改良碳青霉烯灭活法和基于抑制剂的联合纸片扩散法在检测和鉴别产碳青霉烯酶肠杆菌科细菌中的性能
Performance of modified carbapenem inactivation method and inhibitor-based combined disk test in the detection and distinguishing of carbapenemase producing Enterobacteriaceae.
作者信息
Li Juan, Li Congrong, Cai Xuan, Shi Jinling, Feng Lina, Tang Kewen, Tong Yongqing, Li Yan
机构信息
Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China.
出版信息
Ann Transl Med. 2019 Oct;7(20):566. doi: 10.21037/atm.2019.09.43.
BACKGROUND
This study aimed to evaluate the performance of modified carbapenem inactivation method (mCIM) combined EDTA-carbapenem inactivation method (eCIM), and inhibitor-based combined disk test (CDT) in the detection and distinguishing of carbapenemase production in Enterobacteriaceae.
METHODS
A total of 101 nonrepetitive carbapenem insensitive Enterobacteriaceae [minimal inhibitory concentration (MIC) ≥2 µg/mL] were tested by mCIM, eCIM and CDT respectively, and the major carbapenemase genes including blaKPC, blaNDM, blaIMP, blaVIM and blaOXA-48-like genes were detected by polymerase chain reaction (PCR) as control.
RESULTS
Seventy-nine (78.2%) of isolates were found to harbour one or more carbapenemase genes by PCR, with blaKPC and blaNDM being the most common genes. OXA-48-like genes were undetectable. The coincidence rate of mCIM combined eCIM and CDT was 97.5% (77/79) and 96.2% (76/79) respectively, compared with gene detection. Both assays had a misclassification in two bla-producing isolates of . The sensitivity and specificity of two assays above were 100.0% 95.0% and 98.4% 98.4%, respectively in distinguishing serine-carbapenemase, while they were 95.1% 97.6% and 100% 100.0%, respectively in distinguishing metallo-carbapenemase.
CONCLUSIONS
mCIM combined eCIM and the CDT are both useful tools for the reliable detection and distinguishing single serine-carbapenemase or metallo-carbapenemase, but not for mixed types.
背景
本研究旨在评估改良碳青霉烯灭活法（mCIM）联合乙二胺四乙酸碳青霉烯灭活法（eCIM）以及基于抑制剂的联合纸片扩散法（CDT）在检测和区分肠杆菌科细菌中产碳青霉烯酶情况的性能。
方法
分别采用mCIM、eCIM和CDT对总共101株非重复的对碳青霉烯不敏感的肠杆菌科细菌[最低抑菌浓度（MIC）≥2μg/mL]进行检测，并通过聚合酶链反应（PCR）检测包括blaKPC、blaNDM、blaIMP、blaVIM和blaOXA - 48样基因在内的主要碳青霉烯酶基因作为对照。
结果
通过PCR发现79株（78.2%）分离株携带一种或多种碳青霉烯酶基因，其中blaKPC和blaNDM是最常见的基因。未检测到blaOXA - 48样基因。与基因检测相比，mCIM联合eCIM和CDT的符合率分别为97.5%（77/79）和96.2%（76/79）。两种检测方法在两株产bla的分离株中均出现了错误分类。上述两种检测方法在区分丝氨酸碳青霉烯酶时的敏感性和特异性分别为100.0%、95.0%和98.4%、98.4%，而在区分金属碳青霉烯酶时分别为95.1%、97.6%和100%、100.0%。
结论
mCIM联合eCIM以及CDT都是可靠检测和区分单一丝氨酸碳青霉烯酶或金属碳青霉烯酶的有用工具，但不适用于混合型。
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