Resistance to third generation cephalosporins is widely disseminated in Enterobacteriaceae mainly because of extended-spectrum-β-lactamases (ESBL), plasmid AmpC β-lactamases (PABL), and hyper-production of chromosomal AmpC β-lactamases. Here, we evaluated the performance of rapid test using novel fluorogenic probe assay in simulated blood cultures and compared the results with the phenol red assay using a total of 172 characterized isolates (39 ESBL producers, 13 PABL producers, and 120 susceptible isolates). We prepared a pellet by centrifugation and washing, which can also be used for identification with MALDI-TOF directly from positive blood cultures. After that, we mixed the pellet with fluorogenic probe and measured the fluorescent signal using fluorometer. The fluorogenic probe assay showed higher sensitivity than the phenol red assay (96.2% vs. 71.2%, p < .0001) in 172 simulated blood culture bottles especially in detecting PABL (84.6% vs. 0%, p = .0026) and the turnaround time was 1.5 h. This fluorogenic probe assay, combined with the direct identification of pathogens, could be very useful for rapid identification of isolates and detecting cephalosporin resistance caused by ESBL and PABL directly from positive blood cultures.

对第三代头孢菌素的耐药性在肠杆菌科中广泛传播主要是由于广谱β-内酰胺酶（ESBL），质粒AmpCβ-内酰胺酶（PABL）和染色体AmpCβ-内酰胺酶的过量生产。在这里，我们评估了在模拟的血液培养中使用新型荧光探针测定法进行快速测试的性能，并将结果与​​使用总共172个特征分离株（39个ESBL生产者，13个PABL生产者和120个敏感分离株）的酚红测定法进行了比较。我们通过离心和洗涤制备了沉淀，也可以直接从阳性血液培养物中用于MALDI-TOF的鉴定。之后，我们将沉淀物与荧光探针混合，并使用荧光计测量荧光信号。荧光探针检测显示出比酚红检测更高的灵敏度（96.2％对71.2％，p  < 172个模拟血液培养瓶中的浓度（0.0001），特别是在检测PABL时（84.6％vs. 0％，p  = .0026），周转时间为1.5 h。这种荧光探针测定法与病原体的直接鉴定相结合，对于快速鉴定分离物以及直接从阳性血培养物中检测由ESBL和PABL引起的头孢菌素耐药性可能非常有用。