Utility of the nanosphere verigene in the identification of bacteremia isolates from the burn intensive care unit

Abstract

Introduction: The Nanosphere Verigene Blood Culture Nucleic Acid Tests allow pathogen and antimicrobial resistance marker identification within 2.5 hours of a positive blood culture. This study assessed the sensitivity of the Verigene among Burn Intensive Care Unit (BICU) isolates and acceleration to targeted antibiotic therapy. Methods: Bacterial identifications from BICU patients with positive blood cultures over 8 months were compared using 2 different platforms, the Verigene Gram-positive and Gram-negative blood culture tests vs. the bioMerieux Vitek2 automated system. Turnaround times were compared, and Verigene sensitivity for identification and resistance marker detection was calculated. Antimicrobial stewardship was assessed by comparing date/time for empiric and targeted therapy to the Verigene result time. Results: Forty-four isolates (29 target and 15 nontarget) from 17 patients were included. The Verigene correctly identified 15 of 17 Gram-negative (sensitivity 88.2%; 95% confidence interval [CI] [87.9, 88.9]) and 8 of 12 Gram-positive target organisms (sensitivity 66.7%; 95% CI [66.3, 67.5]). None of the nontarget isolates were identified. There were no discordant identifications. Resistance marker identification by the Verigene was 100% concordant with confirmatory testing. For 11 isolates with complete laboratory and clinical data, the median time between Verigene and final culture results was 59.3 hours (37.3, 102.2) and from Verigene results to targeted therapy was 62.2 hours (43.6, 66.2). Discussion: Reasons for lower sensitivity than previously reported are unclear and, on the basis of this limited retrospective review, further study in the BICU population is needed. The Verigene appears useful for antimicrobial stewardship by accelerating the identification of blood isolates.