Rapid AST in practice - a workflow analysis of the QuickMIC

Objectives: Timely administration of appropriate antimicrobial therapy is critical for sepsis management, yet conventional antimicrobial susceptibility testing (AST) methods typically provide results within 24-48 hours after positivity. We evaluated the performance and workflow impact of a novel rapid AST system that delivers actionable results within 2-4 hours, compared to standard in-house laboratory methods used across multiple European centers. Methods: A prospective, multicenter study was conducted at 12 hospitals in the United Kingdom, Germany, Sweden, Italy, and Portugal. Positive blood culture samples were analysed in parallel using the QuickMIC rapid AST system and the local reference AST method (broth microdilution, automated systems, rapid AST, or disk diffusion, depending on site). Essential agreement, categorical agreement, and error rates were calculated as compared to the local method. In addition, workflow analysis quantified the time saved in delivering actionable AST results, defined as the availability of clinically interpretable susceptibility categories. Results: For a total of 306 evaluable isolates (from 309 collected) across all hospitals, QuickMIC demonstrated high concordance with reference methods, with categorical agreement exceeding 90% for the majority of tested antibiotic-pathogen combinations. Workflow analysis revealed a potential reduction in turnaround time of 17-45 hours compared with standard methods. For 88% of all tests, this allowed actionable AST results to be available within the same clinical shift rather than on subsequent days. This acceleration was consistent across both northern and southern European sites despite heterogeneity in reference methods and local laboratory workflows. Conclusions: The novel rapid AST system reliably provides susceptibility results in 2-4 hours directly from positive blood cultures, with performance comparable to established in-house methods. Implementation of this approach can substantially shorten the time to actionable results, offering clinicians the ability to optimize antimicrobial therapy significantly earlier during sepsis management. These findings support the adoption of rapid AST as a valuable tool to improve patient care and stewardship outcomes across diverse European hospital settings.