Multicenter Evaluation of the Accelerate PhenoTest BC Kit for Rapid Identification and Phenotypic Antimicrobial Susceptibility Testing Using Morphokinetic Cellular Analysis.

Preeti Pancholi,Blake W Buchan,Nancy E Tucci,Karen C Carroll,Paul D Stamper,Paul C Schreckenberger,Romney M Humphries,Donna M Wolk,Neelam Dhiman,Nathan A Ledeboer,A Brian Mochon,Matthew R Jindra,Cynthia Zimmerman,Robin Patel,Bradley Ford,Paul A Granato,Patricia J Simner,Diana R Hernández ,Margie Morgan ,Samuel D Miller ,Amanda Harrington ,Raymond C K Chan

doi:10.1128/jcm.01329-17

Abstract

ABSTRACTWe describe results from a multicenter study evaluating the Accelerate Pheno system, a first of its kind diagnostic system that rapidly identifies common bloodstream pathogens from positive blood cultures within 90 min and determines bacterial phenotypic antimicrobial susceptibility testing (AST) results within ∼7 h. A combination of fresh clinical and seeded blood cultures were tested, and results from the Accelerate Pheno system were compared to Vitek 2 results for identification (ID) and broth microdilution or disk diffusion for AST. The Accelerate Pheno system accurately identified 14 common bacterial pathogens and two Candida spp. with sensitivities ranging from 94.6 to 100%. Of fresh positive blood cultures, 89% received a monomicrobial call with a positive predictive value of 97.3%. Six common Gram-positive cocci were evaluated for ID. Five were tested against eight antibiotics, two resistance phenotypes (methicillin-resistant Staphylococcus aureus and Staphylococcus spp. [MRSA/MRS]), and inducible clindamycin resistance (MLSb). From the 4,142 AST results, the overall essential agreement (EA) and categorical agreement (CA) were 97.6% and 97.9%, respectively. Overall very major error (VME), major error (ME), and minor error (mE) rates were 1.0%, 0.7%, and 1.3%, respectively. Eight species of Gram-negative rods were evaluated against 15 antibiotics. From the 6,331 AST results, overall EA and CA were 95.4% and 94.3%, respectively. Overall VME, ME, and mE rates were 0.5%, 0.9%, and 4.8%, respectively. The Accelerate Pheno system has the unique ability to identify and provide phenotypic MIC and categorical AST results in a few hours directly from positive blood culture bottles and support accurate antimicrobial adjustment.

Highlights

Bacteremia and candidemia associated with sepsis are major causes of morbidity and mortality worldwide
After blood is collected for culture, empirical broad-spectrum antimicrobial therapy is initiated in patients suspected to have sepsis, and therapy is continued until the etiological agent is identified and antimicrobial susceptibility testing (AST) results are available to tailor therapy [4]
A Citrobacter braakii isolate that reacted with the Citrobacter species probe was classified as a false-positive result, because Citrobacter braakii is not a species that was originally included in the Accelerate PhenoTest blood cultures (BCs) kit claimed panel

Summary

Introduction

Bacteremia and candidemia associated with sepsis are major causes of morbidity and mortality worldwide. The MIC determination and susceptibility interpretation reports are generated using morphokinetic cellular analysis (MCA) by dark-field microscopy observation of individual, live, growing, immobilized bacterial cells in near real time (approximately every 10 min) in the presence (test) or absence (control) of a single concentration of antimicrobial agents. In this multicenter study, we compared results from the Accelerate Pheno system to those from a previously FDA-cleared semiautomated ID test system and triplicate broth microdilution (BMD) or disk diffusion for AST. A portion of the data generated in this study was used to support regulatory submissions for classification as an in vitro diagnostic (IVD) device

Methods

Results

Conclusion