Direct antimicrobial susceptibility testing from the blood culture pellet obtained for MALDI-TOF identification of Enterobacterales and Pseudomonas aeruginosa

To standardize the methodology for conducting direct antimicrobial susceptibility testing (AST) of Enterobacterales and Pseudomonas aeruginosa causing bacteremia from positive blood culture pellets. Two methods for processing positive blood cultures with Enterobacterales and P. aeruginosa were compared: a conventional method for identification and AST versus a direct method obtaining a pellet for both matrix-assisted laser desorption/ionization–time of flight (MALDI-TOF) identification and direct AST. A total of 157 (145 Enterobacterales, 12 P. aeruginosa ) positive blood cultures were included. Microorganism identification showed 100% concordance between both methods at species and genus level. Definitive AST results were obtained 24 h earlier with the rapid method than the conventional one ( p