Antibiotic-Based Magnetic Nanoprobes Combined with mPCR for Simultaneous Detection of Staphylococcus aureus and Bacillus cereus

Sensitive, simple, and rapid pathogen separation and detection methods are essential for the early diagnosis and immediate medical treatment of bacterial infections. In this study, a novel strategy based on vancomycin (Van)-modified ovalbumin (OVA) mediated magnetic nanoprobes (MBs-OVA-Van) combined with multiplex polymerase chain reaction (mPCR) was developed for efficient isolation and detection of Staphylococcus aureus ( S. aureus ) and Bacillus cereus ( B. cereus ). Van conjugated to ovalbumin coated magnetic microcarrier via strong covalent interaction. In addition, Van binds through hydrogen bonds with d -alanyl- d -alanine moieties on the surface of gram-positive bacteria cell wall. Under optimum conditions, the MBs-OVA-Van showed that the capture efficiency (CE) for S. aureus and B. cereus in PBS and juice samples were around 91%, 92% and 89%, 85%, respectively. In addition, with a mixture containing both target bacteria in PBS and juice samples, the CE for S. aureus and B. cereus were recorded at about 90%, 91% and 80%, 84%, respectively. The MBs-OVA-Van plus mPCR method applied in PBS and juice samples for both bacteria showed limits of detection at 10 2 CFU mL -1 in a < 3 h total assay time. The results indicated that the method holds promise for isolation and enrichment of gram-positive bacteria with S. aureus and B. cereus as models.