Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, USA.
Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
J Appl Lab Med. 2023 May 4;8(3):523-534. doi: 10.1093/jalm/jfac131.
Cefiderocol is a new antibiotic used to treat infections with antibiotic resistant Gram-negative bacilli. The impact of differences between Mueller-Hinton agar (MHA) brands on susceptibility testing is underexplored. Compounding the implementation of cefiderocol susceptibility testing is a lack of harmonization between different regulatory body breakpoint criteria.
We performed Kirby-Bauer disk diffusion using BD, Hardy, and Remel MHA, in addition to broth microdilution for Acinetobacter baumannii (n = 25), Enterobacterales (n = 25), Stenotrophomonas maltophilia (n = 24), and Pseudomonas aeruginosa (n = 23). We analyzed disk diffusion diameters and minimum inhibitory concentrations using interpretive criteria from the Clinical and Laboratory Standards Institute (CLSI), US Food and Drug Administration (FDA), and the European Committee on Antimicrobial Susceptibility Testing (EUCAST).
Breakpoint criteria impacted interpretation of susceptibly testing results, for example with the broth microdilution we found 8% (2/25) of A. baumannii isolates change interpretation between CLSI and EUCAST and 32% (8/25) change between CLSI and FDA, 12% (3/25) of Enterobacterales change between CLSI and EUCAST, 13% (3/23) of P. aeruginosa interpretations change between CLSI and FDA, and 4% (1/25) S. maltophilia change between CLSI and FDA. There was a significant difference between the zone disk diffusion diameters for P. aeruginosa and S. maltophilia between Hardy and BD; which changed interpretation (using CLSI criteria) for 8.7% (2/23) for P. aeruginosa but 0% (0/24) for S. maltophilia.
Breakpoint criteria impact cefiderocol susceptibility testing interpretation for broth microdilution and disk diffusion. Choice of MHA brand can also affect result interpretation.
头孢地尔是一种新型抗生素，用于治疗对耐抗生素革兰氏阴性杆菌的感染。不同 Mueller-Hinton 琼脂 (MHA) 品牌之间对药敏试验的影响尚未得到充分探索。使头孢地尔药敏试验实施复杂化的是，不同监管机构的折点标准之间缺乏协调。
我们使用 BD、Hardy 和 Remel MHA 进行了 Kirby-Bauer 圆盘扩散，此外还进行了肉汤微量稀释，用于鲍曼不动杆菌（n = 25）、肠杆菌科（n = 25）、嗜麦芽窄食单胞菌（n = 24）和铜绿假单胞菌（n = 23）。我们使用来自临床和实验室标准协会（CLSI）、美国食品和药物管理局（FDA）和欧洲抗菌药物敏感性测试委员会（EUCAST）的解释标准分析了圆盘扩散直径和最小抑菌浓度。
折点标准影响药敏试验结果的解释，例如，我们发现通过肉汤微量稀释，CLSI 和 EUCAST 之间有 8%（2/25）的鲍曼不动杆菌分离株改变了药敏试验的解释，CLSI 和 FDA 之间有 32%（8/25）改变，CLSI 和 EUCAST 之间有 12%（3/25）的肠杆菌科改变，CLSI 和 FDA 之间有 13%（3/23）的铜绿假单胞菌解释改变，CLSI 和 FDA 之间有 4%（1/25）的嗜麦芽窄食单胞菌改变。Hardy 和 BD 之间铜绿假单胞菌和嗜麦芽窄食单胞菌的圆盘扩散直径存在显著差异；根据 CLSI 标准，这改变了 8.7%（2/23）的铜绿假单胞菌的解释，但嗜麦芽窄食单胞菌没有改变（0/24）。
折点标准影响肉汤微量稀释和圆盘扩散的头孢地尔药敏试验解释。MHA 品牌的选择也会影响结果的解释。
