On-Chip Raman Spectroscopy for Rapid Antimicrobial Susceptibility Testing from Blood Cultures.

Bloodstream infections are associated with considerable morbidity and mortality, necessitating timely and accurate antimicrobial susceptibility testing (AST) to guide appropriate therapy. Current diagnostic methods primarily rely on culture-based AST, which is time-consuming, or on genotypic approaches that lack phenotypic relevance. We present the RamanBioAssay (RBA) platform, a novel diagnostic tool integrating dielectrophoretic on-chip bacterial enrichment with label-free Raman spectroscopy, to enable rapid phenotypic AST and simultaneous bacterial identification (ID). The RBA platform delivers AST results within 3.5 h from a positive blood culture, substantially reducing the diagnostic turnaround time compared to standard culture-based techniques. The RBA platform demonstrated high concordance with conventional AST using quality control strains: 94.4% and 100% for E. coli treated with ciprofloxacin and S. aureus treated with oxacillin in medium controls, 91.7% and 97.2% in artificial blood cultures, respectively. For proof-of-concept evaluation, six patient blood cultures were analyzed, yielding concordance rates of 91.7% and 83.3% for E. coli treated with ciprofloxacin and S. aureus treated with oxacillin, respectively (1/6 samples showed a S/R mismatch, 1/6 samples was nonconclusive). The mean diagnostic turnaround time for clinical samples was 3 h and 6 min (±24 min). Additionally, the family level classification of E. coli and S. aureus, shown exemplary in medium controls, was achieved with 97.2% accuracy. These findings highlight the RBA platform as a promising tool for rapid phenotypic AST combined with bacterial ID, providing comprehensive and clinically actionable results significantly faster than conventional methods.