EA7361 "Structure, dynamic, function and expression of broad spectrum β-lactamases", Paris-Sud University, Faculty of Medicine, Le Kremlin-Bicêtre, France; Joint research Unit EERA « Evolution and Ecology of Resistance to Antibiotics », Institut Pasteur-APHP-University Paris Sud, Paris, France.
Departamento de Bioquímica Clinica, Hospital de Clínicas José de San Martín, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
Int J Antimicrob Agents. 2020 Feb;55(2):105857. doi: 10.1016/j.ijantimicag.2019.11.014. Epub 2019 Nov 27.
Carbapenemase-producing Enterobacterales expressing OXA-48, KPC, NDM, VIM or IMP enzymes are increasingly reported worldwide. We have characterized LMB-1, a novel metallo-β-lactamase (MBL) of Ambler class B3 from Citrobacter freundii 164 (Cf164) clinical isolate from Buenos Aires, Argentina. Cf164 displayed reduced susceptibility to carbapenems but gave inconsistent results with carbapenemase confirmatory tests, indicating the presence of a weak carbapenemase. Analysis of whole-genome sequencing (WGS) of Cf164 using Resfinder revealed four β-lactamase genes coding for CTX-M-8, PER-2, TEM-1 and CMY-150, a novel chromosomally-encoded CMY variant. Kinetic parameters of purified CMY-150 did not reveal any carbapenemase activity. However, CMY-150 conferred higher minimum inhibitory concentrations (MICs) to E. coli for ceftazidime and aztreonam compared with CMY-2. The in-house-developed β-lactamase search software (ResMiner) in WGS data revealed a novel subclass B3 MBL named LMB-1. LMB-1 conferred resistance to penicillins and expanded-spectrum cephalosporins and reduced susceptibility to carbapenems in E. coli. The bla gene was located on a 176-kb IncA/C2 plasmid. LMB-1 shared 99% amino acid sequence identity with the MBL encoded in the chromosome of Rheinheimera pacifica, it's likely progenitor. Despite repeated attempts, LMB-1 could not be purified, thus only specific activities could indicate hydrolysis of carbapenems. Here we report on CMY-150, a novel CMY-2 variant that confers increased ceftazidime and aztreonam MICs to E. coli and the first description of LMB-1 in Argentina. This work underlines the need for several carbapenemase-producing Enterobacteriaceae (CPE) confirmatory tests, as this novel enzyme might have been missed using only one.
产碳青霉烯酶的肠杆菌科细菌表达 OXA-48、KPC、NDM、VIM 或 IMP 酶在全球范围内的报道越来越多。我们从阿根廷布宜诺斯艾利斯的临床分离株弗氏柠檬酸杆菌 164（Cf164）中鉴定出一种新型的 Ambler 类 B3 金属β-内酰胺酶（MBL）LMB-1。Cf164 对碳青霉烯类药物的敏感性降低，但碳青霉烯酶确证试验结果不一致，表明存在弱碳青霉烯酶。使用 Resfinder 对 Cf164 的全基因组测序（WGS）分析显示，有 4 个β-内酰胺酶基因编码 CTX-M-8、PER-2、TEM-1 和 CMY-150，这是一种新型的染色体编码的 CMY 变体。纯化的 CMY-150 的动力学参数没有显示出任何碳青霉烯酶活性。然而，与 CMY-2 相比，CMY-150 使大肠杆菌对头孢他啶和氨曲南的最小抑菌浓度（MIC）更高。在 WGS 数据中开发的内部β-内酰胺酶搜索软件（ResMiner）发现了一种新型的 B3 类 MBL，命名为 LMB-1。LMB-1 使青霉素和广谱头孢菌素产生耐药性，并使大肠杆菌对碳青霉烯类药物的敏感性降低。bla 基因位于一个 176kb 的 IncA/C2 质粒上。LMB-1 与 Rheinheimera pacifica 染色体上编码的 MBL 氨基酸序列同源性为 99%，它可能是其前体。尽管反复尝试，仍未能纯化 LMB-1，因此只有特定的活性才能表明其对碳青霉烯类药物的水解。在这里，我们报告了一种新型的 CMY-2 变体 CMY-150，它使大肠杆菌对头孢他啶和氨曲南的 MIC 增加，并首次在阿根廷描述了 LMB-1。这项工作强调了需要进行几种产碳青霉烯酶肠杆菌科（CPE）确证试验，因为仅使用一种试验可能会错过这种新型酶。
