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

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 appro-priate 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.

Automated summary

Staphylococcus aureus is a versatile and virulent pathogen. A nanoparticle-based culture-free method using vancomycin modified magnetic nanoparticles and droplet digital PCR was developed to rapidly concentrate and detect S. aureus in blood within 3 hours, significantly shortening the detection time compared to traditional methods. The limit of detection was as low as 10 CFU/mL, improving the diagnostic rate of bacteremia. This new method could be a promising tool for early identification and treatment guidance of S. aureus bloodstream infections, thereby reducing mortality.