Abstract
Identification and antimicrobial susceptibility testing (AST) are critical steps in the management of bloodstream infections. Our objective was to evaluate the performance of the Accelerate Pheno™ System, CE v1.2 software, for identification and AST of Gram-negative pathogens from positive blood culture bottles. A total of 104 bottles positive for Gram-negative bacteria collected from inpatients throughout our institution were randomly selected after Gram staining. The time-to-identification and AST results, and the raw AST results obtained by the Accelerate Pheno™ system and routine techniques (MALDI-TOF MS and VITEK®2, EUCAST guidelines) were compared. Any discrepant AST result was tested by microdilution. The Pheno™ significantly improved turn-around times for identification (5.3 versus 23.7 h; p < 0.0001) and AST (10.7 versus 35.1 h; p < 0.0001). Complete agreement between the Accelerate Pheno™ system and the MALDI-TOF MS for identification was observed for 96.2% of samples; it was 99% (98/99) for monomicrobial samples versus 40% (3/5) for polymicrobial ones. The overall categorical agreement for AST was 93.7%; it was notably decreased for beta-lactams (cefepime 84.4%, piperacillin-tazobactam 86.5%, ceftazidime 87.6%) or Pseudomonas aeruginosa (71.9%; with cefepime 33.3%, piperacillin-tazobactam 77.8%, ceftazidime 0%). Analysis of discrepant results found impaired performance of the Accelerate Pheno™ system for beta-lactams (except cefepime) in Enterobacteriales (six very major errors) and poor performance in P. aeruginosa. The Accelerate Pheno™ system significantly improved the turn-around times for bloodstream infection diagnosis. Nonetheless, improvements in the analysis of polymicrobial samples and in AST algorithms, notably beta-lactam testing in both P. aeruginosa and Enterobacteriales, are required for implementation in routine workflow.
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Acknowledgements
We thank Dr. Philip Robinson (DRCI, Hospices Civils de Lyon, France) for helping in the manuscript preparation.
Funding
Accelerate Diagnostics, Inc., Tucson, AZ, USA provided for the study period two Accelerate Pheno™ system modules, kits, and technical support free of charge.
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Accelerate Diagnostics had no role in study design, data collection and analysis, publication decision, or preparation of the manuscript.
The authors declare that they have no conflict of interest.
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In accordance with legislation in place at the time of the study, a non-opposition consent was obtained from all patients and information was given to patients via the hospital patient information leaflet that describes how blood samples derived from regular clinical care may be used, and which was approved by the hospital ethics committee.
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Descours, G., Desmurs, L., Hoang, T.L.T. et al. Evaluation of the Accelerate Pheno™ system for rapid identification and antimicrobial susceptibility testing of Gram-negative bacteria in bloodstream infections. Eur J Clin Microbiol Infect Dis 37, 1573–1583 (2018). https://doi.org/10.1007/s10096-018-3287-6
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DOI: https://doi.org/10.1007/s10096-018-3287-6