Antimicrobial Susceptibility Test by Surface-enhanced Raman Scattering of Bacterial Metabolites directly from Positive Blood Cultures

Effective management of sepsis requires timely administration of appropriate antibiotics; therefore, a reliable and rapid antimicrobial susceptibility test (AST) is crucial. To meet clinical needs, we developed a novel AST, referred to as SERS-AST, based on the surface-enhanced Raman Scattering (SERS) technology. In this study, we applied SERS-AST to eight most common pathogens causing bacteremia, including Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, E. faecium, Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, and Acinetobacter baumannii. Seven different antibiotics were tested, including oxacillin, levofloxacin, vancomycin, ampicillin, cefotaxime, ceftazidime, levofloxacin, and imipenem. SERS-AST determines antibiotic susceptibility of bacteria directly from positive blood cultures based on variations in bacterial SERS signals derived from secreted purines and their derivatives. The whole process could be completed within 4 hours, and the agreement rates between SERS-AST and VITEK 2 results were 96% for Gram-positive bacteria and 97% for Gram-negative bacteria.