48耐药基因,并对表型筛选试验结果与基因检测结果的一致性进行统计分析。结果 102株碳青霉烯类耐药肠杆菌科细菌中97株检出耐药基因,包括51株blaKPC-2基因、38株blaNDM-1基因、5株blaIMP-4基因以及3株同时携带blaKPC-2和blaNDM-1基因;m CIM检出阳性98株,阴性4株。98株m CIM阳性菌中,e CIM阳性46株,阴性52株。53株碳青霉烯类敏感肠杆菌科细菌耐药基因检测及m CIM试验均为阴性。m CIM试验筛选碳青霉烯类耐药肠杆菌科细菌碳青霉烯酶产生的敏感性为99.0%,特异性为96.6%,与PCR结果一致性Kappa值为0.959;e CIM筛选金属酶敏感性为93.5%,特异性为94.6%,Kappa值为0.881;e CIM筛选丝氨酸碳青霉烯酶敏感性为92.6%,特异性为95.8%,Kappa值为0.882。结论 m CIM试验与e CIM试验联合检测,不仅可以有效筛选碳青霉烯酶产酶株,而且可同时区分碳青霉烯酶类型,对流行病学调查研究及疾病治疗有重要意义。
Objective To evaluate the screening capacity of modified carbapenem inactivation method( m CIM) and EDTAcarbapenem inactivation method( e CIM) for phenotypic activity of carbapenemase in Enterobacteriaceae bacteria. Methods A total of102 isolates of carbapenem-resistant Enterobacteriaceae and 53 isolates of carbapenem-sensitive Enterobacteriaceae were selected and the carbapenemase activities were determined by m CIM and e CIM,respectively. Meanwhile,the carbapenem-resistant genes in Enterobacteriaceae,such as blaKPC-2,blaNDM-1,blaIMP-4,blaVIM-1 and blaOXA-48,were detected by PCR.The consistency of results between phenotypic screening tests and gene examinations was analyzed statistically. Results Of the 102 carbapenem-resistant Enterobacteriaceae strains,97 strains carrying positive drug-resistance gene were detected by PCR,including blaKPC-2 in 51 strains,blaNDM-1 in 38 strains,blaIMP-4 in 5 strains and both blaKPC-2 and blaNDM-1 in 3 strains. Of the 102 carbapenem-resistant Enterobacteriaceae strains,98 strains were detected to be positive phenotype by m CIM,while the other 4 strains were negative phenotype. Of the 98 m CIM positive strains,46 strains were e CIM positive and 52 strains were e CIM negative. Of the 53 carbapenem-sensitive strains,the results of PCR and m CIM were both negative. For screening of carbapenemase by m CIM,the sensitivity was 99.0% and the specificity was 96.6%,and the Kappa value for consistency with PCR results was 0.959. For screening metallo-beta-lactamase gene,the sensitivity of e CIM was 93.5%,the specificity was 94.6% and the Kappa value was 0.881. For screening class A carbapenemase gene,the sensitivity of e CIM was 92.6%,the specificity was 95.8%,and the Kappa value was 0.882. Conclusion The combined detections of m CIM and e CIM may effectively screen carbapenemase-producing strains in Enterobacteriaceae,and also distinguish the type of carbapenemase,which should be of great significance for epidemiological investigation and therapy of infectious diseases.
引文
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