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Published on: September 9, 2015
Assessment of cefiderocol disk diffusion versus broth microdilution results when tested against Acinetobacter
Yanling Liu1,2, Li Ding1,3, Renru Han1,3
1Institute of Antibiotics, Huashan Hospital, Fudan University , Shanghai, China.
Importance:
Carbapenem-resistant Acinetobacter baumannii is a major global health concern due to its high prevalence and limited treatment options. Cefiderocol is the only novel Food and Drug Administration (FDA)-approved β-lactam agent for the salvage treatment of carbapenem-resistant A. baumannii infection. Currently, a commercial automated susceptibility testing panel of cefiderocol is unavailable. Both the preparation of iron-depleted cation-adjusted Mueller-Hinton broth and the performance of broth microdilution are cumbersome in routine microbiology laboratories. A disk diffusion method is convenient for cefiderocol antimicrobial susceptibility testing, but limited data are available specifically for A. baumannii clinical isolates. Moreover, the Clinical and Laboratory Standards Institute published revisions to the A. baumannii cefiderocol disk diffusion breakpoints in 2022. Hence, we evaluated the performance of cefiderocol disk diffusion compared with the reference BMD against A. baumannii clinical isolates, especially those with cefiderocol zone diameters ≤ 14 mm.
Insights
Cefiderocol disk diffusion is a practical method for testing carbapenem-resistant Acinetobacter baumannii susceptibility. This study validates its accuracy against reference methods, especially for challenging clinical isolates.
Area of Science:
- Clinical microbiology
- Antimicrobial susceptibility testing
- Infectious diseases
Background:
- Carbapenem-resistant Acinetobacter baumannii (CRAB) poses a significant global health threat with limited therapeutic choices.
- Cefiderocol, an FDA-approved β-lactam, offers a salvage treatment option for CRAB infections.
- Current cefiderocol susceptibility testing methods are complex and lack commercial automation.
Purpose of the Study:
- To evaluate the performance of cefiderocol disk diffusion testing for Acinetobacter baumannii.
- To compare disk diffusion results with the gold-standard broth microdilution method.
- To assess disk diffusion accuracy, particularly for isolates with small zone diameters (≤ 14 mm).
Main Methods:
- Cefiderocol disk diffusion testing was performed on clinical isolates of Acinetobacter baumannii.
- Results were compared against cefiderocol minimum inhibitory concentrations determined by broth microdilution.
- The study focused on isolates exhibiting zone diameters of 14 mm or less.
Main Results:
- Cefiderocol disk diffusion demonstrated good performance in susceptibility testing of Acinetobacter baumannii.
- The method showed high agreement with broth microdilution, validating its clinical utility.
- Specific attention was given to the interpretation of results for isolates with zone diameters ≤ 14 mm.
Conclusions:
- Cefiderocol disk diffusion is a reliable and convenient method for routine antimicrobial susceptibility testing of Acinetobacter baumannii.
- This method provides a practical alternative to cumbersome broth microdilution, aiding in the management of CRAB infections.
- Updated Clinical and Laboratory Standards Institute breakpoints enhance the accuracy of disk diffusion interpretation.
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