Rapid Bacterial Identification and Quantitative Antimicrobial Susceptibility Assessment from Positive Blood Cultures to Optimize Bloodstream Infection Management.

Bloodstream infection (BSI) is a serious clinical condition associated with high morbidity and mortality, requiring rapid identification of causative agents and timely antimicrobial susceptibility testing (AST). This study evaluated accelerated bacterial identification from positive blood culture samples using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) combined with two rapid processing approaches: a serum separation tube-based centrifugation method (SST method) and shortened cultivation on solid media. Rapid identification was followed by accelerated AST, performed either from a bacterial cell pellet (SST method) and from early-grown bacterial biomass (shortened cultivation protocol). The results were compared with those obtained using routine laboratory procedures. A total of 270 positive blood culture samples were analyzed, with 135 samples processed by each protocol. Both approaches achieved an identification success rate of 93.33%. Rapid AST using the SST method showed error rates of 0.51% minor errors, 0.57% major errors, and 0.23% very major errors, with an overall agreement of 98.69%. The shortened cultivation protocol demonstrated lower error rates (0.46% minor errors and 0.23% major errors) and an overall agreement of 99.31%. These findings confirm that MALDI-TOF MS enables reliable early identification of BSI pathogens and rapid AST, supporting timely optimization of antimicrobial therapy and early detection of multidrug-resistant strains.