Devoos Léa, Biguenet Adrien, Rousselot Julie, Bour Maxime, Plésiat Patrick, Fournier Damien, Jeannot Katy
Laboratoire de Bactériologie, Centre Hospitalier Universitaire de Besançon, Besançon, France.
Laboratoire associé du Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire de Besançon, France.
Clin Microbiol Infect. 2023 May;29(5):652.e1-652.e8. doi: 10.1016/j.cmi.2022.12.021. Epub 2022 Dec 29.
To evaluate the performance of commercially available tests to determine the susceptibility of multidrug-resistant (MDR) clinical Pseudomonas aeruginosa strains to cefiderocol.
A collection of 150 clinical strains of P. aeruginosa resistant to ceftazidime, (MIC, Minimal Inhibitory Concentration, MIC > 8 mg/L) imipenem (MIC> 4 mg/L) and ceftolozane/tazobactam (MIC> 4/4 mg/L), isolated from 2015 to 2022 was selected. Cefiderocol susceptibility was determined in parallel (a) by disc diffusion using Mast, Oxoid and Liofilchem discs deposited on Mueller-Hinton agar batches from Bio-Rad, BioMérieux, Mast, Becton Dickinson, I2A and Oxoid; (b) by MIC gradient test strips (MTS) (Liofilchem); and (c) by EUMDROXF Sensititre microplates. MICs and inhibition zones were compared with the broth microdilution reference method (BMD) MICs.
The MIC and MIC of cefiderocol were 1 mg/L and 8 mg/L by BMD, respectively, including 21.3% (32/150) resistant strains. None of the methods tested fulfilled acceptable criteria (essential agreement [EA] ≥ 90%; bias = ± 30%). Although the Sensititre EUMDROXF microplates overestimated MIC values (categorical agreement [CA] = 86.7% [130/150, 95% CI 80.3-91.2]; EA = 69.3% [104/150, 95% CI 61.6-76.2]; bias = 68.2%), MTS strips underestimated the MIC values for many strains (CA = 86.7%, 130/150, 95% CI 80.3-91.2; EA = 69.3%, 104/150, 95% CI 61.6-76.2; bias = -30.4%), classifying properly only 50% (16/32) of resistant strains. Finally, many cefiderocol-resistant strains were not identified by the disc method, although the CA ranged from 78.0% (117/150, 95% CI 70.7-83.0) to 89.3% (134/150, 95% IC 83.4-93.3) according to Mueller-Hinton agar batches.
Determination of cefiderocol susceptibility in MDR P. aeruginosa clinical strains by Sensititre EUMDROXF microplates is an alternative to the reference BMD method. However, MIC values ± 1 dilution apart from the breakpoint (2 mg/L) should be controlled by BMD whereas the use of MTS gradient strips is discouraged. Disc diffusion might be useful for screening, unfortunately many cefiderocol-resistant strains are not detected.
评估市售检测方法在确定多重耐药（MDR）临床铜绿假单胞菌菌株对头孢地尔敏感性方面的性能。
选取2015年至2022年分离的150株对头孢他啶（最低抑菌浓度[MIC]，MIC>8mg/L）、亚胺培南（MIC>4mg/L）和头孢洛扎/他唑巴坦（MIC>4/4mg/L）耐药的铜绿假单胞菌临床菌株。通过以下方法并行测定头孢地尔敏感性：（a）使用沉积在来自伯乐、生物梅里埃、玛斯特、贝克迪金森、I2A和奥克托的穆勒-欣顿琼脂批次上的玛斯特、奥克托和利奥菲化学药敏纸片进行纸片扩散法；（b）通过MIC梯度测试条（MTS）（利奥菲化学）；（c）通过EUMDROXF Sensititre微孔板。将MIC和抑菌圈与肉汤微量稀释参考方法（BMD）的MIC进行比较。
通过BMD法测得头孢地尔的MIC和MIC分别为1mg/L和8mg/L，其中包括21.3%（n=32/150）的耐药菌株。所测试的方法均未达到可接受标准（基本一致性[EA]≥90%；偏差=±30%）。尽管Sensititre EUMDROXF微孔板高估了MIC值（分类一致性[CA]=86.7%[130/150，95%CI 80.3-91.2]；EA=69.3%[104/150，95%CI 61.6-76.2]；偏差=68.2%），但MTS条带低估了许多菌株的MIC值（CA=86.7%，130/150，95%CI 80.3-91.2；EA=69.3%，104/150，95%CI 61.6-76.2；偏差=-30.4%），仅正确分类了50%（16/32）的耐药菌株。最后，尽管根据穆勒-欣顿琼脂批次不同，纸片扩散法的CA范围为78.0%（117/150，95%CI 70.7-83.0）至89.3%（134/150，95%IC 83.4-93.3），但许多对头孢地尔耐药的菌株未通过纸片扩散法检测出来。
通过Sensititre EUMDROXF微孔板测定MDR铜绿假单胞菌临床菌株对头孢地尔的敏感性是参考BMD法的一种替代方法。然而，与断点（2mg/L）相差±1个稀释度的MIC值应由BMD法控制，不建议使用MTS梯度条带。纸片扩散法可能有助于筛查，但遗憾的是许多对头孢地尔耐药的菌株未被检测到。
