Analytical performance and workflow impact of the FASTinov QUICKprep kit for direct bacterial identification and antimicrobial susceptibility testing from positive blood cultures

Rapid pathogen identification and antimicrobial susceptibility testing (AST) from positive blood cultures are essential for the timely optimization of antimicrobial therapy in patients with bloodstream infections. The FASTinov QUICKprep kit enables recovery of viable microorganisms directly from positive blood cultures, allowing both identification and AST without prior subculture. We evaluated the analytical performance and workflow impact of the FASTinov QUICKprep kit using 112 positive blood cultures processed in a routine clinical microbiology laboratory. Direct identification was performed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and AST was performed using the automated RADIAN system. Results were compared with those obtained using the laboratory's standard subculture-based workflow. Identification accuracy, categorical agreement for AST, reporting times, and turnaround times (TATs) were assessed. Overall, the sensitivity and specificity of direct bacterial identification were 93.4% and 100%, respectively. The QUICKprep workflow enabled same-day identification for all evaluable samples and reduced the median TAT from 7.75 h to 3.0 h. Direct AST performed from QUICKprep-derived pellets demonstrated high categorical agreement with the reference method across 86 isolates. Most discordant AST results involved heteroresistant gram-negative subpopulations and were adjudicated in favor of the QUICKprep results by Etest. Importantly, AST results were consistently available within 24 h irrespective of sample arrival time, whereas the conventional workflow showed substantial delays for cultures received later in the day. In conclusion, the FASTinov QUICKprep kit provides reliable direct identification and AST from positive blood cultures while substantially reducing turnaround times. Integration of this approach into routine clinical microbiology workflows may facilitate earlier optimization of antimicrobial therapy and support antimicrobial stewardship efforts. IMPORTANCE: Bloodstream infections remain a major cause of morbidity and mortality worldwide. Thus, efficient pathogen identification and antimicrobial susceptibility testing are critical to optimizing targeted therapy and antimicrobial stewardship. Despite advances in laboratory automation, routine procedures for positive blood cultures remain dependent on secondary subculture growth. Our study proposes relevant and practical benefits regarding the integration of a subculture-independent workflow for bloodstream infection diagnosis and its potential contribution to improving clinical outcomes.