Multicenter evaluation of rapid antimicrobial susceptibility testing by VITEK®2 directly from positive blood culture

Study objective: To compare the antimicrobial susceptibility testing (AST) performance of positive blood cul-tures (PBC) VITEK (R) 2 off-label use (D0) and traditional VITEK (R) 2 workflow using isolated colonies after over-night (D1).Methods: Patient samples with monomicrobial Gram-negative rod or Gram-positive cocci in clusters bacter-emia were tested on D0 and compared to D1 AST results in 7 laboratories in France.Results: Overall, categorical and essential agreement rates were 98.4% and 96.7%, respectively. Very major discrepancy and major discrepancy rates for Enterobacterales and Staphylococci satisfied the NF EN ISO 20776-2 (2007) criteria for sepsis-relevant drugs. Very major discrepancies were >3% for amoxicillin-clavu-lanate (4.9%, 6/122), piperacillin-tazobactam (7.5%, 4/53) and meropenem (33%,1/3) for Enterobacterales and gentamicin for Staphylococci (4.6%, 4/87).Conclusion: Direct AST from PBC broths by VITEK (R) 2 for Enterobacterales and Staphylococci is reliable and fast and may positively influence antimicrobial stewardship.(c) 2023 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Automated summary

The study aimed to compare the performance of antimicrobial susceptibility testing (AST) using positive blood cultures (PBC) with VITEK(R) 2 off-label use (D0) and traditional VITEK(R) 2 workflow with isolated colonies after overnight incubation (D1). Overall, the categorical and essential agreement rates between D0 and D1 were 98.4% and 96.7%, respectively. The study showed that direct AST using VITEK(R) 2 from PBC is reliable and fast for Enterobacterales and Staphylococci.