Evaluation of the Accelerate Pheno™ system for rapid identification and antimicrobial susceptibility testing of Gram-negative bacteria in bloodstream infections

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.

Evaluation of a new Rapid Antimicrobial Susceptibility system for Gram-negative and Gram-positive bloodstream infections: Speed and accuracy of Alfred 60 AST

“…In our study, the average hands-on time per specimen was not different from routine testing, however the time to deliver susceptibility results has been significantly reduced compared to routine standard automated system (BD Phoenix™). The times to AST results were similar to the times noted in a previous study using the Alfred 60 AST™ system and other the Accelerate Pheno TM system (Accelerate Diagnostics, USA) (Barnini, 2016) (Descours, 2018) (Lutgring, 2018) (Brazelton de Cardenas, 2017). Given high categorical agreement between the BD Phoenix™ and Alfred 60 AST™ and the 16 hour reduction in time to results there are compelling clinical benefits of the Alfred AST 60™.…”

“…The Accelerate Pheno TM system is an alternative rapid phenotypic testing system. In studies using similar AST comparator techniques, an agreement of 93.3% (Marschal, 2017), 94.9% (Pantel, 2018) and 96.4% respectively (Descours, 2018) has been reported. Showing very similar diagnostic performance to the Alfred AST 60™.…”

Novel Approaches to Hasten Detection of Pathogens and Antimicrobial Resistance in the Intensive Care Unit

“…A limitation to the system is the frequency with which alternative ID and AST methods are required as this technology had poor performance for Pseudomonas ID and β-lactam testing. 72 In a study of the Accelerate Pheno System at our institution, 153 blood cultures meeting inclusion criteria from the emergency department and ICUs were evaluated; 110 on-panel GNB, 10 Candida glabrata, 5 Candida albicans. 73 Using standard-of-care microbiology techniques for GNB, median time from blood culture positivity to ID and AST were 28.2 and 52.1 hours, respectively.…”

Evaluation of a new Rapid Antimicrobial Susceptibility system for Gram-negative and Gram-positive bloodstream infections: Speed and accuracy of Alfred 60 AST

“…Showing very similar diagnostic performance to the Alfred AST 60™. The median time to AST results from positive culture bottle to AST result for the Accelerate Pheno TM system is reported as 10.7 [8.6-12.8] hours (Descours, 2018). It should be noted that an advantage of the Accelerate Pheno TM system is that it identifies the species of the isolate in addition to the sensitivity pattern.…”

“…The funding body had no role in study design, data collection, analysis, interpretation of data, writing the manuscript and decision to publish. Technician "hands-on" time (min) 20 min (IQR, 10-30) 15 min (IQR, [10][11][12][13][14][15][16][17][18][19][20]…”