Automated testing of antimicrobial susceptibility is common in clinical microbiology laboratories but their ability to detect low-level resistance has been questioned. This Nordic multicentre study aimed to evaluate the performance of commercially available automated AST systems. A phenotypically well-characterised collection of gram-negative bacilli (Escherichia coli (n = 7), Klebsiella pneumoniae (n = 6) and Pseudomonas aeruginosa (n = 7)) with and without resistance mechanisms was examined by Danish (n = 1), Finnish (n = 6), Norwegian (n = 16) and Swedish (n = 5) laboratories. Minimum inhibitory concentrations (MICs) were determined for 12 antimicrobials with automated systems and compared with MICs obtained with gold standard broth microdilution. The automated systems used were VITEK 2 (n = 23), Phoenix (n = 4), MicroScan (n = 1), and ARIS (n = 1). Very major errors were identified for six antimicrobials; cefotaxime (6.9%), meropenem (0.4%), ciprofloxacin (0.7%), ertapenem (4.3%), amikacin (3.4%) and colistin (6.4%). Categorical agreement of MIC for the automated systems compared to broth microdilution ranged from 83% for imipenem to 100% for ampicillin and trimethoprim-sulfamethoxazole. The analysis revealed several important antimicrobials where resistance was underestimated, potentially with significant consequences in patient treatment. The results cast doubt on the use of automated AST in the management of patients with serious infections and suggests that more work is needed to define their limitations.

中文翻译：

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用于检测革兰氏阴性菌抗菌药物耐药性的自动化药敏测试的性能：NordicAST 研究

抗菌药物敏感性的自动测试在临床微生物学实验室中很常见，但其检测低水平耐药性的能力受到质疑。这项北欧多中心研究旨在评估商用自动化 AST 系统的性能。 丹麦人 ( n  = 1)检查了表型良好的革兰氏阴性杆菌集合（大肠杆菌( n  = 7)、肺炎克雷伯菌( n  = 6) 和铜绿假单胞菌( n = 7)），有或没有耐药机制、芬兰 ( n  = 6)、挪威 ( n  = 16) 和瑞典 ( n  = 5) 实验室。使用自动化系统测定 12 种抗菌剂的最低抑菌浓度 (MIC)，并与金标准肉汤微量稀释法获得的 MIC 进行比较。使用的自动化系统为 VITEK 2 ( n  = 23)、Phoenix ( n  = 4)、MicroScan ( n  = 1) 和 ARIS ( n  = 1)。六种抗菌药物被发现存在非常严重的错误；头孢噻肟（6.9%）、美罗培南（0.4%）、环丙沙星（0.7%）、厄他培南（4.3%）、阿米卡星（3.4%）和粘菌素（6.4%）。与肉汤微量稀释相比，自动化系统的 MIC 类别一致性范围为亚胺培南的 83% 到氨苄青霉素和甲氧苄氨嘧啶-磺胺甲恶唑的 100%。分析揭示了几种重要抗菌药物的耐药性被低估，可能对患者治疗产生重大影响。结果对使用自动化 AST 治疗严重感染患者提出了质疑，并表明需要开展更多工作来明确其局限性。