Department of Medical Microbiology, Ruhr University Bochum, Universitätsstraße 150, Bochum, Germany.
Institute for Hygiene, Microbiology and Tropical Medicine, National Reference Center for Nosocomial Infections and Antimicrobial Resistance, Ordensklinikum Linz Elisabethinen, Fadingerstraße 1, Linz, Austria.
J Antimicrob Chemother. 2018 Sep 1;73(9):2331-2335. doi: 10.1093/jac/dky215.
To identify and characterize a novel MBL gene conferring carbapenem resistance to an isolate of Enterobacter cloacae from Austria.
The novel MBL gene was heterologously expressed in Escherichia coli TOP10 to conduct comparative MIC studies and biochemical assays. Furthermore, WGS was performed using Illumina MiSeq and Oxford Nanopore MinION instruments to analyse the genetic environment of the novel MBL gene.
The novel MBL showed highest sequence homology to a predicted MBL precursor from the marine bacterium Rheinheimera pacifica and hence belongs to Ambler subgroup B3. The comparative MIC studies and biochemical assays showed activity of the novel enzyme against penicillins, cephalosporins and carbapenems, but not against aztreonam. It was named Linz MBL (LMB-1). The blaLMB-1 gene was shown to be located on a 108 kb plasmid of Inc type IncFIB(K). Of note, a gene adjacent to blaLMB-1 coded for a glycerophosphoryl diester phosphodiesterase that was also previously detected in R. pacifica.
Homologies of the MBL gene itself and another gene located on the same plasmid to genes detected in marine bacterial species strongly suggest that this novel MBL was transferred to E. cloacae from a marine bacterium. This underlines the importance of natural reservoirs supplying hitherto unknown resistance genes to clinically relevant bacterial species and the importance of ongoing surveillance and research.
鉴定和表征一株来自奥地利阴沟肠杆菌的新型碳青霉烯类耐药金属β-内酰胺酶（MBL）基因，并对其进行特征分析。
将新型 MBL 基因在大肠杆菌 TOP10 中异源表达，进行比较 MIC 研究和生化分析。此外，采用 Illumina MiSeq 和 Oxford Nanopore MinION 测序仪进行 WGS，以分析新型 MBL 基因的遗传环境。
新型 MBL 与海洋细菌 Rheinheimera pacifica 的预测 MBL 前体具有最高的序列同源性，因此属于 Ambler 亚组 B3。比较 MIC 研究和生化分析表明，新型酶对青霉素、头孢菌素和碳青霉烯类具有活性，但对氨曲南没有活性。它被命名为林茨 MBL（LMB-1）。blaLMB-1 基因位于 Inc 型 IncFIB(K)的 108kb 质粒上。值得注意的是，位于 blaLMB-1 基因旁的一个基因编码甘油磷酸二酯磷酸二酯酶，该酶也在 Rheinheimera pacifica 中被检测到。
MBL 基因本身及其位于同一质粒上的另一个基因与海洋细菌中检测到的基因具有同源性，强烈提示该新型 MBL 是从海洋细菌转移到阴沟肠杆菌的。这强调了天然储库向临床相关细菌物种提供迄今未知的耐药基因的重要性，以及持续监测和研究的重要性。
