Yuan Chao Xue, Natalie Williams-Bouyer, Ping Ren
This single-center study was designed as a real-world comparative clinical laboratory evaluation and is limited by the use of an automated comparator method rather than reference broth microdilution, the local resistance epidemiology, and limited isolate numbers for certain antimicrobial-organism combinations. By providing phenotypic AST results directly from positive blood cultures in less than 8 h, VITEK REVEAL may support earlier therapeutic decision-making and antimicrobial stewardship efforts. Additional multicenter and clinical outcome studies are needed to better determine its clinical impact.
OBJECTIVES: Rapid phenotypic antimicrobial susceptibility testing (AST) has the potential to support earlier optimization of antimicrobial therapy for patients with bloodstream infections. We evaluated the real-world clinical laboratory performance of the bioMérieux VITEK REVEAL® rapid phenotypic AST system using positive blood cultures containing Gram-negative (GN) organisms and compared its results with those obtained using the routine standard-of-care (SOC) MicroScan WalkAway Plus system.
METHODS: A total of 200 positive blood culture bottles yielding GN organisms were evaluated. VITEK REVEAL® performance was assessed using categorical agreement (CA), essential agreement (EA), and error rates, including very major errors (VMEs), major errors (MEs), and minor errors (mEs), with the MicroScan serving as the comparator method. The Etest was performed as a supplemental exploratory method to evaluate selected VME and ME discrepancies.
RESULTS: Within the local resistance epidemiology represented in this study, VITEK REVEAL showed ≥90% EA across evaluated antimicrobial-organism combinations and ≥90% CA for all combinations except amoxicillin/clavulanate (AMC) and ampicillin/sulbactam (SAM). Across the 2,536 antimicrobial-organism combinations evaluated, 14 VMEs (0.6%), 16 MEs (0.6%), and 82 mEs (3.3%) were observed. Several elevated error rates were associated with limited numbers of resistant isolates and breakpoint-adjacent minimum inhibitory concentration (MIC) distributions. Supplemental Etest analysis reduced the number of selected discrepancies, although reference broth microdilution was not performed.
CONCLUSION: This single-center study was designed as a real-world comparative clinical laboratory evaluation and is limited by the use of an automated comparator method rather than reference broth microdilution, the local resistance epidemiology, and limited isolate numbers for certain antimicrobial-organism combinations. By providing phenotypic AST results directly from positive blood cultures in less than 8 h, VITEK REVEAL may support earlier therapeutic decision-making and antimicrobial stewardship efforts. Additional multicenter and clinical outcome studies are needed to better determine its clinical impact.