We optimized and prospectively evaluated a simple MALDI-TOF MS-based method for direct detection of third-generation oxymino-cephalosporin resistance (3rd CephR) in Escherichia coli and Klebsiella spp. from blood cultures (BC). In addition, we assessed the performance of a lateral flow immunochromatographic assay (LFIC) for detecting extended-spectrum β-lactamases (ESBL) (NG-Test CTX-M MULTI assay) using bacterial pellets from BC. A total of 168 BCs from unique patients were included. A pre-established volume of BC flagged as positive was transferred in brain heart infusion with or without ceftriaxone (2 mg/ml). After 2-h incubation, intact bacterial pellets were used for MALDI-TOF MS testing. Identification of bacterial species (index score > 2) in the presence of CRO was considered marker of 3rd CephR. The LFIC assay was evaluated in 141 BC. Bacteremia episodes were caused by E. coli (n = 115) or Klebsiella spp. (n = 53). A total of 49 strains were 3rd CephR by broth microdilution, of which 41 were ESBL producers, seven expressed ESBL and OXA-48 type D carbapenemase, and one harbored a plasmid-mediated AmpC. The MALDI-TOF MS method yielded four very major errors (false susceptibility) and two major errors (false resistance). The overall sensitivity of the assay was 91.8% and the specificity 98.3%. Concordance between the LFIC assay and the MALDI-TOF MS method for detection of ESBL-mediated 3rd CephR was 100%. Both evaluated methods may prove useful for early adjustment of empirical therapy in patients with E. coli and Klebsiella spp. bloodstream infections. Whether their use has a beneficial impact on patient outcomes is currently under investigation.

我们优化并前瞻性评估了一种简单的基于 MALDI-TOF MS 的方法，用于直接检测大肠杆菌和克雷伯氏菌中的第三代羟氨基头孢菌素耐药性 (3rd CephR)属 来自血培养 (BC)。此外，我们使用来自 BC 的细菌颗粒评估了用于检测超广谱 β-内酰胺酶 (ESBL)（NG-Test CTX-M MULTI 测定）的侧向流动免疫色谱测定 (LFIC) 的性能。总共包括来自独特患者的 168 个 BC。将预先确定的标记为阳性的 BC 体积转移到有或没有头孢曲松 (2 mg/ml) 的脑心输液中。孵育 2 小时后，完整的细菌沉淀用于 MALDI-TOF MS 测试。在 CRO 存在下鉴定细菌种类（指数得分 > 2）被认为是第 3 个 CephR 的标志物。LFIC 测定在公元前 141 年进行了评估。菌血症发作是由大肠杆菌（n = 115）或克雷伯氏菌引起的。( n= 53）。通过肉汤微量稀释，共有 49 株是 3rd CephR，其中 41 株是 ESBL 生产者，7 株表达 ESBL 和 OXA-48 D 型碳青霉烯酶，1 株携带质粒介导的 AmpC。MALDI-TOF MS 方法产生了四个非常大的错误（假磁化率）和两个主要错误（假电阻）。该测定的总体灵敏度为 91.8%，特异性为 98.3%。LFIC 测定与 MALDI-TOF MS 方法检测 ESBL 介导的第三个 CephR 的一致性为 100%。两种评估方法都可能证明有助于早期调整大肠杆菌和克雷伯氏菌患者的经验治疗。血流感染。目前正在调查它们的使用是否对患者结果产生有益影响。