Evaluation of the Accelerate Pheno™ system to identify bacteria and determine antimicrobial susceptibility in positive blood cultures

Introduction New platforms have recently been developed to reduce response time of identification and antimicrobial susceptibility of bacterial isolates in positive blood cultures from patients with bloodstream infections. The Accelerate Pheno™ system (Accelerate Diagnostics, Inc.) provides information on pathogen identification and antibiotic susceptibility in approximately 1.5 and 7 hours, respectively. Methods In this study we compared the Accelerate Pheno™ system with the standard procedure used in our laboratory. A total of 41 blood cultures were prospectively analysed with the Accelerate Pheno™ system and our standard methods, which include identification by MALDI-TOF mass spectrometry and antibiotic susceptibility testing (AST) by BD Phoenix system and E-test. Results The correlation between the two methods using Cohen’s kappa coefficient was 0.82; mean (sd) time of identification for MALDI-TOF MS was 0.7 (0.22) hours and 1.43 (0.14) hours for the Accelerate Pheno™ system. The mean (sd) time of AST with the BD Phoenix system was 15.85 (2.57) hours and with the Accelerate Pheno™ system 6.7 (0.12) hours. AST results showed an overall essential agreement of 92% for the minimal inhibitory concentrations (MIC) and an overall category agreement of 96%. Among Gram positive isolates, essential and category agreements of 100% were observed. In Gram negative isolates 10 discrepancies were detected, which were classified as 7 major and 3 minor errors. Discrepancies in the Accelerate Pheno™ system were observed particularly for P. aeruginosa. Conclusion The Accelerate Pheno™ system can improve turn-around time in the management of patients with bloodstream infections.