2. Academic Validation
  3. Performance of discs, sensititre EUMDROXF microplates and MTS gradient strips for the determination of the susceptibility of multidrug resistant Pseudomonas aeruginosa to cefiderocol

Performance of discs, sensititre EUMDROXF microplates and MTS gradient strips for the determination of the susceptibility of multidrug resistant Pseudomonas aeruginosa to cefiderocol

  • Clin Microbiol Infect. 2022 Dec 29;S1198-743X(22)00645-0. doi: 10.1016/j.cmi.2022.12.021.
Léa Devoos 1,  Adrien Biguenet 1,  Julie Rousselot 2,  Maxime Bour 2,  Patrick Plésiat 3,  Damien Fournier 4,  Katy Jeannot 5
Affiliations

Affiliations

  • 1 Laboratoire de Bactériologie, Centre Hospitalier Universitaire de Besançon, boulevard Fleming, 25000 Besançon, France.
  • 2 Laboratoire associé du Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire de Besançon, France.
  • 3 Chrono-environnement UMR 6249, CNRS, Université Franche-Comté, F-25000, Besançon, France.
  • 4 Laboratoire de Bactériologie, Centre Hospitalier Universitaire de Besançon, boulevard Fleming, 25000 Besançon, France; Laboratoire associé du Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire de Besançon, France.
  • 5 Laboratoire de Bactériologie, Centre Hospitalier Universitaire de Besançon, boulevard Fleming, 25000 Besançon, France; Laboratoire associé du Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire de Besançon, France; Chrono-environnement UMR 6249, CNRS, Université Franche-Comté, F-25000, Besançon, France. Electronic address: [email protected].
PMID: 36587736 DOI: 10.1016/j.cmi.2022.12.021
Abstract

Objectives: To evaluate the performance of commercially available tests to determine the susceptibility of multidrug resistant (MDR) clinical Pseudomonas aeruginosa strains to cefiderocol.

Methods: A collection of 150 clinical strains of P. aeruginosa resistant to ceftazidime, (CMI> 8 mg/L) imipenem (CMI> 4 mg/L) and ceftolozane/tazobactam (CMI> 4/4 mg/L), isolated from 2015 to 2022 was selected. Cefiderocol susceptibility was determined in parallel (i) by disc diffusion using MAST, Oxoid and Liofilchem discs deposited on Mueller Hinton agar batches (MHA) from Bio-Rad, BioMérieux, MAST, Becton Dickinson, I2A, and Oxoid, (ii) by MTS gradient strips (Liofilchem), and (iii) by EUMDROXF Sensititre microplates. MICs and inhibition zones were compared to the broth microdilution reference method (BMD) MICs.

Results: The MIC50 and MIC90 of cefiderocol were 1 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%]. While 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 MHA batches.

Conclusion: 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.

Keywords

Pseudomonasaeruginosa; cefiderocol; susceptibility testing.

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