Rapid antimicrobial susceptibility testing in bloodstream infections: current landscape and emerging technologies

Rapid bloodstream infection diagnosis is essential to enable timely targeted therapy, to reduce the risk of progression to sepsis, to limit unnecessary antimicrobial exposure, and to support effective antimicrobial stewardship. However, conventional culture-based workflows in routine practice often require 48-72 hours to deliver organism identification and antimicrobial susceptibility testing (AST) results. This review summarises rapid AST analytical technologies for bloodstream infections, including commercial systems and emerging phenotypic and molecular methods that aim to shorten time to actionable susceptibility information to less than 8 hours from a positive blood culture. Phenotypic platforms are to be preferred, and they are compared and reviewed according to their dominant analytical principle, while the role of genotypic assays for early identification and resistance inference is discussed as a complementary strategy. Across approaches, sample preparation, including bacterial enrichment and matrix removal, emerges as the dominant limitation, while speed and organism-antibiotic coverage shape clinical utility and implementation. Progress of rapid AST platforms toward routine adoption will require streamlined sample preparation, broader panels, and robust evidence of clinical benefit and cost-effectiveness.