Rapid identification of extended-spectrum-β-lactamase (ESBL)-, serine carbapenemase-, and metallo-β-lactamase (MBL)-producing Enterobacterales directly from positive blood culture (BC) bottles is of paramount importance to early optimize antimicrobial management and infection control measures. In this study, we describe and evaluate an improved variant of direct β-lactam inactivation method, named direct ethylenediaminetetraaceticacid-modified-β-lactam inactivation method (deBLIM). The deBLIM test is designed to detect ESBL or carbapenemase activity and to differentiate serine-carbapenemases from MBLs directly from Enterobacterale-positive BCs. The deBLIM was evaluated on both aerobic and anaerobic BCs spiked with 167 characterized Enterobacterale isolates. The deBLIM showed 100% sensitivity in detecting KPC and OXA-48-like serine carbapenemase, CTX-M, SHV variants, and TEM-10 ESBLs both in aerobic and anaerobic conditions. In contrast, a significant discrepancy between aerobic and anaerobic BCs was observed in detecting MBLs. The sensitivity rate in aerobic BCs was of 100% for all metalloenzyme types, whereas only 56.1% and 80% of VIM and NDM producers were detected in anaerobic bottles, respectively. IMP-producing Escherichia coli NCTC 13476 was also not detected in the anaerobic BC. No false positive result was observed among ESBL producers and broad-spectrum-β-lactamase nonproducers, demonstrating an overall specificity of 100%. The deBLIM could be a cost-effective screening method for the identification of ESBLs, serine carbapenemases, and MBLs directly from Enterobacterale-positive BCs on the same day of bottle positivity detection. Nevertheless, it must be considered its poor performance in detecting MBLs in the anaerobic condition.

中文翻译：

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直接乙二胺四乙酸修饰的 β-内酰胺灭活方法：一种直接从阳性血培养中鉴定丝氨酸-碳青霉烯酶、金属-β-内酰胺酶和超广谱-β-内酰胺酶产肠杆菌的改进方法

直接从阳性血培养 (BC) 瓶中快速鉴定产生超广谱β-内酰胺酶 (ESBL)、丝氨酸碳青霉烯酶和金属β-内酰胺酶 (MBL) 的肠杆菌对于早期优化抗菌管理和感染控制措施。在这项研究中，我们描述和评估了直接 β-内酰胺灭活方法的改进变体，称为直接乙二胺四乙酸修饰的 β-内酰胺灭活方法 (deBLIM)。deBLIM 测试旨在检测 ESBL 或碳青霉烯酶活性，并将丝氨酸碳青霉烯酶与 MBL 直接与肠杆菌阳性 BC 区分开来。deBLIM 是在需氧和厌氧 BC 上评估的，这些 BC 掺有 167 种具有特征的肠杆菌属分离株。deBLIM 在检测 KPC 和 OXA-48 样丝氨酸碳青霉烯酶方面表现出 100% 的灵敏度，CTX-M、SHV 变体和 TEM-10 ESBLs 在有氧和无氧条件下。相比之下，在检测 MBL 时观察到有氧和无氧 BC 之间的显着差异。对于所有金属酶类型，需氧 BC 的灵敏度为 100%，而在厌氧瓶中分别检测到 VIM 和 NDM 生产者的分别为 56.1% 和 80%。产生IMP在厌氧 BC 中也未检测到大肠杆菌NCTC 13476。在 ESBL 生产者和广谱 β-内酰胺酶非生产者中未观察到假阳性结果，表明总体特异性为 100%。deBLIM 可能是一种经济高效的筛查方法，用于在瓶子阳性检测的同一天直接从肠杆菌阳性 BC 中鉴定 ESBL、丝氨酸碳青霉烯酶和 MBL。然而，必须考虑其在厌氧条件下检测 MBL 的性能不佳。