Evaluation of Q-linea ASTar rapid phenotypic antimicrobial susceptibility testing and potential impact in patients with gram-negative bloodstream infections

Rapid diagnostics can drive antimicrobial stewardship strategies and allow clinicians to develop more precise and individualized treatment pathways. Q-linea ASTar is an FDA-cleared in vitro diagnostic for rapid phenotypic antimicrobial susceptibility testing (AST) system in patients with gram-negative blood stream infections (BSIs). In this study, we report the performance of Q-linea ASTar compared with the standard of care (SOC) method, MicroScan. A total of 83 clinical samples were enrolled in the study. The overall categorical agreement (CA) after discrepancy analysis was 94.6%, with 0.5% very major errors (1/218; VME) and 0.7% major errors (9/1,282; ME). In addition to assay performance, we assessed the hypothetical impact of rapid AST on antimicrobial stewardship prescribing practices for 57 patients with gram-negative BSI. Twenty-nine patients (50.9%) had a potential impact from ASTar on antimicrobial management, including 27 instances of de-escalation. For patients with potential impact, targeted therapy could be achieved in 22.7 h (IQR 21.0-26.3; P < 0.001) from blood culture collection, with a median time savings of 41.8 h compared with SOC. In summary, Q-linea ASTar performed favorably to SOC methods for AST and demonstrates the potential for shorter time to targeted antibiotic therapy in patients with gram-negative BSI.

Rapid phenotypic antimicrobial susceptibility testing (AST) has the potential to have significant impacts on antimicrobial stewardship and the treatment of blood stream infections (BSIs). There is a gap in information regarding the optimal utilization and clinical impact of rapid AST. This study evaluates new technology in the field of rapid AST, including its performance compared with standard of care practices and its potential impacts on the use of antibiotics in patients with gram-negative BSIs.