Nanoparticles-based Culture-free method for rapid and sensitive detection of Staphylococcus aureus in bloodstream infections

Whole blood and blood culture containing hemolysin were added into the vacuum tube with separation glue for 10 min centrifugation. The bacteria, adsorbed by the separation gel, were then eluted, and further enriched by VMPs. Afterwards, the genomic DNAs of bacteria were released through lysis and analysis by ddPCR for S. aureus detection to identify BSIs. [Display omitted] •Vancomycin was anchored to the magnetic nanoparticles to form the VMPs.•VMPs and separation glue were introduced to enrich S. aureus in blood.•The method can detect S. aureus in the blood quickly with high sensitivity.•The method can guide treatment decisions in early stages of S. aureus bacteremia. Staphylococcus aureus (S. aureus) is a versatile and virulent pathogen and has become one of the leading causes of life-threatening bloodstream infections, such as sepsis and endocarditis. The morbidity and mortality of S. aureus bacteremia remain high in recent years. Rapid identification of S. aureus can lead to faster initiation of appropriate antibiotic treatment, thereby reducing treatment costs and mortality. Blood culture is the gold standard for diagnosing bacteremia, but it is time-consuming and poorly sensitive. Herein, vancomycin modified magnetic nanoparticles (VMPs) and separation glue were introduced to enrich S. aureus in blood in a direct and convenient manner, and then the bacteria were detected by droplet digital PCR (ddPCR). The nanoparticle-based culture-free method can concentrate and detect S. aureus from whole blood within 3 h, significantly shortening the detection time compared with the traditional culture method (3–5 days). The limit of detection of this approach for S. aureus was as low as 10 CFU/mL, which significantly improved the diagnostic rate in blood bacteremia. The developed VMPs-ddPCR strategy could be a promising tool for identifying S. aureus, guiding treatment decisions in the early stages of bloodstream infections, and predicting efficacy and thereby reducing mortality.