Due to the importance of a rapid determination of patients infected by multidrug resistant bacteria, we evaluated two rapid diagnostic tests for the detection of third-generation cephalosporins (3GC)-resistant Enterobacterales directly from positive blood cultures within 1 h: BL-RED^TM (electrochemical method) and β-LACTA^TM test (chromogenic method). A panel of 150 clinical strains characterized for their resistance profiles (e.g., penicillinases, extended-spectrum beta-lactamases (ESBLs), overproduction of cephalosporinase, carbapenemases, impermeability) was tested. Approximately 100 CFU of each isolate was spiked into sterile blood culture bottles and incubated in a BD BACTEC^TM FX automated system (Becton Dickinson, USA). Positive blood cultures were examined to parallel testing using the BL-RED^TM and β-LACTA^TM tests and conventional susceptibility method (disc diffusion following EUCAST recommendations). For all phenotypes combined, the sensitivity, specificity, positive predictive value, and negative predictive value in the detection of 3GC resistance were, respectively (i) with BL-RED^TM: 45.7, 100, 100, and 54.2% and (ii) with β-LACTA^TM test: 52.2, 100, 100, and 56.9%. The positivity of tests allows to adapt antibiotic treatment whereas the negative result requires other tests. Moreover, these tests detect most Ambler class A-producing Enterobacterales (KPC, ESBL, extended-spectrum OXY) with sensitivities and specificities of 87.5 and 99% for BL-RED^TM, respectively and both 100% for β-LACTA^TM test (47/47 isolates). These two rapid tests failed to detect AmpC overexpressed (sensitivities of 2.7% for BL-RED^TM and 0% for β-LACTA^TM test) and Ambler class B-producing Enterobacterales (sensitivities of 40% for both tests) notably strains without ESBLs associated (sensitivities of 0% for both tests). BL-RED^TM and β-LACTA^TM tests are easy-to-use and mainly attractive when a positive result is obtained notably to detect most of the Ambler class A-producing Enterobacterales in <1 h after the positivity of the blood culture, allowing a rapid adaptation of the antibiotic therapy in patients.

由于快速确定感染多药耐药细菌的患者的重要性，我们评估了两种快速诊断测试，用于在1小时内直接从阳性血液培养物中检测出第三代对头孢菌素（3GC）耐药的肠杆菌：BL-RED ^TM（电化学方法）和β-LACTA ^TM试验（显色法）。测试了一组以其抗药性为特征的150种临床菌株（例如青霉菌，广谱β-内酰胺酶（ESBLs），头孢菌素酶的过量生产，碳青霉烯酶，抗渗透性）。将每种分离物约100 CFU加标到无菌血培养瓶中，并在BD BACTEC ^TM中孵育FX自动化系统（美国Becton Dickinson）。检查阳性血培养使用BL-RED以并行测试^TM和β-LACTA ^TM试验和常规的易感性的方法（以下EUCAST建议圆盘扩散）。对于所有组合的表型，检测3GC耐药性的敏感性，特异性，阳性预测值和阴性预测值分别为（i）BL-RED ^TM：45.7％，100％，100％和54.2％，以及（ii） β-LACTA ^TM测试：52.2％，100％，100％和56.9％。测试的阳性可以适应抗生素治疗，而阴性结果则需要其他测试。此外，这些测试检测最安布勒类A-产生具有敏感性和87.5特异性和99％BL-RED Enterobacterales（KPC，ESBL，广谱OXY）^TM，分别和β-LACTA均为100％^TM试验（47 / 47隔离）。这两个快速试验未能检测到的AmpC过表达（2.7％对BL-RED灵敏度^TM和β-LACTA 0％^TM和安布勒类B-产生Enterobacterales（对于这两个试验的40％灵敏度）试验）尤其是菌株不伴有ESBLs的（两种测试的灵敏度均为0％）。BL-RED ^TM和β-LACTA ^TM 该检测方法易于使用，并且在获得阳性结果后，尤其是在血液培养阳性后不到1小时内即可检测出大多数产生Ambler A类肠杆菌的检测方法时，很有吸引力，从而可以使患者快速适应抗生素治疗。