Randomized controlled diagnostic trial to assess dRAST time to result and its utility for antimicrobial stewardship...

Bloodstream infections cause great mortality and morbidity. Real-time microbiological information has been shown to have an impact on prognosis when combined with an antimicrobial stewardship (AMS) program. dRAST is a rapid commercial antimicrobial susceptibility testing (AST) system based on real-time microscopy. The primary outcome of this trial was to compare positive blood culture's time-to-result (TTR), defined as time from Gram stain to AST report, between dRAST and our standard of care in a real-life clinical setting. Secondary outcomes included microbiological concordance, time to antimicrobial stewardship recommendation (TAMS), and time to change antimicrobial prescription (TCAP) in agreement with AMS recommendation. We performed a prospective, open-label, randomized (1:1) diagnostic clinical trial comparing dRAST and our standard of care commercial MicroScan broth microdilution (MBMD) (MicroScan-Walkaway, Beckman-Coulter, USA) in 277 hospitalized patients with bacteremia. Categorical and continuous variables were compared by chi-squared and Mann-Whitney U tests, respectively. Median TTR, TAMS, and TCAP were 25, 28, and 29 hours in the MBMD group, and 9, 11, and 13 hours in the dRAST group, respectively. For gram-negative bacilli, essential agreement (EA) was 93.6%, categorical agreement (CA) 93.2%, very major error (VME) 14%, major error (ME) 3%, and minor error (mE) 1.4%. For gram-positive cocci, EA was 93.7%, CA 92.8%, VME 0%, ME 7.6%, and mE 1.8%. dRAST is a reliable method for guiding an antimicrobial stewardship program for bacteremia, allowing significant reductions in TTR, TAMS, and TCAP that might impact patient management and clinical outcomes.

This study addresses a critical challenge in infectious diseases management by evaluating the efficacy of the dRAST system, a rapid antimicrobial susceptibility testing method, in guiding antimicrobial stewardship programs for patients with bloodstream infections. A randomized diagnostic trial was designed to address this objective. Our findings show that the use of dRAST significantly reduces time-to-result, time to antimicrobial stewardship recommendations, and time to appropriate therapy changes, particularly in critically ill patients. These results underline the potential of rapid diagnostic technologies to optimize patient outcomes and enhance antimicrobial stewardship efforts in real-world clinical settings.